Time of Onset of Ventricular Arrhythmia in Acute Coronary Syndrome Determines its Long-term Prognostic Burden

Introduction: Ventricular arrhythmias (VA) are associated with poorer outcome in acute coronary syndrome (ACS). However, whether the prognostic impact differs with time of VA onset is not well known. Methods: The Acute Coronary Syndrome Prospective Audit Study (ACACIA, PM_L_0051) is a prospective multi-centre registry of 3402 patients involving 39 sites across Australia between November 2005 and June 2007 with 12-month outcome data in 3393 [755 ST elevation myocardial infarction (STEMI), 1942 high-risk (ACS-HR) and 696 intermediate-risk (ACS-IR) non-ST elevation ACS]. Results: The incidence of VA was 207 (6.1%)–150 (4.4%) occurred within (VA < 24 h) and 57 (1.7%) after 24 h of presentation (VA > 24 h). Of all VAs, 60% were ventricular tachycardia and 40% ventricular fibrillation. VA patients were more likely to be male with more hyperlipidemia, heart failure and higher CK peak but less documented coronary artery disease and lower systolic blood pressure vs. those without arrhythmia (CTL) (P < 0.005). In addition, VA patients were discharged on more new medications and had longer hospitalisations vs. CTL (P = 0.0001). VA was associated with worse 12-month composite outcome of death, myocardial infarction and stroke (adjusted HR 1.4, P = 0.047). When analysed according to time of onset and adjusted for confounding factors, VA > 24 h but not VA < 24 h, was associated with worse longer term outcome (adjusted HR 2.9 vs. 0.7, P = 0.03). Conclusions: Ventricular arrhythmias are common in ACS with a significant negative prognostic impact at 12 months. Onset of VA after 24 h of presentation carries a much higher long-term prognostic burden.