Prevalence and associated factors of mortality after percutaneous coronary intervention for adult patients with ST-elevation myocardial infarction: A systematic review and meta-analysis

Fanghong Yan; Yuanyuan Zhang; Yayan Pan; Sijun Li; Mengqi Yang; Yutan Wang; Chen Yanru; Wenli Su; Yuxia Ma; Lin Han

doi:10.4103/jrms.jrms_781_21

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J Res Med Sci 2023, 28:17

Prevalence and associated factors of mortality after percutaneous coronary intervention for adult patients with ST-elevation myocardial infarction: A systematic review and meta-analysis

Fanghong Yan¹, Yuanyuan Zhang², Yayan Pan³, Sijun Li⁴, Mengqi Yang³, Yutan Wang⁵, Chen Yanru³, Wenli Su³, Yuxia Ma³, Lin Han⁶
¹ Evidence-Based Nursing Center, School of Nursing; The First School of Clinical Medicine, Lanzhou University, Lanzhou, China
² Department of Respiratory Medicine, Henan Cancer Hospital, Affiliated Cancer Hospital of Zhengzhou University, Zhengzhou, China
³ Evidence-Based Nursing Center, School of Nursing, Lanzhou University, Lanzhou, China
⁴ Department of New Technology Development, SceneRay, Suzhou, 215000, China
⁵ Department of Hepatopancreatobiliary Surgery, The Second Affiliated Hospital Zhejiang University School of Medicine, Hangzhou, China
⁶ Evidence-Based Nursing Center, School of Nursing; The First School of Clinical Medicine, Lanzhou University, Lanzhou, China; Department of Nursing, Gansu Provincial Hospital, Lanzhou, Gansu Province, China

Date of Submission	06-Sep-2021
Date of Decision	13-Oct-2022
Date of Acceptance	17-Nov-2022
Date of Web Publication	16-Mar-2023

Correspondence Address:
Prof. Lin Han
Evidence-Based Nursing Center, School of Nursing, Lanzhou University, Lanzhou; The First Hospital of Lanzhou University, Lanzhou; Department of Nursing, Gansu Provincial Hospital, Lanzhou
China

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/jrms.jrms_781_21

Abstract

Background: There is a paucity of systematic reviews on the associated factors of mortality among ST-elevation myocardial infarction (STEMI) patients after percutaneous coronary intervention (PCI). This meta-analysis was designed to synthesize available evidence on the prevalence and associated factors of mortality after PCI for adult patients with STEMI. Materials and Methods: Databases including the Cochrane Library, PubMed, Web of Science, Embase, Ovid, Scopus, ProQuest, MEDLINE, and CINAHL Complete were searched systematically to identify relevant articles published from January 2008 to March 2020 on factors affecting mortality after PCI in STEMI patients. Meta-analysis was conducted using Stata 12.0 software package. Results: Our search yielded 91 cohort studies involving a total of 199, 339 participants. The pooled mortality rate for STEMI patients after PCI was 10%. After controlling for grouping criteria or follow-up time, the following 17 risk factors were significantly associated with mortality for STEMI patients after PCI: advanced age (odds ratio [OR] = 3.89), female (OR = 2.01), out-of-hospital cardiac arrest (OR = 5.55), cardiogenic shock (OR = 4.83), renal dysfunction (OR = 3.50), admission anemia (OR = 3.28), hyperuricemia (OR = 2.71), elevated blood glucose level (OR = 2.00), diabetes mellitus (OR = 1.8), chronic total occlusion (OR = 2.56), Q wave (OR = 2.18), without prodromal angina (OR = 2.12), delay in door-to-balloon time (OR = 1.72), delay in symptom onset-to-balloon time (OR = 1.43), anterior infarction (OR = 1.66), ST-segment resolution (OR = 1.40), and delay in symptom onset-to-door time (OR = 1.29). Conclusion: The pooled prevalence of mortality after PCI for STEMI patients was 10%, and 17 risk factors were significantly associated with mortality for STEMI patients after PCI.

Keywords: Meta-analysis, mortality, percutaneous coronary intervention, ST-elevation myocardial infarction

How to cite this article:
Yan F, Zhang Y, Pan Y, Li S, Yang M, Wang Y, Yanru C, Su W, Ma Y, Han L. Prevalence and associated factors of mortality after percutaneous coronary intervention for adult patients with ST-elevation myocardial infarction: A systematic review and meta-analysis. J Res Med Sci 2023;28:17

How to cite this URL:
Yan F, Zhang Y, Pan Y, Li S, Yang M, Wang Y, Yanru C, Su W, Ma Y, Han L. Prevalence and associated factors of mortality after percutaneous coronary intervention for adult patients with ST-elevation myocardial infarction: A systematic review and meta-analysis. J Res Med Sci [serial online] 2023 [cited 2023 Jun 2];28:17. Available from: https://www.jmsjournal.net/text.asp?2023/28/1/17/371845

#These authors contributed equally to this work.

