Study Investigates Impact of Moderate or Severe MR in TAVR Patients

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While moderate or severe mitral regurgitation (MR) may increase early mortality in patients undergoing transcatheter aortic valve replacement (TAVR), late mortality appears unaffected, with MR improving in more than half of moderate/severe cases by 1 year, according to results published online April 4, 2012, ahead of print in the Journal of the American College of Cardiology. The findings, the authors say, suggest that TAVR may be appropriate for carefully selected patients with moderate/severe MR.

Researchers led by John G. Webb, MD, of St. Paul’s Hospital (Vancouver, Canada), looked at 451 patients who received TAVR at 2 Canadian hospitals between January 2005 and July 2010. Over two-thirds of the patients (70.7%) had mild or better than mild MR at baseline (n = 319), while 19.7% (n = 89) had moderate MR, and 9.5% (n = 43) had severe MR. Valves implanted included the Cribier-Edwards (12%), Sapien (60%), and Sapient XT devices (28%; all Edwards Lifesciences, Irvine, CA).

Early Mortality, Late Improvement

Preliminary results from the series were reported in November 2011 at the annual Transcatheter Cardiovascular Therapeutics scientific symposium in San Francisco, CA.

Procedural characteristics and outcomes including access route, prosthesis size, mean gradient, aortic valve area, and major stroke were equivalent regardless of MR status. Survival rates at 30 days, 1 year, and 2 years decreased with baseline MR severity (table 1).

Table 1. Kaplan-Meier Survival Estimates

Compared with patients with mild or less than mild MR, those with moderate or severe MR had a higher adjusted mortality risk in the first 30 days after TAVR, but no increased risk after 30 days (table 2).

Table 2. Mortality Risk, Moderate or Severe vs. Mild or Less MR

At 1-year follow-up, New York Heart Association (NYHA) functional class had improved, with only 6% of patients with moderate MR and 5% of patients with severe MR in NYHA class III or IV. In addition, 1 year after TAVR, moderate MR had improved by at least 1 grade in 58% of patients, remained the same in 17%, and worsened in 1%. Severe MR, meanwhile, had improved by at least 1 grade in 49% and remained severe in 16%. Overall, at 1 year, MR was improved in 55% of patients with moderate or severe MR at baseline.

Predictors of MR improvement at 1 year included:

• Mean transaortic gradient ≥ 40 mm Hg (OR 2.92; 95% CI 1.20-6.60; P = 0.01)
• Presence of functional (as opposed to structural) MR (OR 2.85; 95% CI 1.27-6.39; P = 0.01)
• Absence of pulmonary hypertension (OR 2.57; 95% CI 1.07-6.16; P = 0.03)
• Absence of atrial fibrillation (OR 2.55; 95% CI 1.19-5.46; P = 0.02)

At 1 year, patients with moderate or severe MR had significant improvements in LVEF, left ventricular end-diastolic diameter, and pulmonary artery systolic pressure, but 28% had died.

The authors note that despite the increased procedural mortality in patients with MR undergoing TAVR, “these findings demonstrate late functional benefit in survivors and are consistent with, but do not prove, a possible late survival benefit. . . . TAVR may be a reasonable strategy in carefully selected patients with combined aortic and mitral valve disease.”

Addressing Patients Excluded from PARTNER

Dr. Webb and colleagues add that after aortic valve replacement, MR is expected to improve immediately due to a reduction in afterload and may, in fact, diminish further in the mid and long term if positive LV remodeling occurs. However, as in the current study, “MR reduction may be less likely in patients with structural mitral valve disease, such as might occur in the presence of deformed leaflets or moderate or severe annular calcification,” they write.

In a telephone interview with TCTMD, Ted Feldman, MD, of Evanston Hospital (Evanston, IL), noted that the paper addresses a key population that was excluded from the PARTNER trial, patients with severe MR. “The article answers a question that PARTNER can’t,” Dr. Feldman said. “The big item is that more than half of those patients with severe MR had an improvement. It also tells us, not surprisingly, that it’s a marker for worse outcomes, so they don’t all get better.”

But that should not give clinicians pause. “These are patients who don’t really have an option, so you’re not going to deny them the therapy,” Dr. Feldman said. “This may be an extreme example of bigger risk and bigger reward. Once they get better, it’s a 2-valve therapy by treating 1 valve. It’s a huge reward for the risk.”

Proper Patient Selection Key

The critical aspect is selecting those patients with severe MR who will benefit. “It’s really encouraging to see that more than half improved, and it’s imperative now that we try and figure out what separates out those who improve from those who don’t survive,” Dr. Feldman said.

Philippe Genereux, MD, of Columbia University Medical Center (New York, NY), agreed that “this is still an area where we need to know more about how to select patients.” A key component that was missing from the paper that could help risk stratification is right ventricular function, Dr. Genereux told TCTMD.

Nevertheless, he added, “this opens the door to interesting combinations. Perhaps you do TAVR in these very sick patients and reevaluate the MR at 1 or 3 months. If they still have MR and aren’t responding, you can do a mitral clip or some other less invasive procedure.”

The effect of these findings on referring cardiologists is also important, Dr. Genereux noted. “Noninterventional cardiologists [have been] reluctant,” he said. “They would look at the MR and say, ‘Well, it’s too late, [the patient] has severe MR.’ But that’s not true, [because] all severe MR is not the same.”

Dr. Genereux acknowledged that mortality with TAVR is higher with concomitant MR, “but if you do nothing, they will die in 1 or 2 years,” he said. “This will bring some help for this category of patient, and that’s good news.”

 

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Source:
Toggweiler S, Boone RH, Rodés-Cabau J, et al. Transcatheter aortic valve replacement: Outcomes of patients with moderate or severe mitral regurgitation. J Am Coll Cardiol. 2012;Epub ahead of print.

 

 

Related Stories:

• Mitral, Aortic Regurgitation Increase Mortality After Transcatheter Valve Replacement
• Study Looks at Long-term Mortality Predictors in TAVR Patients
• PARTNER: TAVR Remains as Effective as Surgery at 2 Years

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