Early detection of atrial high rate episodes predicts atrial fibrillation and thromboembolic events in patients with cardiac resynchronization therapy

Background In patients without any history of atrial fibrillation (AF), detection of subclinical atrial high rate episodes (AHRE) by implanted devices has been associated with an increased thromboembolic risk. The predictive value of AHREs in patients with cardiac resynchronization therapy (CRT) is uncertain. Objective We aimed to investigate the prognostic value of early detected AHRE in patients with CRT. Methods This observational study included patients who received CRT and no history of AF. Patients had standard indication for CRT treatment. They were screened for early detected AHREs longer than 6 minutes occurring before 6-month follow-up, and the longest duration of AHREs was recorded. Information on clinical AF and thromboembolic events was obtained from the Danish National Patient Registry. The Cox regression model was used to compute hazard ratios (HRs) with 95% confidence intervals (CIs). Results Of 394 eligible patients, 79 patients (20%) had early AHRE detected. During a median follow-up of 4.6 years, patients with early detected AHREs had an increased risk of clinical AF (HR 2.35; 95% CI 1.47-3.74; P <.001) and thromboembolic events (HR 2.30; 95% CI 1.09-4.83; P =.028). For patients with AHREs longer than 24 hours, these associations were stronger. The risk of mortality was not higher with early detected AHREs (HR 0.97; 95% CI 0.64-1.45; P =.87). Of the 27 patients with thromboembolic events, only 10 patients (37%) had AHREs detected within a 2-month period before the thromboembolic event. Conclusion In patients without any history of AF, detection of early AHREs after CRT implantation is associated with a significantly increased risk of clinical AF and thromboembolic events, particularly AHRE longer than 24 hours.