CT-derived extracellular volume fraction is associated with heart failure biomarkers in patients with atrial fibrillation

Background Heart failure (HF) is one of the important events in patients with atrial fibrillation (AF). Several markers representing hormonal, anatomical, and functional aspect of left ventricle are reported to be associated with HF in AF. However, prognostic/diagnostic importance of extracellular volume fraction (ECV), which represents diffuse fibrosis in the left ventricle, remains unclear. Purpose To evaluate whether ECV is associated with surrogate markers of HF (B-type natriuretic peptide (BNP), left atrial volume index, and tissue Doppler-derived E/e’ ratio) in patients with AF. Methods We carried out a cohort study, including 200 consecutive patients (median age 70 years, 72% male, 49% paroxysmal AF, left ventricular ejection fraction 58±13%) scheduled for catheter ablation. ECV in the left ventricle can be measured using routine contrast-enhanced computed tomography (CT). Serum BNP levels and echocardiography were documented before catheter ablation. Results The mean ECV was 29.8±6.5%, and the median BNP was 94.5 [43.4-170.6] pg/mL. High ECV, defined as >35%, was observed in 21% of the participants. ECV was associated with log BNP, left atrial volume index, and E/e’ (r=0.418 p<0.001, r=0.282 p<0.001, and r=0.256 p<0.001, respectively, Figure). Multivariable logistic regression analysis revealed that ECV was independently associated with BNP >100 pg/mL after adjustment with age, sex, AF phenotype, and left ventricular ejection fraction (odds ratio=1.14, 95%CI: 1.07-1.21 per 1 % increase of ECV, p<0.001). Conclusions Elevated left ventricular CT-ECV is easily measured by routine CT for catheter ablation and was associated with established markers of HF. A prospective study is needed to elucidate the predictive value of CT-ECV for the incidence of HF.