Risks of Appropriate Implantable Cardioverter Defibrillator Therapy and Hospitalization Are Increased Around Device-Detected Atrial High-Rate Episodes Longer Than 6 min.

Background: The prognostic significance of device-detected atrial high-rate episodes (AHRE) in patients with implantable cardioverter defibrillator (ICD) remains poorly understood. We aimed to evaluate whether device-detected AHRE ≥ 6 min is temporally associated with appropriate ICD therapy and cardiac hospitalization. Methods: We studied consecutive patients with dual chamber or cardiac resynchronization therapy ICD with predominantly sinus rhythm and followed with remote monitoring (RM). Risk of ICD therapy and hospitalization was compared inside a 60-day peri-AHRE period (from 30 days before to 30 days after AHRE detection) with risk outside the peri-AHRE period. We included appropriate ICD therapies only. Adjusted extended Cox model with time-varying exposure analysis was used to assess potential associations between AHRE and ICD therapies and hospitalization. Results: We included 882 patients. Median age 67 years [interquartile range; 59-73], 81% male, 76% had coronary artery disease, and 61% CRT-D. The 30-day risk of appropriate ICD shock was 0.8% inside the peri-AHRE period compared with 0.2% outside the peri-AHRE period (adjusted hazard ratio [aHR] 3.04; 95% confidence interval [CI]: 1.67-5.52; Conclusion: The risk of appropriate ICD shock is three-fold elevated during a 60-day period surrounding AHRE detection. A comparable temporal pattern was noted for cardiac hospitalizations, supporting that AHREs may indicate clinical worsening of heart disease.