Intraoperative defibrillation threshold testing durino implantable cardioverter-defibrillator insertion: Do we really need it?

Background The assessment of defibrillation efficacy using a safety margin of 10 J has long been the standard of carefor insertion of implantable cardioverter-defibrillator (ICD), but physicians are concerned about complications related toinduction test. Therefore, the need for testing has been recently questioned. The aim of our study was to assess the impact ofdefibrillation threshold (DFT) testing of ICD on the efficacy of ICD therapy.Methods We analyzed data obtained from follow-up visits of 122 consecutive patients who underwent ICDimplantation at our institute from April 1996 to June 2008, with (n = 42) or without (n = 80) DFT testing. Patients in the DFTgroup were less likely to be men (83.3% vs 96.3%, P b .031) than those in the non-DFT group. Conversely, the 2 groupswere similar in age, left ventricular ejection fraction at baseline, functional class, and underlying cardiovascular disease.Results during a 12-month follow-up, 13 (31.0%) and 30 (37.5%) ventricular tachyarrhythmic episodes were recorded in theDFT and non-DFT groups, respectively (P = .472). Antitachycardia pacing (ATP) terminated most of episodes, reducing theneed of defibrillation at 7.7% in the DFT group and 3.3% in the non-DFT group (P = .533). Similar percentages ofinappropriate ATP interventions (7.1% vs 3.8%, P = .413) and shock deliveries (2.4% vs 5.0%, P = .659) were recordedbetween DFT and non-DFT groups.Conclusions At 1-year follow-up, the performance of DFT testing does not seem to add any significant efficacyadvantage in patients undergoing ICD implantation. Prospective randomized trials and long-term follow-up are warranted toclarify whether routine DFT testing may be safely abandoned leading to a revision of current guidelines.