Heart rate is associated with progression of atrial fibrillation, independent of rhythm

Objective Atrial fibrillation (AF) often progresses from paroxysmal or persistent to more sustained forms, but the rate and predictors of AF progression in clinical practice are not well described. Methods Using the Outcomes Registry for Better Informed Treatment of AF, we analysed the incidence and predictors of progression and tested the discrimination and calibration of the HATCH (hypertension, age, TIA/stroke, chronic obstructive pulmonary disease, heart failure) and CHA(2)DS(2)VASc scores for identifying AF progression. Results Among 6235 patients with paroxysmal or persistent AF at baseline, 1479 progressed, during follow-up (median 18 (IQR 12-24) months). These patients were older and had more comorbidities than patients who did not progress (CHADS(2) 2.3 +/- 1.3 vs 2.1 +/- 1.3, p<0.0001). At baseline, patients with AF progression were more often on a rate control as opposed to a rhythm control strategy (66 vs 56%, p<0.0001) and had higher heart rate (72(64-80) vs 68 (60-76) bpm, p<0.0001). The strongest predictors of AF progression were AF on the baseline ECG (OR 2.30, 95% CI 1.95 to 2.73, p<0.0001) and increasing age (OR 1.16, 95% CI1.09 to 1.24, p<0.0001, per 10 increase), while patients with lower heart rate (OR 0.84, 95% CI 0.79 to 0.89, p<0.0001, per 10 decrease <= 80) were less likely to progress. There was no significant interaction between rhythm on baseline ECG and heart rate (p=0.71). The HATCH and CHA(2)DS(2)VASc scores had modest discriminatory power for AF progression (C-indices 0.55 (95% CI 0.53 to 0.58) and 0.55 (95% CI 0.52 to 0.57)). Conclusions Within 1.5 years, almost a quarter of the patients with paroxysmal or persistent AF progress to a more sustained form. Progression is strongly associated with heart rate, and age.