Diffuse Ventricular Fibrosis Measured by T1 Mapping on Cardiac MRI Predicts Success of Catheter Ablation for Atrial Fibrillation

Background-There is a complex interplay between the atria and ventricles in atrial fibrillation (AF). Cardiac magnetic resonance (CMR) imaging provides detailed tissue characterization, identifying focal ventricular fibrosis with late gadolinium enhancement (ventricular late gadolinium enhancement) and diffuse fibrosis with postcontrast-enhanced T-1 mapping. The aim of the present study was to investigate the relationship between postcontrast ventricular T-1 relaxation time on CMR and freedom from AF after pulmonary vein isolation. Methods and Results-One hundred three patients undergoing catheter ablation for symptomatic AF (66% paroxysmal AF; age, 58 +/- 10 years; left atrial area, 27 +/- 7 cm(2)) underwent preprocedure CMR to determine postcontrast ventricular T-1 time. Followup included clinical review and 7-day Holter monitors at 6 monthly intervals. All patients underwent successful pulmonary vein isolation. At a mean follow-up of 15 +/- 7 months, the single procedure success was 74%. Postcontrast ventricular T-1 time was significantly shorter in patients with recurrent AF (366 +/- 73 ms) versus patients without AF recurrence (428 +/- 90 ms; P= 0.002). Univariate predictors of AF recurrence included postcontrast ventricular T-1 time, AF type (paroxysmal versus persistent), AF duration, and body mass index. After multivariate analysis, ventricular T-1 time (P=0.03) and AF duration (P= 0.03) were the only independent predictors. Freedom from AF was present in 84% of patients with a postcontrast ventricular T-1 time >380 ms versus 56% in patients with a postcontrast ventricular T-1 time <380 ms (P=0.002). Conclusions-A shorter postcontrast ventricular T-1 relaxation time on CMR is associated with reduced freedom from AF after catheter ablation. Diffuse ventricular fibrosis as demonstrated by CMR may, in part, explain recurrent AF after AF ablation.