The Effect of Existence of Advanced Collateral Circulation on Myocardial Viability and Functional Recovery After Revascularization

Hibernating myocardium that is dysfunctional due to chronic ischemia but still viable show functional improvement after revascularization. In this study, the effect of the collateral circulation to related territory of the totally occluded vessel on myocardial viability was assessed by dobutamine stress echocardiography (DSE) and functional improvement after coronary artery bypass surgery (CABG). Fifty-eight patients with coronary artery disease and left ventricular dysfunction, who had at least one totally occluded coronary artery and planned to have elective CABG were included into the study. The collateral circulation to the totally occluded vessel territory was graded from 0 to 3 according to the Rentrop classification. Before CABG, myocardial viability was evaluated by low dose DSE and left ventricular functions and functional recovery of the hibernating myocardium were assessed three months after CABG via echocardiography. Thirty cases with advanced coronary collateral circulation were compared to the twenty eight cases without collateral circulation. The groups were similar in terms of age, gender, previous myocardial infarction and the number of diseased vessels. The parameters of the cases with and without collateral circulation were as follows. The number of akinetic segments in cases with and without collateral circulation were 141 and 144, respectively (not significant). The number of preoperative DSE (+) segments were 83 (58%) and 56 (41%) in cases with and without collateral circulation (p<0.05), respectively. The preoperative wall motion score index (WMSI) were 1.88 and 1.94, respectively (p<0.05). Preoperatively, left ventricular ejection fraction (EF) were 41.1% and 40.4%, respectively. The number of segments with improvement were 66 and 47 (p < 0.05), the ratio of improvement in the segments were 69% and 68%, respectively. Postoperative WMSI's were 1.43 and 1.63 (p < 0.05) and postoperative EF was 47% and 44,4% (p < 0.05), respectively. In both groups after CABG significant improvement in DSE (+) segments, decrease in WMSI and increase in EF were noted. In cases with advanced collateral circulation myocardial viability assessed by DSE and functional improvement after CABG were significantly increased. Though basal ventricular functions are similar in cases with advanced collateral circulation they have much more viable segments and higher ratios of functional improvement after CABG. These findings underline the beneficial effects of advanced collateral circulation on myocardial viability. (Türk Kardiyol Dern Arş 2004; 32: 335-343)