Comparison of threshold values between steroid and nonsteroid unipolar membrane leads

The aim of this study was to evaluate whether steroid membrane leads can reduce pacing thresholds and thereby save energy as compared to nonsteroid membrane leads. The study was a random sample, double blind test consisting of 90 patients between 49-94 years of age admitted to seven hospitals in Europe for pacemaker implantation. The two leads compared in this study had contoured activated carbon tips covered with ion exchange membranes. The leads were identical except that 30 micrograms of dexamethasone was dissolved in the ion exchange membrane of one of the leads. Normal lead implant procedures were used. Follow-up procedures were conducted at 2 weeks and 1, 3, 6, and 12 months after lead implantation. The pulse generator was programmed to an amplitude of 2.5 or 5 V and a duration of 0.5 msec. The stimulation threshold was measured using the VARIO function. The threshold was measured a total of three times in order to determine the presence of microdislocations. At the 2- and 4-week follow-ups, the stimulation threshold was significantly lower for the steroid leads than for the membrane leads without steroid (0.54 +/- 0.19 vs 0.76 +/- 0.25 V, P = 0.0005; and 0.59 +/- 0.19 vs 0.74 +/- 0.26 V, P = 0.005), but after 3 months, the threshold values were almost the same for both leads.