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Ann Thorac Surg 1997;64:1713-1717
© 1997 The Society of Thoracic Surgeons

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Original Articles: Cardiovascular

Favorable Results of Implantable Cardioverter-Defibrillator Implantation in Patients Older Than 70 Years

Divisions of Cardiothoracic Surgery and Cardiology, Case Western Reserve University School of Medicine, University Hospitals of Cleveland, Cleveland, Ohio

Accepted for publication June 9, 1997.

	Abstract

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
Background. The clinical results of implantable cardioverter-defibrillator (ICD) implantation in the elderly have received limited documentation. As the longevity of the U.S. population has increased, so has the need for ICD implantation in the elderly. We evaluated the efficacy and outcome of ICD implantation in elderly patients (>70 years) compared with younger patients.

Methods. The case records of all consecutive patients who underwent ICD implantation at our institution between 1986 and 1994 were reviewed. Of a total of 238 patients, 78 patients were 70 years of age or older and 160 patients were younger than 70 years of age.

Results. The mean age of the younger group was 58 years and that of the elderly group was 74 years. There were no statistical differences in the presence of coronary artery disease, left ventricular systolic function, the inducibility of arrhythmias, or the history of sudden cardiac death. The hospital morbidity rate was similar in both groups (6.9% in the younger group and 7.7% in the elderly group; p = not significant). The operative mortality rate was 1.9% for the younger group and 1.3% for the elderly group (p = not significant). At a mean follow-up of 33 ± 26 months, Kaplan-Meier survival curves demonstrated similar survival rates, with 93%, 82%, and 65% of the patients alive at 1, 3, and 6 years, respectively.

Conclusions. Implantable cardioverter-defibrillator implantation was equally effective in the treatment of patients older than 70 years as in younger patients. No differences in theoretic survival or morbidity were observed.

	Introduction

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
Over the past decade, the implantable cardioverter-defibrillator (ICD) has become used widely for the prevention of recurrent sudden cardiac death and the treatment of life-threatening ventricular tachyarrhythmias [1, 2]. The remarkable efficacy of the ICD in preventing sudden cardiac death, with freedom from sudden or arrhythmic death demonstrated to be 95% at 3 years, has led to its ever-increasing use. Although the ICD represents only a palliative modality in the sense that the arrhythmia is recognized and corrected when it occurs, its effectiveness has led many to suggest that the ICD should be considered as first-line therapy for these arrhythmias [3, 4].

When the life expectancy of a population exceeds 65 years, cardiovascular disease is the principal cause of morbidity and mortality. As the U.S. population ages, an increasing number of elderly patients will be considered for ICD therapy for the management of malignant ventricular tachyarrhythmias. It is estimated that by the year 2000, two thirds of all patients who receive an ICD will be of Medicare age [5], yet the clinical results and efficacy of the ICD in the elderly have received sparse attention. Previous studies of ICD implantation have included a heterogeneous population of patients, and this has not allowed for the analysis of an elderly population compared with a younger cohort [6–9]. It is believed that elderly patients have higher surgical mortality and higher complication rates, but this has not undergone critical analysis in large populations [10]. This study analyzes two cohorts of patients undergoing ICD therapy over an 8-year period in an effort to determine ICD efficacy and analyze patient outcome in elderly patients (>70 years) compared with younger patients.

	Material and Methods

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
Patients
The case records of consecutive ICD recipients with or without concomitant operations at the University Hospitals of Cleveland/Case Western Reserve University between 1986 and 1994 were reviewed. Patients with ICD generator changes were excluded. Of a total of 238 patients, 78 patients were identified as being 70 years or older and 160 patients as being younger than 70 years. Patients were selected for ICD implantation when they had symptomatic ventricular tachycardia, inducible ventricular tachycardia, or survival after sudden cardiac death. Selection criteria were applied equally to both age groups.

