Effects of Coronary Bypass Surgery on Myocardial Performance Index (MPI or Tei index)

Background- Coronary artery bypass grafting (CABG) is a common surgical procedure performed in the world. Coronary artery disease (CAD) has become prevalent in Iran, and the aim of this study is to assess the effects of CABG on LV systolic and diastolic function indices. We also attempted to disclose the CABG effect on the myocardial performance (Tei) index. Methods- 50 patients were enrolled in this study, all of whom were given instructions about the research program. They were admitted to our center electively for CABG; the first echocardiography was taken just prior to surgery, and the second TTE was performed between 1 and 43 weeks after surgery (mean=11 weeks). Results- CABG had dramatic effects on the patients, as their mean left ventricular ejection fraction (LVEF) rose from 48.88% to 52.54% (P<0.001). It was more obvious in patients with preoperative LVEF less than 40%, Tei index<0.49, male gender and those with complete revascularization. LVEF had no change in the case of incomplete revascularization. MPI (Tei) decreased significantly after CABG from 0.4992 to 0.4462 (P=0.001), which was more pronounced in those whose preoperative Tei index was equal or more than 0.49 and in patients with triple vessel or left main CAD. Diastolic function recovery had a time- dependent manner with no change or even deterioration during the first few days after CABG, but after 4 weeks nearly half of the patients had normal diastolic function. History of systemic hypertension and old age (>60 years old) are both associated with more preoperative diastolic dysfunction and are negative predictors for diastolic function recovery after CABG. Isovolumetric relaxation time (IVRT), E-wave deceleration time (EDT), peak E-wave velocity (PEV) and peak A-wave velocity (PA) all show significant improvement after CABG. There was no mortality in our series. Conclusion- CABG has important positive and significant effects on many LV systolic and diastolic indices including LVEF, LVESV, IVRT, PEV, PAV and EDT as well as on the myocardial performance (Tei) index