Patient survival and instrument performance with permanent cardiac pacing.

Among 313 patients who received cardiac pacemakers between 1961 and 1973, there was a 65% survival rate after five years, a progressive decrease in premature pulse generator failures, and a low, stable incidence of electrode malfunction. Decreased survival among more recently paced patients was attributed to an evolution of the selection for pacing that favored older patients with associated diseases. Death due to unexpected pacing failure was extremely rare. Premature pulse generator failures decreased from 0.8 per 100 pacing months among early units to 0.06 per 100 months among units implanted during 1971 to 1973, when a prophylactic replacement policy was in effect. Electrode revisions were required at a frequency of 0.5 to 0.8 per 100 months in both epicardial and endocardial systems. Electrode failures may limit the predictive value of surveillance systems, since these rely on a change of pacing frequency or pulse width to indicate battery depletion.