Durable, Long-term Results Seen With Percutaneous Mitral Balloon Valvuloplasty

More than three-quarters of patients who undergo percutaneous mitral balloon valvuloplasty (PMBV) for severe symptomatic rheumatic mitral stenosis will have good outcomes without the need for reintervention for up to 23 years of follow-up, a Brazilian study suggests.

At a single center with experienced operators, 76.4% of patients remained free from mortality and reintervention, 99.0% remained free from mortality, and 86.5% did not require either mitral surgery or repeat PMBV, according to researchers led by Rafael Meneguz-Moreno, MD (Instituto Dante Pazzanese de Cardiologia, São Paulo, Brazil).

Independent predictors of mortality or the need for reintervention during follow-up were NYHA functional class III or IV, older age, presence of A-fib, and a mitral valve area of 1.75 cm2 or less immediately after the procedure, they report in a study published online August 1, 2018, ahead of print in JACC: Cardiovascular Interventions.

“To the best of our knowledge, this is the largest series of a single-center experience with very long-term follow-up results of patients following PMBV,” the investigators say. “As main findings, we could highlight the high rate of acute procedure success and the long-term clinical and echocardiographic maintenance of the results.”

Commenting for TCTMD, Ashish Pershad, MD (Banner - University Medicine Heart Institute, Phoenix, AZ), said the study—though subject to various limitations, including a roughly 20% loss to follow-up—“has a lot of historical importance” in terms of confirming that the procedure works with high technical and procedural success and a low complication rate.

“It solidifies what we already know about transcatheter mitral valvuloplasty as the stand-alone treatment of choice for rheumatic mitral stenosis in the right subgroup of patients,” he said.

Dearth of Very Long-term Data

PMBV remains preferred over conventional mitral valve surgery for patients with severe symptomatic rheumatic mitral stenosis, which is a declining problem worldwide because of reductions in rheumatic heart disease in recent years, but continues to take a toll in developing countries. However, information on very long-term outcomes after the procedure is lacking.

To try to fill that gap, Meneguz-Moreno and colleagues looked at data on all 1,582 patients (mean age 34.4; 86.1% women) who underwent PMBV at their center between August 1987 and July 2010. The specific valvuloplasty technique used in each case was left to the discretion of the operators. All patients underwent right and left heart catheterization and Doppler echocardiography before and after the procedure and were then followed yearly thereafter.

Acute procedural success—defined as a postprocedure valve area ≥ 1.5 cm2 and angiographic mitral regurgitation ≤ 2+ in the absence of in-hospital MACCE—was achieved in 90.9%.

Mean mitral valve area increased from 0.93 to 2.00 cm2 immediately after the procedure, with drops in mean and maximum mitral gradients that were sustained over time. Severe mitral regurgitation after valvuloplasty was observed in only 5.5% of patients.

Follow-up lasted up to 23 years, with a median of 8.3 years and a mean of 15.6 years; 20.9% of patients were lost to follow-up.

The primary endpoint of the study was a composite of all-cause mortality or the need for mitral surgery or repeat PMBV. During follow-up, 19.1% of patients had a primary endpoint event, including 0.6% who died, 8.8% who underwent mitral valve surgery, and 10.0% who had another PMBV.

Most patients (93.1%) had an improvement in NYHA class after the first postprocedural year; only 13.0% developed NYHA class III or IV symptoms, which were associated with poor outcomes, during follow-up.

Limitations Abound

In an accompanying editorial, Zoltan Turi, MD (Hackensack University Medical Center, NJ), notes, “With the low prevalence of mitral stenosis in industrialized nations, the interest in PMBV has largely waned, and there have been only a few major additions to the database in the past decade.”

He says the experience of the Brazilian researchers is admirable, but argues that a number of limitations “unfortunately narrow the study’s utility.” Those shortcomings include the young age and relatively healthy status of the patients, the use of data from a single center, the lack of independent data monitoring or use of core labs, the retrospective design, the use of open-label assessments, and the high loss to follow-up, which “is of concern for involuntary censoring of less favorable data,” he says.

Turi also questions whether the median/mean lengths of follow-up are truly “very long,” raises issues related to the techniques used for PMBV, and says that some potentially important data were not reported.

Pershad, who is also program director of the interventional fellowship program at the University of Arizona College of Medicine in Phoenix, acknowledged that the study has limitations but defended the work.

Regarding the loss to follow-up in particular, Pershad said, “If you actually look at it, you realize how hard it is even with current EMR [electronic medical record] technology to have solid follow-up like they did, and for them to do it in a pre-EMR era and capture as much data as they did in a meaningful way is truly incredible.”

Overall, he added, “it’s a paper that adds a lot to the field.”

Even though rheumatic mitral stenosis has become less of a problem in many parts of the world, the findings of this study are relevant for physicians treating older patients with degenerative mitral stenosis, Pershad said. “More complex patients or older patients may not have the same stellar results like the original patients with rheumatic mitral stenosis who were younger in the developing world, but [the study] gives us hope that [PMBV could] be like a palliative bridge to a definitive treatment in older patients with degenerative mitral stenosis that ultimately—I think within the next decade—will be treated with transcatheter mitral valve replacement.”