METHODS: The AVATAR trial randomly assigned patients with severe, asymptomatic AS and LV ejection fraction ≥50% to undergo either early surgical aortic valve replacement (AVR) or conservative treatment with watchful waiting strategy. All patients had negative exercise stress testing. The primary hypothesis was that early AVR will reduce a primary composite endpoint comprising all-cause death, acute myocardial infarction, stroke or unplanned hospitalization for heart failure (HF), as compared to conservative treatment strategy.

RESULTS: A total of 157 low-risk patients (mean age 67 years, 57% men, mean Society of Thoracic Surgeons score 1.7%) were randomly allocated to either early AVR group (n=78) or conservative treatment group (n=79). In an intention-to-treat analysis, after a median follow-up of 63 months, the primary composite endpoint outcome event occurred in 18/78 patients (23.1%) in the early surgery group and in 37/79 patients (46.8%) in the conservative treatment group (hazard ratio [HR] early surgery vs. conservative treatment 0.42; 95% confidence interval [CI] 0.24-0.73, p=0.002). The Kaplan-Meier estimates for individual endpoints of all-cause death and HF hospitalization were significantly lower in the early surgery compared with the conservative group (HR 0.44; 95% CI 0.23-0.85, p=0.012 for all-cause death, and HR 0.21; 95% CI 0.06-0.73, p=0.007 for HF hospitalizations).

CONCLUSIONS: The extended follow-up of the AVATAR trial demonstrates better clinical outcomes with early surgical AVR in truly asymptomatic patients with severe AS and normal LV ejection fraction compared with patients treated with conservative management on watchful waiting.