The natural history of long-term cardiac pacing.

During the past ten years, 504 patients have received one or more pacemakers for complete heart block or other arrhythmia. Of these patients, 306 (61%) are alive. Actuarial analysis shows a steady attrition of 9.4% per year for the first five years, decreasing to 7% per year for the second five years. The overall survival was decreased for patients with congestive heart failure and advanced age and was not affected by the history of Stokes-Adams attacks, initial pulse rate below 50 per minute, or a QRS duration greater than 0.12 second prior to pacing. Cardiac problems were the primary cause of death in 71% of the patients. The natural history of patients with permanent pacemakers depends, more than any other factor, on the function of the left ventricle.