The Efficacy of Medical Stabilization Prior to Myocardial Revascularization in Early Refractory Postinfarction Angina

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Abstract
The timing of coronary artery bypass graft (CABG) surgery in patients with persistent, severe myocardial ischemia after an acute myocardial infarction is controversial. Based on the previous disappointing clinical experience with urgent surgery, a period of medical stabilization (mean ten days, range two to 28) prior to surgery was employed in a prospective nonrandomized clinical trial. The frequent use of intravenous nitro-glycerin and intra-aortic balloon pumping was important in allowing preoperative clinical stabilization in these patients who were refractory to conventional medical therapy. The combined medical-surgical treatment protocol was associated with no early or late mortality in 20 patients who suffered preoperative myocardial infarction and demonstrated refractory post-infarction angina. Although these patients were considered to be high-risk surgical candidates, the incidence of perioperative myocardial damage in this selected group was comparable with that observed in patients undergoing elective CABG surgery at this institution without recent preoperative myocardial infarction. In order to determine the hemodynamic effectiveness of this selected patient management process, perioperative changes in left ventricular performance were determined by multigated cardiac blood pool imaging. Computer-based analysis of this radionuclide-related data allowed the accurate determination of ejection fraction (EF). Those patients with preoperative subendocardial infarction (N = 12) had no decrease in global EF 24 hours after operation and significant increases in EF seven days and eight months after operation. This pattern is analogous to that observed in patients without preoperative myocardial necrosis undergoing elective CABG surgery at this institution. Those patients with recent preoperative transmural myocardial infarction (N = 8) showed a decrease in EF 24 hours after operation, but recovered to preoperative levels seven days and eight months after operation. There was, however, no increase in EF in this subgroup of patients. On the basis of this study, the authors tentatively recommend a concerted effort at preoperative medical stabilization prior to CABG surgery in patients with persistent refractory myocardial ischemia soon after acute myocardial necrosis. A prospective, randomized study comparing urgent and delayed surgery, as well as nonsurgical treatment, will be necessary to define more precisely optimal management of this subgroup of cardiac patients.

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