Sudden Cardiac Death After NSTE Acute Coronary Syndrome
What is the risk for sudden cardiac death (SCD) after non–ST-segment elevation acute coronary syndrome (NSTE ACS) in the modern era?
Individual data from 48,286 participants in four trials (APPRAISE-2, PLATO, TRACER, and TRILOGY ACS) were merged and analyzed. The cumulative incidence of SCD and cardiovascular death was examined according to time after NSTE ACS. Using competing risk and Cox proportional hazards models, clinical factors at baseline and after the index event that were associated with SCD after NSTE ACS were identified. Baseline factors were used to develop a risk model.
Of the initial 48,286 patients, 37,555 patients were enrolled after NSTE ACS (67.4% men; median age, 65 years). Among these, 2,109 deaths (5.6%) occurred after a median follow-up of 12.1 months. Of 1,640 cardiovascular deaths, 513 (31.3%) were SCD. At 6, 18, and 30 months, the cumulative incidence estimates of SCD were 0.79%, 1.65%, and 2.37%, respectively. Reduced left ventricular ejection fraction, older age, diabetes mellitus, lower estimated glomerular filtration rate, higher heart rate, prior myocardial infarction, peripheral artery disease, Asian race, male sex, and high Killip class were significantly associated with SCD. In a multivariable model, SCD was associated with recurrent myocardial infarction (hazard ratio [HR], 2.95) and any hospitalization (HR, 2.45), whereas coronary revascularization had a negative relationship with SCD (HR, 0.75). A model developed to calculate the risk for SCD had a C-index of 0.77. An integer-based score was developed from this model and yielded a calculated SCD probability ranging from 0.1% to 56.7% (C-statistic, 0.75).
According to this study, SCD accounts for about one-third of cardiovascular deaths after NSTE ACS. Risk stratification can be performed with good accuracy using commonly collected clinical variables.
Total mortality after NSTE ACS is relatively low; one-third of deaths in follow-up are due to SCD. SCD accrues continuously over time rather than plateaus even after the first year from the acute event. The authors show that a relatively simple plug-in-value model has reasonable accuracy in predicting SCD. SCD is not synonymous with arrhythmic death, and some patients may die suddenly as a result of recurrent myocardial infarction or its immediate complications. Nonetheless, patients at highest risk for SCD could be targeted with implantable cardioverter-defibrillators (ICDs) or wearable defibrillators in future studies to assess the impact of such intervention on overall mortality.
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