In a study of patients with low-flow, low-gradient aortic stenosis (LFLG-AS) undergoing transcatheter aortic valve replacement (TAVR), researchers reported that most candidates demonstrated some degree of mitral regurgitation (MR) post-TAVR. Additionally, MR improvement at one year was associated with risk of postoperative complications. This study was published in JACC Cardiovascular Interventions.
“Patients with classical low LFLG-AS represent around 5% to 10% of the population with severe AS,” the authors wrote. “This entity is associated with a higher perioperative mortality and worse long-term outcomes (survival rates <50% at three-year follow-up) when compared with patients with high-gradient AS and/or preserved left ventricular ejection fraction.”
They continued, “Additionally, an important proportion of these patients have functional mitral regurgitation (MR), in part caused by enlarged left ventricular (LV) cavities and associated ischemic cardiomyopathy. The presence of significant MR at baseline and its persistence following aortic valve replacement (either surgical aortic valve replacement or transcatheter aortic valve replacement [TAVR]) has also been associated with a worse survival (2, 3, 4, 5).
For this study, the investigators queried the True or Pseudo-Severe Aortic Stenosis–Transcatheter Aortic Valve Implantation (TOPAS-TAVI) Registry. The primary outcomes were incidence, clinical impact, and changes over time in MR among TAVR patients with LFLG-AS.
“Few data exist on the clinical impact and changes in severity over time of MR in patients with LFLG-AS undergoing TAVR,” they noted.
Total, 308 TAVR candidates were included, then categorized according to MR severity at baseline and MR improvement at 12 months. Patients underwent follow-up at one month and 12 months and then annually thereafter. Follow-up assessments included echocardiography.
The incidence of baseline mild MR was 38.3%, or 118 patients. Moderate-to-severe-MR was present in 115 patients (37.3%). MR was of functional etiology in 77.2% of patients and mixed etiology in 22.7%.
In total, 131 patients (42.5%) died after a median of two years. The researchers reported that baseline moderate-to-severe MR did not significantly impact mortality (HR=1.34; 95% CI, 0.72 to 2.48). Moderate-to-severe MR was also not significantly associated with a higher risk for heart failure hospitalization (HR=1.02; 95% CI, 0.49 to 2.10).
At one year, 44.3% of patients demonstrated MR improvement and 55.7% remained unchanged or had MR worsen. Patients who did not show MR improvement were found to have a higher risk of all-cause mortality (HR=2.02; 95% CI 1.29-3.17), cardiac mortality (HR=3.03; 95% CI, 1.27 to 7.23), and rehospitalization for cardiac-related issues (HR=1.50; 95% CI, 1.04 to 2.15). These patients also demonstrated an increased risk of combined overall mortality/heart failure rehospitalization risk (HR=1.94; 95% CI, 1.25 to 3.02).
The authors noted that a higher baseline left ventricular end-diastolic diameter and increase in left ventricular ejection fraction were predictive for MR improvement at one year (OR=0.69 and 0.81, respectively)
In conclusion, the authors wrote, “Most TAVR candidates with LFLG-AS had some degree of MR, of functional origin in most cases. MR improved in about one-half of patients, with larger left ventricular size and a higher increase in left ventricular ejection fraction post-TAVR determining MR improvement over time. The lack of MR improvement at one year was associated with poorer outcomes.”