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.