Incidence and timing of serious arrhythmias after early revascularization in non ST-elevation myocardial infarction

Background: In contrast to ST-elevation myocardial infarction (STEMI), in non-STEMI (NSTEMI) patients the need for continuous rhythm monitoring in a coronary care unit, respective incidence and timing of serious arrhythmias are poorly defined. Methods: We used a derivation-validation design and data from two independent prospective cohorts of consecutive haemodynamically stable NSTEMI patients to evaluate the incidence and timing of serious arrhythmias after successful early percutaneous revascularization. Serious arrhythmia was prospectively defined as any arrhythmia that requires immediate medical attention including persistent ventricular tachycardia (>30 s), ventricular fibrillation, asystole, and high degree atrioventricular (AV)-block requiring pacemaker insertion during hospitalization. Results: In the derivation cohort, among 228 NSTEMI patients who underwent successful early percutaneous revascularization, one patient (0.4%, 95% confidence interval 0.02-2.8%) had a serious arrhythmia which occurred 21 h after revascularization. In the validation cohort, among 293 NSTEMI patients who underwent successful early percutaneous revascularization, no patient (0%, 95% confidence interval 0-1.6%) had a serious arrhythmia after revascularization. Conclusion: The incidence of serious arrhythmias in NSTEMI patients after successful early revascularization seems to be very low.