A RANDOMIZED COMPARISON OF A BIPOLAR STEROID-ELUTING ELECTRODE AND A BIPOLAR MICROPOROUS PLATINUM-ELECTRODE - IMPLICATIONS FOR LONG-TERM PROGRAMMING

Differences in acute and chronic pacing thresholds were compared in pa tients receiving either the Medtronic Model 4004 steroid-eluting lead or the Medtronic Model 4012 microporous platinum lead. Patients (n = 3 5) were randomized at the time of implant to receive either a steroid- eluting (n = 17) or a microporous (n = 18) lead. Pacing thresholds wer e determined within 24 hours and at 2, 4, 6, 12, 24, and 52 weeks post implant. By 2 weeks postimplant, pacing thresholds measured at 0.8, 1. 6, 2.5, 3.3, and 4.2 V were significantly lower in the steroid lead gr oup compared to the microporous lead group (P < 0.05). At 24 weeks, th e voltage threshold at 0.3 msec was 0.8 V in 88% of patients with a st eroid lead whereas this threshold was only observed in 33% of patients with the microporous lead (P < 0.01). At 52 weeks the pacing energy m easured at 1.6 V, twice pulse duration threshold, was significantly lo wer in the steroid lead group (0.81 +/- 0.59 muJ) compared to the micr oporous lead group (1.25 +/- 0.60 muJ, P < 0.05). Thirteen patients in the steroid lead group and 9 patients in the microporous lead group h ave been programmed at a pulse amplitude of 1.6 V since the 24-week fo llow-up visit. These patients have been followed for a minimum of 6 mo nths without documented failure to capture. This study shows that pace maker/lead systems with stable chronic low thresholds can be safely pr ogrammed to low pulse amplitude settings. This practice will prolong t he longevity of pulse generators.