Better to intervene early with a new valve in patients with severe aortic stenosis (AS) who are asymptomatic, even during exercise, than to wait for the disease to progress and symptoms to emerge before operating, suggests a small, randomized trial that challenges the guidelines.
Dr. Marko Banovic
Of the trial’s 157 patients, all with negative results on stress tests and normal left ventricular (LV) function despite severe AS, those assigned to early surgical aortic valve replacement (SAVR), compared with standard watchful waiting, showed a better-than-50% drop in risk for death or major adverse cardiac events (MACE) over 2-3 years. The benefit appeared driven by fewer hospitalizations for heart failure (HF) and deaths in the early-surgery group.
The findings “advocate for early surgery once aortic stenosis becomes significant and regardless of symptom status,” Marko Banovic, MD, PhD, said during his presentation at the American Heart Association scientific sessions.
Dr. Banovic, from the University of Belgrade Medical School in Serbia, is coprincipal investigator on the trial, called AVATAR (Aortic Valve Replacement vs. Conservative Treatment in Asymptomatic Severe Aortic Stenosis). He is also lead author on the study’s publication in Circulation, timed to coincide with his AHA presentation.
“The AVATAR findings provide additional evidence to help clinicians in guiding their decision when seeing a patient with significant aortic stenosis, normal left ventricular function, overall low surgical risk, and without significant comorbidities,” Dr. Banovic told this news organization.
European and North American Guidelines favor watchful waiting for asymptomatic patients with severe aortic stenosis, with surgery upon development of symptoms or LV dysfunction, observed Victoria Delgado, MD, PhD, Leiden (the Netherlands) University Medical Center, an invited discussant for the AVATAR presentation.
AVATAR does suggest that “early surgery in truly asymptomatic patients with severe aortic stenosis and preserved ejection fraction seems to provide better outcomes as compared to the conservative treatment,” she said. “But I think that the long-term follow-up for potential events, such as valve durability or endocarditis, is still needed.”
The trial has strengths, compared with the recent RECOVERY trial, which also concluded in favor of early SAVR over watchful waiting in patients described as asymptomatic with severe aortic stenosis. Dr. Delgado and other observers, however, have pointed out limitations of that trial, including questions about whether the patients were truly asymptomatic – stress testing wasn›t routinely performed.
In AVATAR, all patients were negative at stress testing, which required them to reach their estimated maximum heart rate, Dr. Banovic noted. As he and his colleagues write, the trial expands on RECOVERY “by providing evidence of the benefit of early surgery in a setting representative of a dilemma in decision making, in truly asymptomatic patients with severe but not critical aortic stenosis and normal LV function.”
A role for TAVR?
Guidelines in general “can be very conservative and lag behind evidence a bit,” Patricia A. Pellikka, MD, Mayo Clinic, Rochester, Minn., who is not associated with AVATAR, said in an interview.
“I think when we see patients clinically, we can advise them that if they don’t have symptoms and they do have severe aortic stenosis,” she said, “they’re likely going to get symptoms within a reasonably short period of time, according to our retrospective databases, and that doing the intervention early may yield better long-term outcomes.”
The results of AVATAR, in which valve replacement consisted only of SAVR, “probably could be extrapolated” to transcatheter aortic valve replacement (TAVR), Dr. Pellikka observed. “Certainly, TAVR is the procedure that patients come asking for. It’s attractive to avoid a major surgery, and it seems very plausible that TAVR would have yielded similar results if that had been a therapy in this trial.”
In practice, patient age and functional status would figure heavily in deciding whether early valve replacement, and which procedure, is appropriate, Dr. Banovic said in an interview. Importantly, the trial’s patients were at low surgical risk and free of major chronic diseases or other important health concerns.
“Frailty and older age are known risk factors for suboptimal recovery” after SAVR, Dr. Banovic said when interviewed. Therefore, frail patients, who were not many in AVATAR, might be “more suitable for TAVR than SAVR, based on the TAVR-vs.-SAVR results in symptomatic AS patients,” he said.
“One might extrapolate experience from AVATAR trial to TAVR, which may lower the bar for TAVR indications,” but that would require more supporting evidence, Dr. Banovic said.