Objectives To examine the prognostic significance of atrial fibrillation (AF) versus sinus rhythm (SR) on the management and outcomes of patients with severe aortic stenosis (AS).

Methods 1847 consecutive patients with severe AS (aortic valve area ≤1.0 cm² and aortic valve systolic mean Doppler gradient ≥40 mm Hg or peak velocity ≥4 m/s) and left ventricular ejection fraction ≥50% were identified. The independent association of AF and all-cause mortality was assessed.

Results Age was 76±11 years and 46% were female; 293 (16%) patients had AF and 1554 (84%) had SR. In AF, 72% were symptomatic versus 71% in SR. Survival rate at 5 years for AF (41%) was lower than SR (65%) (age- and sex-adjusted HR=1.66 (1.40–1.98), p<0.0001). In multivariable analysis, factors associated with mortality included age (HR per 10 years=1.55 (1.42–1.69), p<0.0001), dyspnoea (HR=1.58 (1.33–1.87), p<0.0001), ≥ moderate mitral regurgitation (HR=1.63 (1.22–2.18), p=0.001), right ventricular systolic dysfunction (HR=1.88 (1.52–2.33), p<0.0001), left atrial volume index (HR per 10 mL/m²=1.13 (1.07–1.19), p<0.0001) and aortic valve replacement (AVR) (HR=0.44 (0.38–0.52), p<0.0001). AF was not a predictor of mortality independent of variables strongly correlated HR=1.02 (0.84–1.25), p=0.81). The 1-year probability of AVR following diagnosis of severe AS was lower in AF (49.8%) than SR (62.5%) (HR=0.73 (0.62–0.86), p<0.001); among patients with AF not referred for AVR, symptoms were frequently attributed to AF instead of AS.

Conclusion AF was associated with poor prognosis in patients with severe AS, but apparent differences in outcomes compared with SR were explained by factors other than AF including concomitant cardiac abnormalities and deferral of AVR due to attribution of cardiac symptoms to AF.