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PARIS -- Transcatheter mitral valve replacement (TMVR) could be the better choice over conservative therapy for secondary (or functional) mitral regurgitation (MR), according to researchers settling for an indirect retrospective comparison in the face of absent randomized data.

People who received investigational TMVR devices as part of the CHOICE-MI registry were propensity-matched with peers from the guideline-directed medical therapy (GDMT) arm of COAPT, the controls of a trial originally designed to test another technology, transcatheter edge-to-edge repair (TEER).

Based on 97 matched pairs, 2-year clinical outcomes largely favored the TMVR cohort, according to Sebastian Ludwig, MD, of University Heart and Vascular Center Hamburg, Germany:

• Mitral regurgitation: graded as mild or none in all TMVR recipients vs more severe cases observed in the GDMT arm
• New York Heart Association: more favorable mix of function with more TMVR recipients in class I or II
• Mortality: no significant difference between groups (36.8% vs 40.8%, log-rank P=0.98)
• Heart failure hospitalization: significantly reduced with TMVR (32.8% vs 54.4%, log-rank P=0.04)

Ludwig presented his group's findings at the EuroPCR conference and had the full study manuscript published simultaneously in .

"In the absence of randomized controlled trials, these results provide important preliminary evidence on the benefits of TMVR," he said.

He cautioned, however, that this was an exploratory analysis that featured highly selected populations and was not powered to detect a difference in survival. His report also left room for selection bias given the likelihood of unaccounted-for anatomical differences between TMVR and GDMT groups. Echocardiographic follow-up was also incomplete.

Secondary MR differs from primary MR in that it is related to left ventricular dysfunction instead of abnormalities in the mitral valve leaflets and chords themselves.

Patients with secondary MR showed clinical benefits from MitraClip TEER in the COAPT trial. Nevertheless, mere clipping may not be enough for this MR subtype, as suggested by in which TMVR was associated with better secondary MR reduction and superior symptom improvement (notwithstanding an early disadvantage in survival) compared with TEER.

During a press conference, Ludwig said more definitive randomized data are absent primarily due to a high rate of screening failure that has resulted in early feasibility trials of TMVR being slow to enroll.

CHOICE-MI is a retrospective registry that includes patients screened for TMVR regardless of ultimate treatment. Participants received a variety of dedicated devices, albeit mostly transapical ones (i.e., the Tendyne bioprosthetic valve), according to Ludwig.

He suggested that a transfemoral system may produce better results, particularly when it comes to TMVR's lackluster mortality data, currently the "elephant in the room."

Yet the reduction in heart failure hospitalization is in itself a "huge" achievement by TMVR as this was not seen in the surgical literature, according to session panelist Patrizio Lancellotti, MD, PhD, of University of Liège, Belgium.

And there is more room for hope as operators move away from transapical approaches, suggested fellow panelist Ralph Stephan von Bardeleben, MD, PhD, of Universitätsmedizin der Johannes Gutenberg-Universität Mainz, Germany. The later experience with TMVR may also improve, as CHOICE captured the first compassionate use cases, von Bardeleben said.

He concluded that the present study marks an "important step," as it shows there's "at least no disadvantage" but instead a possible advantage in clinical outcomes after TMVR for secondary MR.