Avatar Trial: Is It Time to Use Surgical Aortic Valve Replacement in Asymptomatic Patients?

It is still unclear whether surgical aortic valve replacement (SAVR) is beneficial in asymptomatic patients with severe aortic stenosis (AS) and conserved left ventricular function (C1 indication according to AHA guidelines). The European American guidelines only recommend intervention in asymptomatic patient when there is ventricular compromise (ejection fraction <50%, class I indication) or with a positive s tress test (class IIA Indication).

Avatar Trial ¿Es momento de plantear la intervención valvular aórtica quirúrgica para los pacientes asintomáticos?

At present, there is only one randomized study on asymptomatic patients (RECOVERY Trial, NEJM 2020), which included patients with very severe aortic stenosis (velocity >4.5m/s or mean gradient >50 mmHg) and low surgical risk from four tertiary centers from South Korea, who received early SAVR. It showed reduced primary end point of perioperative or cardiovascular death at followup (HR 0.09, CI95% 0.01-0.67; P=0.03). However, these “asymptomatic” patients had not been stress tested. 

This was the question behind the AVATAR, a randomized multinational study (seven European countries) assessing the safety and efficacy of early SAVR compared against conservative medical therapy, in patients with severe aortic stenosis, conserved ejection fraction, asymptomatic, who had a negative stress test. 

It included 157 patients, mean age 67, 57% mean, STS mortality 1.7% (low risk), with mean followup of 32 months. AS etiology was 84% degenerative. 53% in the SAVR branch got the mechanical valve and 47% the biological one. Of the 79 patients in the conservative branch, 25 crossed over to SAVR because of symptoms at followup (significant crossover).

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Primary end point was a combination of all-cause mortality or major adverse cardiovascular events (AMI, stroke, hospitalization for cardiac failure – MACE). Secondary end points included post operatory mortality at 30 days, new aortic surgery, major bleeding, hospitalization for cardiac failure, among others. 

Analyzing intention to treat, there was a significant reduction of primary end point (HR 0.47, CI95% 0.23-0-90; P=0.02). When looking at primary and secondary outcomes individually, there was no significant reduction of cardiovascular death or hospitalization. 


This study has shown a significant reduction of primary end point, as did its predecessor RECOVERY, with fewer events in patients receiving early SAVR. 

Is this true for the whole asymptomatic population? This calls for data collection and followup. Primary end point included all-cause mortality (in general in low-risk patients, one of the most relevance outcomes is cardiovascular death) cardiovascular death did not drop after the intervention, at secondary analysis, which is why we need confirmation of this benefit from larger trials. This benefit is also seen when looking at ongoing studies such as the EARLY TAVR, EASY AS and EVOLVED.

Dr. Omar Tupayachi

Dr. Omar Tupayachi.
Member of the editorial board of SOLACI.org .

Original Title: Aortic Valve Replacement Versus Conservative Treatment in Asymptomatic Severe Aortic Stenosis: The AVATAR Trial.

Reference: Banovic, Marko et al. “Aortic Valve Replacement Versus Conservative Treatment in Asymptomatic Severe Aortic Stenosis: The AVATAR Trial.” Circulation vol. 145,9 (2022): 648-658. doi:10.1161/CIRCULATIONAHA.121.057639.

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