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Moderate or severe mitral regurgitation (MR) at baseline contributes to poorer prognosis in patients undergoing transcatheter aortic valve replacement (TAVR), according to results of a large registry study published online October 2, 2013, ahead of print in Circulation. The authors suggest that although TAVR improves MR in many such patients, any benefit may be overwhelmed by comorbidities.

A research team led by Luca Testa, MD, PhD, of Istituto Clinica S. Ambrogio (Milan, Italy), evaluated 1,007 patients with MR who underwent TAVR for severe aortic stenosis with the third-generation 18-Fr CoreValve Revalving System (Medtronic, Minneapolis, MN) at 11 Italian centers between June 2007 and April 2011 and were enrolled in a nationwide registry.

Transthoracic echocardiography showed that at baseline, 66.5% had no/mild (grade 0-1) MR, 24.1% had moderate (grade 2) MR, and 9.3% had severe (grade 3) MR. No differences were seen across the groups in terms of procedural characteristics or results.

Moderate, Severe MR Confer Higher Mortality Risk

At both 1 month and 1 year (after censoring of 1-month mortality), rates of overall mortality were similar between patients with severe or moderate MR (OR 1.1; P = 0.21 and P = 0.06, respectively), but both groups had higher rates of death than those with no or mild MR (OR 2.2; P < 0.001 and OR 1.9; P = 0.02, respectively, for 1 month; HR 1.7; P < 0.001 and HR 1.4; P = 0.03, respectively, for 1 year). The same pattern held true for cardiac mortality, except that at 1 year the moderate and no/mild MR groups had similar rates. There was no difference in noncardiac mortality among the MR groups at either time point.

In addition, at 30 days the percentage of patients in New York Heart Association (NYHA) class 1 or 2 tended to be lower among patients with severe baseline MR compared with those with moderate and no/mild MR (59% vs. 67% and 73%) and rates of hospitalization for heart failure tended to be higher (18% vs. 13% and 8%; P = 0.09 for all comparisons).

In Cox regression analysis, independent predictors of 1-year overall mortality were:

• Severe pulmonary hypertension (HR 1.5; P = 0.03)
• A-fib (HR 1.6; P = 0.01)
• Creatinine clearance less than 30 mL/min (HR 1.92; P = 0.003)
• Moderate or severe MR (HR 2.9; P = 0.001)

At 1 year, mitral regurgitation had improved by at least 1 grade in 47% of patients with severe MR at baseline and in 35% with moderate MR, while valve function worsened in 3% of those with moderate MR and 8.4% of those with mild or no MR. In no case did MR decline by more than 1 grade.

Regardless of MR severity at baseline, patients who showed improvement in mitral valve function had a lower rate of severe pulmonary hypertension and A-fib compared with those in whom MR remained unchanged or worsened. LVEF and end diastolic volume did not change over time within either category.

Predictors of MR Improvement

Cox regression analysis identified the following independent predictors of improvement in MR severity:

• Absence of severe pulmonary hypertension (HR 2.9; P = 0.002)
• Absence of A-fib (HR 2.02; P = 0.003)
• Functional etiology of MR (HR 2.6; P = 0.005) 

According to the authors, “the clinical impact and evolution of MR after TAVR [are] still a matter of concern.” They note that while the randomized PARTNER A and B trials suggest a greater mortality benefit in TAVR patients with moderate-to-severe MR, in several national registries, the presence of such MR has been consistently associated with a worse prognosis.

The question is complicated by use of devices with different designs, Dr. Testa and colleagues observe, with some suggesting that the longer CoreValve device may interfere with the anterior leaflet of the mitral valve, especially when implanted in a low position. However, they assert, the current data appear to exonerate CoreValve in that “the incidence of a worsened MR was quite low and no difference was observed in the low implantation rate between those with and without a worsened MR.”

Countervailing Forces

The fact that decreasing MR severity did not increase the likelihood of survival may be due to the attenuation of the positive effects of TAVR by other, negative factors, the authors say. Key clinical features such as renal failure, COPD, previous stroke, and frailty as well as procedural issues such as paravalvular leak, periprocedural stroke, and bleeding may overwhelm any improvement in mitral valve function, they note

In an accompanying editorial, Alexandra Gonçalves, MD, and Scott D. Solomon, MD, of Brigham and Women’s Hospital (Boston, MA), write that given the high prevalence of MR in patients who undergo TAVR and the frequency of events among those with significant MR, trials to determine whether such patients benefit from the procedure are warranted to inform decision making.

In a telephone interview with TCTMD, Ted Feldman, MD, of Evanston Hospital (Evanston, IL), cautioned against concluding that TAVR does not help in moderate or severe MR. “I still make the presumption that these patients got something out of TAVR, but that MR has a graded [adverse] effect on late outcomes,” he said.

Managing Patient Expectations

“For me, the utility of this paper is in managing patient expectations,” he continued. “On the better extreme, you can say, ‘If you have mild MR and you don’t have A-fib or pulmonary hypertension, this procedure is going to be very favorable in terms of its impact on outcomes.’ At the other end of the spectrum, I’d say to severe MR patients, ‘I still think TAVR is reasonable. If you have pulmonary hypertension and A-fib, there’s a good chance that this therapy won’t help, but it’s far from a sure thing.’” In terms of deciding which patients should not be offered TAVR, these findings “will inform the borderline,” Dr. Feldman added.   

Although concurrent mitral repair with MitraClip is not yet an option in the United States, the proposed strategy represents “a logical sequence of therapies,” Dr. Feldman commented. In his own practice, he reported, in patients with severe MR he first performs aortic balloon valvuloplasty, and if after 4 to 8 weeks their MR has improved to at least moderate status, “then we feel much more comfortable offering TAVR.” 

1. Bedogni F, Latib A, Brambilla N, et al. Interplay between mitral regurgitation and transcatheter aortic valve replacement with the CoreValve Revalving System: A multicenter registry. Circulation. 2013;Epub ahead of print.

2. Gonçalves A, Solomon SD. Mitral regurgitation in TAVR: The complexity of multivalvular disease [editorial]. Circulation. 2013;Epub ahead of print.

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