Coronary vasodilatory action after nicorandil: A quantitative angiographic study

Vasodilatory effects of nicorandil on major coronary arteries were investigated in 22 patients undergoing cardiac catheterization. Nicorandil, 20 mg, was administered sublingually to 11 consecutive patients and 40 mg to 11 others. Systemic blood pressure decreased significantly without affecting the heart rate. A total of 103 selected coronary artery segments, including 17 stenotic segments, were analyzed quantitatively using a computer-assisted coronary angiographic analysis system. After administration of 20 or 40 mg of nicorandil, a significant increase of the mean diameter was observed in the proximal (+9% and +7%), midportion (+10% and + 11%) and distal (+15% and +13%) parts of the left anterior descending coronary artery. Corresponding values for the proximal (+13% and +10%) and distal (+10% and +15%) segments of the circumflex artery were observed. An increase in the obstruction diameter was also observed in all but 3 of the analyzed stenotic segments. The results demonstrate that nicorandil, in the route and doses used, causes significant vasodilatation in the normal epicardial coronary segments as well as in most of the stenotic segments.