Asymptomatic patients with severe aortic stenosis (AS) may benefit from early aortic valve replacement surgery due to a reduced risk of death, heart attack, stroke and heart failure, according to late-breaking research presented at the American Heart Association’s Scientific Sessions 2021 (AHA 2021; 13–15 November; virtual).
This was the conclusion of the AVATAR—Aortic valve replacement versus conservative treatment in asymptomatic severe aortic stenosis—trial, presented by Marko Banovic, professor of cardiology at University Clinical Center of Serbia and the University of Belgrade Medical School, Belgrade, Serbia.
The decision to operate on an asymptomatic patient with severe AS and normal left ventricular (LV) function remains a matter of debate, Banovic said in his presentation, commenting that this remains a significant unmet need. Observational studies have challenged watchful waiting in such patients by noting increased mortality and morbidity, he noted, adding that recent randomised trial data suggest a benefit of early valve surgery in patients with critical aortic stenosis and high prevalence of bicuspid aortic valves.
“Managing an asymptomatic patient with severe aortic stenosis can make for a much more difficult decision since valve replacement is not needed to improve the person’s quality of life, and the risk of sudden cardiac death is perceived to be low—around 1% per year, though still higher than in the general population,” said Banovic.
“Another factor to consider, though, is that sustained pressure overload of the left heart chamber in severe aortic stenosis during a watchful waiting period is associated with structural and functional cardiac impairment. Without treatment, these impairments may progress and become irreversible by the time valve replacement surgery is done, and there may be potentially more serious complications including heart attack, stroke and death.”
The study was designed to evaluate the safety and effectiveness of performing aortic valve replacement surgery earlier for adults who are asymptomatic and have normal left ventricle function. The study was conducted at nine centres across seven European countries and included a total of 157 adults, 57% men, with an average age of 67 years.
All study participants were confirmed to have no symptoms associated with severe aortic stenosis via standardized exercise testing, and they did not have any significant health conditions such as severe lung disease, chronic kidney disease or an overall high surgical risk. The patients were randomly assigned to have early surgery (78 patients) or to receive conservative, non-surgical treatment of watchful waiting (79 patients), in accordance with current treatment guidelines.
Analysis of both study groups found that 72 participants in the early surgery group received an aortic valve replacement. After an average follow-up of 32 months, they had lower rates of combined death, heart attack, stroke or unplanned hospitalization for heart failure compared to the watchful waiting group. Only 13 patients in the early surgery group experienced one or more of cardiac issues (death, heart attack, stroke or unplanned hospitalisation for heart failure), compared to 26 people in the non-surgical treatment group.
One person in the early surgery group died within 30-days after the operation. Banovic noted the 1.4% intra-operative mortality rate in this group aligned with the anticipated mortality for elective isolated surgical aortic valve replacement.
In conclusion, Banovic told AHA attendees that the AVATAR trial demonstrates the preliminary efficacy and safety of early surgical valve replacement in improving the clinically-relevant composite endpoint of all cause death, acute MI, stroke and unplanned heart failure hospitalisation. The findings advocate for early surgery once aortic stenosis becomes significant regardless of symptoms, Banovic said.
“We believe our results provide new evidence to aid clinicians when they are considering treatment options for those patients who have undergone systematic exercise testing to assess truly asymptomatic aortic stenosis with mainly progressive disease and normal left ventricular function,” Banovic commented. “Our data deliver the additional degree of evidence needed to support the decision for early surgery and reassure a clinician when caring for a patient with severe asymptomatic aortic stenosis and normal left ventricular function. In such cases of low surgical risk and absence of other major health conditions, one may advocate for an early surgery for select patients.”