Early surgery shows benefit vs watchful waiting for asymptomatic severe aortic stenosis
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In the AVATAR trial, patients with asymptomatic severe aortic stenosis and normal left ventricular function assigned early surgical aortic valvular replacement, compared with watchful waiting, had a lower incidence of death and CV outcomes.
“This is the largest randomized trial closely reflecting the clinical dilemma of a low-risk, truly asymptomatic patient with severe mainly degenerative aortic stenosis and normal left ventricular function,” Marko Banovic, MD, PhD, associate professor of cardiology at University Clinical Centre of Serbia and University of Belgrade Medical School, said during a press conference at the virtual American Heart Association Scientific Sessions. “Overall, the findings advocate for early surgery once aortic stenosis becomes significant, regardless of symptom status.”
Among 157 patients, after a mean follow-up of 32 months, those assigned to undergo early surgical AVR had a lower rate of the primary composite endpoint, which included all-cause death, MI, stroke or unplanned hospitalization for HF, compared with patients assigned to a conservative strategy of watchful waiting (HR = 0.46; 95% CI, 0.23-0.9; P = .02), Banovic said.
“The benefit of early surgery started to be seen approximately 11 months after randomization and was sustained throughout the trial,” Banovic said during the late-breaking science presentation.
Thirteen primary endpoint events occurred in the early surgery group and 26 in the watchful waiting group. The difference was mainly driven by all-cause death and in part by HF hospitalization in the conservative management group, Banovic said.
The rate of intraoperative mortality in the early surgery group was 1.4% (one patient).
“Intraoperative mortality in the early surgery group was in line with anticipated mortality for elective isolated surgical AVR,” Banovic said.
Results showed no significant differences between the early surgery and watchful waiting groups in other secondary outcomes such as repeated major adverse CV events (3.8% vs. 8.9%; OR = 0.41; 95% CI, 0.1-1.65), thromboembolic complications (2.6% vs. 2.3%; OR = 1.03; 95% CI, 0.14-7.67) and major bleeding (5.1% vs. 1.3%; OR = 3.52; 95% CI, 0.37-32.68).
Among the 157 patients involved in the trial, the mean age was 67 years and 57% were men. The prospective, randomized, open-label, parallel-group trial was conducted at nine centers in seven countries in Europe. All patients had confirmed severe aortic stenosis and were without symptoms, confirmed by a mandatory exercise stress test, and had a Society of Thoracic Surgeons score below 8%.
The results were published simultaneously in Circulation.
The AVATAR trial was designed to evaluate safety and efficacy of early surgical AVR, as “the decision to operate on an asymptomatic patient with severe aortic stenosis and normal LV function remains a matter of debate,” Banovic said. Previous observational studies have challenged the strategy of watchful waiting in these patients by showing increased mortality and morbidity, he said. The RECOVERY trial, reported by Healio at the AHA Scientific Sessions in 2019 and published in The New England Journal of Medicine, suggested a benefit of early surgical AVR, in terms of lower rates of operative mortality and CV death, compared with conservative care in patients with very severe but asymptomatic aortic stenosis, according to Banovic.
“Early surgery in truly asymptomatic patients with severe aortic stenosis seems to provide better outcomes as compared to conservative treatment,” Victoria Delgado, MD, with Leiden University Medical Center in the Netherlands, said during a discussion of the trial. “The need for additional concomitant interventions … questions the allocation to ‘early’ surgery. Long-term follow-up with potential events — valve durability, endocarditis — are still needed.”
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Joanna Chikwe, MD, FRCS
The AVATAR trial results are a rather positive finding for early intervention in pretty low-risk patients with asymptomatic severe aortic stenosis. We certainly see a real preponderance of patients who have been observed until they are symptomatic and then referred for surgery. I think a lot of that reflects a natural caution among cardiologists based on older outcomes with surgery. The AVATAR trial had pretty phenomenal outcomes: operative mortality was 1% and the patients did extraordinarily well with surgery. It’s something we see across the board with surgery: Asymptomatic patients with severe valve lesions, and particularly mitral valve regurgitation, are followed until they become symptomatic; generally, most of the data we have suggest that they just do better with an earlier intervention.
One of the caveats when you look at the data is it was a small number of patients, and the findings are driven by a very few endpoints. For confidence, you have to put the AVATAR trial in the context of the RECOVERY trial, which found broadly similar findings. I think my bias is that if you’ve got a surgical team that you know can deliver consistently good outcomes and you have a low-risk patient who is asymptomatic, it’s appropriate and probably beneficial to send them for surgery, or at least surgical assessment, before they develop symptoms.
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Banovic M, et al. LBS.01. Valves, Veins and New Viewpoints in Cardiothoracic Surgery. Presented at: American Heart Association Scientific Sessions; Nov. 13-15, 2021 (virtual meeting).
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