Introduction

ST-elevation myocardial infarction (STEMI) is the most common type of myocardial infarction, accounting for 74.15% of all myocardial infarcts,^[1] and it is the leading cause of death in cardiovascular patients.^[2] Percutaneous coronary intervention (PCI) is recommended as the preferred treatment for patients with STEMI due to reduce reinfarction, mortality compared with fibrinolysis.^[3] However, STEMI patients still have to face a series of physiological and psychological problems after PCI, especially all-cause death events. Moreover, it is not clear whether this development will improve survival in patients with STEMI. Most national studies reported a consequent reduction in mortality in unselected STEMI patients compared with thrombolysis, which was insufficient to assess the extent of the improvement.^[4],[5],[6] There was a considerable difference in mortality (1.5% to 48.1%) in studies with 1-year follow-up after PCI.^[7],[8] Therefore, it is necessary to systematically synthesize the mortality rate for patients with STEMI following PCI.

Furthermore, the occurrence and development of mortality were the results of the additive effect of multiple factors. Studies have shown that there were many risk factors for mortality, including age,^[9] gender,^[10] blood glucose levels,^[11] and door-to-balloon time (DTB)^[12]. However, no systematic review has synthesized the evidence of screening-associated factors. Therefore, this study will systematically evaluate the mortality and risk factors of STEMI patients after PCI, to provide a theoretical basis for designing a cost-effective prevention program to control factors, and further improve the prognosis and reduce the mortality of adult STEMI patients after PCI.^[13],[14]

Methods

The manuscript has been prepared according to the meta-analysis of observational studies in epidemiology guidelines.^[15] Ethical approval was unnecessary in this study, because it was a meta-analysis of existing articles, and no individual patient data were handled. This review has been registered on PROSPERO (CRD 42017070969) and the protocol^[16] has been published, the authors declare that all method details are available within the article, and any additional information is available from the corresponding author on reasonable request.

In this study, we stratified participants based on factors that reported an association with mortality for STEMI patients after PCI, and then assessed mortality prevalence. Studies associated with a specific factor for which there are ≤2 studies will be excluded. Due to the inconsistency between the retrieved factors and the categories defined in the protocol,^[16] we did not categorize the included factors for presentation. Some risk factors, grouping criteria, and follow-up periods varied by study and were not standardized. Therefore, subgroup analyses were performed according to factors' grouping criteria and follow-up period when significant and practicable. If a study held two or more grouping criteria and follow-up period, which were included in each subgroup analysis. Moreover, due to the small weight in the pooled effect of Chinese literature, we did not retrieve the Chinese database according to the content in the protocol.

Results

According to the search strategy, the initial search retrieved 28,015 articles, of which 9554 were duplicates. After screening titles and abstracts, 333 articles were selected on the basis of inclusion criteria. The full-text of the remaining 333 studies were further evaluated in detail, of which 91 were considered eligible for this review, and more details are in [Figure 1].

Figure 1: Flowchart of study selection

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Ninety-one studies examined 23 risk factors for mortality after PCI for adult STEMI patients. Of them, 65 articles were prospective cohort studies, while 26 articles were retrospective cohort studies. The number of patients in the included studies ranged from 131^[17] to 17,021,^[18] other characteristics of included studies are summarized in [Table 1]. Quality assessment results are listed in [Table 2], of which 42 studies were evaluated to be at low risk of bias.

Table 1: Characteristics of included studies

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Table 2: The quality of included studies

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Prevalence of mortality

The prevalence of mortality ranged from 2% to 59% among 91 studies available for this analysis. The pooled mortality rate for STEMI patients after PCI was 10% (95% confidence interval [CI]: 9%–11%) with high heterogeneity (I² = 98.8%, P < 0.001) [Figure 2]. Funnel plot indicated no publication bias, and more details are in [Figure 3].

Figure 2: The pooled mortality rate for STEMI patients after PCI. STEMI = ST-elevation myocardial infarction; PCI = Percutaneous coronary intervention

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Figure 3: Funnel plot for assessing publication biases

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Mortality prevalence based on associated factors

Advanced age

Advanced age was a risk factor (odds ratio [OR] = 3.89, 95% CI: 3.47–4.37, I² = 78.60%, P < 0.001, Population Attributable Fraction (PAF) = 32.9%) we retrieved from 15 articles (N = 28, 360) in this study [Table 3]. The pooled mortality rate for STEMI patients after PCI at an advanced age was 17% (95% CI: 14%–21%) with high heterogeneity (I² = 97.50%, P < 0.001). In a subgroup of two studies (N = 4, 148) with advanced age definition at or above 45 and 30-day follow-up (OR = 2.42, 95% CI: 1.28–4.59, I² = 0.00%, P = 0.007, PAF = 6.6%), the pooled mortality rate was 5% (95%CI: 4%-5%) with low heterogeneity (I² = 11.80%, P = 0.287). For the subgroup of nine studies (N = 15, 339) with advanced age definition at or above 75 (OR = 4.90, 95% CI: 3.95–6.09, I² = 50.40%, P < 0.001, PAF = 41.2%), the pooled mortality rate was 18% (95% CI: 14%–22%) with high heterogeneity (I² = 89.70%, P < 0.001). The high heterogeneity could be explained by the variation of the follow-up period, the pooled mortality rate for six studies (N = 13, 168) with 30-day follow-up was 11% (95% CI: 9%–12%) with low heterogeneity (I² = 0.00%, P = 0.49), while the pooled mortality rate for four studies (N = 7, 006) with 1-year follow-up was 17% (95% CI: 15%–20%) with low heterogeneity (I² = 55.70%, P = 0.079). For the remaining three studies (N = 7, 831) with advanced age definition at or above 80 (OR = 4.36, 95%CI: 3.66–5.19, I² = 32.90%, P < 0.001, PAF = 51.8%), the pooled mortality rate was 32% (95% CI: 23%–40%) with high heterogeneity (I² = 84.50%, P = 0.002). The significant heterogeneity could also be explained by the variation of the follow-up period, the pooled mortality rate for two studies (N = 5, 829) with 30-day follow-up was 18% (95% CI, 12%–25%) with medium heterogeneity (I² = 72.60%, P = 0.056), while the pooled mortality rate for two studies (N = 5, 829) with 1-year follow-up was 27% (95% CI, 24%–31%) with low heterogeneity (I² = 0.00%, P = 0.5).

