Cardiothoracic Surgical Trials Network: Surgical Treatment of Moderate Ischemic Mitral Regurgitation - CTSN: CABG/MVr vs. CABG

Apr 03, 2016
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Presenter/Author:
Robert E. Michler, MD, FACC
Author/Summarized by Author:
Dharam J. Kumbhani, MD, SM, FACC
Summary Reviewer:
Deepak L. Bhatt, MD, MPH, MBA, FACC
Trial Sponsor:
National Heart, Lung, and Blood Institute
Date Presented:
04/03/2016
Date Published:
04/03/2016
Date Updated:
04/03/2016
Original Posted Date:
11/18/2014
References

Description:

Myocardial infarctions (MIs) are frequently associated with ischemic mitral regurgitation (MR), and are associated with worse outcomes. The current trial sought to compare whether coronary artery bypass grafting (CABG) + mitral valve repair (MVr) was superior to CABG alone in patients with moderate ischemic MR undergoing CABG.

Contribution to the Literature: The trial showed that CABG + MVr is not superior in reducing left ventricular (LV) stroke volume and clinical outcomes up to 2 years compared with CABG alone in patients with multivessel disease and moderate ischemic MR undergoing CABG.



Study Design

  • Blinded
  • Parallel

Patient Populations:

  • Multivessel coronary artery disease
  • Moderate ischemic MR

    Number of enrollees: 301
    Duration of follow-up: 12 months, 2 years
    Mean patient age: 65 years
    Percentage female: 32%
    EF: 40%
    New York Heart Association class: III/IV (32%)

Primary Endpoints:

  • Degree of LV reverse remodeling, as measured by changes in LVESVI at 12 months and 2 years

Secondary Endpoints:

  • MACCE
  • Mortality
  • Residual MR
  • Serious adverse events
  • Hospitalizations
  • Quality of life

Drug/Procedures Used:

Patients with moderate ischemic MR and multivessel disease undergoing CABG were randomized to undergo CABG alone or CABG + MVr. MVr was performed with a rigid or semirigid complete annuloplasty ring in patients undergoing MVr. Ring size was downsized by 2 sizes when possible to correct for annular dilation. CABG was done on-pump with standard techniques.

Principal Findings:

A total of 301 patients were randomized, 151 to CABG alone and 150 to CABG/MVr. Baseline characteristics were fairly similar between the two arms. About 45% of patients had diabetes, 3% had undergone prior CABG, 16% prior percutaneous coronary intervention (PCI), and 8% had prior stroke. The mean baseline left ventricular end-systolic volume index (LVESVI) was approximately 57 ml/m2, with a mean baseline ejection fraction (EF) of 40%. Atrial fibrillation (AF) was more common in patients undergoing CABG alone (23.3% vs. 12.8%, p = 0.02), but rates of atrial maze were approximately 8% in both arms. The mean number of grafts per patient was 3.2. The duration of aortic cross-clamp time (74.7 vs. 117.2 min, p < 0.001) and cardiopulmonary bypass time (106.8 vs. 163.1 min, p < 0.001) were both significantly lower in the CABG alone arm.

At 12 months, LVESVI was similar between the CABG vs. CABG/MVr arms (46.1 vs. 49.6 ml/m2, p = 0.61). All-cause mortality was similar at 30 days (2.7% vs. 1.3%, p = 0.68) and 1 year (7.3% vs. 6.7%, p = 0.83). Major adverse cardiac and cerebrovascular event (MACCE) rates at 1 year were also similar (25.2% vs. 25.3%, p = 0.97). Other endpoints including stroke (1.3% vs. 4.0%, p = 0.17) and rehospitalization for congestive heart failure (13.2% vs. 14.7%, p = 0.72) were similar; any neurological event (3.1% vs. 9.6%, p = 0.03), supraventricular tachycardia (SVT) (8.4% vs. 17.8%, p = 0.03), and postoperative length of stay (9.4 vs. 11.3 days) were all lower in the CABG alone arm. Proportion of patients with residual moderate/severe MR at 12 months was higher in the CABG arm (31% vs. 11.2%, p < 0.0001). However, no differences were noted in quality-of-life measures such as Short Form-12 and the Minnesota Living with Heart Failure questionnaire.

Two-year results: LVESVI for CABG vs. CABG/MVr: 41.2 vs. 43.2 ml/m2, p = 0.71. All-cause mortality: 10.6% vs. 10.0%, p = 0.78. Moderate/severe MR: 32.3% vs. 11.2%, p < 0.001. There were no differences in quality-of-life measures.

Interpretation:

The results of this trial indicate that CABG + MVr is not superior in reducing LV stroke volume and clinical outcomes up to 2 years compared with CABG alone in patients with multivessel disease and moderate ischemic MR undergoing CABG. Cross-clamp and pump times were longer, with a greater risk of neurological events and SVT, and a longer length of stay. CABG/MVr carries a Class IIb recommendation for this indication in the current guidelines, and appears to be a reasonably common practice among surgeons. This trial provides data against its routine use. However, longer-term data are awaited, especially because a larger proportion of patients in the CABG alone arm had moderate to severe MR at 1- and 2-year follow-up, and this could impact on long-term outcomes such as CHF and mortality.

References:

Michler RE, Smith PK, Parides MK, et al., on behalf of the CTSN. Two-Year Outcomes of Surgical Treatment of Moderate Ischemic Mitral Regurgitation. N Engl J Med 2016;Apr 3:[Epub ahead of print].

Presented by Dr. Robert E. Michler at the American College of Cardiology Annual Scientific Session, Chicago, IL, April 3, 2016.

Smith P, Puskas JD, Ascheim DD, et al. Surgical treatment of moderate ischemic mitral regurgitation. N Engl J Med 2014;371:2178-2188.

Presented by Dr. Annetine Gelijns at the American Heart Association Scientific Sessions, Chicago, IL, November 18, 2014.

Keywords: Coronary Artery Disease, Tachycardia, Supraventricular, Stroke, Myocardial Infarction, Minnesota, Mitral Valve Insufficiency, Percutaneous Coronary Intervention, Length of Stay, Heart Failure, Stroke Volume, Atrial Fibrillation, Surveys and Questionnaires, Cardiopulmonary Bypass, Coronary Artery Bypass, Diabetes Mellitus, AHA Annual Scientific Sessions


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