Hypertrophy induced alteration of action potential and effects of the inhibition of angiotensin converting enzyme by perindopril in infarcted rat hearts.

Not much is known about alterations in electrical activity in the healthy part of a heart made hypertrophic as a result of local ischaemia, yet such an investigation might allow us to predict the stages leading to cardiac failure and so aid its prevention. We therefore studied the electrophysiological changes which occurred in rats in which ligation of the left coronary artery had produced hypertrophy of the non-infarcted myocardium. One month after the intervention the overall degree of hypertrophy of the ventricles reached 15.3%. This was accompanied in the healthy part of the left ventricle (septum) by altered electrical activity consisting of a lengthening of the action potentials at 25, 50, 75 and 90% of repolarisation. Myocardial hypertrophy was absent after chronic treatment of the animals with perindopril, an angiotensin converting enzyme inhibitor, given orally at 2 mg.kg-1 body weight, and the electrophysiological alterations induced by the infarct were partially eliminated: phase 2 of the myocardial action potential was shortened and phase 3 completely restored. We postulate that angiotensin may have a direct effect on the cardiac cell.