Types of atrial arrhythmias and efficacy of device
therapies were evaluated in 30 patients implanted with the Medtronic model 7250 Jewel AF
implantable cardioverter defibrillator (ICD). All patients had structural
heart disease and documented sustained ventricular and atrial arrhythmias (27 with
atrial fibrillation [AF]) before implant. Twenty patients were taking
amiodarone, and three were taking
sotalol. During 20+/-10 months of follow-up, 600 atrial
arrhythmia recurrences were documented in 50% of patients. AF was diagnosed in 19%, fast polymorphic atrial
tachycardia (AT) in 20%, fast monomorphic AT in 57%, and slow AT in 4% of episodes. The two adaptive pacing
therapies, burst and ramp, together with the 50-Hz burst, were successful in 57% of detected atrial arrhythmias. Burst and ramp were responsible for 49% and 50-Hz burst for 51% of successfully treated arrhythmias; 33% of the episodes terminated spontaneously. No ventricular proarrhythmia was observed due to atrial pacing
therapies. In 30% of episodes, dual chamber pacing was required due to post termination
bradycardia. Atrial
arrhythmia recurrences in patients with
dilated cardiomyopathy were not amenable to pacing
therapies. Several aspects of atrial
arrhythmia diagnosis,
therapy, and documentation that are specific for functioning of the Jewel AF are discussed.
CONCLUSION: Atrial arrhythmias in ICD patients with diseased hearts who are taking Class III antiarrhythmics frequently had longer cycle lengths than AF. Half of these arrhythmias could be terminated with pacing
therapies; one third terminated spontaneously.