Effects of angiotensin-converting enzyme inhibition on exercise-induced angina and ST segment depression in patients with microvascular angina

J Am Coll Cardiol. 1994 Mar 1;23(3):652-7. doi: 10.1016/0735-1097(94)90750-1.

Abstract

Objectives: This study was conducted to test the hypothesis that angiotensin-converting enzyme inhibition may lessen myocardial ischemia in patients with microvascular angina.

Background: Patients with syndrome X (angina pectoris, positive findings on exercise testing and normal coronary arteriogram) have a reduced coronary vasodilator reserve ("microvascular angina") and may show an increased sympathetic drive. Angiotensin-converting enzyme inhibition attenuates sympathetic coronary vasoconstriction in patients with coronary artery disease.

Methods: Ten patients (seven women and three men, mean age [+/- SD] 53 +/- 6 years) with syndrome X and a reduced coronary flow reserve underwent a randomized, single-blind, crossover, placebo-controlled study of the effects of the angiotensin-converting enzyme inhibitor enalapril on angina and exercise-induced ST segment depression. Assessment was by symptom-limited treadmill exercise testing after 2 weeks of treatment with 10 mg/day of enalapril and after 2 weeks of placebo administration.

Results: All patients had positive findings on exercise testing (> or = 1 mm ST segment depression and angina) while taking placebo, whereas six patients had a positive test result (four with angina) during enalapril therapy. Total exercise duration and time to 1 mm of ST segment depression were prolonged by enalapril over those obtained with placebo (mean 779 +/- 141 vs. 690 +/- 148 s, p = 0.006 and 690 +/- 204 vs. 485 +/- 241 s, p = 0.007, respectively). The magnitude of ST segment depression was also less with enalapril than with placebo (mean 1.1 +/- 0.4 vs. 1.5 +/- 0.2 mm, p = 0.004). Heart rate and blood pressure at peak exercise and at 1 mm of ST depression were not significantly different during placebo and enalapril treatment.

Conclusions: Angiotensin-converting enzyme inhibition lessens exercise-induced ischemia in patients with syndrome X and microvascular angina, probably by a direct modulation of coronary microvascular tone, which results in an increased myocardial oxygen supply.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Coronary Circulation / drug effects
  • Electrocardiography / methods*
  • Enalapril / therapeutic use*
  • Exercise Test
  • Exercise Tolerance / physiology
  • Female
  • Hemodynamics / drug effects*
  • Hemodynamics / physiology
  • Humans
  • Male
  • Microvascular Angina / diagnosis
  • Microvascular Angina / drug therapy*
  • Microvascular Angina / physiopathology
  • Middle Aged
  • Signal Processing, Computer-Assisted*
  • Single-Blind Method

Substances

  • Enalapril