Antianginal drug effects on normal, ischemic and scar myocardial segments in man

In order to assess acute effects of nitroglycerin, nifedipine and metoprolol on normal, ischemic and scar myocardial segments in man, non-invasive hemodynamic and radionuclide measurements of left ventricular function were performed. Sixteen patients with single left anterior descending (LAD) disease were studied at rest and during exercise: 9 patients with angina and exercise-induced ischemia (LAD stenosis) and 7 patients with previous transmural myocardial infarction and no ischemic changes at thallium imaging (LAD occlusion). Effects on regional ejection fraction were compared between involved antero-septal and normal postero-lateral areas. Global ejection fraction at rest was unchanged after nitroglycerin, increased after nifedipine and decreased after metoprolol. In patients with ischemia, improvement in exercise ejection fraction after all drugs was due to increased regional ejection fraction in ischemic segments, i.e. a real anti-ischemic effect could be demonstrated. In regions of myocardial scar, regional ejections fraction was not changed after either drug. In normal areas, regional ejection fraction remained unchanged after nitroglycerin and nifedipine but decreased after acute beta-blockade. Despite the very similar anti-ischemic effects of all drugs, underlying hemodynamic mechanisms were quite different: Reduction in preload and afterload after nitroglycerin, vasodilatation and reflex sympathetic activity after nifedipine and reduction in double product and contractility after metoprolol. Thus, the mode of action of nitroglycerin, nifedipine and metoprolol on normal, ischemic and scar myocardial segments could be demonstrated in man. Non-invasive antianginal drug testing as shown in this study should allow optimal medical therapy for patients with chronic ischemic heart disease.(ABSTRACT TRUNCATED AT 250 WORDS)