LONG-TERM THRESHOLDS OF NONSTEROIDAL PERMANENT PACING LEADS - A 5-YEAR STUDY

The present commercial market supports many nonsteroidal endocardial p acing leads of differing construction. In order to compare the perform ance of these configurations, we studied the long-term pacing properti es of three representative lead types by randomized clinical trial in 99 patients undergoing a first elective VVI implant. Thirty-one patien ts received sintered platinum leads, 36 activated pyrolytic carbon lea ds, and 32 vitreous carbon leads. All received generators capable of n oninvasive threshold testing Acute sensing parameters were R wave ampl itude and ST segment elevation measured from the endocardial electrogr am. Noninvasive voltage thresholds were measured at implantation, 2 da ys, 1, 3, and 6 months, and yearly thereafter for 5 years. There were no significant differences between leads in pacing or sensing capabili ties at implantation. All three demonstrated similar increases in thre sholds, peaking at 1 month, then falling to a plateau by 6 months and did not vary significantly thereafter There were no significant differ ences in thresholds between leads during 5 years of follow-up. The low est mean threshold at 5 years was 0.93 V at 0.5 ms. This study suggest s that: (1) although these lead types all perform well, none offers an y particular clinical advantage over another; (2) the degree of early threshold peaking precludes immediate postimplant output reduction, bu t later thresholds are sufficiently low to. enable reductions in pacin g output; (3) safe low energy pacing requires greater attention to the lead-generator combinations; (4) data obtained at subsequent annual f ollow-up provided no additional useful clinical information to that ob tained at 1 year; and (5) in the absence of other differences, cost ca n be the deciding factor in lead selection.