Table 3: Meta-analysis of the correlation between risk factors and mortality

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Female

Across 15 studies (N = 47, 782) in [Table 3] reported female was a risk factor (OR = 2.01, 95% CI: 1.87–2.16, I² = 46.30%, P < 0.001, PAF = 10.0%) of mortality for STEMI patients after PCI. The pooled mortality rate for female patients was 11% (95% CI: 8%–13%) with high heterogeneity (I² = 91.30%, P < 0.001). In a subgroup of 11 studies (N = 43, 236) with 30-day follow-up, the pooled mortality rate was 8% (95% CI: 6%–10%) with significant heterogeneity (I² = 92.90%, P < 0.001). For the subgroup of six studies (N = 23, 155) with 1-year follow-up, the pooled mortality rate was 13% (95% CI: 9%–17%) with high heterogeneity (I² = 91.60%, P < 0.001). This may be due to differences in the age range of the included study subjects or large differences in the sample size. For two studies (N = 1, 674) with 2-year follow-up, the pooled mortality rate was 9% (95% CI: 6%–12%) with low heterogeneity (I² = 0.00%, P = 0.529).

Obesity

The pooled analysis result from five studies (N = 6, 739) in [Table 3] showed that obesity (OR = 0.41, 95% CI: 0.16–1.04, I² = 82.80%, P = 0.061, PAF = 2.9%) did not reach statistical significance. The pooled mortality rate for obesity STEMI patients after PCI was 5% (95% CI: 3%–8%) with high heterogeneity (I² = 92.80%, P < 0.001).

Smoking

The pooled analysis result from two articles (N = 3, 515) in [Table 3] showed that smoking (OR = 0.90, 95% CI: 0.64–1.28, I² = 0.00%, P = 0.563, PAF = 0.3%) did not reach statistical significance. The pooled 30-day mortality rate for smoking STEMI patients after PCI was 3% (95% CI: 0%–7%) with high heterogeneity (I² = 93.90%, P < 0.001).

Out-of-hospital cardiac arrest

Across three studies (N = 15, 054) in [Table 3] reported out-of-hospital cardiac arrest (OHCA) was a risk factor (OR = 5.55, 95% CI: 2.58–11.94, I² = 87.10%, P < 0.001, PAF = 58.5%) of mortality for STEMI patients after PCI. The pooled mortality rate after PCI for STEMI patients with OHCA was 31% (95% CI: 21%–41%) with medium heterogeneity (I² = 74.90%, P = 0.019). In a subgroup of two studies (N = 14, 287) with 30-day follow-up, the pooled mortality rate was 25% (95% CI: 1%–49%) with significant heterogeneity (I² = 95.60%, P < 0.001). For the subgroup of two studies (N = 2, 417) with 1-year follow-up, the pooled mortality rate was 27% (95% CI: 12%–42%) with insignificant heterogeneity (I² = 72.20%, P = 0.058).

Elevated hemoglobin A1c level

Across two studies (N = 1, 239) in [Table 3] reported elevated hemoglobin A1c (Hb1Ac) level (≥6.5 mmol/L) was a risk factor (OR = 4.53, 95% CI: 0.52–39.46, I² = 95.20%, P = 0.171, PAF = 43.7%) of mortality for STEMI patients after PCI. The pooled mortality rate after PCI for STEMI patients with elevated Hb1Ac levels was 22% (95% CI: 6%–50%) with high heterogeneity (I² = 97.90%, P < 0.001).

Cardiogenic shock

Across two studies (N = 8, 386) in [Table 3] reported cardiogenic shock (CS) was a risk factor (OR = 4.83, 95% CI: 3.71–6.29, I² = 92.5%, P < 0.001, PAF = 56.6%) of mortality for STEMI patients after PCI. The pooled mortality rate after PCI for STEMI patients with CS was 34% (95% CI: 13%–81%) with high heterogeneity (I² = 99.00%, P < 0.001).

Renal dysfunction

Across four studies (N = 4, 935) in [Table 3] reported renal dysfunction (RD) was a risk factor (OR = 3.50, 95% CI: 1.56–7.84, I² = 89.90%, P = 0.002, PAF = 32.2%) of mortality for STEMI patients after PCI. The pooled mortality rate after PCI for STEMI patients with RD was 19% (95% CI: 5%–33%) with high heterogeneity (I² = 97.70%, P < 0.001). In a subgroup of two studies (N = 1, 744) with estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m², the pooled mortality rate was 26% (95% CI: 22%–30%) with low heterogeneity (I² = 33.00%, P = 0.222). For the subgroup of two studies (N = 3, 191) with RD definition of serum creatinine level ≥ 115 μmol/L, the pooled mortality rate was 9% (95% CI: 2%–20%) with high heterogeneity (I² = 87.10%, P = 0.005).