Before ICD insertion, all patients underwent extensive preoperative clinical evaluation. Left heart catheterization and coronary arteriography were performed. Coronary artery disease was defined as the presence of at least one obstructive lesion causing at least 70% reduction in luminal diameter in one of the three major coronary arteries. Left ventricular ejection fractions were calculated from the ventriculogram, radionuclide ventriculography, or echocardiography. Electrophysiologic studies were performed in the drug-free state using two right ventricular sites, two basic cycle lengths, and up to three extrastimuli. Inducible sustained ventricular tachycardia was defined as an organized ventricular arrhythmia that had a cycle length of 200 ms or longer, had a duration of more than 30 seconds, or required cardioversion because of hemodynamic instability. Ventricular fibrillation was defined as a ventricular tachyarrhythmia that had a cycle length of less than 200 ms.

Surgical Technique
Sternotomy was used exclusively for ICD placement when an associated open heart operation was required. All patients with critical coronary artery lesions underwent associated coronary artery bypass grafting. Our technique has been reported elsewhere [11]. Before the availability of transvenous lead systems, a limited anterolateral thoracotomy or subxiphoid approach was used for patients with a history of cardiac operations. In these situations, the ICD system consisted of two epicardial patch electrodes and two screw-in sensing leads. After 1992, all the implants were performed by the transvenous approach. The transvenous electrode lead systems used were either Endotak (Cardiac Pacemaker Inc., Minneapolis, MN) or Transvene (Medtronic, Inc., Minneapolis, MN). The characteristics of the lead systems have been described elsewhere [12]. Defibrillation thresholds of 20 J or less were confirmed, and a 10-J safety margin was used.

Postoperative Follow-up
After discharge from the hospital, all patients were followed up at 1- to 2-month intervals at our arrhythmia clinic. This was supplemented by telephone contact with the patients' personal physicians. Follow-up was available through November 1995. At each clinic visit, the ICD was interrogated to determine the number of delivered shocks. Patients who had ICD discharges were questioned regarding the circumstances of the shocks and any associated symptoms of palpitations, light-headedness, near-syncope, or syncope.

Appropriate shocks were defined by analysis of telemetered rhythms or by associated symptoms in nontelemetry ICDs. Inappropriate shocks were defined as telemetered atrial arrhythmias or device malfunction. In nontelemetry ICDs, all shocks were classified as unknown when there was no associated syncope.

Statistical Analysis
All data are expressed as the mean ± standard deviation. Comparisons between groups were performed by the paired t test and ² analysis, with statistical significance set at p less than 0.05. From the survival status of patients as of November 1995, actuarial survival curves were generated using the Kaplan-Meier method. Survival analysis included cardiac deaths and deaths from all causes, including perioperative deaths. The log-rank test was used to compare survival rates. Those variables found to be significant at p less than 0.05 were tested in a Cox proportional hazards regression model.

	Results

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
Clinical Data
The demographic and clinical data are summarized in Table 1. Of the 238 patients, 78% were men. The mean age was 63 ± 11 years (range, 15 to 83 years). Five patients were octogenarians. The mean left ventricular ejection fraction was 0.34 ± 0.14 (range, 0.10 to 0.80). The demographics of each group were similar in regard to sex, clinical presentation, left ventricular function, and incidence of coronary artery disease. No significant difference was noted in the use of surgical coronary revascularization between the two groups, although a trend toward greater use of coronary bypass grafting was noted in the younger group.

Hospital Course
Postoperative antiarrhythmic medication use did not differ significantly within and between the two age groups. Forty-nine percent of the elderly patients and 41% of the younger patients were taking either a class I or a class III agent at the time of hospital discharge. The choice of medication was made on the basis of physician preference or on patient enrollment in multicenter antiarrhythmic drug trials.

Appropriate ICD discharges were seen in 40% of elderly patients and in 48% of younger patients. There was no significant difference in the average number of shocks between age groups. There also was no difference in the number of shocks between patients who were and were not taking antiarrhythmic medication.

