A controlled clinical trial to assess the effect of a calcium channel blocker on the progression of coronary atherosclerosis To determine whether calcium channel blockers influence the progression of coronary atherosclerosis, 383 patients age 65 years or less with 5-75% stenoses in at least four coronary artery segments were selected at random within 1 month of coronary arteriography to participate in double-blind therapy with a placebo or nicardipine 30 mg three times daily. Coronary events (5 deaths, 22 myocardial infarctions, and 28 unstable anginas) occurred in 28 of 192 nicardipine patients and 23 of 191 placebo patients (p = NS). At 24 months coronary arteriography was repeated in 335 patients. Progression, defined as a 10% or more worsening in diameter stenosis, measured quantitatively, was found in 147 of 1,153 lesions (12.7%) in 168 nicardipine patients and in 170 of 1,170 lesions (14.5%) in 167 placebo patients (p = NS). Ninety-two nicardipine patients (55%) and 95 placebo patients (57%) had progression at one or more sites (p = NS). Regression, that is, an improvement by 10% or more in diameter stenosis, was seen in 140 of 2,323 lesions (6.0%) overall, with no significant intergroup difference. Among the 217 patients with 411 stenoses of 20% or less in the first study, such minimal lesions progressed in only 15 of 99 nicardipine patients compared with 32 of 118 placebo patients (15% versus 27%, p = 0.046). In this subgroup, 16 of 178 minimal lesions in nicardipine patients and 38 of 233 minimal lesions in placebo patients progressed (p = 0.038). By stepwise logistic-regression analysis, baseline systolic blood pressure (p = 0.04) and the change in systolic blood pressure between baseline and 6 months (p = 0.002) correlated with progression of minimal lesions. This suggested blood pressure reduction may account for the beneficial action of nicardipine. These results suggested nicardipine has no effect on advanced coronary atherosclerosis but may retard the progression of minimal lesions. 