Symptomatic bradyarrhythmias in the adult: natural history following ventricular pacemaker implantation.

The preimplantation arrhythmias, coexistent medical conditions, the causes of death, and survival course are described for 399 patients who received their initial ventricular pacemaker implantation for a bradyarrhythmia (AV block, sinus node disease, and hypersensitive carotid sinus syndrome) at the University of Michigan from 1961 to 1979. Factors which correlated with a poor survival are elucidated. Survival for those with sinus node disease was virtually identical to those with AV block, with only 63% surviving over five years. Advanced age and congestive heart failure prior to implantation, and underlying ischemic or hypertensive heart disease portended a poorer survival in both groups. Patients with hypersensitive carotid sinus syndrome had a distinctly better prognosis--no deaths occurred until the eight year after pacing. Patients with no underlying heart disease and those with valvular disease did remarkably better than those with an ischemic or myopathic etiology. Apparent progression or complications of the underlying heart disease was the major cause of mortality. Sudden death, congestive heart failure, myocardial infarction, and major arrhythmias were the causes of death in 48% of those who died. Implications of improved pacing modalities on late complications and death are discussed.