Actual conditions of implantable defibrillation therapy over 5 years in Japan

PurposeThe aim of this study was to describe the recent conditions associated with implantable defibrillation therapy for individual underlying heart diseases.MethodsTen thousand six hundred and five patients with implantable cardioverter-defibrillators (ICDs) or cardiac resynchronization therapy defibrillators (CRT-Ds) that were implanted from 2006 to 2010 were selected from the Japan Cardiac Device Therapy Registry database. They were divided into 12 disease categories and further divided into either primary or secondary prevention of sudden cardiac death.ResultsThe major underlying diseases of the patients in this cohort were ischemic heart disease (IHD, 35%), dilated cardiomyopathy (DCM, 25%), hypertrophic cardiomyopathy (HCM, 8%), and Brugada syndrome (Brugada, 8%). There were no structural heart diseases in this cohort; the incidence of IHD was relatively lower than that of western countries, while the incidence of cardiomyopathy was higher. The percentage of primary prevention (% primary) among the individual diseases varied. IHD was the most prevalent underlying condition in the patient cohort; however, the % primary was 33%, which was relatively lower than that of the other structural heart diseases. The % primary was relatively higher in patients with DCM (57%) and Brugada (47%). Over 5 years, the % primary gradually increased in patients with DCM, IHD, and HCM, with a particularly dramatic increase in those with DCM. A decrease in the % primary among patients with Brugada began in 2008.ConclusionsIn patients that underwent implantable defibrillation therapy, there was a relatively lower % primary in the IHD group, and a substantial increase in the % primary in patients with DCM.