RCT: Early Surgical AVR Improved Outcomes in Asymptomatic Severe Aortic Stenosis
6 Oct, 2024 | 16:29h | UTCBackground: Severe aortic stenosis (AS) is a prevalent valvular heart disease requiring intervention in symptomatic patients. The optimal timing for surgical aortic valve replacement (AVR) in truly asymptomatic patients with severe AS and normal left ventricular (LV) systolic function remains uncertain and is under investigation.
Objective: To determine whether early surgical AVR improves clinical outcomes compared to conservative management with watchful waiting in asymptomatic patients with severe AS and normal LV ejection fraction (LVEF ≥50%).
Methods: The AVATAR trial was a multicenter, randomized controlled trial involving 157 low-risk, asymptomatic patients (mean age 67 years, 57% men) with severe AS and normal LVEF. Patients were randomized to early surgical AVR (n=78) or conservative treatment (n=79). All participants had negative exercise stress tests to confirm asymptomatic status. The primary composite endpoint included all-cause death, acute myocardial infarction, stroke, or unplanned hospitalization for heart failure (HF). Secondary outcomes encompassed individual components of the primary endpoint, cardiovascular death, serious adverse events, and procedural metrics.
Results: Over a median follow-up of 63 months, the primary composite endpoint occurred in 23.1% of the early surgery group versus 46.8% of the conservative group (hazard ratio [HR] 0.42; 95% confidence interval [CI], 0.24–0.73; P=0.002). All-cause mortality was significantly lower in the early surgery group (16.7% vs. 34.2%; HR 0.44; 95% CI, 0.23–0.85; P=0.012). Unplanned HF hospitalizations were also reduced (4.0% vs. 17.0%; HR 0.21; 95% CI, 0.06–0.73; P=0.007). There were no significant differences in stroke rates between the groups. Serious adverse events occurred less frequently in the early surgery group (26.4% vs. 49.4%; P=0.013). Sudden cardiac death was less common in the early surgery group, though not statistically significant (5.1% vs. 11.4%; P=0.17).
Conclusions: Early surgical AVR in asymptomatic patients with severe AS and normal LVEF significantly improved clinical outcomes, including reductions in all-cause mortality and HF hospitalizations, compared to conservative management.
Implications for Practice: These findings support considering early surgical AVR in truly asymptomatic patients with severe AS and normal LV function to reduce the risk of adverse events and improve long-term outcomes. Clinicians should weigh the benefits of early intervention against surgical risks, emphasizing careful patient selection and monitoring.
Study Strengths and Limitations: Strengths of the study include its randomized design, extended follow-up period, and strict inclusion of truly asymptomatic patients confirmed by negative exercise testing. Limitations involve a smaller sample size than initially projected, potential impacts of the COVID-19 pandemic on follow-up and healthcare access, and early termination of enrollment, which may affect the generalizability of the results.
Future Research: Further large-scale randomized trials are needed to validate these findings and explore the role of early intervention strategies, including transcatheter aortic valve implantation (TAVI), in asymptomatic patients with severe AS.