Admission anemia

Across three studies (N = 3, 680) in [Table 3] reported admission anemia was a risk factor (OR = 3.28, 95% CI: 2.57–4.18, I² = 0.00%, P < 0.001, PAF = 36.3%) of mortality for STEMI patients after PCI. The pooled mortality rate after PCI for STEMI patients with admission anemia was 25% (95% CI: 13%–28%) with high heterogeneity (I² = 90.50%, P < 0.001).

Hyperuricemia

Across two studies (N = 1, 045) in [Table 3] reported hyperuricemia was a risk factor (OR = 2.71, 95% CI: 1.67–4.39, I² = 44.90%, P < 0.001, PAF = 17.0%) of mortality for STEMI patients after PCI. The pooled mortality rate for hyperuricemia STEMI patients after PCI was 12% (95% CI: 8%–15%) with high heterogeneity (I² = 0.00%, P = 0.473).

Elevated blood glucose level

Across three studies (N = 2, 112) in [Table 3] reported elevated blood glucose level (≥7.8 mmol/L) was a risk factor (OR = 2.56, 95% CI: 1.98–3.04, I² = 0.00%, P < 0.001, PAF = 39.6%) of mortality for STEMI patients after PCI. The pooled mortality rate for exposure group patients was 42% (95% CI 11%–74%) with high heterogeneity (I² = 98.80%, P < 0.001). In a subgroup of two studies (N = 1, 854) with 30-day follow-up, the pooled mortality rate was 26% (95% CI: 4%–56%) with significant heterogeneity (I² = 98.20%, P < 0.001). For the subgroup of two studies (N = 466) with 1-year follow-up, the pooled mortality rate was 48% (95% CI: 43%–54%) with insignificant heterogeneity (I² = 38.70%, P = 0.202).

Diabetes mellitus

Across four studies (N = 6, 222) in [Table 3] reported diabetes mellitus (DM) was a risk factor (OR = 2.00, 95% CI: 1.62–2.46, I² = 0.00%, P < 0.001, PAF = 10.7%) of mortality for STEMI patients after PCI. The pooled mortality rate after PCI for STEMI patients with DM was 12% (95% CI: 6%–18%) with high heterogeneity (I² = 89.80%, P < 0.001). In a subgroup of four studies (N = 6, 222) with 30-day follow-up, the pooled mortality rate was 9% (95% CI: 3%–14%) with significant heterogeneity (I² = 88.40%, P < 0.001). For the subgroup of two studies (N = 5, 245) with 3-year follow-up, the pooled mortality rate was 15% (95% CI: 7%–22%) with significant heterogeneity (I² = 85.10%, P = 0.01).

Elevated heart rate

Across two studies (N = 4, 689) in [Table 3] reported elevated heart rate was a risk factor of mortality for STEMI patients after PCI. However, a meta-analysis could not be conducted due to differences in grouping criteria. One study was based on previous studies in populations with various cardiovascular diseases including postprimary PCI,^[19] while the other did not mention the basis for the classification.

Elevated ratio of neutrophils to lymphocytes

Across four studies (N = 4, 045) in [Table 3] reported elevated neutrophils to lymphocytes (NLR) was a risk factor of mortality for STEMI patients after PCI. NLR was calculated as the ratio of NLR. However, the grouping criteria of the four studies were different, and the basis of grouping was not clearly mentioned. Therefore, we compare with grouping criteria of NLR according to mortality for STEMI patients after PCI [Figure 4].

Figure 4: Comparison of grouping criteria of NLR according to mortality. NLR = neutrophils to lymphocytes

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Chronic total occlusion

Across two studies (N = 1, 043) in [Table 3] reported chronic total occlusion (CTO) was a risk factor (OR = 3.03, 95% CI: 2.08–4.41, I² = 2.80%, P < 0.001, PAF = 28.9%) of mortality for STEMI patients after PCI. The pooled mortality rate after PCI for STEMI patients with CTO was 20% (95% CI: 11%–30%) with high heterogeneity (I² = 81.00%, P = 0.022).

Q wave on presentation

Across three studies (N = 7, 922) in [Table 3] reported Q wave on presentation was a risk factor (OR = 2.18, 95% CI: 1.74–2.73, I² = 17.30%, P < 0.001, PAF = 7.6%) of mortality for STEMI patients after PCI. The pooled mortality rate after PCI for STEMI patients with Q wave on presentation was 7% (95% CI: 5%–9%) with medium heterogeneity (I² = 73.90%, P = 0.022). In a subgroup of two studies (N = 7, 253) with 30-day follow-up, the pooled mortality rate was 4% (95% CI: 2%–5%) with significant heterogeneity (I² = 83.30%, P = 0.014). For the subgroup of two studies (N = 3, 392) with 1-year follow-up, the pooled mortality rate was 6% (95% CI: 3%–9%) with medium heterogeneity (I² = 74.50%, P = 0.048). This may be the reason for the large heterogeneity caused by the large difference in sample size.

Without prodromal angina

Across two studies (N = 6, 491) in [Table 3] reported without prodromal angina (PA) was a risk factor (OR = 2.12, 95% CI: 1.58–2.85, I² = 51.90%, P < 0.001, PAF = 16.0%) of mortality for STEMI patients after PCI. The pooled mortality rate after PCI for STEMI patients without PA was 17% (95% CI: 13%–22%) with high heterogeneity (I² = 95.10%, P < 0.001).

