Factors associated with successful implantation of nonthoracotomy defibrillation lead systems.

Two hundred forty-three consecutive patients underwent attempted implantation of nonthoracotomy defibrillation lead (NTL) systems. The importance of clinical and lead-related factors were analyzed regarding their relation with implantation failure caused by an unacceptably high defibrillation threshold (DFT). Overall, 33 (14%) of 243 patients failed NTL implantation. Patients undergoing attempted implantation of NTL systems with monophasic shock waveforms (monophasic group, n = 145) had an incidence of failed implantation of 22% (n = 32) versus an incidence of 1% (n = 1) among patients undergoing attempted implantation by using biphasic shock waveforms (biphasic group, n = 98; odds ratio, 26.9; p < 0.001). The incidence of success and simplicity of implantation of NTL systems was markedly improved in patients undergoing NTL implantation by using biphasic shock waveforms. Clinical factors could be used to stratify patients in the monophasic group for their risk of implantation failure. In the biphasic group, no clinical factor could be correlated with a low DFT with a fully endovascular system.