In patients who undergo transcatheter mitral valve repair for mitral valve regurgitation (MR), residual mild (+2) regurgitation has been considered procedural success, but a team of Italian investigators has provided evidence that such a result may actually foretell far worse long-term outcomes than residual trace (≤1) MR.

The investigators from San Raffaele Scientific Institute in Milan reported their findings in the January issue of the Journal of Thoracic and Cardiovascular Surgery ( J Thorac Cardiovasc Surg 2016;151:88-96 ). They compared follow-up outcomes of 223 consecutive patients with residual MR 2+ and MR ≤1 after implantation of the MitraClip system (Abbott Vascular). The procedures were performed between October 2008 and December 2014.

“In this study we found a clear unfavorable impact on follow-up outcomes of acute residual 2+ MR after MitraClip repair when compared to residual ≤1+ MR,” lead author Dr. Nicola Buzzatti and colleagues said.

The study cited a scarcity of data on the long-term impact of residual mild MR. “This topic is therefore particularly of interest, especially when assessing the convenience to expand transcatheter mitral repair procedures to intermediate or low-risk patients,” Dr. Buzzatti and coauthors said.

The study group all had moderate or greater (≥3+) MR when they underwent mitral valve repair (MVR). The post-MVR study cohort excluded patients who had residual MR of 3 or greater, which was considered a procedural failure. Four patients died within 30 days, each from a different cause: multi-organ failure, lung rupture, pneumonia with heart failure, and sudden death. The overall 30-day death rate was 1.8%.

Among the remainder of patients, the average follow-up was 20.5 months, with some follow-up extending to 75 months. The overall survival was 74.4% at 24 months and 63% at 48 months.

The study calculated the cumulative incidence function, or the probability of failure, of cardiac death in patients with residual MR ≤1 at 7.1% at 24 months and 10.9% at 48 months, compared with 26.9% at 24 months and 35.3% at 48 months in those with MR 2+. The probability of failure of recurrence of moderate or severe MR with residual MR ≤1 was 5.6% at 24 months and 13.3% at 48 months, compared with 45.2% at both 24 and 48 months with residual MR 2+. “The difference between MR ≤1 and MR=2 was significant,” Dr. Buzzatti and colleagues said.

The researchers separately evaluated outcomes among those who had functional MR (FMR) and degenerative MR (DMR). In FMR, patients with MR 2+ had a higher risk profile at baseline because of a slightly higher rate of advanced heart disease; they typically had larger ventricles with larger mitral valves and greater pulmonary pressure than the ≤1 MR patients. “Notably, these features could have impaired the surgeon’s ability to achieve acute optimal MR reduction during the MitraClip procedure,” Dr. Buzzatti and coauthors said. “For sure, advanced left ventricle remodeling was a strong independent predictor of increased cardiac death.” The study authors could not draw a similar conclusion with DMR because only three patients in the group died of cardiac causes.

MR recurrence was “remarkably higher” in MR 2+ patients, compared with the MR ≤1 group with FMR and DMR, and MR 2+ developed in 21.4% of the FMR group within 30 days of the procedure. “This poor efficacy results in a population of patients who were supposed to have had a ‘procedural success’ is striking,” Dr. Buzzatti and coauthors noted.

Dr. Buzzatti and coauthor Dr. Paolo Denti disclosed receiving consultant fees from Abbott Vascular. Coauthor Dr. Fabio Barili disclosed receiving consultant fees from St. Jude Medical. The other coauthors had no relationships to disclose.