A new study concludes that patients with secondary mitral regurgitation (SMR) undergoing mitral valve (MV) surgery for transcatheter edge-to-edge repair (TEER) failure face a poorer prognosis compared with those with primary mitral regurgitation (PMR).

The research team found SMR patients underwent more operations for mitral stenosis, with fewer cases of MV repair, resulting in a significantly higher 1-year mortality and a lower cumulative survival at 3 years after surgery.

These findings were observed despite no differences in the scenario of TEER failure and timing of surgery.

“We can speculate that this was mainly due to the greater comorbidity burden in SMR patients with a subsequent higher surgical risk,” said the U.S.- and European-based research team,” the authors wrote. “Second, SMR patients presented more frequently with mitral stenosis as the mechanism of TEER failure, with higher mean gradients at the time of MV surgery. Third, SMR patients more often underwent MV replacement instead of repair. Finally, tricuspid regurgitation (TR) severity at the time of index TEER was an independent predictor of one-year mortality in SMR patients.”

Data to improve outcomes

Results of the study, published Monday online and in the May 22 issue of JACC: Cardiovascular Interventions, provide valuable data for further research to improve these outcomes.

Led by Syed Zaid, MD, from the Houston Methodist DeBakey Heart and Vascular Center, the team began retrospectively analyzing data from the CUTTING-EDGE registry, a multicenter, international record of patients who underwent MV surgery after TEER.

Here, 330 patients underwent MV surgery after TEER between July 2009 and July 2020, of whom 155 (47%) had PMR and 175 (53%) had SMR.

The patients’ mean age was 73.8±10.1 years and median Society of Thoracic Surgeons (STS) risk at initial TEER was 4.0% (interquartile range [IQR]: 2.2% to 7.3%).

The team also included scenarios of TEER failure leading to MV surgery, which were classified as aborted TEER, acute MV surgery and delayed MV surgery.

The primary outcomes included in-hospital, 30-day and 1-year mortality rates after MV surgery.

Secondary outcomes were defined as the median interval from TEER to MV surgery, major in-hospital complications, intensive care unit stay, hospital length of stay, and 30-day stroke and readmission rates.

Surgical risk was calculated for each patient using the Society of Thoracic Surgeons Predicted Risk of Mortality (STS-PROM) and the European System for Cardiac Operative Risk Evaluation (EuroSCORE II).

Results of analysis

Results revealed that compared with PMR, SMR patients had a higher EuroSCORE, more comorbidities, lower left ventricular ejection fraction (LVEF )pre-TEER and presurgery (all P<0.05).

SMR patients had more aborted TEER (25.7% vs 16.3%; P=0.043), more surgery for mitral stenosis after TEER (19.4% vs 9.0%; P=0.008) and fewer MV repairs (4.0% vs 11.0%; P=0.019).

Further findings revealed that 30-day mortality was numerically higher in SMR (20.4% vs 12.7%; P=0.072), with an observed-to-expected ratio of 3.6 (95% confidence interval [CI]: 1.9-5.3) overall, 2.6 (95% CI: 1.2- 4.0) in PMR, and 4.6 (95% CI: 2.6-6.6) in SMR.

SMR had significantly higher 1-year mortality (38.3% vs 23.2%; P=0.019). On Kaplan-Meier analysis, the actuarial estimates of cumulative survival were significantly lower in SMR at 1 and 3 years.

Discussing the impact of MR etiology on clinical outcomes, the study highlighted the SMR patient cohort as having a higher prevalence of coronary artery disease, diabetes, chronic kidney disease and atrial fibrillation, with consequently higher surgical risk and higher comorbidity.

SMR patients also had lower LVEF before TEER and at the time of MV surgery. LV dysfunction has been shown to be a predictor of mortality after mitral TEER.

“Thus, the poorer clinical outcomes observed in patients with SMR undergoing surgery for failed TEER might be related to differences in clinical phenotype, degree of LV dysfunction and comorbidity burden,” the team suggested, “with subsequently higher preoperative risk profile, rather than the technical success of the intervention itself.”

Explanation for TEER failure

The research team also put forward a possible explanation for the mechanism of TEER failure that led to MV surgery, citing two studies that found an increased residual MV gradient in SMR patients was associated with worse outcomes.

This included higher all-cause mortality, left ventricular assist device implantation and MV surgery.

“Although the reasons for this conflicting evidence are unclear, several factors (heart rate, cardiac output, baseline MV area, left ventricular or left atrial systolic and diastolic function, number of clips) may influence mitral gradient and subsequent outcomes, irrespective of the underlying MR etiology,” the authors wrote.

In an accompanying editorial comment, Gilles D. Dreyfus, MD, PhD, from the Hôpital Européen Georges Pompidou in Paris, and Benjamin Essayagh, MD, from the Mayo Clinic in Rochester, Minnesota, and the Cardio X Clinic in Cannes, France. noted that in the study, TR severity was an independent predictor of 1-year mortality, especially in SMR.

“Patients showing more than moderate TR after failed TEER underwent combined mitral and tricuspid surgery, with no increased mortality at 30 days and at 1-year follow up,” the editorialists wrote. “Some interventional cardiologists are convinced that addressing both valves during the same procedure is beneficial to patients, but not all of them, and the current practice should include both valves more liberally, especially regarding TR[‘s] considerable independent impact on PMR or SMR outcome.”

MV replacement the best option

On the causes for MR surgery after failed TEER in a high-risk patient, the editorialists agreed that MV replacement seems the best option.

“It is not really an issue for SMR patients but could be considered as a loss of the chance of having a good surgical MV repair at 73 years old for PMR,” they wrote.

“This cohort also shows that SMR patients present with significant mitral stenosis, ranging from 19% to 37% in contemporary studies despite the use of new devices,” Dreyfus and Essayagh added. “It also shows that TR at the time of indexed TEER is an independent predictor of mortality at 1 year.”

The editorialists concluded by stating that TEER is part of the therapeutic armamentarium to address both PMR and SMR, but patient selection can be refined.

Surgical MV repair is a true repair with its inherent risks, they added, but once performed, results on residual/recurrent MR are well-known and stable throughout time.

“Percutaneous therapy’s main advantage over surgery is that it is truly mini-invasive, mainly due to the absence of cardiopulmonary bypass and inflammatory response,” the expert commenters wrote.

Sources:

Zaid S, Avvedimento M, Vitanova K, et al. Impact of Mitral Regurgitation Etiology on Mitral Surgery After Transcatheter Edge-to-Edge Repair: From the CUTTING-EDGE Registry. JACC Cardiovasc Interv. 2023;16:1176–1188.

Dreyfus, GD, Essayagh B. Can Transcatheter Edge-to-Edge Mitral Repair Be Considered as Efficient as Surgical Mitral Valve Repair? JACC Cardiovasc Interv. 2023;16:1189–1191.

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