Myocardial contractility improvement after coronary artery by-pass grafting in a 1-year observation: The role of myocardial viability assessment

Abstract

Background: Left ventricular (LV) contractility impairment in coronary artery disease patients may be the effect of heart muscle hibernation due to chronic ischemia. Revascularization is the only method to restore contractile function in these patients. The time and degree of LV function improvement have not been precisely determined, and the published data are discordant. The aim of our study was to evaluate the time of myocardial contractility recovery after surgical revascularization in patients with systolic LV dysfunction in relation to the results of echocardiography stress tests.
Methods: The study included 50 patients with multivessel coronary artery disease and decreased left ventricular ejection fraction (LVEF < 40%) qualified for coronary artery by-pass grafting. The intervention was preceded by rest echocardiography, low dose dobutamine stress test (5-10 µg/kg/min) and by low dose dipyridamole stress test (0.24 mg/kg during 4 min) performed on the next day. Consecutive rest echocardiograms were performed immediately after the intervention and after 3, 6 and 12 months. LVEF and the index of left ventricular contractility (WMSI, wall motion score index) were evaluated at each examination.
Results: During 1-year follow-up after coronary artery by-pass grafting (CABG), significant improvement in LV systolic function was observed (LVEF increased, WSMI reduced), with major changes occurring over the first 6 months. The correlation of echocardiography parameters (EF, WMSI) at stress tests and during 1-year follow-up showed that the strongest relationship exists between the change in WMSI both in dobutamine and dipyridamole stress tests and the improvement in WMSI observed after 6 months.
Conclusions: LV function improvement after CABG in patients with systolic LV dysfunction was most pronounced 3 to 6 months after the intervention. Both types of stress tests are characterized by similar diagnostic value for assessing LV myocardial viability. WMSI calculated during stress was identified to have the strongest prognostic value. (Cardiol J 2007; 14: 246-251)