169-05: Atrial high rate episodes are frequently detected in patients with cardiac resynchronization therapy and longer episodes increases the risk of thromboembolic events

Abstract

Background: Knowledge about the incidence of atrial high rate episodes (AHRE) in patients with cardiac resynchronization therapy (CRT) is limited and conflicting, likewise whether the duration of AHRE have implication for the risk of thromboembolic events (TE). Methods: This observational study included patients who received a CRT device at Aarhus University Hospital between 2000-2010, and with no history of atrial fibrillation. All patients had standard indication for CRT treatment. All device-detected AHRE ≥6 minutes were included, and patients were divided into 3 groups; no AHRE, short AHRE (between 6 minutes and 24 hours) and long AHRE (>24 hours). The annual risk was calculated as events per patient-year with 95% confidence intervals (CI). Results: Of 304 patients, 79 (26%) develop short AHRE and 63 (21%) had long AHRE during a median follow-up of 4.8 years, resulting in an annual risk of short AHRE of 13 (95% CI, 11–15) % and long AHRE of 4 (95% CI, 3–6) %. The mean age was 65 (SD 13) years, mean LVEF was 24 (SD 6) % and median CHA2DS2-VASc score was 3 (IQR 2–5) with no significant difference between the three groups. CRT pacing was lower in patients with long AHRE than those with short or no AHRE (97 (IQR 94–99) vs. 99 (IQR 97–100) vs. 99 (IQR 96–100) %, P < 0.001 and P = 0.44). Anticoagulation therapy was more likely to be initiated in patients with long AHRE than those with short or no AHRE (68 vs. 25 vs. 17%; P < 0.001 and P = 0.12). The annual risk of TE events was similar in patients without AHRE and in patients after the detection of short AHRE, but significantly increased after detection of long AHRE (1.4 (95% CI, 0.9–2.4) % vs. 1.8 (95% CI, 0.8–4.0) % vs. 4.0 (95% CI, 2.0–8.0) %, P = 0.65 and P = 0.03). Conclusion: AHRE ≥6 minutes are detected in nearly half of the patients with no prior atrial fibrillation after CRT implantation, but only AHRE lasting longer than 24 hours are significantly associated with TE events.