U.S. sites that perform transcatheter mitral valve interventions should treat a minimum of 20 such patients each year or at least 40 every 2 years, according to revised recommendations and requirements released on Dec. 16, 2019, by several U.S. cardiology and cardiac surgery societies.
Dr. Robert O. Bonow
The revised recommendations also for the first time address patient selection for using transcatheter mitral valve (MV) intervention in patients with mitral regurgitation (MR) secondary to heart failure and a left ventricular ejection fraction of 21%-49%, a patient target for transcatheter interventions approved by the Food and Drug Administration in March 2019. The FDA first approved the same transcatheter MV intervention system (MitraClip) in 2013 for patients with primary MR caused by an abnormality of the MV and a prohibitive risk for surgical MV repair or replacement, and the same societies had previously issued their recommendations based on that approval (J Am Coll Cardiol. 2014 Oct; 64[14]:1515-26).
The need for updated recommendations on the delivery of transcatheter MV interventions including the personnel and facilities required for a valid U.S. program was driven by “new transcatheter technology, new trial results, and the new FDA-approved indication” of secondary MR. “We did the update for patients with secondary MR,” said Robert O. Bonow, MD, professor of medicine at Northwestern University, Chicago, and chair of the committee that wrote the revised recommendations.
“Primary and secondary MR are like two different diseases. Primary MR is a disease of the MV leaflets. Secondary MR is a disease of heart failure, left ventricular dysfunction, and left ventricular enlargement.” That makes secondary MR an indication with a potentially huge upside, given how many patients have heart failure today, plus projections for steadily increasing numbers of patients as the geriatric population grows.
“Heart failure is a huge issue, and the numbers are growing, which is why we felt it was important to say which heart failure patients should be candidates. We did not endorse this for all patients, although MR is very common in heart failure,” with estimated prevalence rates as high as two-thirds of all heart failure patients, Dr. Bonow said.
The new recommendations spell out an approach to patient selection that aims to apply transcatheter MV intervention to patients who match those enrolled in the COAPT (Cardiovascular Outcomes Assessment of the MitraClip Percutaneous Therapy for Heart Failure Patients With Functional Mitral Regurgitation) trial, which randomized 614 patients with MR secondary to heart failure and found for that MV intervention cut the rate of heart failure hospitalization by about half during 2 years of follow-up, a statistically significant effect for the study’s primary endpoint (N Engl J Med. 2018 Dec 13;379[24]:2307-18). The new recommendations provide “a way to replicate the COAPT trial” in routine practice, Dr. Bonow said in an interview.”We thought it was important to try to replicate the COAPT results,” and a key step toward trying to accomplish that is to apply the multidisciplinary team concept to evaluating patients and determining their management strategy. Dr. Bonow coauthored a commentary that discussed how the COAPT results should influence routine practice (N Engl J Med. 2018 Dec 13;379[24]:2374-6).
“In this case, perhaps the most important member of the multidisciplinary team is the heart failure specialist, because secondary MR is a disease of heart failure and it’s important to also optimize medical therapy to reduce MR and prolong life,” he said. Treatment optimization before undertaking a transcatheter MV intervention involves not only drug treatment but also treatment with indicated devices, such as biventricular pacing, to optimize left ventricular size and function. The 2019 FDA approval of the transcatheter approach for treating MV disease specified that eligible patients had to continue to have significant MR despite receiving optimal drug and device treatment.
Treatment decisions for patients with MR must be highly individualized, and unlike transcatheter aortic valve replacement (TAVR), which occurs against a background of “really good results” for surgical aortic valve replacement, surgical treatment of MR “has never been shown to prolong life, although it can improve function,” Dr. Bonow said. In addition, open surgical repair or replacement of a faulty MV “is much better than the MitraClip for elimination a MV leak; usually with transcatheter intervention there is some residual leak. And other etiologies of MR, such as atrial fibrillation causing atrial enlargement and dilatation of the mitral annulus, generally have much better results with surgery than with a transcatheter intervention. For both primary and secondary MR, deciding when to use surgery and when to do a transcatheter intervention is very individualized,” concluded Dr. Bonow, and a fact that distinguishes transcatheter MV interventions from TAVR, which has been shown to have efficacy that’s comparable with surgical aortic valve replacement. The MitraClip system is currently the only device with U.S. marketing approval for transcatheter MV intervention, although other devices are in development.