EFFECT OF NIFEDIPINE ON LEFT-VENTRICULAR FUNCTION DURING EXERCISE IN PATIENTS WITH STABLE EFFORT ANGINA - RELATION OF ITS EFFICACY TO THE SEVERITY OF CORONARY-ARTERY DISEASE

To evaluate whether the effect of nifedipine on left ventricular function relates to the severity of coronary artery disease (CAD) or not, supine graded ergometer exercise testing was performed before and after sublingual administration of 10 mg nifedipine in 24 patients with stable effort angina. To minimize the effect of nifedipine on myocardial oxygen consumption, exercise before and after nifedipine was discontinued at the same target rate pressure product. Percent (%) left ventricular ejection fraction (EF) [EF during exercise/EF at rest.100] was measured before and after nifedipine by radionuclide angiocardiography. The angiographic degree of CAD was defined by Gensini's CAD scoring as follows: severe CAD: greater than or equal to 50, moderate: less than 50 greater than 20 and mild: less than or equal to 20. After nifedipine, left ventricular function (%EF) was improved in all 6 patients with mild CAD, but was worsened in all 9 patients with severe CAD. Maximal ST segment depression during exercise was improved in 5 of 6 patients with mild CAD, while improvement was induced in 5 of 9 patients with moderate CAD and in 3 of 9 patients with severe CAD. Jeopardy of coronary collateral vessels may have an influence on the effect of nifedipine. It is suggested that the effect of nifedipine on left ventricular function is influenced by the severity of CAD when most of its effect on myocardial oxygen consumption is eliminated.