Surgical Treatment of Patients with Ischemic Cardiomyopathy: The Significance of Right Ventricular Function
Abstract
Background: Patients with ischemic cardiomyopathy (ICMP) awaiting heart transplantation (HT) have a high mortality rate, in part because of the lack of donor organs. Given this limitation, we propose to broaden the indications for coronary artery bypass grafting (CABG) in this group and to more accurately select patients with ICMP requiring myocardial revascularization or HT. In this study, we assessed the short and long-term results of CABG in patients with ICMP. We also assessed the role of the right ventricle and the diastolic function of both ventricles in patients with ICMP. Using this information, we propose indications for CABG and/or HT in patients with ICMP.
Methods: We analyzed 49 patients with ICMP undergoing workup as potential heart transplant candidates. The patients were divided into two groups. Group A included 19 patients submitted to isolated CABG based on the preoperative assessment of myocardial viability. Group B consisted of 30 patients determined to be best suited for HT (with five patients actually receiving a donor heart). All patients were assessed by radionuclide ventriculography (RVG) and functional testing in order to assess their myocardial viability. RVGs were obtained prior to coronary bypass as well as at two and twelve months postoperatively.
Results: Preoperative data in group A were: left ventricular end-diastolic dimension (LVEDD) 7.0±0.32 cm, left ventricular ejection fraction (LVEF) 24.2±2.6%, and right ventricular ejection fraction (RVEF) 32.4±2.6%. For Group B, LVEDD was 7.7±0.29 cm , LVEF was 22±2.7%, and RVEF 26±2.6%. The operative mortality in group A was 16.6%. Three patients died in the early postoperative period, two of them due to acute cardiac failure, and one due to cerebral complications. The number of grafted arteries was 3.6±0.2. One year after coronary artery bypass, the resting LVEF increased to 33.3% (a 36% improvement compared with preoperative, p < 0.001). Three-year survival was 77%in group A and 26.8% in group B. Examination of the myocardial functional state after CABG showed that the LV diastolic and RV systolic parameters statistically improved. The decrease of RVEF was revealed in the orthostatic test in patients (group A) who died after CABG in the early postoperative period, and in group B that correlated with their parameters of the myocardial viability.
Conclusions: TCABG in the patients with ICMP significantly increases the functional reserves of the myocardium of both ventricles, mostly because of the improvement in the diastolic function of the LV. In the RV, the systolic function could restore even in the early postoperative period.
Preoperative analysis of the parametric images made after orthostatic test and nitroglycerin intake allow predic-tion, with 85 % sensitivity and 95% specificity, of the areas of the myocardium which will restore their function immediately after CABG (“hibernated myocardium”) . The recovery of regional wall motion amplitude and of the response of the myocardium to coronary revascularization could continue during the first year after revascularization (“stunned myocardium “), most often beginning in the LV.
The decrease of the EF of the RV as a response to the “unloading” tests could be a result of the disturbance of the ventricles’ interaction as well as the spreading of the scarring of the RV myocardium. This decrease could be a predictor of the possible development of the low cardiac output syndrome after CABG.
