Evaluating Impact of Surgical Myocardial Revascularization on Global Left Ventricular Systolic Function and Immediate Postoperative Outcome using Transesophageal Echocardiography

Abstract

Abstract Background and Aims: Surgical myocardial revascularization is supposed to improve the global left ventricular (LV) function by improving the blood supply in significantly occluded coronary arteries. Transesophageal echocardiography (TEE) provides an excellent opportunity to evaluate cardiac function in operating room. Present study was aimed at evaluating impact of surgical myocardial revascularization on global LV systolic function. Comparison of LV fractional shortening (LV-FS), fractional area change (LV-FAC), ejection fraction (LV-EF), indexed LV volumes (indexed LV volumes at end diastole, LV volumes at end systole) and “Tei” (Myocardial performance) index obtained prior and after surgical myocardial revascularization was done for quantitative analysis. Also, the determinants of immediate postoperative outcome were evaluated based on need of pharmacological and/or mechanical cardiovascular support, mechanical ventilation, intensive care unit (ICU) stay, morbidity and mortality in immediate postoperative period. These outcome measures were correlated with baseline values of TEE derived echo indices. Methods: One hundred and ten subjects with significant coronary artery disease scheduled for elective myocardial revascularization surgery. Fourteen subjects were excluded due to presence of either hemodynamic instability requiring either pharmacological or mechanical cardiovascular support, before coronary revascularization (n = 6), presence of Grade III mitral regurgitation (MR) in baseline TEE (n = 2) and arrythmias (n = 6). Ninety six subjects were evaluated for global LV systolic function using TEE before and after surgical revascularization. Subjects were followed in ICU for the outcome. Immediate postoperative outcome was measured as “good” or “poor” based on vasoactive inotropic score, requirement of Intra-aortic balloon counter pulsation (IABP) and mechanical cardiovascular support (VA-ECMO) to maintain cardiac output, duration of mechanical ventilation, postoperative ICU stay, morbidity and mortality. Results: In 96 subjects analyzed, there was a significant improvement in TEE derived LV-FS (38.60 ± 16.38 vs. 31.31 ± 13.14) (P = 0.002), FAC (51.94 ± 16.06 vs. 43.99 ± 16.02) (P ≤ 0.001), EF (53.08 ± 9.97 vs. 46.71 ± 7.53) (P < 0.00001), LV end diastolic volume index (34.84 ± 13.43 vs. 40.08 ± 17.22) (P = 0.0188) and “Tei” index (0.47 ± 0.13 vs. 0.53 ± 0.13) (P = 0.0007). Thirty three subjects required either prolonged stay in ICU (>7 days), (n = 20) and/or mechanical ventilatory support (>24 h), (n = 10) and/or mechanical cardiovascular support (IABP/VA ECMO placement), (n = 7) and/or suffered mortality (n = 2) in postoperative period were categorized as “poor” outcome. Presence of type II diabetes mellitus, Chronic obstructive pulmonary disease (COPD), higher grade of ischemic MR, larger LV end diastolic volume, use of cardiopulmonary bypass and allogenic blood transfusion during surgery were the determinants of “poor” outcome. Conclusion: Surgical myocardial revascularization improved global LV systolic function irrespective of baseline LV EF. Immediate postoperative outcome was strongly determined by presence of diabetes, COPD, higher grade of ischemic MR and larger LV end diastolic volumes. Preoperative (Baseline) LV EF and myocardial performance index did not determine “poor” postoperative outcome following surgical myocardial revascularization in subjects with LVEF >35%.