The Relevance of the Primary Prevention Criteria for Implantable Cardioverter Defibrillator Implantation in Korean Symptomatic Severe Heart Failure Patients

Background and Objectives: Implantable cardioverter defibrillator (ICD) therapy is recommended as the primary tool for prevention of sudden cardiac death (SCD) in symptomatic patients with severe left ventricular dysfunction. There is a paucity of information on whether this recommendation is appropriate for the Korean population with severe heart failure. Subjects and Methods: The study group consisted of 275 consecutive patients (mean age 65 years, 71% male) who met the ICD implantation criteria for primary prevention (left ventricular ejection fraction ${\leq}$30% and New York Heart Association functional class II or III). We analyzed the clinical characteristics and outcomes of an ischemic cardiomyopathy (ICMP) group (n=131) and a non-ischemic cardiomyopathy (NICMP) group (n=144). The outcomes of these 2 groups were compared with the Multicenter Automatic Defibrillator Implantation Trial II (MADIT-II) conventional and Defibrillators in the Non-ischemic Cardiomyopathy Treatment Evaluation (DEFINITE) standard therapy groups, respectively. Results: Eighty patients (29%) died during a follow-up period of 40${\pm}$17 months. The NICMP group had better all-cause mortality rates than the ICMP group (19% vs. 40%, p<0.001), however both groups had a similar incidence of SCD (7% vs. 10%, p=0.272). The 2-year all-cause mortality and SCD for the ICMP group were similar to those of the MADIT-II conventional therapy group (20% vs. 20%, 7% vs. 10%, respectively, all p>0.05). All-cause mortality and the incidence of SCD in the NICMP group were comparable to those of the DEFINITE standard therapy group (13% vs. 17%, 6% vs. 6%, respectively, all p>0.05). Conclusion: Korean patients with severe heart failure in both the ICMP and NICMP groups had all-caused mortality and risk of SCD comparable to patients in the MADIT-II and DEFINITE standard therapy groups. Therefore, the primary prevention criteria for ICD implantation would be appropriate in both Korean ICMP and NICMP patients.