Impact of the Relationship between the Defibrillation Threshold (DFT) and Clinical Outcomes in Recipients of Modern Era Implantable Cardioverter Defibrillator (ICD).

Abstract

Defibrillation threshold (DFT) testing during implantable cardioverter defibrillator (ICD) implantations is considered necessary for appropriate shock therapy and to measure the safety margin. However, the relationship between the DFT with modern era devices and the clinical outcome, including the total mortality is limited, which may lead to DFT testing itself being questioned. This study aimed to evaluate the relationship between the DFT and clinical outcome in ICD recipients.We enrolled 81 consecutive patients (66 males, aged 64.6 ± 13.8 years) who received an ICD implantation and underwent DFT testing. The DFT was measured with a step-by-step method in the patients upon implant. Further, we evaluated the relationship between the DFT and the clinical outcome, which included major cardiac adverse events and any cause of death.The mean DFT was 11.6 ± 9.24J in total. In 40 patients (49.4%), VF was terminated by a low output (5J), whereas 11 patients (13.6%) had a high DFT. The rates of atrial fibrillation were significantly higher in the high DFT group (63.6% versus 24.2%, P = 0.007). During the observational period (median 432 days; range from 151 days to 1146 days), the incidence of clinical events occurred in 22 patients (27.2%) in total. In a multivariate analysis, a high DFT was the only predictive factor for the incidence of the clinical outcome (OR 4.54, 95% CI 1.03-21.9, P = 0.045).