The hospital morbidity rate was 6.9% in patients younger than 70 years and 7.7% in patients older than 70 years. Perioperative complications included myocardial infarction, hematoma, respiratory infection, postpericardiotomy syndrome, and respiratory insufficiency. All cardiovascular and pulmonary complications occurred in patients with ejection fractions of less than 0.40. There was no significant difference in complication rates between age populations (Table 3). There also was no significant difference in complication rates between the age groups that received transvenous systems.

Follow-up
Of the late complications, infections occurred in 5 patients, for an overall infection rate of 2.1%. Infections occurred in 2 patients with transvenous systems. They were managed with lead and ICD generator removal, followed by reimplantation at a later date. In the 3 patients with epicardial system generator infections, aggressive local debridement and antibiotic irrigation of the generator pocket [13] was successful, and these patients continued to do well for a mean follow-up of 33 months.

The causes of death in both age groups are shown in Table 3. Most of the deaths in both patient groups were secondary to congestive heart failure, with ejection fractions of less than 0.20. The mean follow-up period for the entire group was 33 ± 26 months. Kaplan-Meier actuarial survival curves for observed overall survival and freedom from sudden cardiac death for the entire cohort of patients are shown in Figure 1. At a projected follow-up period of 7 years, freedom from sudden cardiac death remained near 90%, demonstrating the reliability of the ICD in terminating sudden cardiac death. Overall survival, including operative mortality, was 75% at 5 years and 63% at 7 years.

View larger version (25K): [in this window] [in a new window]   Fig 1. . Kaplan-Meier actuarial survival curves for overall freedom from death and freedom from sudden cardiac death. Time 0 is the time of operation.

View larger version (27K): [in this window] [in a new window]   Fig 2. . Kaplan-Meier actuarial survival curves as stratified by older and younger age groups. No difference was noted by log-rank test.

View larger version (23K): [in this window] [in a new window]   Fig 3. . Kaplan-Meier actuarial survival curves as stratified by left ventricular function. The difference was statistically significant by the log-rank test. (LVEF = left ventricular ejection fraction.)

	Comment

Top Footnotes Abstract Introduction Material and Methods Results Comment References

The definition of "elderly" in ICD recipients is arbitrary. Previous studies have used the age of 65 years as the criterion, but no study has evaluated critically ICD implantation in patients older than 70 years. Tresch and colleagues [10] compared the benefits and complications of ICD therapy in patients older than 65 years versus those younger than 55 years. Higher surgical mortality was noted in the older cohort, although long-term survival was similar. In a more recent study [14], these investigators found no significant differences in mortality or morbidity in patients older or younger than 65 years who were undergoing ICD implantation. Late complications of cerebrovascular accidents were seen in 3 of 54 patients older than 65 years. This was in contrast to 0 of 79 patients in the younger cohort.

In contrast, other studies comparing the results of ICD implantation in elderly patients with those in younger patients have shown decreased survival, increased morbidity, and decreased functional capacity in elderly patients. Manolis and colleagues [15] reported a 7% operative mortality rate in 85 patients older than 65 years versus a 1% rate in younger patients. Notwithstanding this discrepancy in outcome analysis in the older population, our present study demonstrates that ICD implantation can be performed with low operative mortality and morbidity in patients older than 70 years. The operative mortality rate of 1.3% in the elderly group is comparable to some of the published data on younger cohorts of patients [16, 17]. In our study, no difference was noted in either mortality or morbidity when comparing older and younger patients.

The increased use of transvenous lead systems, which has simplified greatly the approach to ICD implantation, may explain the encouraging results. The older cohort of patients was comparable to the younger cohort in terms of demographic factors such as clinical presentation, sex, presence of structural heart disease, left ventricular function, and results of electrophysiologic testing. The only difference was the increased use of transvenous lead systems in the older cohort (p = 0.04).

Saksena and colleagues [18] have reported the outcomes of 686 patients treated with nonthoracotomy ICD implantation during a mean follow-up period of 5.6 ± 4.0 months. The perioperative mortality rate was 0.8% and the 2-year total mortality rate was 12.4%. Other studies have confirmed that patients with transvenous ICDs have better outcomes than patients with thoracotomy ICDs [16, 19]. In a multicenter study of 1,221 patients undergoing either epicardial system implants (616 patients) or transvenous system implants (605 patients), the operative mortality rate was 0.8% with transvenous systems versus 4.2% with epicardial systems (p < 0.001) [20].

