Lower chronic stimulation threshold in the carbon-tip than in the platinum-tip endocardial electrode: a randomized...

Seventy-nine patients admitted for VVI pacemaker treatment were randomly given a Siemens-Elema 412 S endocardial electrode (tip material vitreous carbon, tip area 12 mm2) (41 patients) or a Siemens-Elema 415 S endocardial electrode (tip material platinum, tip area 12 mm2) (38 patients). The groups did not differ in age, sex, magnitude of intracardiac signal or indication for pacemaker treatment. Pacing threshold was measured by the vario technique at 3 and 15 months after the implantation. In the group of carbon-tip electrodes and in the group of platinum-tip electrodes stimulation thresholds at implantation were 0.49 +/- 0.10 V and 0.54 +/- 0.14 V (ns), at months 31.40 +/- 0.45 V and 1.57 +/- 0.53 V (ns), and at months 15 1.12 +/- 0.33 V and 1.37 +/- 0.38 V (P = 0.003), respectively. After 1 year, 88% of the patients in the carbon-tip group and 66% (P = 0.04) in the platinum-tip group fulfilled our criteria for reducing pacemaker output from 5.0 V to 2.5 V. In comparable platinum-tip and carbon-tip pacing electrodes, the chronic stimulation threshold was lower in the carbon-tip than in the platinum-tip electrode.