New-onset atrial fibrillation predicts malignant arrhythmias in post–myocardial infarction patients—A Cardiac Arrhythmias and RIsk Stratification after acute Myocardial infarction (CARISMA) substudy

Abstract

After myocardial infarction (MI) the risk of sudden cardiac death due to arrhythmias is substantial. The purpose of this study was to investigate if new-onset atrial fibrillation (AF) is associated with development of potential malignant brady- and tachyarrhythmias after an acute MI. The study included 277 post-MI patients from the CARISMA study with left ventricular ejection fraction ≤ 40%, New York Heart Association class I, II, or III and no history of AF. All patients were implanted with an implantable cardiac monitor within 4 to 27 days after an acute MI and followed every 3 months for 2 years. Time-dependent association between new-onset AF > 30 s and the development of bradyarrhythmias and/or ventricular tachyarrhythmias were investigated using Cox proportional hazard regressions. New-onset AF was associated with an increased risk of bradyarrhythmias when adjusting for male gender and baseline age, left ventricular ejection fraction and QRS width (HR = 2.8 [1.3-5.8], P = .006). Similarly, new-onset AF predicted ventricular tachyarrhythmias when adjusting for New York Heart Association class ≥ II and baseline QRS width (HR = 2.3 [1.2-4.4], P = .019). After dividing ventricular tachyarrhythmias into subgroups of non-sustained ventricular tachycardia (VT), sustained VT and ventricular fibrillation (VF), new-onset AF was significantly associated with an increased risk of non-sustained- and sustained VT but not VF (non-sustained VT: HR = 3.5 [1.7-7.2], P < .001, sustained VT: HR = 4.2 [1.1-15.7], P = .035, VF: HR = 1.1 [0.2-5.8], P = .877). In patients surviving a MI with reduced left ventricular systolic function, new-onset AF is associated with a significantly increased risk of developing ventricular brady- and tachyarrhythmias.