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Outcome of bypass surgery in patients with chronic ischemic left ventricular dysfunction. Predictive value of MR
N E Kløw1, H J Smith, L Gullestad
1Department of Radiology, National Hospital, Oslo, Norway.
Purpose:
To determine the preoperative findings of MR imaging of the left ventricle (LV) that could best predict the functional outcome of the 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 after bypass surgery with MR in a study on the effects of revascularization after mean 22 months.
Results:
Angina pectoris was relieved in all patients except one, but the maximum workload during the exercise test was increased in only 3 patients. Coronary angiography showed that 37 of 45 (82%) of the distal anastomoses were open. The LV ejection fraction 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 thickening was seen in 65% of the segments that had had an end-diastolic wall thickness (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.
Conclusion:
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.