Comparison of ICD shock rates in Japanese and non-Japanese patients in the PainFree SST study.

BackgroundThe PainFree Smart Shock Technology (SST) study showed a low implantable cardioverter-defibrillator (ICD) inappropriate shock rate. However, the majority of patients were from Western countries with patient characteristics different from those in Japan. ICD shock rates using the novel SST algorithms in Japanese patients are still unknown. MethodsAll 2,770 patients in the PainFree SST study (Japan [JPN]: N=181, other geographies [OJPN]: N=2,589) were included in this analysis. ResultsJapanese patients had higher average left ventricular ejection fraction (P<0.0001), higher prevalence of secondary prevention indications (P<0.0001), nonischemic cardiomyopathy (P<0.0001), and permanent atrial fibrillation (P<0.0001). The appropriate shock rate at 12 months was not different between JPN and OJPN: 6.4% and 6.3%, respectively (P=0.95). The inappropriate shock rate at 12 months was significantly higher in Japanese patients (2.9%vs 1.7%, P=0.017). However, after propensity score matching to adjust for the difference in baseline characteristics, the difference in inappropriate shock rate was not statistically significant (P=0.51). ConclusionsThere was no difference in the appropriate shock rate between Japan and other geographies. The inappropriate shock rate in Japan was low, although it was slightly higher compared to other geographies due to baseline characteristics, including a higher prevalence of permanent AF. There was not a statistically significant difference after adjusting for baseline characteristics.