Effect of intravenous diltiazem on myocardial ischemia occurring during percutaneous transluminal coronary angioplasty

To investigate the antiischemic efficacy of intravenously administered diltiazem, 42 patients were randomlY allocated to receive placebo or active treatment before 1-vessel percutaneous transluminal coronary angioplasty (PTCA). The development of myocardial ischemia was studied using subjective (pain) and objective electrocardiography) parameters. Pretreatment with intravenous diltiazem resulted in a significantly delayed onset of ischemic pain and ST-segment elevation; these variables also returned to baseline earlier after balloon deflation. Thus, intravenous diltiazem prevents or delays the onset of myocardial ischemia during repetitive transient coronary occlusions; improvement of the myocardial blood flow distal to the coronary occlusion or impedance of calcium entry into the ischemic cell are considered as possible mechanisms. Because PTCA is increasingly used in patients with poor left ventricular function and more extensive disease, and because recent evidence suggests that better PTCA results could be obtained by the use of longer inflation times, the addition of diltiazem to the classic armamentarium could be beneficial. (Am J Cardiol 1989;64:1103-1107)
Percutaneous transluminal coronary angioplasty (PTCA) is a procedure for treating narrowed coronary arteries, which are the major blood vessels that bring blood to the heart. A catheter or tube-like structure with a small inflatable balloon is inserted into the narrowed portion of the artery, and the balloon is inflated, thereby mechanically dilating the narrowed coronary artery. In PTCA, inflation of the balloon causes transient occlusion, or blockage, of the coronary artery. This leads to regional ischemia, or insufficient blood flow to specific portions of the heart. Medications can be given before PTCA to reduce or prevent regional ischemia. The anti-ischemic effect of the drug diltiazem was assessed in 42 patients who were scheduled to undergo PTCA; half the patients received pretreatment with diltiazem while the other half received an inert placebo. During the PTCA procedure, chest pain and changes in the electrocardiogram, a recording of the electrical activity of the heart, were used as indicators of ischemia. Pretreatment with diltiazem delayed the onset of pain and ECG changes associated with ischemia, and both of these indicators returned to normal after deflation of the balloon more quickly with diltiazem than without. The results show that intravenous diltiazem delays the onset of myocardial ischemia during repetitive and brief blockage of the coronary arteries. Diltiazem may exert its effects by improving blood flow beyond the blocked portion of the coronary artery, or by blocking the entry of calcium into the ischemic cell; diltiazem is a calcium blocking agent. Thus, diltiazem may be a useful medication for delaying the onset of ischemia in patients undergoing PTCA; it may be particularly helpful if longer balloon inflation periods (which may prove to be more effective than briefer periods) are utilized in the future. (Consumer Summary produced by Reliance Medical Information, Inc.)