Transcatheter mitral valve replacement (TMVR) is associated with high rates of mortality in patients with severe mitral annular calcification (MAC), but survivors show significant improvements in heart-related symptoms.
These findings from the TMVR in MAC Global Registry were published online April 23 in the Journal of the American College of Cardiology.
Lead author Mayra Guerrero, MD, and colleagues analyzed 106 patients at extreme surgical risk who underwent TMVR using balloon-expandable aortic transcatheter valves. Their average age was 73, 63 percent were female and 90 percent were in New York Heart Association (NYHA) functional class III or IV at baseline.
A quarter of the patients died at 30 days and 53.7 percent died within a year. But among those that lived to 30 days, 63.6 percent were alive at one year and 71.8 percent of those survivors were in NYHA functional class I or II—a significant improvement from baseline.
“Although there were important complications and a high 30-day mortality, we interpreted the results as encouraging considering this study represents the first human experience with a THV (transcatheter heart valve) not designed for the mitral position and used in an extremely high-risk patient population with a mean Society of Thoracic Surgeons risk score much higher than in the PARTNER I (Placement of Aortic Transcatheter Valves) trial,” wrote Guerrero, an interventional cardiologist at Evanston Hospital in Evanston, Illinois, and coauthors.
Indeed, comorbidities and the baseline STS risk score of 15.3 percent appeared to contribute to the high rate of noncardiovascular mortality observed during follow-up. Noncardiovascular deaths accounted for nearly half of the 30-day mortality and more than half of the one-year mortality.
It is precisely this high level of risk that makes surgery a nonstarter in this population, the authors noted.
“TMVR in carefully selected patients may be an alternative with the potential to provide significant improvement in symptoms and quality of life,” they wrote.
The authors pointed out there was trend toward lower 30-day mortality (31 versus 19 percent) in the second half of the study and a lower need for a second valve (19 versus 10.3 percent). Four patients needed to be converted to surgery in the first half of the study and none in the second—suggesting procedural techniques and patient selection improved as operators became more experienced.
But three authors of an accompanying editorial weren’t convinced. They said the high complication rates throughout the study were concerning—particularly for left ventricular outflow tract obstruction (LVOT), which was found to increase from 9.3 percent in the researchers’ first report from this registry to 11.2 percent in the new report.
“Because reporting all cases was not mandatory, and there was no way to fully adjudicate the data to ensure full reporting, it is both possible and likely that selective reporting, or cherry-picking, occurred to make the data look better,” wrote Danny Ramzy, MD, PhD, and colleagues, all with Cedars-Sinai Medical Center in Los Angeles. “This possibility suggests that significant limitations to this technology remain and that further device innovations are required to improve procedural success and to limit the development of LVOT obstruction.”
The editorialists called LVOT obstruction “the Achilles’ heel of TMVR” and said the high 30-day mortality supports that the procedures themselves remain too dangerous.
However, Ramzy et al. acknowledged the high rate of one-year survival among those who made it to 30-days post-operation is reason for optimism, as well as their improved NYHA functional class. But they said TMVR is not quite “ready for prime time,” and judicious patient selection will be the best way to prevent excess mortality in these patients until more information is available.
“We are encouraged, as this study and others seem to indicate that the main issues are procedural success and LVOT obstruction,” the Cedars-Sinai researchers wrote. “Therefore, the 2 challenges posed to the field are to improve implant technique and valve design. It is apparent that the transcatheter approach to the mitral valve is more complicated than that of the aortic valve, and it requires its own separate technique, valve design, and patient assessment. The technique will also require joint efforts from the surgeons, cardiologists, and imaging experts.”
Daniel joined TriMed’s Chicago editorial team in 2017 as a Cardiovascular Business writer. He previously worked as a writer for daily newspapers in North Dakota and Indiana.