Influence of nifedipine on coronary haemodynamics and myocardial metabolism in coronary artery disease

The effect of 30 mg sublingual nifedipine on cardiac metabolismand haemodynamics was studied during two identical periods ofpacing in 11 patients with chronic coronary artery disease.The pace time to angina pectoris improved after nifedipine in6 patients, deteriorated in 2 and was unchanged in 3. Nifedipinedecreased blood pressure (12%), rate pressure product (10%)and coronary vascular resistance (17%) during pacing. Aorto-coronarysinus (A-Cs) oxygen difference decreased at rest (9%) and postpacing(10%) after nifedipine, although an opposite tendency in coronarysinus blood flow resulted in unchanged myocardial oxygen uptakethroughout the study. Although mean myocardial lactate extractionafter nifedipine was unchanged during pacing in the whole groupof patients, it increased in 9 patients who showed a net lactaterelease at control pacing (from –50.9±33.5% to–35.9±30.2%, P>0.05). Nifedipine increased freefatty acid (FFA) extraction during pacing (from 1.5±12.9%to 17.4±13.1%, P<0.02) and uptake (from 1.8±8.5to 11.1±10.6 µmol min^–1, P<0.05). Nifedipineinfluenced only glucose exchange significantly (46% decreasedextraction) at 5 min postpacing. The A–Cs citrate gradientlessened 30–40% postpacing after nifedipine administration. Since the unloading effects of nifedipine did not alter myocardialoxygen uptake, the most important net haemodynamicfinding wasthe decrease in coronary vascular resistance. Although no significantantianginal effect of a fixed dose of nifedipine was found,the increased uptake of FFA may reflect improved myocardialoxidative metabolism after nifedipine