Background: The epidemiology and clinical implications of asymptomatic atrial tachyarrhythmias (AT) including both atrial fibrillation and flutter in pacemaker recipients with and without arrhythmia history are not well understood. The Atrial High Rate Episodes (A-HIRATE) in Pacemaker Patients Trial was designed to identify and compare the incidence of AT in patients with and without previously diagnosed AT and a standard indication for dual chamber pacing, and to provide useful diagnostic information for clinical management.
Methods: Four hundred twenty-seven patients were implanted with a pacemaker (Kappa 7-900, Medtronic, Inc., Minneapolis, MN, USA) capable of detecting and storing multiple atrial high rate episodes (AHRE) and followed for 2 years. Group I included 331 patients without prior history of AT and Group II included 96 patients with prior AT history.
Results: Pacemaker diagnostics appropriately detected 93% of reviewed AHRE. The rate of occurrence of first AHRE was significantly higher (P < 0.0001) in Group II patients, as was average AHRE burden. The rate of first AHRE occurrence was 88.6% for patients in Group II and 53.8% in Group I at 24 months post-implant. The rate of AHRE occurrence was similar in both groups after the first month post-implant. The majority of stored AHRE were asymptomatic; symptoms did not correspond to an actual AHRE in most patients.
Conclusions: The incidence of AT in pacemaker recipients is high. Most device-detected AHRE are asymptomatic. Prior history of AT is associated with higher arrhythmia burden. AHRE diagnostics have a high positive predictive value for identifying AT events.