[Effects of drugs on preventing recurrent myocardial infarction in patients with healed myocardial infarction]

Retrospective analysis showing less cardiac events in post-myocardial infarction patients treated with metoprolol. Secondary Prevention Group

This analysis was carried out to clarify the capacity of metoprolol to prevent cardiac events in Japanese post-myocardial infarction patients during a follow-up period of 16.3 months. Cardiac events occurred in 44 of 650 patients treated without beta-blockers (6.8%) and in 13 of 432 patients treated with metoprolol (3.0%), which represents a significant decline in the incidence of cardiac events among patients receiving metoprolol (p<0.01, odds ratio 0.43, 95% confidence interval 0.23-0.80). Because this was a retrospective analysis, there were unavoidable differences in the backgrounds of the patients in the 2 groups. Subgroup analyses, each focusing on a specific patient characteristic, were therefore performed. These showed that metoprolol effectively reduced cardiac events in many subgroups. Furthermore, multivariate analysis carried out to exclude any modification based on the differences in patient background confirmed metoprolol to be effective in reducing subsequent cardiac events in post-myocardial infarction patients. A large, randomized, placebo-controlled clinical trial needs to be performed in the Japanese population to confirm the present result.

Long-term nitrate treatment increases cardiac events in patients with healed myocardial infarction. Secondary Prevention Group

BACKGROUND

Nitrates dilate coronary arteries, ameliorate myocardial ischemia, minimize left ventricular remodeling, and reduce mortality in patients with acute myocardial infarction. However, the effects of long-term treatment with nitrates on cardiac events in patients with healed myocardial infarction are not known.

METHODS AND RESULTS

A total of 1,002 patients with healed myocardial infarction (789 male and 213 female) were randomly divided into 2 groups: treatment with nitrates or nontreatment. The mean observation period was 18.0 +/- 19.9 months. Primary end points were nonfatal and fatal recurrent myocardial infarction, death from congestive heart failure, and sudden death. Baseline characteristics of the 2 groups were also compared to determine any effects on outcome. Among the 621 cases treated with nitrates, 41 cases (6.6%) experienced cardiac events during the observation period, whereas only 12 of the 381 cases that were not treated with nitrates (3.1%) had cardiac events. This difference was statistically significant (p < 0.05; odds ratio 2.17; 95% confidence interval 1.13-4.19). There were no differences in the incidence of noncardiac death or being lost to follow-up between the 2 groups. Although the precise mechanism of this increase in the occurrence of cardiac events by long-term treatment with nitrates is not clear, nitrate tolerance with possible rebound and neurohormonal effects may be involved.

CONCLUSION

Long-term treatment with nitrates increased cardiac events in patients with healed myocardial infarction.