Sudden cardiac death (SCD) after myocardial infarction (MI) has not recently been assessed in the community. Post-MI risk stratification for SCD commonly relies on baseline characteristics and little is known about the relationship between recurrent ischemia or heart failure (HF) and SCD.
To evaluate the risk of SCD after MI and the impact of recurrent ischemia and HF on SCD.
Design, setting, and participants
2,997 Olmsted County residents experiencing an MI between 1979 and 2005.
Main outcome measures
SCD defined as out-of-hospital death due to coronary disease. Observed survival free of SCD compared to that expected in Olmsted County.
During a median follow-up of 4.7 years (25th–75th percentile 1.6–7.1, date of last follow-up 02-29-2008), 1,160 deaths occurred, 282 (24%) SCD. The 30-day cumulative incidence of SCD was 1.2% (95% confidence interval [CI] 0.8–1.6%). Thereafter, the rate of SCD was constant at 1.2%/year yielding a 5-year cumulative incidence of 6.9% (95% CI 5.9% to 7.9%). The 30-day incidence of SCD was 4-fold higher than expected (standardized mortality ratio=4.2, 95% CI 2.9 to 5.8). In the year thereafter, the risk of SCD was lower than expected (standardized mortality ratio=0.66, 95% CI 0.50 to 0.85). The risk of SCD declined over time (hazard ratio=0.62, 95% CI 0.44 to 0.88 for MIs in 1997–2005 compared to 1979–1987; p =0.03). Recurrent events, ischemia (n=842) or HF (n=365), occurred in 2,080 patients. After adjustment for baseline characteristics, recurrent ischemia was not associated with SCD (hazard ratio=1.26, 95% CI 0.96 to 1.65; p=0.09), while HF markedly increased the risk of SCD (hazard ratio= 4.20, 95% CI 3.10 to 5.69; p<0.001)
The risk of SCD is highest during the first month after MI and declined over time. SCD is independently associated with HF but not with recurrent ischemia.