Atrial fibrillation in aortic stenosis--echocardiographic assessment and prognostic importance

Abstract

Background: Atrial fibrillation (AFib) exists more frequently in patients with aortic stenosis (AS) than in patients without, and AFib may be a sign of progressive deterioration of AS. Echocardiographic assessment of AS in sinus rhythm is well documented, however, little is known about AFib in AS since such patients often are excluded from clinical echocardiographic trials.

Aim: The purpose of this study was to assess the prognostic importance of AFib in AS.

Methods: The study was designed as a single-center case-control study. Patients with AS and AFib were enrolled as cases (n = 103) and subsequently matched to controls (103 patients with AS but sinus rhythm). Cases and controls were matched according to age, gender and severity of AS. Primary outcome was all cause mortality and follow-up was 100% complete.

Results: Compared to controls the group with AFib had lower mean ejection fraction (42% vs. 49%; p < 0.001) and stroke volume (47 mL vs. 55 mL; p = 0.004), but higher heart rate (81 bpm vs. 68 bpm; p < 0.001) and no significant difference with regard to cardiac output (3.8 L vs. 4.0 L; p = 0.29). Accordingly, aortic jet velocity and gradients were significantly lower in AFib compared to controls but there were no differences (p = 0.38) in aortic valve area calculated by the continuity equation. During a median follow-up of 2.3 years (IQR: 1.2-3.6), 70 (34%) patients with AS died: 42 patients with AFib and 28 patients with sinus rhythm (p < 0.02). After adjusting for echocardiographic significant differences, AFib remained an independent predictor of mortality (HR 2.72 (95% CI: 1.12-6.61), p < 0.03). There was no significant interaction (p = 0.62) between AFib and AS on the risk of mortality, indicating that AFib predicted bad outcome regardless of the severity of AS.

Conclusions: AFib is an independent risk factor in patients with AS and the prognostic impact of AFib seems to be the same despite the severity of AS.

Figure 1

Kaplan - Meier survival curves. Shown is the cumulative survival in patients with aortic stenosis and atrial fibrillation (+AFib), compared to patients with aortic stenosis in sinus rhythm (-AFib). The curves are compared using the log-rank test.

Figure 2

Calculation of the Aortic Valve Area by the continuity equation, patient in atrial fibrillation. Aortic jet velocity, left ventricular outflow velocity and diameter of the left ventricular outflow tract. Male patient aged 77 with severe aortic stenosis, matched to the patient in Figure 3. Aortic valve area (0.80 cm²). Ejection fraction (31%). Cardiac Index (1.80 l/m²). Stroke volume (50 ml).

Figure 3

Calculation of the Aortic Valve Area by the continuity equation, patient in sinus rhythm. Aortic jet velocity, left ventricular outflow velocity and diameter of the left ventricular outflow tract. Male patient aged 77 with severe aortic stenosis, matched to the patient in Figure 2. Aortic valve area (0.88 cm²). Ejection fraction (43%). Cardiac Index (1.93 l/m²). Stroke volume (63 ml).