Survival rates after pacemaker implantation: a study of patients paced for sick sinus syndrome and atrioventricular block.

It is still a matter of controversy as to whether the patients paced for atrioventricular block (AVB) have different prognosis and survival rates than those paced for Sick Sinus Syndrome (SSS). We have compared the survival rates of 962 AVB patients (group A) with that of 283 SSS patients (group B) who underwent pacemaker implantation during the period January 1968 to December 1986. The survival rate graphs of the examined groups were calculated using the actuarial method and the differences in the survival rates between the groups were evaluated using the Logrank test. Our results show that SSS patients have a higher survival rate than AV block with a difference on the rate of survival between the two groups reaching the borderline of statistical significance. Multivariate discriminant analysis was then used to assess that of the parameters (i.e., age at the time of implantation, sex, electrophysiological indication to pacing, etiology or pacing mode) could have had the main influence upon mortality and the different pattern of the survival rate graph within the two groups of patients. Our data show that survival is mostly related to age, pacing mode and, although more slightly, to underlying heart disease; the electrophysiological indication to pacing, instead, does not significantly influence it.