OUTCOME OF BYPASS-SURGERY IN PATIENTS WITH CHRONIC ISCHEMIC LEFT-VENTRICULAR DYSFUNCTION - PREDICTIVE VALUE OF MR-IMAGING

Purpose: To determine the preoperative findings of MR imaging of the l eft ventricle (LV) that could best predict the functional outcome of t he LV after surgical revascularization. Material and Methods: Patients with angina pectoris, previous myocardial infarction, and dysfunction of the LV, and who had a preoperative cine MR, were re-evaluated afte r bypass surgery with MR in a study on the effects of revascularizatio n after mean 22 months. Results: Angina pectoris was relieved in all p atients except one, but the maximum workload during the exercise test was increased in only 3 patients. Coronary angiography showed that 37 or 45 (82%) of the distal anastomoses were open. The LV ejection fract ion was the same before and after operation both at angiography and MR imaging. MR showed LV end-diastolic volume to be increased from 190+/ -50 ml to 250+/-70 ml. Compared to angiography, MR provided additional information regarding myocardial wall thickness and function, and the size of myocardial infarction. Improvement in systolic wall thickenin g was seen in 65% of the segments that had had an end-diastolic wall t hickness (EDWT) greater than 15 mm before operation, while only 4% of the segments with EDWT <6 mm improved. In the wall thickness range of 6-15 mm, MR was unable to predict the functional outcome of the LV. Co nclusion: Preoperative MR findings of thick myocardial walls with poor function seem predictive of improved function after revascularization . When the LV wall thickness is less than 6 mm, no improvement should be expected.