Aspirin and angiotensin-converting enzyme (ACE) inhibitors have been proved to reduce mortality and morbidity in patients with coronary artery disease and congestive heart failure. Recent studies, however, have questioned the effectiveness of this combination therapy in treating heart disease. ACE inhibitors promote the release of vasodilating prostaglandins, while aspirin can block the synthesis of these prostaglandins. In theory, these opposing actions may reduce the effectiveness of both agents. Leor and colleagues evaluated the effectiveness of combination therapy in reducing five-year mortality rates in patients with known coronary artery disease.

Data from a large coronary artery disease trial were analyzed to identify patients taking an ACE inhibitor alone and those taking combination therapy. The end point was the five-year mortality rate in these patients. The common dose of aspirin used during the study period was 250 mg per day.

A total of 1,247 patients were taking ACE inhibitors, and of these, 618 were taking ACE inhibitors and aspirin. At the end of five years, the all-cause mortality rate in patients taking combination therapy was 19 percent, compared with 27 percent in patients taking ACE inhibitors alone. The mortality rate from cardiovascular events was also significantly lower in patients taking combination therapy (12 percent) compared with those taking ACE inhibitors alone (18 percent).

The authors conclude that the five-year mortality rate is lower in patients with known coronary artery disease who take combination therapy compared with those who take ACE inhibitors alone. In patients with congestive heart failure, the benefit of combination therapy was even more pronounced. Despite the theory that ACE inhibitors and aspirin should act as antagonists, patients clearly benefited from the combination therapy.