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STICH: Influence of mitral valve repair on survival in the surgical treatment for Ischemic heart failure trial

Heart Failure (HF)


Presenter | see Discussant report

Marek Deja Marek Deja (Poland)

List of Authors:
MA Deja, V Rao, B Sun, YL Chua, R Daly, M Senni, L Menicanti, E Velazquez

Abstract:


Functional mitral regurgitation (MR) decreases survival in patients with ischemic cardiomyopathy. Whether surgical revascularization improves survival in ischemic mitral regurgitation (MR) remains unknown. The use of mitral repair during coronary artery bypass grafting (CABG), to improve survival in patients with moderate MR remains controversial.
The Surgical Treatment for Ischemic Heart Failure (STICH) trial randomized 1,212 patients to evidence-based medical therapy (MED) or MED with CABG but left the decision about MVR to the operating surgeon. In this report we evaluate the prognostic influence of baseline MR severity in patients enrolled in STICH; compare survival of patients with varying degrees of MR severity by treatment assignment to MED or CABG; and compare survival among patients with moderate-severe MR who did or did not receive MVRep at the time of CABG versus those assigned to MED.

Background: Functional mitral regurgitation (MR) decreases survival in patients with ischemic cardiomyopathy. Whether surgical revascularization improves survival in ischemic mitral regurgitation (MR) remains unknown. The use of mitral repair during coronary artery bypass grafting (CABG), to improve survival in patients with moderate MR remains controversial.
The Surgical Treatment for Ischemic Heart Failure (STICH) trial randomized 1,212 patients to evidence-based medical therapy (MED) or MED with CABG but left the decision about MVR to the operating surgeon. In this report we evaluate the prognostic influence of baseline MR severity in patients enrolled in STICH; compare survival of patients with varying degrees of MR severity by treatment assignment to MED or CABG; and compare survival among patients with moderate-severe MR who did or did not receive MVRep at the time of CABG versus those assigned to MED.

Methods: Patients with ejection fraction ≤ 35% and coronary artery disease amenable to CABG were randomized at 99 sites worldwide to medical therapy (MED) with or without CABG.
MR severity was assessed at baseline as either none/trace, mild, moderate, or severe. The decision to treat the mitral valve during CABG was left to the surgeon. The primary outcome of all-cause death was assessed in 1,207 (99.6%) of the 1,212 randomized patients during the last four months of 2010.

Results: Of 1212 randomized patients, 435 (36%) had none/trace, 554 (46%) mild, 181 (15%) moderate, and 39 (3%) severe MR. Excluding crossovers, 401 patients with none/trace, 493 with mild, and 195 with moderate-severe MR were available for per-protocol analysis.
In the medical arm, 67 deaths (33%) occurred in patients with none/trace, 107 (47%) with mild (HR vs. no MR 1.60 95%CI 1.18–2.18) and 53 (51%) in moderate-severe MR (HR vs. no MR 1.97 95%CI 1.37–2.83). CABG significantly decreased mortality in patients with mild MR (86 deaths [32%]) (HR vs. MED 0.64 95%CI 0.48–0.85; p=0.0023). In patients with moderate-severe MR, there were 22 deaths (52%) among 42 CABG-only patients (HR vs. MED 1.13, 95%CI 0.69–1.86) and 21 deaths (43%) among 49 patients who received mitral surgery (HR vs. MED 0.69, 95%CI 0.41–1.14). After adjustment for baseline prognostic variables the HR for CABG with mitral surgery vs. CABG alone was 0.45 (95%CI 0.23–0.90; p=0.025).

Conclusions: In patients with severe left ventricular dysfunction and mild MR, CABG alone improves survival. In patients with moderate-severe MR, adding mitral repair to CABG tends to decrease perioperative risk and increase survival compared with CABG alone or MED alone.
In patients with severe left ventricular dysfunction and mild MR, CABG alone improves survival. In patients with moderate-severe MR, adding mitral repair to CABG tends to decrease perioperative risk and increase survival compared with CABG alone or MED alone.

Discussant | see Presenter abstract

Alec Vahanian (France)

Presentation webcast

Presentation slides

Report:


The management of patients with ischaemic mitral regurgitation who undergo coronary bypass surgery is an important clinical issue for which, unfortunately, there is no recognised evidence-based strategy.

STICH was a randomised trial including 1212 patients with left ventricular ejection fraction (LVEF ) <35%, who were amenable to CABG , and were randomly assigned to medical therapy or coronary by-pass surgery (CABG). The presentation here is a sub analysis of the results of the trial focusing on the prognostic influence of baseline MR severity and comparing survival among patients with moderate or severe mitral regurgitation (MR) according to whether mitral valve surgery (MVR) was or was not used at the time of CABG.

Before inclusion, MR was moderate in 15 % of patients and severe in 3%, which confirms that significant MR is frequent in this population. Patients who have moderate or severe MR had worse presenting characteristics and finally higher estimated operative risk. The baseline evaluation leads to the following comments. Firstly, there are limitations in the assessment of the severity of MR which was not core- lab analysed. The precise criteria for quantification were not provided.. Secondly the different characteristics of patients with and without ischaemic MR with left ventricular dysfunction raises the often-asked question “is MR the chicken or the egg?”

In patients treated medically according to randomisation, the outcome was worse in patients with MR and the prognosis parallels the severity of MR. In the absence of multivariate analysis however, it’s not possible to know if MR was an independent predictor of poor outcome.

91 patients had moderate or severe MR and 49 underwent MVR (repair in 98%) in addition to CABG. Patients who underwent MVR had worse LVEF but their operative mortality was only 2%. All-cause mortality was 41% at 5 years, which was significantly lower than that of patients who underwent CABG only, or medical therapy. These findings should be interpreted with caution for several reasons: the decision for MVR was left to the operator, this could well lead to heterogeneity in repair techniques with the inherent consequences on the results. A lack of randomisation, and even of multivariate analysis, doesn’t allow a firm conclusion to be drawn on the added value of MVR. Finally, we lack information on the incidence of residual or, even more importantly, recurrent MR which is a very strong prognostic factor in these patients.

In the future, we must improve the evidence for the use of mitral valve repair in patients who have ischemic MR and undergo CABG. For this purpose we will need to work in several directions: evaluate the strategy using randomised trials which are the only way to control the numerous confounding factors present in ischaemic MR; preoperative evaluation should use a uniform quantification of MR at rest and ideally during stress. Predictors of recurrence of MR should be better identified and finally myocardial viability studies are necessary in these patients with low ejection fraction. In parallel, techniques should be improved, this is true for the annuloplasty techniques and also for left ventricular remodelling devices. Finally, it will be important to evaluate the potential of Catheter-based techniques in this group of patients who are often at high risk for surgery because of their comorbidities.

Thus, the findings reported here are of interest because they relate to a large series with long and comprehensive follow up but are not sufficient to provide us with strong evidence which may lead to increasing the level of evidence of the recommendations on the use of MVR during CABG from level C to level B in the current guidelines.

References


710011 - 710012

SessionTitle:

Clinical Trial Update II - Rate and rhythm

The content of this article reflects the personal opinion of the author/s and is not necessarily the official position of the European Society of Cardiology.