Delay in door-to-balloon time

Delay in DTB time was a risk factor (OR = 1.72, 95% CI: 1.47–2.01, I² = 5.30%, P < 0.001, PAF = 4.8%) we retrieved from six articles (N = 17, 501) in this study [Table 3]. The pooled mortality rate for STEMI patients after PCI at the delay in DTB time was 7% (95% CI: 5%–9%) with high heterogeneity (I² = 91.70%, P < 0.001). In a subgroup of two studies (N = 5, 802) with a delay in DTB time definition at or above 45 min (OR = 1.42, 95% CI: 0.66–3.02, I² = 58.40%, P = 0.367, PAF = 2.5%), the pooled mortality rate was 6% (95% CI: 3%–10%) with high heterogeneity (I² = 89.40%, P = 0.002). For the subgroup of five studies (N = 12, 781) with delay in DTB time definition at or above 60 min (OR = 1.72, 95% CI: 1.45–2.03, I² = 17.70%, P < 0.001, PAF = 5.4%), the pooled mortality rate was 8% (95% CI: 5%–12%) with high heterogeneity (I² = 94.00%, P < 0.001). The high heterogeneity could be explained by the variation of follow-up period, the pooled mortality rate for four studies (N = 7, 538) with 30-day follow-up was 7% (95% CI: 4%–10%) with significant heterogeneity (I² = 87.20%, P < 0.001), while the pooled mortality rate for two studies (N = 6, 132) with 1-year follow-up was 9% (95% CI: 8%–10%) with low heterogeneity (I² = 0.00%, P = 0.786). For the remaining three studies (N = 16, 080) with delay in DTB time definition at or above 90 min (OR = 1.92, 95% CI: 1.20–3.09, I² = 89.40%, P = 0.007, PAF = 7.6%), the pooled mortality rate was 9% (95% CI: 5%–12%) with high heterogeneity (I² = 95.40%, P < 0.001).

Delay in symptom onset-to-balloon time

Across four studies (N = 11, 353) in [Table 3] reported delay in symptom onset-to-balloon time (STB) time was a risk factor (OR = 1.43, 95% CI: 1.18–1.72, I² = 0.00%, P < 0.001, PAF = 2.1%) of mortality for STEMI patients after PCI. The pooled mortality rate for STEMI patients after PCI at the delay in STB time was 5% (95% CI: 4%–6%) with low heterogeneity (I² = 63.20%, P = 0.043). In a subgroup of three studies (N = 10, 834) with delay in STB time definition at or above 3 h (OR = 1.43, 95% CI: 1.17–1.76, I² = 0.00%, P = 0.001, PAF = 2.1%), the pooled mortality rate was 5% (95% CI, 4%–5%) with low heterogeneity (I² = 0.00%, P = 0.531). Different studies involved the variation of the follow-up period, the pooled mortality rate for three studies (N = 10, 834) with 30-day follow-up was 4% (95% CI, 3%–5%) with low heterogeneity (I² = 29.70%, P = 0.241), while the pooled mortality rate for two studies (N = 10, 275) with 90-day follow-up was 5% (95% CI, 4%–5%) with low heterogeneity (I² = 0.00%, P = 0.485). For the subgroup of two studies (N = 1, 452) with delay in STB time definition at or above 4 h (OR = 1.55, 95% CI: 1.00–2.39, I² = 0.00%, P = 0.048, PAF = 3.7%), the pooled mortality rate was 7% (95% CI, 4%–11%) with low heterogeneity (I² = 61.40%, P = 0.108).

Anterior infarction

Across three studies (N = 7, 292) in [Table 3] reported anterior infarction was a risk factor (OR = 1.66, 95% CI: 1.46–1.90, I² = 0.00%, P < 0.001, PAF = 18.3%) of mortality for STEMI patients after PCI. The pooled mortality rate for anterior infarction STEMI patients after PCI was 34% (95% CI: 0%–74%) with high heterogeneity (I² = 99.80%, P < 0.001). In the group of three studies (N = 7, 292) with 30-day follow-up, the pooled mortality rate was 30% (95% CI: 0%–65%) with significant heterogeneity (I² = 99.70%, P < 0.001). For the subgroup of two studies (N = 7, 080) with 1-year follow-up, the pooled mortality rate was 35% (95% CI: 0%–86%) with significant heterogeneity (I² = 99.90%, P < 0.001). This may be the reason for the large heterogeneity caused by the large difference in sample size.

ST-segment resolution

Across four studies (N = 4, 958) in [Table 3] reported ST-segment resolution (STR) (≤70%) was a risk factor (OR = 1.40, 95% CI: 1.12–1.75, I² = 43.10%, P = 0.003, PAF = 3.5%) of mortality for STEMI patients after PCI. The pooled mortality rate for exposure group patients was 9% (95% CI: 6%–12%) with high heterogeneity (I² = 80.80%, P = 0.001). In a subgroup of two studies (N = 3, 835) with 3-year follow-up, the pooled mortality rate was 7% (95% CI, 6%–8%) with low heterogeneity (I² = 46.10%, P = 0.173). For the subgroup of two studies (N = 2, 251) with 5-year follow-up, the pooled mortality rate was 10% (95% CI, 5%–14%) with high heterogeneity (I² = 85.70%, P = 0.008). Other confounding factors may affect heterogeneity due to the long follow-up time.

