QRS Complex Fragmentation as a Marker of In-Hospital Mortality and Adverse Long-Term Prognosis in Patients with ST-Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention: A Systematic Review and Meta-Analysis

Background. QRS complex fragmentation (fQRS) is regarded as an electrocardiographic marker of inhomogeneous intraventricular conduction that may reflect ischemic injury, scar formation, and myocardial electrical instability. In patients with ST-elevation myocardial infarction (STEMI) undergoing percutaneous coronary intervention (PCI), the presence of fQRS may be associated with an increased risk of early and long-term adverse cardiovascular outcomes.
Objective: To evaluate the prognostic value of fQRS in patients with STEMI who underwent PCI with respect to in-hospital mortality and major adverse cardiovascular events during long-term follow-up.
Materials and methods. A systematic search was conducted in the PubMed and Cochrane Library databases covering the period from January 1, 2010, to May 1, 2026. Prospective and retrospective observational studies of STEMI patients who underwent primary PCI were included if they reported data on in-hospital mortality and/or long-term adverse cardiovascular outcomes stratified by fQRS status. The quality of included studies was assessed using the Newcastle–Ottawa Scale. Quantitative synthesis was performed using a random-effects model to calculate the pooled odds ratio (OR) for in-hospital mortality and risk ratio (RR) for long-term outcomes. Heterogeneity was assessed using the I² statistic; the robustness of the findings was assessed by sequential leave-one-out sensitivity analysis.
Results. Nine studies comprising a total of 3,834 patients were included in the analysis. The presence of QRS complex fragmentation on ECG was associated with an increased risk of in-hospital mortality (OR 3.15; 95% CI: 1.70–5.84; p = 0.0003; I² = 65%) and adverse long-term cardiovascular outcomes (RR 3.43; 95% CI: 1.78–6.61; p = 0.0002; I² = 61%) in STEMI patients after primary PCI. Following exclusion of two outlier studies, heterogeneity for the in-hospital mortality outcome decreased (I² = 27%) while the statistical significance of the effect was maintained.
Conclusion. The results of this meta-analysis indicate an association between QRS complex fragmentation and an increased risk of in-hospital mortality and adverse long-term cardiovascular outcomes in STEMI patients who underwent primary PCI. However, the heterogeneity of results and the predominantly observational nature of the included studies necessitate cautious interpretation of the findings. Further prospective studies are warranted to clarify the prognostic value of fQRS.

For citation: Ilchenko RS, Zakirzyanov AYu, Kokorin VA, Lebedeva AYu, Gordeev IG. QRS complex fragmentation as a marker of in-hospital mortality and adverse long-term prognosis in patients with ST-elevation myocardial infarction undergoing primary percutaneous coronary intervention: A systematic review and meta-analysis. Therapy (Moscow). 2026;12(5S):86–93.
https://doi.org/10.18565/ therapy.2026.5-s5.86-93

INTRODUCTION

ST-elevation myocardial infarction (STEMI) remains one of the most severe manifestations of acute coronary syndrome and carries a high risk of early and long-term cardiovascular death and heart failure [1]. Current STEMI management focuses on prompt restoration of coronary blood flow, most commonly by primary percutaneous coronary intervention (PCI), to limit ischemic myocardial injury and improve clinical outcomes [1, 2]. Nevertheless, some patients remain at high risk of adverse outcomes despite successful reperfusion, underscoring the need for simple, readily available, and reproducible markers to refine risk stratification.

A standard 12-lead electrocardiogram (ECG) remains central to the diagnosis and serial assessment of STEMI. Beyond ST-segment elevation, pathological Q waves, and rhythm or conduction disturbances, QRS morphology may provide additional prognostic information. One such feature is fragmented QRS (fQRS), a proposed electrocardiographic marker of heterogeneous intraventricular conduction in coronary artery disease [3]. Das M.K. et al. defined fQRS as an additional R wave (R′), notching at the nadir of the S wave, or more than one R′ in at least two contiguous leads corresponding to a major coronary artery territory, with a QRS duration <120 ms [4]. In acute myocardial infarction, fQRS may be associated with more extensive myocardial injury, impaired microvascular perfusion, larger infarct size, and subsequent left ventricular remodeling [5, 6]. These associations suggest that fQRS may serve as a marker of poor prognosis after primary PCI.

Previous studies and meta-analyses of mixed STEMI and non-ST-elevation myocardial infarction (NSTEMI) populations have associated fQRS with higher risks of in-hospital and long-term mortality, major adverse cardiovascular events, ventricular arrhythmias, reduced left ventricular ejection fraction, and heart failure [7–9]. However, its clinical significance specifically in patients with STEMI treated with primary PCI remains uncertain. The available studies differ in patient populations, timing of ECG recording, endpoint definitions, and adjustment for risk factors. These differences limit comparisons across studies and support the need for quantitative synthesis. This meta-analysis therefore evaluated the prognostic value of fQRS for mortality and major adverse cardiovascular events in patients with STEMI treated with primary PCI.

MATERIALS AND METHODS

Study design

This systematic review and meta-analysis evaluated the prognostic value of fragmented QRS (fQRS) in patients with STEMI treated with primary PCI. Reporting followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Literature search

PubMed and the Cochrane Library were searched using the terms “QRS fragmentation”, “STEMI”, and “PCI”. The search covered publications from January 1, 2010, through May 1, 2026, and yielded 70 records from PubMed and 11 from the Cochrane Library. Ten records retrieved from the Cochrane Library were duplicates of records identified in PubMed. After deduplication, 71 unique records remained for screening.

Eligibility criteria

To be eligible, a study had to enroll patients with STEMI treated with primary PCI; report in-hospital or long-term all-cause mortality, cardiovascular mortality, or major adverse cardiovascular events (MACE); assess fQRS on a standard 12-lead ECG according to the criteria proposed by Das M.K. et al.; and compare patients with and without fQRS [4]. Studies also had to provide data on in-hospital mortality or long-term adverse outcomes. Across studies, long-term outco...

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R.S. Ilchenko, A.Yu. Zakirzyanov, V.A. Kokorin, A.Yu. Lebedeva, I.G. Gordeev