Sudden death after myocardial infarction

Abstract

Context: Sudden cardiac death after myocardial infarction (MI) has not been assessed recently in the community. Risk stratification for sudden cardiac death after MI commonly relies on baseline characteristics and little is known about the relationship between recurrent ischemia or heart failure and sudden cardiac death.

Objective: To evaluate the risk of sudden cardiac death after MI and the impact of recurrent ischemia and heart failure on sudden cardiac death.

Design, setting, and participants: Population-based surveillance study of 2997 residents (mean [SD] age, 67 [14] years; 59% were men) experiencing an MI in Olmsted County, Minnesota, between 1979 and 2005, and followed up through February 29, 2008.

Main outcome measures: Sudden cardiac death defined as out-of-hospital death due to coronary disease; and observed survival free of sudden cardiac death compared with that expected in Olmsted County, Minnesota.

Results: During a median follow-up of 4.7 years (25th-75th percentile, 1.6-7.1 years), 1160 deaths occurred, 282 from sudden cardiac death (24%). The 30-day cumulative incidence of sudden cardiac death was 1.2% (95% confidence interval [CI], 0.8%-1.6%). Thereafter, the rate of sudden cardiac death was constant at 1.2% per year yielding a 5-year cumulative incidence of 6.9% (95% CI, 5.9%-7.9%). The 30-day incidence of sudden cardiac death was 4-fold higher than expected (standardized mortality ratio, 4.2; 95% CI, 2.9-5.8). The risk of sudden cardiac death has declined significantly over time (hazard ratio [HR], 0.62 [95% CI, 0.44-0.88] for MIs that occurred between 1997 and 2005 compared with between 1979 and 1987; P = .03). The recurrent events of ischemia (n = 842), heart failure (n = 365), or both (n = 873) occurred in 2080 patients. After adjustment for baseline characteristics, recurrent ischemia was not associated with sudden cardiac death (HR, 1.26 [95% CI, 0.96-1.65]; P = .09), while heart failure markedly increased the risk of sudden cardiac death (HR, 4.20 [95% CI, 3.10-5.69]; P < .001).

Conclusions: The risk of sudden cardiac death following MI in community practice has declined significantly over the past 30 years. Sudden cardiac death is independently associated with heart failure but not with recurrent ischemia.

Figure 1

Cumulative incidence of sudden death and all-cause mortality after myocardial infarction among residents of Olmsted County, Minnesota.

Figure 2

Cumulative incidence of recurrent ischemic events and heart failure after myocardial infarction among residents of Olmsted County, Minnesota.