Jan. 17, 2024
About half of the patients with severe aortic stenosis (AS) are asymptomatic at the time of diagnosis, and roughly 19% of patients are asymptomatic at the time of referral for treatment of severe AS. Atrial fibrillation (AFib), a common cardiac arrhythmia found in patients with AS, is associated with higher morbidity and mortality in patients with AS.
Since AFib and AS symptoms can be similar, patients with symptoms in the setting of severe AS are sometimes not referred for aortic valve replacement (AVR) because clinicians may attribute the symptoms to AFib instead of AS. Whether AFib in patients with asymptomatic severe AS is associated with higher mortality has not been adequately investigated.
A propensity-matched analysis of the impact of AFib on outcomes in patients with asymptomatic severe AS was published in the June 2023 issue of Frontiers of Cardiovascular Medicine. The study looked at the association of AFib versus sinus rhythm (SR) with outcomes in patients with asymptomatic severe AS and preserved left ventricular ejection fraction (LVEF) ≥ 50% during routine clinical practice.
"This study shows that AFib is a marker of increased risk in asymptomatic patients with AS and preserved left ventricular ejection fraction," says Vuyisile T. Nkomo, M.D., M.P.H., a cardiologist at Mayo Clinic in Rochester, Minnesota, and one of the study's lead authors. "The presence of AFib is not really factored into decision-making when it comes to timing or urgency of AVR, but we know from already published data that AFib is associated with worse outcomes in symptomatic patients and following AVR."
In this study, patients were identified retrospectively in the Mayo Clinic Echocardiography Laboratory database from Jan. 1, 2008, to Dec. 31, 2016. Out of 3,208 consecutive patients, 909 were asymptomatic with severe AS and LVEF ≥ 50%. Patients were divided by rhythm (AFib versus SR) at the time of transthoracic echocardiogram showing severe AS.
Propensity matching was used to match 89 patients with AFib to 174 patients with SR by age, sex and clinical comorbidities. The median age was 82 years with 58% male and a follow-up period of 2.6 years.
Key findings in the study:
- AFib was common and found in about 10% of patients with asymptomatic severe AS and preserved LVEF.
- Overall mortality was higher in patients with AFib compared with SR even when matched by age, sex and clinical comorbidities.
"Patients with AFib were matched by age, sex and clinical comorbidities to patients with SR to remove the effects of these differences on outcomes," says Dr. Nkomo. "In the matched patients, the rates of AVR during follow-up were not different and both groups benefited similarly from AVR. However, overall mortality was higher in patients with AFib compared with SR even when matched by age, sex and comorbidities."
The increased risk of mortality in patients with AFib was linked to structural heart changes more commonly found in patients with AFib such as abnormal right ventricular systolic function, functional mitral valve regurgitation and lower forward flow.
"In clinical practice, the presence of AFib in patients with asymptomatic severe AS should be considered a marker of higher risk. Whether earlier surgery before the development of symptoms in patients with AFib and AS would be beneficial needs to be investigated," says Dr. Nkomo.
For more information
Oguz D, et al. Impact of atrial fibrillation on outcomes in asymptomatic severe aortic stenosis: A propensity-matched analysis. Frontiers in Cardiovascular Medicine. 2023;10:1195123.
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