Delay in symptom onset-to-door time

Across two studies (N = 10, 335) in [Table 3] reported delay in symptom onset-to-door time (STD) time longer than 2 h was a risk factor (OR = 1.29, 95% CI: 1.10–1.51, I² = 0.00%, P = 0.002, PAF = 2.0%) of mortality for STEMI patients after PCI. The pooled mortality rate for exposure group patients was 7% (95% CI: 5%–9%) with high heterogeneity (I² = 88.90%, P = 0.003).

Off-hour operation

Across four studies (N = 11, 618) in [Table 3] reported off-hour operation was a risk factor (OR = 1.11, 95% CI: 1.00–1.24, I² = 0.00%, P = 0.053, PAF = 1.2%) of mortality for STEMI patients after PCI. The pooled mortality rate for exposure group patients was 11% (95%CI: 4%–18%) with high heterogeneity (I² = 98.80%, P < 0.001). In a subgroup of two studies (N = 4, 090) with 1-year follow-up, the pooled mortality rate was 7% (95% CI: 2%–11%) with high heterogeneity (I² = 93.80%, P < 0.001). For the subgroup of two studies (N = 8, 374) with 3-year follow-up, the pooled mortality rate was 14% (95% CI: 1%–29%) with high heterogeneity (I² = 99.50%, P < 0.001).

Discussion

Being 45 or older and female increased the risk of mortality after percutaneous coronary intervention for ST-elevation myocardial infarction patients

Our study reported that mortality prevalence increased with age criteria and follow-up criteria for grouping. STEMI patients at or above 80 years old after PCI held the highest mortality rate at 32%. This may have something to do with the elderly, who have multiple chronic comorbidities, and their basic cardiac functions were worse.^[20] Moreover, when the follow-up period was taken into account, the 1-year mortality rate was higher than the 30-day mortality rate, and the 1-year mortality rate for STEMI patients after PCI at or above 80 was the highest at 27%, similar to previous findings.^[21],[22] However, it was slightly lower than Christiansen's study result,^[23] which showed that the 1-year mortality rate for American STEMI patients after PCI at or above 80 was 25.6%. This may be related to the deterioration of body functions with complications, leading to slow postoperative recovery and the increased risk of noncardiac death in elderly STEMI patients after PCI with the extension of follow-up time. Therefore, it is indicated that patients aged at or over 45 years are already at risk, and risk assessment before PCI treatment, targeted preoperative preparation, and regular follow-up for at least 1 year after surgery should be carried out actively to prevent adverse events, especially for STEMI patients at or over 80 years old.

The results of the meta-analysis showed that female was a risk factor for STEMI patients after PCI, and the mortality in female patients within 1 year after PCI was higher than that in more than 1 year, which was consistent with Stone's study results.^[24] The symptoms of female STEMI patients are often atypical, it is likely to miss the best time for treatment due to ignorance, which leads to the relatively severe condition compared with men patients and prolonged recover time after PCI.^{[25],[26],[27]} Therefore, it is suggested that health education and transitional care for female patients after PCI should be strengthen, especially how to identify dangerous signs timely and carry forward follow-up examinations regularly.

Complicated with out-of-hospital cardiac arrest, cardiogenic shock, renal dysfunction, admission anemia, hyperuricemia, blood glucose level ≥7.8 mmol/L, and diabetes mellitus increased the risk of mortality after percutaneous coronary intervention for ST-elevation myocardial infarction patients

This study evidenced the greatest risk of mortality after PCI for STEMI patients complicated with OHCA (OR = 5.55). As one of the most dangerous complications, OHCA can seriously affect the prognosis of patients significantly.^[28],[29] Previous studies have reported that poor nervous system recovery associated with the prolonged recovery time of spontaneous circulation and myocardial dysfunction associated with ischemic load influenced the short-term prognosis of patients,^[30],[31] which may also explain why the association between OHCA and mortality is higher at 30 days than at 1 year. Therefore, it is suggested that patients can achieve more significant benefits from effective medical treatment aimed to shorten the aid and transport time and restore spontaneous circulation as soon as possible.

The results of the meta-analysis showed that CS was significantly associated with mortality after PCI in this study, but pooled mortality in the CS group was much higher (25%) than unexposure group. The fundamental reason may be the difference in clinical manifestation between the two groups. Compared with patients without CS, the angiographic performance of CS patients is more serious, for example, they are often diagnosed with multivessel coronary disease, and the percentage of left anterior descending artery disease is much higher (50%–79%).^[32],[33] In addition, baseline TIMI 0-1 blood flow is more likely to occur (62%) in infarct-related arteries.^[33] Patients with CS are prone to no reflow, and their infarct-related arteries are more likely to be completely blocked for a longer time, resulting in microvascular dysfunction very quickly.^[34],[35] This finding indicates that early rescue and effective treatment regimens are crucial for STEMI patients complicated with CS to improve the survival rate.

As an important factor reflecting vascular physiological abnormalities, renal function affect the occurrence of cardiovascular adverse events significantly.^[28],[29] In the sense that it is important to establish criteria for RD. This study evidenced the significant risk of mortality after PCI for STEMI patients complicated with renal dysfunction (OR = 5.32) when eGFR was used as the indicator and calculated with the modification of diet in the renal disease equation. More specially, angiography is required during PCI, and the contrast agent itself may cause damage to renal function.^[36] Therefore, this finding evidenced the risk of RD and emphasizes the preventative role that continuous monitoring of renal function, prudent use of nephrotoxic drugs, and practical guidance on the excretion of contrast agents may have in terms of mortality after PCI.

