SAN FRANCISCO — Mitral valve surgery in patients with mitral regurgitation and advanced systolic heart failure induces reverse ventricular structural remodeling, a major benefit that's further augmented by implantation of the CorCap cardiac support device at the time of the valve operation, Michael A. Acker, M.D., reported at the annual meeting of the American Association for Thoracic Surgery.
A new secondary analysis of a 300-patient multicenter randomized trial of the Acorn Cardiovascular Inc. CorCap cardiac support device similarly showed that while mitral valve (MV) surgery alone also improved patient symptoms and enhanced quality of life scores, the extent of these benefits was substantially greater when the MV procedure was combined with placement of the cardiac support device (CSD) designed to directly target the ventricle, he added.
“Improvement in symptoms and left ventricular function along with a very low mortality risk justifies strong consideration to offering mitral valve surgery in combination with a CSD to nonischemic heart failure patients who've been medically optimized yet remain symptomatic with significant mitral insufficiency,” said Dr. Acker, professor of surgery and chief of the division of cardiothoracic surgery at the University of Pennsylvania, Philadelphia.
The overall results of the Acorn CSD trial were presented last fall at the annual scientific sessions of the American Heart Association. The data showed that the CSD—a synthetic mesh bag surgically placed around the heart to provide passive ventricular restraint—resulted in reduced left ventricular (LV) volume and a transformation from the dysfunctional spherical-shaped heart characteristic of advanced heart failure to a more mechanically efficient and electrically stable elliptical one. This translated into improved cardiac function; a marked reduction in heart transplantation or need for an LV assist device during follow-up; and significant quality-of-life gains, compared with optimal medical management in this population of patients with mainly New York Heart Association class III heart failure of nonischemic etiology.
Dr. Acker's subanalysis focused on the 193 trial participants with severe mitral regurgitation who underwent MV surgery plus randomization to the CSD or medical therapy alone: 84% of the MV operations were valve repairs, and the rest were replacements. In-hospital mortality was 1.6%. The 1- and 2-year survival rates were 86.5% and 85%, respectively, with no significant difference between patients who got the CSD and those who had MV surgery alone.
At 2 years' follow-up, patients who received MV surgery alone had a highly significant mean 27.8-mL reduction in LV end-diastolic volume, compared with baseline. However, patients who had MV surgery and got a CSD showed an even more impressive 45.7-mL reduction.
Similarly, patients who got MV surgery alone showed a significantly improved heart sphericity index, compared with baseline—but the improvement in sphericity score was nearly threefold greater in those who also got a CSD. Patients who underwent MV surgery alone also showed a significant reduction in LV end-systolic volume, a benefit that was substantially larger in the group that received a CSD. Two years following MV surgery, nearly 90% of patients had either no, or only mild, mitral regurgitation.
The traditional view has been that the MV functions as a sort of pop-off valve for the failing ventricle. The belief has been that the increase in afterload following surgical correction of the severe mitral regurgitation that commonly accompanies advancing heart failure would result in prohibitive mortality and, at best, only short-term improvement in MV function.
This view was first challenged a decade ago by Steven Bolling, M.D., who famously proposed what he described as an annular solution for what he argued was essentially a ventricular problem. The Bolling hypothesis held that using an undersized ring in the repair of the MV annulus would fix the abnormal annular geometry, alleviate excessive LV workload, improve LV geometry, and boost ventricular function. The Acorn CSD study provides the first definitive proof in the form of prospective multicenter clinical trial data.
Discussant D. Craig Miller, M.D., professor of cardiovascular surgery at Stanford (Calif.) University, said many Stanford cardiologists were skeptical of the initial Acorn CSD findings presented at the AHA. They thought the observed benefits were simply due to the MV surgery and doubted the CSD added anything. “When our heart failure cardiologists see these new data, it's going to open their eyes,” Dr. Miller predicted.
Another important finding in the new subanalysis, Dr. Miller continued, is that the benefits don't wane with time. In fact, the additional 6 months of follow-up included in the secondary analysis demonstrated that the improvement is progressive. “Clearly the device is inducing some uncharacterized biologic signal which is good for these folks,” he added.