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Patients with severe aortic stenosis fared well getting surgery before developing symptoms as opposed to watchful waiting, according to the small AVATAR trial.

The cohort randomized to early aortic valve replacement went under the knife at a median 55 days -- the delay related to the COVID-19 pandemic -- compared with peers waiting 400 days with conservative treatment. Cumulative major adverse cardiovascular events over a median 32 months were fewer with the former strategy (HR 0.46, 95% CI 0.23-0.90). These included:

• All-cause deaths: 9 vs 16
• Unplanned heart failure hospitalizations: 1 vs 7
• Acute MIs: 1 vs 2
• Strokes: 2 vs 1

Intraoperative mortality reached 1.4% in early surgery, which is expected for elective isolated surgical aortic valve replacement (SAVR), according to Marko Banovic, MD, PhD, of University Clinical Centre of Serbia and Belgrade Medical School.

"Overall findings advocate for early surgery once AS [aortic stenosis] becomes significant, regardless of symptom status," Banovic said in a presentation of the AVATAR data at the American Heart Association (AHA) virtual meeting. The results were simultaneously published in .

"The decision to operate on asymptomatic patients with severe AS and normal LV [left ventricular] function remains a matter of debate. Traditionally, a watchful waiting strategy has been favoured as the risk of sudden death in such patients has been reported low and it appeared safe to delay surgery until symptoms develop," the authors wrote.

Their 157-person trial stands out for including only aortic stenosis patients who were truly asymptomatic (per an exercise test) and had normal LV function.

The earlier trial had also shown early surgery to be better than conservative care, though participants in that study were not necessarily really asymptomatic, recalled AHA session discussant Victoria Delgado, MD, PhD, of Leiden University Medical Center in the Netherlands.

"The AVATAR trial expands these findings by providing evidence of the benefit of early surgery in a setting representative of a dilemma in decision making," Banovic's group said. "Inclusion criteria of the AVATAR trial correspond to conventional echocardiographic assessment of severe AS and with predominantly degenerative aetiology. This is in contrast to patients in the RECOVERY trial that presented with more critical AS with a peak velocity >4.5 m/s with mainly bicuspid aortic valve aetiology."

Joanna Chikwe, MD, of Cedars-Sinai Medical Center in Los Angeles, highlighted the low mortality rate in SAVR in Banovic's report. "That superb safety means there's less benefit to waiting," she commented at an AHA press conference.

Transcatheter aortic valve replacement could be a "great option" for higher-risk patients, she added.

AVATAR was conducted at nine centers in seven European countries. The 157 participants had a mean age of 67 and 43% were women. Mean STS score was 2%. Over 80% had degenerative aortic stenosis, and mean LV ejection fraction was just under 70%.

Early SAVR and watchful-waiting groups shared similar rates of 30-day mortality, repeated major adverse cardiovascular events, thromboembolic complications, and major bleeding complications.

Three individuals died with COVID-19 in the watchful-waiting group, while none did in the early surgery arm.

Study investigators had excluded people with a need for aortic surgery or a history of coronary artery bypass grafting (CABG) or any heart valve surgery.

However, a few patients did have concomitant CABG during valve replacement, which throws the concept of AVATAR's "early" surgery into question, Delgado said.

There is a still need for long-term follow-up addressing valve durability, endocarditis, and thromboembolic complications in these patients, she added.

Chikwe noted that AVATAR had a small sample but acknowledged the difficulties of recruiting for cardiac surgery trials.

"I feel confident about intervening early as long as I can guarantee the patient a great outcome," she said.