Survival and Functional Independence after Implantation of a Permanent Pacemaker in Octogenarians and Nonagenarians: A Population-Based Study

Methods

Patient Selection

The study sample consisted of all residents of Olmsted County, Minnesota who were at least 80 years of age and had initially received a pacemaker between January 1962 and December 1988. Patients were categorized according to the presence or absence of symptomatic heart disease. Symptomatic heart disease was defined as documented coronary artery disease, cardiomyopathy, valvular heart disease, or other cardiac disease with symptoms of angina or congestive heart failure (New York Heart Association class II or more) [6]. Orthopedic disability was defined as degenerative or traumatic orthopedic injuries that resulted in the need for a device to assist in ambulation. Dementia was defined as diminished intellectual functioning or impaired memory as detected and documented by primary physicians.

Data Collection

We used a centralized system that provided complete records of pacemakers implanted in patients followed at the Mayo Clinic and its two affiliated hospitals (Saint Marys Hospital and Rochester Methodist Hospital).

Follow-up

The follow-up study was completed on 31 December 1992. Each patient was followed for at least 4 years after implantation of a pacemaker for the assessment of physical and functional capabilities.

Statistical Analysis

Survival after implantation of a permanent pacemaker was estimated by the Kaplan-Meier method and was compared with expected survival based on age- and sex-matched actuarial data from persons living in Minnesota in 1980 [7]. Observed and expected survival were plotted together (overall and in subgroups), and comparisons between observed and expected survival were based on the one-sample log-rank test. Two-group survival curve comparisons were based on the two-sample log-rank test. Univariable and multivariable associations of baseline variables with survival were assessed using the log-rank test and the Cox regression model [8]. Multivariable models were summarized in the form of point estimates and 95% CIs for the adjusted hazard ratios.

Results

Demographic Characteristics

Between January 1962 and December 1988, 157 patients (87 women and 70 men) 80 years of age or older from Olmsted County, Minnesota, were treated with permanent cardiac pacing. The mean age (±SD) of the study group was 85.2 ± 3.9 years. The mean age for women was 85.8 ± 4.2 years; that for men was 84.3 ± 3.5 years (P > 0.2). The mean duration of follow-up was 4.8 ± 2.4 years; the longest follow-up was 15.4 years. Ninety of the 157 patients had a history of structural heart disease. Age, sex, and duration of follow-up did not differ significantly between patients with and those without heart disease.

Indications

Of the 157 patients, 81 (52%) received permanent cardiac pacing for atrioventricular block, 50 (32%) received it for the sick sinus syndrome, and 12 (8%) received it for chronic atrial fibrillation with bradycardia. The 14 other patients received a permanent pacemaker for other indications, including carotid sinus hypersensitivity, vasovagal syncope, and drug-induced bradycardia.

Overall Survival and Heart Disease

Observed survival in the study group overall was significantly worse than had been expected on the basis of age- and sex-matched data (P < 0.001) (Figure 1, top). Observed survival was significantly worse than expected (P < 0.001) for patients with heart disease (Figure 1, middle) but was similar to expected survival in patients without heart disease (P > 0.2) (Figure 1, bottom).

Association between Survival and Disease of the Conduction System

Observed survival was significantly worse than expected for atrioventricular block (P = 0.001) and for chronic atrial fibrillation with bradycardia (P = 0.0058). However, it was similar to that expected for the sick sinus syndrome (P = 0.15) and other indications (P > 0.2). When patients were stratified by cause and associated heart disease, observed survival was worse than expected in patients with atrioventricular block who had (P = 0.005) and did not have heart disease (P = 0.02). However, survival was significantly worse than expected in patients with the sick sinus syndrome (P = 0.0068) than it was in those without (P > 0.2) other forms of heart disease.

Predictors of Death

Independent predictors of death were identified by multivariable analysis (Table 1). Among risk factors, the strongest independent predictor of death was the presence of congestive heart failure.

Survival was analyzed with respect to ventricular or dual-chamber pacing. One hundred twenty-eight patients (82%) received ventricular pacing, and 29 (18%) received dual-chamber pacing. Observed survival was significantly worse than expected in the group with ventricular pacing (P < 0.001), but it did not differ significantly between the two cardiac pacing groups. The mode of cardiac pacing was not an independent risk factor for poor survival (P > 0.2).

Mortality Rate and Causes of Death

By the end of follow-up, 126 patients (80%) had died. Death resulted from cardiac causes in 54 patients (43%) and from noncardiac causes in 72 (57%). The most common cause of death was an infectious process that was not related to the pacemaker (20%).

Functional and Physical Independence

Functional and physical variables were assessed before and after implantation of a permanent pacemaker. Of the total sample, symptoms decreased in 118 patients (75%). The predominant clinical presentations at the time of implantation of a permanent pacemaker were syncope or presyncope (121 patients [77%]); congestive heart failure (31 patients [20%]); and such features as angina, fatigue, and drug-induced pauses (5 patients [3%]). During the first year of follow-up, 101 patients (84%) had alleviation of symptoms of syncope or presyncope. During the first follow-up visit after implantation (usually 1 to 3 months), symptoms of congestive heart failure had been alleviated in 16 patients (52%). Twenty-three study patients were in nursing homes at the time of pacemaker implantation, and another 70 were permanently placed in nursing homes after implantation. The probabilities of nursing home placement were 12%, 37%, and 49% at 6 months, 1 year, and 3 years after pacemaker implantation, respectively. Before implantation, 31 patients had had a history of myocardial infarction, 32 had symptomatic cerebrovascular disease, 19 had orthopedic disability, and 22 had dementia. After implantation, new events occurred or symptoms worsened in 20 patients who had had myocardial infarction, 42 patients with cerebrovascular disease, 41 patients with orthopedic disability, and 51 patients with dementia.

