The purpose of the study was to compare the feasibility of low amplitude output programming (2.5 V/0.5 msec) 3 or more months after pacemaker implantation in patients receiving steroid and nonsteroid lead systems. Chronic pacing voltage, current, and energy thresholds were determined from 0.05- to 1.0-msec pulse duration in 44 patients with steroid lead systems, and in 36 patients with nonsteroid lead systems; all patients received pacemakers from the same manufacturer, which utilized the same programming and telemetry features. Chronaxie, pulse duration at the lowest pacing current, and energy were assessed from individual threshold curves. Steroid-eluting leads had significantly lower pacing voltage, current, and energy thresholds than nonsteroid leads. A 100% safety threshold margin could be achieved in 43 (98%) patients with steroid lead systems and in 27 (75%; P < 0.05) patients with nonsteroid lead systems with output programming of 2.5 V/0.5 msec. Chronaxie (0.22 +/- 0.17 msec vs 0.44 +/- 0.31 msec; P < 0.05), pulse duration at lowest pacing current (0.28 +/- 0.12 msec vs 0.49 +/- 0.22 msec; P < 0.05), and pulse duration at lowest pacing energy (0.31 +/- 0.17 msec vs 0.53 +/- 0.22 msec; P < 0.05) were significantly shorter for steroid than for nonsteroid lead systems. In 42 patients of the former group, a 100% safety margin could be maintained either with a 2.5 V/0.3 msec or with a 1.6 V/0.5 msec output. Conclusions Low amplitude output programming can be obtained in almost all pacemakers connected to steroid-eluting lead systems, and in a significantly higher number of patients than when connected with nonsteroid leads systems.(ABSTRACT TRUNCATED AT 250 WORDS)