Revascularization in Severe Left Ventricular Dysfunction | Ten Points to Remember
- Velazquez EJ, Bonow RO.
- Revascularization in Severe Left Ventricular Dysfunction. J Am Coll Cardiol 2015;65:615-624.
The following are 10 points to remember on the roles of surgical revascularization, surgical ventricular reconstruction, and mitral valve surgery in patients with ischemic cardiomyopathy and severe left ventricular (LV) systolic dysfunction:
- The STITCH (Surgical Treatment for Ischemic Heart Failure) trial is the only prospective randomized trial that has specifically investigated the role of coronary artery bypass grafting (CABG) in patients with left ventricular ejection fraction (LVEF) ≤35% who are also receiving guideline-directed medical therapy (GDMT).
- The surgical revascularization hypothesis of the STICH trial evaluated CABG compared to GDMT alone (n = 1,212). Although there was no difference observed in the primary outcome of all-cause mortality between patients randomized to CABG versus GDMT over a median follow-up period of 56 months, the CABG group had improved rates of death from cardiovascular causes and improved rates of a combined endpoint of death from any cause and hospitalization for heart failure. The authors suggest an “overall benefit of CABG against the background of GDMT in patients with severe ischemic LV dysfunction.” STITCHES (STICH Extended Study) will report outcomes in patients followed up to 10 years after initial randomization.
- The survival benefits associated with CABG in patients with severe LV systolic dysfunction may be predicted by clinical factors, patient comorbidities, and severity of LV remodeling, but not by biomarkers or objective assessments of myocardial viability.
- In adjusted analyses, myocardial viability was not associated with improved survival. And, viability analysis did not identify patients who would preferentially benefit from CABG.
- While viability does not appear to identify patients who stand to benefit incrementally from CABG, the following factors are associated with higher survival rates with CABG: functional status (as assessed by a 6-minute walk and/or Kansas City Cardiomyopathy Questionnaire) and the interaction of angiographic severity of coronary artery disease, severity of LV systolic dysfunction, and severity of LV remodeling (with higher end-systolic volume index favoring CABG + GDMT).
- The surgical ventricular reconstruction (SVR) hypothesis of the STITCH trial evaluated CABG with and without SVR (n = 1,000). There was no significant difference in the two groups with respect to the primary outcome or multiple secondary endpoints (including quality of life). The authors write, “SVR added to CABG does not appear to improve quality of life compared to CABG alone, but does increase healthcare costs.”
- A secondary analysis of the SVR hypothesis of the STITCH trial examined the influence of baseline LV volumes and LVEF on outcomes. Interestingly, patients with smaller baseline LV end-systolic and end-diastolic diameters (perhaps suggest of less extensive remodeling) were more likely to benefit from CABG with SVR.
- Even mild degrees of secondary mitral regurgitation (MR) that arise from LV remodeling and dysfunction may identify patients with LV dysfunction who have higher mortality risk than those without MR.
- Patients with severe ischemic MR who are undergoing CABG should have concomitant valve surgery. Surgical mitral valve repair may not be durable in ischemic MR, and mitral valve replacement may be the preferred strategy even at experienced centers. Further research will clarify the role of percutaneous mitral valve therapies in those with secondary MR related to ischemic cardiomyopathy.
- Future trial data will inform the indications for concomitant mitral valve surgery in patients undergoing CABG and who have moderate MR.
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