In our experience, the operative mortality has been similar for patients older than 70 years compared with younger cohorts. In addition, the actuarial survival at 12, 24, and 36 months did not differ from that of younger patients. It is notable that on long-term follow-up, most of the deaths resulted from cardiac causes (mainly end-stage heart failure) in both the older and younger cohorts of patients. This raises the possibility that the elderly patients who underwent ICD implantation with or without concomitant cardiac operations were functionally active before the occurrence of syncope or the ventricular arrhythmias. Therefore, it was a select group of patients who were included in the study.

With regard to the mortality rate of patients with severe left ventricular dysfunction who undergo ICD implantation, several studies have noted a significantly higher mortality rate in patients with an ejection fraction of less than 0.30, compared with patients with an ejection fraction of 0.30 or greater [16, 21, 22]. With the evolution of the ICD implantation technique and defibrillator technology, reductions in both perioperative mortality and sudden cardiac death are occurring. Therefore, more patients are exposed to competing causes of death, such as end-stage congestive heart failure or myocardial infarction. The Cox proportional hazards regression analysis in the present study demonstrated that cardiac mortality was predicted most powerfully by left ventricular ejection fraction, and not by age.

The role of antiarrhythmic medications after ICD implantation remains controversial. Fazio and colleagues [23] found that the presence of an antiarrhythmic medication did not reduce the recurrence of ventricular arrhythmias. In the present study, the selection of an antiarrhythmic medication depended on the physician, and also may have been influenced by the patient's enrollment in a clinical trial. However, the number of appropriate ICD shocks was not different among the groups, so the inability to control for the selection and use of an antiarrhythmic medication does not appear to be significant.

The limitations of this study include its retrospective nature, such that variables such as concurrent medications and comorbid diseases were not controlled. However, the effects of these variables did not appear to be significant with regard to overall survival.

Within the limitations of this study, these findings have significant implications for a population with improving longevity. The mortality and morbidity of ICD implantation in patients older than 70 years were not different from those of a younger subset of patients. Chronologic age itself does not appear to affect mortality, morbidity, or long-term survival. Because transvenous ICD implantation decreases perioperative mortality and produces a significant survival benefit, the use of the ICD in the elderly is warranted.

	Footnotes

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
Address reprint requests to Dr Lee, Division of Cardiothoracic Surgery, University Hospitals of Cleveland, 11100 Euclid Ave, Cleveland, OH 44106.

	References

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 

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14. Tresch DD, Troup PJ, Thakur RK, et al. Comparison of efficacy of automatic implantable cardioverter defibrillator in patients older and younger than 65 years of age. Am J Med 1991;90:717–24.[Medline]
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17. Mosteller RD, Lehmann MH, Thomas AC, et al. Operative mortality with implantation of the automatic cardioverter-defibrillator. Am J Cardiol 1991;68:1340–5.[Medline]
18. Saksena S, Poczobutt-Johanos M, Castle LW, et al. Long-term multicenter experience with a second generation implantable pacemaker-defibrillator in patients with malignant ventricular tachyarrhythmias. J Am Coll Cardiol 1992;19:490–9.[Abstract]
19. Bardy GH, Hofer B, Johnson G, et al. Implantable transvenous cardioverter-defibrillators. Circulation 1993;87:1152–68.[Abstract/Free Full Text]
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21. Gohn D, Edel T, Pollard C, et al. Determinants of operative mortality in implantable cardioverter defibrillator. J Am Coll Cardiol 1991;17(Suppl A):86A.
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This Article Abstract Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Jai H. Lee Helen K. Murrell Alexander S. Geha Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Quan, K. J. Articles by Geha, A. S. Search for Related Content PubMed PubMed Citation Articles by Quan, K. J. Articles by Geha, A. S.