Mechanical AVR Associated With Significant Survival Benefit vs. Bioprosthetic AVR in Patients ≤60 Years
Mechanical surgical aortic valve replacement (AVR) was associated with lower all-cause mortality in patients ≤60 years old compared with bioprosthetic AVR, according to a study on the longitudinal survival difference among more than 100,000 patients presented at the Society of Thoracic Surgeons (STS) Annual Meeting and simultaneously published in JACC.
Michael E. Bowdish, MD, MS, et al., evaluated outcomes in 109,842 patients aged 40-75 years undergoing primary isolated mechanical or bioprosthetic AVR from 2008-2019 from the STS-Adult Cardiac Surgery Database (STS-ACSD), which captures 97% of all procedures performed in the U.S., linked with the National Death Index (NDI). Patients were excluded if they had endocarditis, emergency/salvage status, shock, LVEF ≤25% and any prior cardiac surgery. Median follow-up was 5.44 years.
Patients undergoing mechanical AVR (n=15,717; 14.3%) had a higher baseline predicted risk of operative mortality (PROM) in each age category compared with bioprosthetic AVR (n=94,125; 85.7%). They tended to be younger (55.7 vs. 65.2 years) and less likely to have hypertension (71.8% vs. 78.7%) or prior PCI (3.7% vs. 6.7%). They also had a higher BMI (32.2 vs. 31.0 kg/m2), body surface area (2.06 vs. 2.01 m2) and chance of severe aortic insufficiency (23.6% vs. 15.3%).
Results after robust risk adjustment (using age-specific inverse probability weighing and restricted cubic splines to model nonlinear age relationships) showed that in patients ≤60 years, mechanical AVR was independently associated with a survival benefit compared with bioprosthetic AVR. These results remained consistent after sensitivity analyses excluding pure aortic insufficiency, intermediate/high-risk patients (STS PROM >4%) and discontinued valve types.
At 12 years, the risk adjusted all-cause mortality for mechanical vs. bioprosthetic AVR by age group was 0.69 (95% CI, 0.59-0.79 for 40-49 years, 0.99 (95% CI, 0.91-1.08 for 60-69 years, 0.87 (95% CI, 0.80-0.94) for 50-59 years and 1.12 (95% CI, 0.97-1.29).
"The linkage of the STS-ACSD and NDI has permitted the novel ability to relate detailed, adjudicated, patient-level clinical data on preoperative and operative characteristics to long-term mortality outcomes in a manner not previously documented for AVR analyses," write the authors, noting that previous studies tended to utilize only institutional or statewide data.
The authors also note that in the almost 12-year study, the percentage of mechanical AVR procedures vs. bioprosthetic AVR decreased from nearly 20% in 2008 to less than 10% in 2019. "Favorable survival data demonstrated in the current study may provide a basis for a clinical reconsideration of these valves as an option," Bowdish, et al., write.
Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Aortic Surgery
Keywords: Cardiac Surgical Procedures, Aortic Valve