Primary prevention implantation of cardioverter defibrillator without defibrillation threshold testing: 2-year follow-up.

Background: Even though the intraoperative threshold testing of the implantable cardioverter defibrillator (ICD) may cause hemodynamic impairment or be unfeasible, it is still considered required standard practice at the time of implantation. We compared the outcome of ICD recipients who underwent defibrillation threshold testing (DFT) with that of patients in whom no testing was performed.

Methods: A total of 291 subjects with ischemic dilated cardiomyopathy received transvenous ICDs between January 2000 and December 2004 in five Italian cardiology centers. In two centers, DFT was routinely performed in 137 patients (81% men; mean age 69+/-9 years; mean ejection fraction 26+/-4%) (DFT group), while three centers never performed DFT in 154 patients (90% men; mean age 69+/-9 years; mean ejection fraction 27+/-5%) (no-DFT group).

Results: We compared total mortality, total cardiovascular mortality, sudden cardiac death (SCD), and spontaneous episodes of ventricular arrhythmia (sustained ventricular tachycardia, VT, and ventricular fibrillation, VF) between these groups 2 years after implantation (median 23 months, 25th-75th percentile, 12-44 months). On comparing the DFT and no-DFT groups, we found an overall mortality rate of 20% versus 16%, cardiovascular mortality of 13% versus 10%, SCD of 3% versus 0.6%, VT incidence of 8% versus 10%, and VF incidence of 6% versus 4% (no significant difference in any comparison).

Conclusions: No significant differences in the incidence of clinical outcomes considered emerged between no-DFT and DFT groups. These results should be confirmed in larger prospective studies.