Admission anemia was significantly associated with mortality after PCI for STEMI patients in this study. The chronic state of admission anemia may cause hemodynamic adaptation, which has a significant impact on microvascular remodeling and atherosclerosis. Previous studies^[37],[38] have showed that anemia of chronic disease can lead to decreased blood viscosity accompanied by decreased afterload, and eventually result in failure and death. Although the significant heterogeneity may have been due to differences in follow-up time, which varied from 1 year to 6 years across included three studies, mortality increased along with prolonged follow-up time in three included studies. This finding has established that the active prevention and correction of anemia in STEMI patients before PCI can reduce the risk of death and improve long-term outcomes.

Hyperuricemia was significantly associated with mortality after PCI for STEMI patients in this study. However, included studies in this meta-analysis indicated that mortality decreased with prolonged follow-up time from 11.7% at 1 year to 7% at 7.3 years.^[39],[40] Such findings suggest that patients with hyperuricemia should strongly be considering for active control of uric acid levels before PCI and regular detection of uric acid levels after PCI. Meanwhile, dietary guidance is necessary for patients and their co-residents, so as to effectively control purine intake.

DM and blood glucose levels ≥7.8 mmol/L (hyperglycemia) were significantly associated with mortality after PCI for STEMI patients in this study, and blood glucose level ≥7.8 mmol/L (OR = 2.56) demonstrated a greater risk than DM (OR = 2.00). More specially, DM and blood glucose levels are highly correlated. DM patients are in a state of hyperglycemia for a long time, previous studies^[41],[42] have shown that hyperglycemia can increase the tendency for blood clots to form and cytokines to release, thus lead to endothelial dysfunction and oxidative stress, and eventually aggravate myocardial injury. Moreover, results showed that 1-year mortality in STEMI patients after PCI with hyperglycemia was highest (48%), mortality increased along with prolonged follow-up time in both the exposure group and unexposure group for patients with DM or hyperglycemia, while OR decreased along with prolonged follow-up time. There are two aspects of this finding that need to deserve some explanation. On the one hand, this finding indicated the actual effect that would be expected to be prevented following the elimination of exposure to DM or hyperglycemia, which was consistent with trends in PAF. On the other hand, studies^[43] have shown that a large proportion of STEMI patients experience glucose intolerance during acute events, but over time, the symptoms of glucose intolerance in some patients will be alleviated, which may be the reason why the association became progressively weaker with prolonged follow-up time. Therefore, it is important to keep the preoperative blood glucose under control to improve the prognosis of patients, regardless of whether or not they have diabetes.

The manifestation and feature of chronic total occlusion, Q wave on presentation, without prodromal angina, delay in door-to-balloon time, delay in symptom onset-to-balloon time, anterior infarction, ST-segment resolution ≤70%, and delay in symptom onset-to-door time increased the risk of mortality after percutaneous coronary intervention for ST-elevation myocardial infarction patients

CTO, as the most challenging form of PCI, has received more and more clinical attention. Previous reports^[44],[45] of non-IRA CTO, in particular, have been demonstrated higher short-term and long-term mortality, which was consistent with this study. This relationship is known to be robust^[46] and constitutes the basis for guideline recommendations promoting CTO-PCI with aggressive attempts involving dissection techniques and retrograde collateral channel crossing.^[47] In this study, only two studies with 1-year follow-up were synthesized, and the pooled risk was lower compared with a previous meta-analysis,^[48] which reported a pooled OR of 3.76 at 30 days and 2.9 at a median follow-up of 25.2 months. The inconsistency regarding the trends of the relationship between the occurrence of non-IRA CTO and mortality after PCI for STEMI patients, at least in part, from the exclusion of patients with prior PCI and prior MI in this study.

In this study, STR and Q wave on presentation were significant electrocardiography manifestations associated with mortality after PCI for STEMI patients. Prior studies^[46],[49] have shown that ST-segment monitoring after PCI is a widely available, well-validated, noninvasive tool to reflect effective perfusion of myocardial tissue and microvascular integrity. However, research on the relationship between the extent of STR and clinical outcomes, particularly long-term outcomes, have been inconsistent.^{[46],[49],[50]} The uncertainty stems at least in part from the different methods they used for quantifying and categorizing STR. Included studies with the same grouping criteria for STR extent, this study evidenced the robust relationship between STR and long-term mortality for STEMI patients. In addition, subgroup meta-analysis results showed a stronger association between STR and 5-year mortality than 3-year mortality. However, moderate heterogeneity, possible concurrency problems from the differences in the measured time of STR in the original literature, indicates the results may not reliable and future research may benefit from expanding the samples' quantity and defining the measured time of STR so as to more robustly test the association. Q wave on presentation, as a physiological indicator of the development stage of infarction, indicates a broader myocardial invasion. Studies^[51] have demonstrated that patients with Q wave on presentation were much less likely to reach the appropriate STR immediately after PCI when compared with patients without Q wave, resulting in higher mortality. Moreover, the subgroup meta-analysis results showed that the correlation between Q wave on presentation and mortality was higher at 30 days than 1 year, suggesting that Q wave may have a significant influence on the short-term prognosis. At last, based on the points discussed above, the combined application of Q wave to predict short-term mortality and STR to predict long-term mortality can be strongly practical with the evidence of definite measure time and method.

