Atrioventricular block: natural history after permanent ventricular pacing.

The preimplantation status, postimplantation morbidity and causes of late mortality were summarized for 246 patients who underwent pacing for atrioventricular (A-V) block at the University of Michigan for the 14 years from 1961 to 1974. The survival rate at 1, 5 and 10 years was 88, 61 and 49 percent, respectively. Risk of death was greatest among patients with antecedent ischemic or hypertensive heart disease or congestive heart failure in the period before pacemaker implantation, patients older than 74 years at initial implantation and those receiving a pacemaker before 1965. Forty-two percent of the 109 deaths were related to apparent progression of underlying cardiac disease. Pacing system malfunction was a contributing documented cause of only 3 deaths. Even with permanent pacemaker implantation, patients with A-V block have a higher age-specific mortality rate than the general U.S. population. Survival improved steadily over the period of study. This change is attributed to apparent improvements in treatment of cardiovascular disease including more effective treatment of congestive heart failure and valve replacement for selected patients as well as elimination of immediate postoperative mortality.

Symptomatic sinus node disease: natural history after permanent ventricular pacing.

Fifty-nine patients between the ages of 13 and 88 with sinus node disease, who received a permanent ventricular pacemaker between 1965 and 1976 at one institution, were followed to determine the natural history of the disorder after permanent pacing. Nineteen had ischemic heart disease, six had primary myocardial disease, and eight valvular heart disease. In 26, no etiology for the arrhythmia was apparent. The one- and five-year survival was 85.5% and 73.1%, respectively. Patients with underlying heart disease had a significantly poorer survival when compared to those without (58% versus 94% at 36 months) and all but 3 of 13 deaths in the first 36 months were in those with ischemic heart disease. There was a distinct trend toward poor survival in those with heart failure prior to pacemaker implant and those over age 65. Patients with sinus bradycardia alone did best (91% survival three years after implant), while those with bradycardia-tachycardia syndrome and those with sinoatrial arrest alone did distinctly worse (76% and 65% survival at three years, respectively). Twelve of 18 deaths were due to progression of underlying heart disease. The long-term prognosis with symptomatic sinus node disease can be predicted in part by (1) etiology of the underlying heart disease, (2) pre-implant arrhythmia, and (3) ventricular function prior to implant.