Impact of atrial fibrillation in clinical outcomes of low gradient aortic stenosis

Abstract Introduction Aortic stenosis (AS) is the most common significant valvular heart disease in developed countries. A significant portion of the AS populations have low-gradient AS (LGAS), defined as aortic valve area ≤1.0 cm2 and a trans-aortic mean systolic gradient and peak velocity <40 mmHg and <4 m/s, respectively. LGAS has been shown previously to have worse mortality compared to high-gradient AS (HGAS). Atrial fibrillation (AF) is associated with LGAS and AF has been associated with worse outcomes compared to sinus rhythm (SR) in HGAS. The prognostic impact of AF in LGAS is not well described in previous literature. Hypothesis AF will be associated with worse clinical outcomes compared to SR in patients with LGAS. Methods 3400 patients diagnosed with LGAS from 2010–2020 were retrospectively identified and analyzed. Their electrical rhythm was analyzed at the time of their echocardiographic diagnosis of LGAS and patients were split into 3 separate groups: SR (n=2036), SR with history of AF (n=519), and AF (n=845). After adjustment for age, sex, and Charlson Comorbidity Index (CCI), primary endpoints of overall mortality and cardiac mortality were assessed for patients. Results Compared to those with SR, patients with AF and history of AF had significantly higher overall mortality (HR 1.52, p<0.0001 and HR 1.22, p=0.004, respectively) and cardiac mortality (HR 2.05, p<0.0001 and HR 1.37, p=0.03, respectfully) (Figure 1). On further sub group analysis, AF seemed to be most importantly associated with mortality and cardiac mortality in patients with preserved ejection fraction (EF >50%, normal flow LGAS) compared to those patients with reduced EF (classical low-flow LGAS), where there was no statistically significant difference in outcomes between AF and SR (Figure 2). Conclusions Atrial fibrillation, compared to sinus rhythm, is associated with worse overall mortality and cardiac mortality in patients with LGAS and preserved EF. Specifically, this association was strongest in patients with preserved EF >50%. Given these findings, the presence of AF should be factored into clinical decision making regarding LGAS management given the higher risk of age, sex, and CCI adjusted overall and cardiac mortality. Further research needs to be done to see if earlier aortic valve intervention in these patients would improve mortality compared to their SR counterparts. Funding Acknowledgement Type of funding sources: None.