Angiotensin-converting enzyme inhibitors have been shown experimentally to prevent restenosis after balloon injury. We previously reported that quinapril reduced the 6-month restenosis (percent diameter stenosis ≥50%) rate after percutaneous coronary intervention (PCI). However, it was not established whether this favorable outcome was maintained for longer periods.

This study was a prospective, randomized, open, and non–placebo controlled trial. Patients with coronary artery disease were enrolled after successful coronary balloon angioplasty or stenting. Two hundred and fifty-three patients were randomly assigned to the quinapril (10–20 mg per day) or control groups. The major clinical end points included death, myocardial infarction, cerebrovascular accident, or revascularization (either coronary artery bypass grafting or repeat PCI). These were tabulated according to the intention-to-treat principle.

Long-term follow-up was available with a median of 4.8 (interquartile range 4.2–5.1) years after the procedure. The incidence of combined end points of mortality and morbidity (myocardial infarction and cerebrovascular accident) in the quinapril group was lower than that in the control group (6.1% vs 14.8%; relative risk [RR] 0.42, 95% CI 0.18–0.96, P = .033). The overall incidence of end-point events in patients with quinapril also occurred less frequently (29.8% vs 46.7%; RR 0.58, 95% CI 0.38–0.86, P = .007).

These clinical outcomes show that the benefit of quinapril in patients following PCI is maintained for 4 years.