Beneficial effects of nifedipine on regional myocardial blood flow in patients with coronary artery disease.

Nifedipine inhibits the slow-channel calcium current, which plays a major role in vascular smooth-muscle contraction. However, the effect of nifedipine on regional myocardial blood flow (RMBF) in patients with coronary artery disease (CAD) is unknown. In 18 patients with chest pain syndromes, RMBF was determined with xenon-133 before and after nifedipine. In patients with CAD. 25 regions were analyzed distal to significant coronary obstruction(greater than 70% reduction in luminal diameter) and eight regions were analyzed in patients with normal coronary arteries. In patients with CAD, RMBF increased in 21 of 25 regions (average 17.4 /+- 5.7%,p less than 0.01), but decreased in all eight regions in patients with normal coronary arteries, by an average of 14.4 /+- 2.3% (p less than 0.01). The difference between groups was significant (p less than 0.01). In our patients with CAD, improved RMBF appears to be related to a decrease in coronary vascular tone and suggests a physiologic basis for the beneficial effect of nifedipine in ischemic heart disease.