The symptom of PA was significantly associated with mortality after PCI for STEMI patients in this study. The analyzed data indicated that the prevalence of mortality was lower among patients with symptoms of PA (9%) than among those without (17%). The difference may result from enhanced myocardial endurance by ischemic preconditioning, the establishment of collateral circulation, and accelerated coagulation lysis by thrombolytic substances accompanying angina before infarction.^[52] Murry^[53] reported that the transient, nonfatal myocardial ischemic attack made the heart preconditioned and greatly reduced the infarction area, and proposed the concept of “preconditioned effect.” Therefore, PA does not only mean the occurrence of the disease but may have a positive effect on the prognosis. It is a well-worth effort to introduce the warning role of PA as the end result will be much more timely and effective treatment.

The current analysis documented several interval metrics, delay in the STD, DTB, and STB time, constituted risk factors for mortality after PCI for STEMI patients. Previous studies^{[54],[55],[56]} have demonstrated that delay in the STD time, DTB time, and STB time was significantly associated with mortality, and the correlates constitute the basis for guideline recommendations shortening of DTB time to within 90 min.^[57] The subgroup analysis of DTB time also indicated the strongest protective effect of mortality when STEMI patients were treated with PCI within 90 min upon arrival at the hospital. However, it is estimated that nearly 90% of patients have a DTB duration of 90 min^[58] currently. The delay may result from the deficiency of associated knowledge, inconvenience of hospital visits, and inadequate emergency system. Studies have shown that the time of STD has remained relatively stable in recent years. In this study, the protective effect of STD time with grouping criteria of 2 h was the lowest, compared with DTB time or STB time with any grouping criteria. STB time, the sum of STD time and DTB time, was a valid measure of the efficiency of a health-care system, and the protective effect of STB time with grouping criteria of 3 h was lower than that with grouping criteria of 4 h.

The meta-analysis results showed that the prevalence of mortality was higher among patients with anterior infarction (34%) than among those with nonanterior infarction (27%). It was demonstrated that the anterior wall was the place where the heart contracts most powerfully, and patients with anterior infarction were at greater risk of infarction area dilatation, and the more vessels involved, the more likely it was to cause CS, leading to poor prognosis.^[32],[59] Consistent with these results, this study has well established that anterior infarction was significantly associated with mortality after PCI for STEMI patients (OR = 1.66). Moreover, the subgroup meta-analysis results showed that the correlation between anterior infarction and mortality was higher at 30 days than at 1 year, suggesting that anterior infarction may have a significant influence on the short-term prognosis. Studies^[60] have proved that an electrocardiogram was of great value in the diagnosis of acute myocardial infarction, and clinicians need to carefully analyze the characteristics of electrocardiogram, so as to predict the infarct-related arteries of acute myocardial infarction well. In addition, the combination of coronary angiography results can better select vessels requiring emergency intervention, provide more accurate information for early treatment and prognosis assessment, and strengthen specialized medical care to improve the long-term prognosis of patients.

Strengths and limitations

A fundamental strength of the current analysis is the adoption of robust methodology. Nine electronic databases were searched systematically to identify relevant articles. This extensive effort, undertaken by two reviewers, enhanced the ability to accurately catalog the entire information on associated factors of mortality among STEMI patients after PCI and allowed stratifying the studies based on the degree of controlling for grouping criteria or follow-up time. However, the potential limitations of this study should be noted. First, the differences in the measurement of exposure factors and the definition of outcome indicators among different studies may become one of the sources of heterogeneity. Second, the review gathered 91 cohorts, but each analysis was based on 2 to 15 studies. Although a small number of studies were included in each index, the sample size was large and did not affect the outcome of the research results. Third, further analysis of some risk factors as described in the protocol, such as sensitive analysis and meta-regression, was not conducted to explore sources of heterogeneity due to the small number of studies on individual risk factors. Fourth, some eligible studies published in other languages were excluded due to the language filter, which limited the comprehensiveness of this study. In view of the limitations of this study, more high-quality studies are needed to verify the above conclusions.

Conclusions

To sum up, this systematic review found that the pooled mortality rate after PCI for STEMI patients was 10%. Such a high prevalence indicates the urgent need for controlling associated factors: Advanced age, female, OHCA, CS, RD, admission anemia, hyperuricemia, blood glucose level ≥7.8 mmol/L and DM, CTO, Q wave on presentation, without PA, delay in DTB time, delay in STB time, anterior infarction, STR ≤70%, and delay in STD time.

Among the factors above, modifiable factors include blood glucose level, RD, hyperuricemia, DM, STD time, DTB time, and STB time, which lead to the interventions for reasonable lifestyle, good medication compliance, and correct first aid knowledge to improve the outcome for STEMI patients after PCI. This research can provide a theoretical basis for the prevention of mortality after PCI for STEMI patients.^[135]

Financial support and sponsorship

National Nature Science Foundation of China (71704071, 72274087)
The National Social Science Fund of China (20CGL053)
China Medical Board (Gant #20-374)
Nature Science Foundation of Gansu Province (20JR10RA603)
The Fundamental Research Funds for the Central Universities (lzujbky-2020-10, lzujbky-2021-33)
2020 Research project of School of Nursing, Lanzhou University (LZUSON202008)
2022 Undergraduate Education and Teaching Development Project of the School of Nursing, Lanzhou University.

Conflicts of interest

There are no conflicts of interest.

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