Temporal trends on the risk of arrhythmic vs. non-arrhythmic deaths in high-risk patients after myocardial infarction: a combined analysis from multicentre trials

Abstract

An understanding of the temporal trends on the risks of arrhythmic death (AD) vs. non-arrhythmic deaths (NAD) after myocardial infarction (MI) is crucial in deciding the optimal timing for risk stratification and treatment window for prophylactic antiarrhythmic treatment. However, contemporary data on such information is lacking. Individual patient data were pooled from the placebo arms of EMIAT, CAMIAT, SWORD, TRACE, and DIAMOND-MI who had a recent MI and left ventricular ejection fraction (LVEF) <40% or frequent ventricular premature beats (VPBs). Temporal trends were investigated for all studies from day 45 after acute myocardial infarction (AMI) to account for different recruitment periods between trials, and then from the onset of MI for TRACE and DIAMOND-MI that recruited patients within 2 weeks after MI. In total, 3104 patients (median age 65, range: 23-92; 2471 males) were pooled from all five studies, with a total of 487 deaths at 2-year follow-up; 220 deaths were ADs and 172 were NADs. The risks of both AD and NAD were highest in the first 6 months but the risk of AD was consistently higher than that of NAD throughout the 2-year period [rate of death/100 person-year at risk (AD/NAD): 8.09/6.07 (45 days to 6 months), 4.07/3.35 (>6-12 months), 4.34/3.60 (>12-18 months), 3.76/2.77 (>18-24 months)]. There were significant interactions between the temporal trends of mortalities and gender (P=0.03) and history of hypertension (P=0.04). A similar trend was observed when mortality was measured from time of onset of MI from the combined TRACE and DIAMOND-MI dataset. Our study provided the first contemporary evidence that in high-risk post-MI patients with LVEF <40% or frequent VPBs, the risk of AD was higher than that of NAD for up to 2 years although in female patients, they became increasingly more likely to die from NAD after 6 months. Therefore, risk stratification of post-MI patient at high risk of AD remains a worthwhile exercise. However, the risks of AD (and NAD) were highest in the first 6 months after AMI and level-off thereafter, suggesting that the optimal window period for risk stratification for implantable cardioverter defibrillator after AMI is in the first 6 months.