Early and late effects of coronary artery bypass grafting on cardiac haemodynamics during daily physical activities in patients with coronary artery disease.

This study investigated the early and late effects of coronary artery bypass grafting (CABG) on left ventricular (LV) function during different physical daily activities in patients with multivessel coronary artery disease (CAD). In ten patients with multivessel CAD, cardiac haemodynamics were assessed during a 6-min walk test and during stair climbing 8+/-2 days before (study 1) and 15+/-3 days (study 2) and 120+/-3 days (study 3) after CABG. LV function was monitored by an ambulatory radionuclide system. In study 1, the walk test induced a significant increase in relative end-diastolic volume (EDV) and end-systolic volume (ESV) and no change in LV ejection fraction as compared to rest. In both study 2 and study 3, EDV increased significantly and ESV was unchanged. As a consequence, LV ejection fraction rose from 48%+/-8% to 52%+/-10% and from 48%+/-7% to 51%+/-6%, respectively (both P<0.05). In study 1, stair climbing induced a significant increase in EDV and ESV and as a consequence LV ejection fraction decreased from 46%+/-8% to 42%+/-9% (P<0.05) as compared to rest. In both study 2 and study 3, EDV increased significantly whereas ESV did not change. As a consequence, LV ejection fraction rose from 48%+/-8% to 52%+/-7% and from 48%+/-8% to 51%+/-7%, respectively (both P<0.05). In conclusion, CABG has beneficial effects on cardiac performance during moderate or more intense physical activity in patients with multivessel CAD and these effects are due to improvement in systolic function. Radionuclide monitoring of LV function provides an objective method for quantitative evaluation of cardiac performance after CABG.