The MATTERHORN trial, presented at ESC Congress 2024, revealed that transcatheter edge-to-edge repair (TEER) is non-inferior to traditional surgery for patients with secondary mitral regurgitation (MR). The randomized controlled trial, conducted across 16 centers in Germany, challenges existing guidelines and offers a less invasive option for high-risk patients.
MATTERHORN Trial Details
The investigator-initiated trial enrolled 210 patients with secondary MR and a left ventricular ejection fraction (LVEF) ≥20%, who exhibited heart failure symptoms (New York Heart Association [NYHA] class ≥2) despite optimal guideline-directed medical therapy. All patients were deemed at high surgical risk by a local Heart Team and were randomized 1:1 to either mitral TEER or surgical mitral valve therapy (repair or replacement).
The primary efficacy endpoint was a composite of death, hospitalization for heart failure, mitral reintervention, assist device implantation, and stroke at 1 year. A key secondary endpoint was the recurrence of MR grade ≥3 at 1 year. The primary safety endpoint, assessed at 30 days, included death, myocardial infarction, major bleeding, stroke or transient ischaemic attack, rehospitalization, all reinterventions, non-elective cardiovascular surgery, renal failure, deep wound infection, mechanical ventilation >48 hours, gastrointestinal complications requiring surgery, new-onset atrial fibrillation (AF), septicemia, and endocarditis.
Key Findings
The study population had an average age of 70.5 years, with 40% being female. The mean LVEF was 43%, and 86% of patients were classified as NYHA class III or IV heart failure. The median European System for Cardiac Operative Risk Evaluation (EuroSCORE) II score was 3%. In the surgical group, 72% underwent mitral valve repair, and 28% underwent mitral valve replacement.
At 1 year, the primary composite endpoint occurred in 16.7% of patients in the TEER group and 22.5% in the surgical group (odds ratio [OR] 0.69; 95% confidence interval [CI] 0.33-1.44; p=0.320), confirming non-inferiority (p<0.01). There was no significant difference in the recurrence of MR grade ≥3 at 1 year: 8.9% in the TEER group versus 1.5% in the surgical group (OR 6.22; 95% CI 0.75- 51.95; p=0.091). After 1 year, 73.2% of patients in the TEER group and 87.3% of patients in the surgical group had MR grade ≤1, demonstrating the efficacy of both therapies.
Safety Benefits of TEER
The primary safety endpoint occurred in significantly more patients in the surgical group (54.8%) than in the TEER group (14.9%; p<0.001). This difference was largely driven by more major bleeding (29% vs. 3%, respectively), all reinterventions (19% vs. 8%), and new-onset AF (33% vs. 9%).
Implications for Clinical Practice
"The MATTERHORN trial is the first randomized trial to demonstrate the non-inferiority of TEER and surgery in patients with secondary MR. These new data may become important to guide decision making as European guidelines currently recommend TEER may be considered in patients who are judged inoperable or at high surgical risk by the Heart Team," said Professor Stephan Baldus from the University of Cologne, Germany, the trial's Principal Investigator. The findings suggest a potential shift in treatment strategies, particularly for patients at high surgical risk.
