The largest dedicated registry on mitral transcatheter edge-to-edge repair (M-TEER) in primary mitral regurgitation (MR) has shown a constant decline in complication rates, which has corresponded with a gradual decline in the proportion of residual MR and overall improvements in outcomes over time.
These were the headline conclusions from the presentation of preliminary results of the PRIME-MR registry, presented by Benedikt Koell (University Heart Center Hamburg, Hamburg, Germany) at PCR London Valves (27–29 November, London, UK) in a late-breaking trial and innovation session.
To date, Koell said, the EVEREST II trial and large registry studies of mitral valve edge-to-edge repair have either focused upon primary or secondary mitral regurgitation, Koell said. However, he noted that since the publication of results from the COAPT and MITRA-FR trials, “scientific focus has shifted towards secondary MR,” commenting that there is a lack of data on primary MR for TEER patients.
In order to bridge this gap, Koell and colleagues initiated PRIME-MR, an international, retrospective registry, collecting data from 24 high-volume TEER centres in Europe, the USA and Canada. In total, the registry has collected data from 2,363 patients treated between 2008 and 2022.
Koell’s presentation focused on temporal trends for M-TEER, focusing on safety endpoints according to the Mitral Valve Academic Research Consortium (M-VARC) and all-cause mortality. In total, 361 patents were excluded from the analysis due to missing follow-up. The remaining 2,002 patients were subdivided into four groups based upon the timing of their procedure, with 276 taken from 2008–2014, 384 from 2014–2016, 822 from 2017–2019, and 530 from 2020–2022.
Koell noted that the registry included elderly patient cohort, with the main reason for patients being denied surgery being advanced age, followed by comorbidities, frailty, and previous heart surgery.
Most patients (83.7%) presented with isolated primary MR, while a smaller proportion (16.3%) had mixed MR, albeit with primary MR as the leading cause. Looking at the main MR pathology, Koell noted that there was a relatively even split between patients with prolapse (44%) and flail 49.8%. Implanted devices included MitraClip (Abbott) generations one through four, as well as Pascal (Edwards Lifesciences) P10 and ACE.
Koell described the patients treated as an “older, symptomatic cohort”, with an average age of 81 years across the 14-year duration of the study. Looking at the different time intervals, Koell noted that, interestingly, the study saw a decline in symptomatic patients, detailing that the proportion of patients in New York Heart Association (NYHA) class III/IV stood at 86.2% among the patients treated between 2008–2013, 86.4% in 2014–2016, 76.4% in 2017–2019 and 67 in 2020–2022. The data also point to a decline in Society of Thoracic Surgeons (STS) Score over time, spanning 5.7±4.5 in 2008–2013, 5.1±4 in 2014–2016, 4.8±3.5 in 2017–2019 and 4.8±3.9 in 2020–2022.
Turning to the safety endpoints, Koell reported that there was a decline in safety endpoints and reintervention rates from 2008 through to 2022, with no M-VARC safety endpoints reported in 45.8% of patients between 2008–2013, 43.3% between 2014–2016, 58% in 2017–2019, and 69.5% in 2020–2022. Reintervention rates within 12 months of the procedure stood at 4.8% in 2008–2013, 1.8% for the 2014–2016 period, 1.7% for 2017–2019, and 2.3% for 2020–2022.
Detailing the M-VARC safety endpoints he noted that there was a low procedural mortality, with about 1% over time, also a low procedural stroke rate of about 1.2%, but what is important, is that we see a constant decrease in minor bleeding, major bleeding and minor vascular complications over time,” Koell reported.
The data also demonstrated gradually improving rates of residual MR at discharge, with none or trace MR reported in 70.7% of patients in 2020–2022, compared to 51.9% of patients at 2008–2013.
“This is the largest registry on M-TEER in primary MR patients, and in this first preliminary analysis, we see that the complication rates constantly decline, and more importantly that the proportion of residual MR also gradually declines and the overall outcomes improve,” Koell concluded.