This study assessed the survival impact of functional mitral regurgitation (MR) in patients with ischemic heart disease and low ejection fraction (EF<35%). The authors also assessed the impact of adding mitral valve repair (MVrep) at the time of CABG on prognosis versus those assigned to medical therapy (MED). Survival data from the present study suggest that presence of even mild MR is associated with poor survival. Furthermore, observational data indicates that adding MVRep to CABG in patients with left ventricular (LV) dysfunction and moderate to severe MR may improve survival compared with CABG alone or MED alone.
European practice guidelines recommend mitral valve repair (MVRep) in patients with severe or even moderate ischemic mitral regurgitation (MR) and an ejection fraction (EF) >30% who are undergoing coronary artery bypass grafting (CABG).
Retrospective analyses shows no survival benefit of adding MVRep to CABG. The need to add MVRep in patients with an indication for CABG becomes even less clear when MR is less severe and left ventricular (LV) dysfunction is more severe.
Aim of the Study
The present study evaluated the prognostic influence of baseline MR severity in patients, compared the survival of patients with various degrees of MR severity by treatment assignment to medical therapy (MED) or CABG, and compared survival among patients with moderate-to-severe MR who did or did not receive MVRep at the time of CABG versus those assigned to MED.
The authors assessed their hypotheses in the 1212 STICH trial study patients patients randomized to CABG (n=610) or MED (n=602). Eligible patients had coronary artery disease amenable to CABG and LVEF ≤35%. Major exclusion criteria included significant (>50%) left main disease and/or Canadian Cardiovascular Society Class 3 or 4 angina, recent acute myocardial infarction, hemodynamic instability, planned percutaneous revascularization, or aortic valvular surgery.
Among patients undergoing CABG, the decision to repair or not repair the mitral insufficiency was not randomized. Patients were followed up at 30 days (or at discharge, whichever occurred earlier), at four-month intervals during the first year, and every six months thereafter. The majority of patients were followed up for 56 months. The primary end point was mortality.
Of 1212 randomized patients, 435 (36%) had none/trace MR, 554 (46%) had mild MR, 181 (15%) had moderate MR, and 39 (3%) had severe MR.In the medical arm, 70 deaths (32%) occurred in patients with none/trace MR, 114 (44%) in those with mild MR, and 58 (50%) in those with moderate to severe MR.
In patients with moderate-to-severe MR there were 29 deaths (53%) among 55 patients randomized to CABG who did not receive mitral surgery (hazard ratio versus medical therapy, 1.20; 95% confidence interval, 0.77–1.87), and 21 deaths (43%) among 49 patients who received mitral surgery (hazard ratio versus medical therapy, 0.62; 95% confidence interval, 0.35–1.08).
After adjustment for baseline prognostic variables, the hazard ratio for CABG with mitral surgery versus CABG alone was 0.41 (95% confidence interval, 0.22– 0.77; P=0.006). Finally, although STICH patients with an MVRep added to CABG had a more complicated early postoperative period, peri-operative mortality was higher in the CABG alone group (14.3% vs 2%, P=0.046).
Survival data from the present study suggest that the presence of even mild MR is associated with poor survival. Furthermore, observational data indicate that adding MVRep to CABG in patients with LV dysfunction and moderate-to-severe MR may improve survival compared with CABG alone or MED alone. Despite greater morbidity from adding MVRep to CABG, there may also be harm from failure to address moderate to severe MR in patients undergoing CABG.
This report is limited by the small number of patients in the moderate-to-severe MR cohort, and the lack of a secondary randomization to MVRep. The authors cannot exclude the possibility that surgeons were more reluctant to perform a mitral procedure in less healthy patients. Compared with other reports of operative treatment of moderate-to-severe ischemic MR reporting no long term survival benefit, STICH patients had lower EF, less angina and more heart failure, and were selected because of clinical equipoise for the need for CABG. Therefore, because of possible confounding by indication, a prospective randomized trial to confirm the validity of these observations is justified.
Corresponding author from original paper
Marek A. Deja, MD, PhD, Second Department Cardiac Surgery, Medical University of Silesia, Katowice, Poland. E-mail firstname.lastname@example.org
Citation: Circulation. 2012;125:2639-2648