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Addition of mitral valve repair to CABG showed no benefit in ischemic mitral regurgitation
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CHICAGO — Among patients with moderate ischemic mitral regurgitation, mitral valve repair in addition to CABG was not associated with improvements in left ventricular end systolic volume index or reductions in mortality at 1 year compared with patients treated with CABG alone, according to results presented at the American Heart Association Scientific Sessions.
In a study conducted by the NHLBI-sponsored Cardiothoracic Surgical Trials Network, Robert E. Michler, MD, and colleagues randomly assigned 301 patients (mean age, 65 years; approximately 30% female; 20% nonwhite) with ischemic mitral regurgitation to undergo either CABG alone (n=151) or CABG and mitral valve repair (n=150). Nearly all patients (93%) had moderate ischemic regurgitation at baseline.
The primary endpoint was the degree of left ventricular reverse remodeling, as indicated by changes to LV end systolic volume index (LVESVI) at 1 year. Secondary endpoints included MACCE, death, residual regurgitation, rehospitalization, quality of life and incidence of serious adverse events. Outcomes were measured at 6 and 12 months, with ongoing assessment to 24 months.
Among patients who survived, the mean LVESVI at 1 year was 49.6 ± 31.5 mL/m2 in the group that underwent mitral valve repair compared with 46.1 ± 22.4 mL/m2 in the group that received CABG alone, with statistically significant mean changes from baseline of -9.3 mL/m2 and -9.4 mL/m2, respectively. The two groups did not differ according to rank-based assessment of LVESVI at 1 year (P=.61).
Mitral regurgitation improved in 88% of patients who underwent valve repair compared with 70% of those who received CABG alone. Moderate or severe mitral regurgitation following treatment was significantly less likely in the valve repair group (11% vs. 31%; P<.001). However, neurological events, such as stroke, transient ischemic attack and metabolic encephalopathy, were more common in the valve repair group (P=.03), along with supraventricular arrhythmias (P=.03). Researchers also observed associations between valve repair and longer bypass time (P<.001) and length of postoperative hospital stay (P=.002).
Mortality rates at 1 year were 6.7% in the valve repair group and 7.3% in the CABG-only group (HR=0.9; 95% CI, 0.38-2.12). No significant difference was observed in incidence of MACCE, death, hospital readmission, functional status or quality of life at 1 year.
“This trial did not demonstrate a clinically meaningful advantage to the routine addition of mitral repair to CABG for patients with chronic/moderate ischemic MR,” Michler, professor and chairman of the departments of surgery and cardiovascular and thoracic surgery and director of the Heart Center at the Montefiore Medical Center/Albert Einstein College of Medicine in New York, said during a presentation here. “Longer-term follow-up is ongoing to determine whether the observed difference in the prevalence of moderate or severe MR at 1 year will result in a net clinical benefit for patients undergoing repair at the time of bypass.” – by Adam Taliercio
For more information:
Michler RE. Abstract #20772. Presented at: American Heart Association Scientific Sessions; Nov. 15-19, 2014; Chicago.
Smith PK. N Engl J Med. 2014;doi:10.1056/NEJMoa1410490.
Disclosure: Michler reports no relevant financial disclosures.
Perspective
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Anthony N. DeMaria, MD, MACC
At this stage of the game, it’s hard to justify mitral valve repair in a patient with moderate mitral regurgitation.
About two-thirds of patients who only received CABG had their mitral regurgitation either eliminated or dramatically reduced; so we’re talking about perhaps one-third who might benefit with less regurgitation from the repair, at the cost of some complications. It’s possible that 2, 3 or 5 years from now I could change my mind, if in fact it turns out that having less mitral regurgitation over the long haul actually is a huge benefit. But at least for now, on the 12-month follow-up, I don’t think there’s much to support going ahead with mitral valve repair.
In terms of study limitations, whenever you talk about a surgical procedure, surgical volumes and expertise always come into play; that’s a variable that’s difficult to control. The other variable is the use of cardiac ultrasound in determining the endpoint. Ultrasound measurements are good, but not as precise and reproducible as MRI might’ve been.
If you're going to use a surrogate endpoint like end-systolic volume, I think that you could come closer to testing the procedure itself by performing MRI. If you restricted the number of participating centers and got high-volume operators, then you could reduce that variable. And, certainly, long-term follow-up — which is what they’re planning — would be very important. But being left with some degree of moderate mitral regurgitation seems to be a better outcome at this stage than taking a chance on having a neurologic event.
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