Mortality rates for patients with moderate to severe mitral regurgitation who underwent transcatheter aortic valve replacement (TAVR) were significantly higher than for patients with mild or no mitral regurgitation in an analysis of multicenter registry data.

In the Nov. 5 issue of Circulation, Francesco Bedogni, MD, of the Insituto Clinico S. Ambrogio in Milan, and colleagues reported the results from a study of 1,007 consecutive patients who underwent TAVR using the CoreValve Revalving System (Medtronic) third-generation 18-F device. The procedures took place between June 2007 and April 2011 in patients with severe aortic stenosis.

“[W]hen considering the baseline comorbidities, it is unclear whether the coexistence of mitral regurgitation (MR) could worsen the outcome after TAVR,” they wrote. “It is also uncertain whether TAVR could exert a beneficial effect on MR severity by reducing afterload.”

They graded MR severity as no or mild (0/1), moderate (2) or severe (3). Of the 1,007 patients studied, 66.5 percent had no/mild MR, 24.1 percent had moderate MR and 9.3 percent had severe MR at baseline.

Mortality rates at one month were 5 percent in the no/mild MR group, 9 percent in the moderate MR group and 11 percent in the severe MR group. At one year, the rates changed to 10 percent, 12 percent and 17 percent, respectively. Cardiac mortality was higher in the moderate and severe MR groups compared with the no/mild MR group at one month and one year.

Almost half (47 percent) of patients with severe MR and 35 percent with moderate MR at baseline experienced improvement of one or more grade in MR after TAVR. In 3 percent, valve function worsened. Moderate to severe MR, atrial fibrillation and severe pulmonary hypertension independently predicted mortality.

“[B]oth moderate MR and severe MR determine a worse prognosis compared with mild/no MR but do not confer a statistically different risk of mortality when compared head to head,” Bedogni et al wrote. “Overall, there is a stepwise increased risk of mortality from mild/none to severe MR.”

They noted that some physicians have speculated that characteristics of the CoreValve design compared with Sapien (Edwards Lifesciences) valve might impair mitral valve function, particularly with low implantation. “Our data actually rule out this phenomenon because the incidence of worsened MR was quite low and no difference was observed in the low implantation rate between those with and those without a worsened MR.”

In an accompanying editorial, Alexandra Goncalves, PhD, and Scott D. Solomon, MD, of Brigham and Women’s Hospital in Boston, pointed out that the benefit of TAVR might be greater in patients with moderate to severe MR despite their overall higher morbidity and mortality. “Considering the high prevalence of MR and the frequency of events in patients undergoing TAVR with significant MR, additional trials to determine whether patients with moderate to severe MR will benefit from TAVR are certainly warranted to support the best medical decision,” they proposed.