Cardiac magnetic resonance imaging for myocardial viability assessment: Optimizing surgical revascularization in ischemic heart disease

Background Patients with poor ejection fraction undergoing coronary artery bypass grafting carry higher operative risk and have poor long-term survival. Cardiac magnetic resonance is a useful modality to assess viability which can identify patients likely to benefit most from revascularization. In this study, we aimed to assess the outcome in patients selected for surgical revascularization by cardiac magnetic resonance imaging and identify predictors associated with poor outcomes. Methods The study included patients with severely impaired left ventricular function but with at least six viable segments. Patients requiring emergency surgery, undergoing combined procedures, or where cardiopulmonary bypass was required were excluded. Cardiac magnetic resonance was carried out both preoperatively and at six months postoperatively by the same radiologist in all cases. Late gadolinium enhancement was used for the evaluation of myocardial viability. Results Amongst a total of 493 segments studied, there were 89 (18.1%) non-viable, 117 (23.7%) hibernating and 287 (58.2%) viable segments. At six months, the number of non-viable segments changed from 89 (18.1%) to 97 (19.7%), with an increase in viable segments from 287 (58.2%) to 374 (75.8%) and a corresponding reduction of hibernating segments from 117 (23.7%) to 22 (4.5%). There was improvement in ejection fraction from 28 +/- 5.54 to 37 +/- 5.86 (p < 0.0001) in the entire cohort at six months. Overall mortality was 1 (3.2%). Preoperative left ventricular end-systolic volume had the strongest negative correlation with post-operative ejection fraction. Conclusion Cardiac magnetic resonance aided revascularization is associated with low mortality. Preoperative left ventricular end-systolic volume is an important determinant of postoperative ejection fraction.