Sinus node inhibitors for reducing exercise-induced myocardial ischemia: Evidence from experimental animal studies

Abstract

The physician is faced with the dilemma of how best to protect the myocardium subjected to effort-induced ischemia. The ultimate therapeutic solution is the elimination of the stenotic lesion. However, prior to vessel dilation or surgery (or in patients in which such procedures may not be advisable), treatment to minimize ischemic damage to the post-stenotic myocardium is indicated. The reduction of heart rate (or prevention of tachycardia) is an attractive therapeutic approach in the treatment of effort angina pectoris since it has a dual beneficial effect on the potentially ischemic post-stenotic myocardium. On the one hand, reduction of the number of contractions per minute of the heart reduces its work and, consequently, oxygen demand. At the same time, heart rate reduction acts to enhance myocardial blood flow and to improve its distribution within the ischemic myocardium by prolonging the diastolic interval and reducing coronary “steal”. Thus, the inequality between an enhanced metabolic demand and a reduced nutritive supply is lessened from both sides of the supply-demand equation.