Discussion

In our population-based study of octogenarians and nonagenarians, observed survival rates at 1 and 5 years were 80% and 40%, respectively, after implantation of a permanent pacemaker. This overall survival was less than that expected for age- and sex-matched cohorts from the general population. Our study included all residents of Olmsted County, Minnesota, who were 80 years of age or older and required a pacemaker. We thus provide unique clinical information about outcomes of pacemaker implantation in an unselected population.

Survival

Several studies have addressed the issue of survival after implantation of a permanent pacemaker in the very elderly [4, 5, 9, 10]. The survival rates observed in our study are similar to those reported by Strauss and Berman (Canadian referral practice case series) [5], better than those reported by Breivik and Ohm (Norwegian clinic-based study) [4], and worse than those reported by Elizabeth and Green (British population) [9]. The explanation for the different outcomes is not known, but it probably has to do with the differences in indications for cardiac pacing, patient selection criteria, presence and severity of underlying heart disease and with study periods. In addition to being a complete sample of initial pacemaker implantations in an entire geographically defined population, our study included careful evaluation of the effect of heart disease and medical illness on survival after implantation of a permanent pacemaker in very elderly patients. Our results confirm the negative effect of pre-existing congestive heart failure on survival after implantation of a permanent pacemaker [3]. Other significant independent predictors for early death include chronic obstructive pulmonary disease, old age, syncope, and cancer.

Conduction System Disease and Survival

The benefit of permanent cardiac pacing on survival in patients with high-degree atrioventricular block cannot be disputed. The prognosis of patients with untreated high-degree atrioventricular block is poor [11], and improved survival has been reported after implantation of a permanent ventricular pacemaker [3, 12, 13].

An important finding of our study is the relatively poor survival seen in octogenarians and nonagenarians after implantation of a permanent pacemaker for atrioventricular block; poor survival was noted regardless of the presence or absence of heart disease. Observed survival in this group was significantly worse than expected in patients with (P = 0.005) and without (P = 0.02) additional forms of heart disease. This is consistent with the general observation that the causes of death are probably multifactorial in the very elderly, as reflected by the significant number of patients who died of noncardiac causes; it also may imply that the presence of underlying heart disease may remain undiagnosed in many elderly patients.

Data on survival for octogenarians and nonagenarians after implantation of a permanent pacemaker for the sick sinus syndrome are limited. Earlier studies reported that this survival was similar to that of the general population [14]. More recent retrospective analyses with atrial or dual-chamber pacing have shown improved survival compared with VVI (ventricular pace, ventricular sense, inhibited mode) pacing [15-19].

Our results confirm that relative survival in octogenarians and nonagenarians after implantation of a permanent pacemaker for the sick sinus syndrome was similar to that in matched controls in the absence of other types of heart disease (P > 0.2). In the presence of other heart disease, observed survival in very elderly persons with the sick sinus syndrome was significantly worse than expected (P = 0.0068). Only 18% of our study patients received dual-chamber pacing systems, and our data cannot resolve the controversy about the mode of cardiac pacing and long-term survival in patients with the sick sinus syndrome. However, our results suggest that VVI pacing does not negatively affect survival in octogenarians and nonagenarians who have the sick sinus syndrome but no other form of heart disease. Whether outcome would be improved by dual-chamber pacing in patients with other forms of heart disease is an important area for further investigation.

Physical and Functional Independence

Symptoms were dramatically alleviated after patients with a definitive indication for cardiac pacing received permanent pacemakers. When symptoms of syncope, presyncope, and lightheadedness strongly correlate with bradycardia, relief of symptoms in the elderly is as complete as in younger patients [4, 5]. When congestive heart failure is the predominant indication for cardiac pacing, the therapeutic benefit of pacing is less. Our data agree with these earlier observations.

Our study indicates that octogenarians and nonagenarians are frequently placed in nursing homes after implantation of a permanent pacemaker. The number of patients placed in nursing homes after implantation appears to be similar to the estimated probability of lifetime use of nursing homes from the National Mortality Followback Survey [20]. Onset or worsening of cardiac, neurologic, and orthopedic disabilities occur frequently after implantation of a permanent pacemaker in the very elderly.

Conclusions

As a group, octogenarians and nonagenarians are highly heterogeneous with respect to severity of cardiac illness, coexisting medical problems, and functional capabilities. Reliable information from studies of very elderly patients is needed to determine whether permanent cardiac pacing favorably affects the survival and physical and functional capabilities of this rapidly expanding segment of our population. Our data suggest that cardiac pacing in octogenarians and nonagenarians must be tailored to the individual patient. Relative survival is inversely related to significant heart disease coexisting with medical illness. In patients who have atrioventricular block, the sick sinus syndrome, and other forms of heart disease, assessment of benefits from physiologic cardiac pacing is an important area for further investigation. In patients who have the sick sinus syndrome but no other forms of heart disease, our data support the opinion that VVI pacing does not negatively affect survival in very elderly patients. Our study also indicates that placement in a nursing home and neurologic and orthopedic disabilities occur frequently after implantation of a permanent pacemaker. Additional patient-derived information is needed to better understand functional status and quality of life after pacemaker implantation in the elderly.

Dr. Bailey: Department of Health Sciences Research, Mayo Clinic, 200 First Street SW, Rochester, MN 55905.

Dr. Ballard: Emory University Center for Clinical Evaluation Sciences, Atlanta, GA 30030.

Dr. Gersh: Division of Cardiology, Georgetown University Medical Center, 3800 Reservoir Road, Washington, DC 20007.