Effects of isosorbide dinitrate on the response to atrial pacing in coronary heart disease

Abstract

To study the efficacy of isosorbide dinitrate in prevention of myocardial ischemia, 20 patients with angiographically proved coronary artery disease underwent atrial pacing (mean rate 138/min) before (P 1), 10 minutes after (P 2) and 65 minutes after (P 3) sublingual administration of 5 mg of isosorbide dinitrate. The symptomatic, hemodynamic and metabolic responses were evaluated at rest and during each pacing period. Angina occurred in all subjects during P 1. Angina did not recur or was less severe in 17 of 19 patients during P 2 and in 19 of 20 patients during P 3. Resting left ventricular end-diastolic pressure for the group was normal at 11 ± 4 mm Hg (mean ± standard deviation). On interruption of pacing at 4.5 minutes during P 1, average end-diastolic pressure during sinus rhythm was abnormal (18 ± 6 mm Hg). After administration of isosorbide dinitrate mean left ventricular end-diastolic pressure was significantly decreased at rest and remained normal when pacing was interrupted during P 2 and P 3. Brachial arterial pressure, cardiac index, tension-time index, left ventricular stroke work index and maximal rate of rise of left ventricular pressure were all diminished at rest before and during P 2 and P 3. S-T segment depression was less during P 2 and P 3 than during p 1. Before isosorbide dinitrate was given, resting myocardial lactate extraction was 15 ± 11 percent; during P 1 lactate extraction decreased to − 2 ± 25 percent. Lactate extraction was significantly greater during P 2 and P 3 than during P 1. This study demonstrates that sublingual administration of 5 mg of isosorbide dinitrate has a significant protective effect against pacing-induced myocardial ischemia at 10 and 65 minutes after administration.