An exploratory prospective study of marijuana use and mortality following acute myocardial infarction.

BACKGROUND The relationship of marijuana use with coronary heart disease, including prognosis among patients with coronary heart disease, is uncertain. METHODS We conducted an inception cohort study of 1913 adults hospitalized with myocardial infarction at 45 US hospitals between 1989 and 1994, with a median follow-up of 3.8 years. We ascertained total mortality according to self-reported marijuana use in the preceding year. RESULTS A total of 52 patients reported marijuana use during the prior year, and 317 patients died during follow-up. Compared with nonuse, marijuana use less than weekly was associated with a hazard ratio of 2.5 (95% CI, 0.9-7.3). The corresponding hazard ratio for weekly use or more was 4.2 (95% CI, 1.2-14.3). The age- and sex-adjusted hazard ratios associated with any use were 1.9 (95% CI, 0.6-6.3) for cardiovascular mortality and 4.9 (95% CI, 1.6-14.7) for noncardiovascular mortality. In a comparison of 42 marijuana users and 42 other patients matched on propensity scores, there were 6 deaths among marijuana users and one among non-users (log-rank P = .06). CONCLUSIONS These preliminary results suggest possible hazards of marijuana for patients who survive acute myocardial infarction. Although marijuana use has not been associated with mortality in other populations, it may pose particular risk for susceptible individuals with coronary heart disease.