Impact of Increased Right Atrial Size on Long-Term Mortality in Patients With Heart Failure Receiving Cardiac Resynchronization Therapy

Abstract

The ability to visualize the right atrium (RA) by echocardiography allows a quantitative, highly reproducible assessment of the RA volume (RAV). The aim of this study is to evaluate the relation between RAV and long-term mortality in a prospective cohort of heart failure and reduced ejection fraction patients in sinus rhythm receiving cardiac resynchronization therapy. 172 patients were included. The right atrium volume index (RAVI) was calculated using Simpson's method from the apical four-chamber view and indexed to body surface area. The relation between RAVI and mortality during follow up was studied. Median follow up was 68 months (interquartile range 62 to 73 months). Mean RAVI was 27 ± 14 mL/m² (IQR 22 to 33 mL/m²). Cumulative 5-year all-cause mortality was 22 ± 6% in patients with RAVI ≤ 19 mL/m², 24 ± 6% for RAVI 19 to 29 mL/m² and 58 ± 7% for RAVI >29 mL/m² (p for trend <0.001). After adjustment on clinical and echocardiographic predictors of outcome including indices of right ventricular function, there was a significant increase in overall mortality risk with increasing RAVI (adjusted hazard ratio 1.02 [95% confidence interval, 1.00 to 1.03], per 1 mL/m2 increment; p = 0.042). Patients in the highest tertile (RAVI >29 mL/m²) had significantly greater risk of death compared with those with RAVI ≤29 mL/m² (adjusted hazard ratio 2.01 [95% confidence interval, 1.15 to 3.50]; p = 0.014). In conclusion, RA enlargement is a powerful and highly reproducible independent predictor of long-term mortality in patients with heart failure and reduced ejection fraction in sinus rhythm receiving cardiac resynchronization therapy.