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Ann Thorac Surg 1997;63:1309-1314
© 1997 The Society of Thoracic Surgeons

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Original Article: Cardiovascular

Risks of Cardiac Operations for Elderly Patients: Reduction of the Age Factor

Departments of Surgery and Biomathematics and Biostatistics, Georgetown University Medical Center, Washington, DC

Accepted for publication November 20, 1996.

	Abstract

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
Background. Age has been considered an important risk factor for cardiac operations. Recent refinements have been designed to reduce cardiac, neurologic, and renal complications.

Methods. Analysis of cardiac surgical outcomes including mortality, length of stay, complications, and costs were undertaken for a consecutive series of 285 patients 70 years old and older and 568 patients younger than 70 years who underwent operation during 1991 through 1995. Management included antegrade and retrograde cold and warm blood cardioplegia, epicardial echocardiography, retrosternal dissection for reoperations, maintenance of "normal" arterial pressure, and measures to avoid renal dysfunction. Parsonnet risk stratification and multiple regression were used to account for risk factors.

Results. The 30-day mortality rate for elderly patients was 1.8% (5/285) and 1.8% (10/568) for patients less than 70 years old (p = not significant). The hospital mortality rate for the elderly patients was 3.2% (9/285) versus 2.5% (14/568) for the younger group (p = not significant). The frequencies of complications were not different. Over the 5-year period, length of stay decreased from 12.5 ± 1.5 days to 8.9 ± 0.9 days for patients 70 years old and older and from 11.5 ± 0.1 to 6.4 ± 0.3 days for patients less than 70 years old. Hospital charges for the elderly group were 13% higher.

Conclusions. Modern cardiac surgical techniques and clinical practices have reduced the importance of the age factor.

	Introduction

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
See also page 1314.

An increasing number of elderly patients with ischemic heart disease are being evaluated for cardiac surgical procedures. With today's emphasis on cost containment, results and costs of cardiac operations in elderly patients are being carefully weighed. Past studies [1–4] have documented increased mortality, complications, and length of hospitalization in older patients. New techniques such as catheter-based interventions and minimally invasive procedures are being advocated to avoid conventional cardiac operations, especially in elderly patients. With advances in cardiovascular surgical techniques and intensive care, risks and costs of cardiac surgical interventions for elderly patients may, in fact, be lower than in the past. Recently, encouraging results for cardiac operations in patients aged 70 years and older and in octogenarians have been reported [5–7].

Although it is recognized that hospitalization of the elderly patient for a cardiovascular operation may be more costly than that for a less invasive procedure, surgical intervention for these patients offers the possibilities of more sustained clinical improvement and fewer total days of hospitalization in the long term and, accordingly, lower overall costs. It therefore seems important to define the current risks and results.

	Material and Methods

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
The computerized cardiovascular surgery database for Georgetown University Medical Center was used to obtain the characteristics of patients undergoing cardiac operations by one of us (N.M.K.) from January 1991 through December 1995. During that time, 285 patients 70 years of age and older underwent cardiac operations and form the study group of elderly patients. Ages ranged from over 70 years to 91 years. The age distribution is shown in Table 1. The types of operations were as follows: isolated coronary artery bypass grafting (CABG), 209 (73%); valve procedure, 35 (12%); combined CABG and valve procedure, 28 (10%); and other, 13 (5%). The distribution of ejection fractions is shown in Table 2. There were 263 primary operations (92%), 21 first reoperations (7%), and 1 second reoperation (0.4%). Operations were considered elective in 29 patients (10%), urgent in 236 (83%), and emergent in 20 (7%). Emergency operation was defined as an operation that was considered immediately necessary and was performed as soon as the patient could be taken to the operating room. In the 209 patients undergoing isolated CABG, the mean number of grafts per patient was 2.9 ± 0.1, and 186 (89%) received at least one internal mammary artery graft.

Hospital charges were calculated for each patient on the basis of data from the Hospital Information System. The total hospital charge calculated for each patient included the following charges: operating room, intensive care unit and step-down unit nursing, pharmacy, laboratory, radiology, respiratory, cardiology, supplies, and miscellaneous. A hospital charge ratio was used for comparing the charges in patients 70 years of age and older with those in patients less than 70 years old and was determined by dividing the mean charges for the elderly patients by the mean charges for the younger patients.

Standard techniques of cardiopulmonary bypass were employed. Intraoperative measures to prevent atherosclerotic emboli included liberal use of epicardial echocardiography with changes in cannulation and clamping techniques as indicated. In general, a tangential clamp was used for proximal anastomoses. If major atherosclerotic disease was detected in the ascending aorta or if the procedure was a reoperation, a single cross-clamp technique was employed. Myocardial preservation was achieved by antegrade and retrograde cold and warm blood cardioplegia with monitoring of myocardial temperature. Pericostal wires were used frequently to reinforce sternal closure. In reoperations, retrosternal dissection was employed before sternal division [9]. Carotid endarterectomy was combined with the cardiac procedure for concomitant critical carotid disease in 4 patients. Of the 285 patients in the elderly study group, 222 were eligible for 1-year follow-up and 183, for 2-year follow-up. Follow-up information was obtained for all of these patients.

Clinical practices included (1) maintenance of "normal" arterial pressure during and after operation; (2) measures to prevent renal failure, such as preoperative volume infusion, mannitol during cardiopulmonary bypass, and low-dose dopamine hydrochloride postoperatively; (3) elective moderate anticoagulation for prevention of deep venous thrombosis and prevention of emboli related to atrial fibrillation; and (4) short-acting anesthetic agents to facilitate early extubation and early mobilization. Dopamine was infused at 1.5 µg•kg^-1•min^-1 and was used for prophylaxis against renal failure. Intravenous heparin sodium was employed for prevention of deep venous thrombosis in patients with a prior history of venous thrombosis or in patients who could not be easily mobilized. The target level for the partial thromboplastin time was 40 to 50 seconds. If anticoagulation was needed for more than a few days for this indication, crystalline warfarin sodium (Coumadin; Du Pont Pharma, Wilmington, DE) was employed to achieve an international normalized ratio of 1.5 to 2.5. If atrial fibrillation developed that did not respond to pharmacologic treatment within 4 hours, intravenous heparin was used to achieve a partial thromboplastin time of 40 to 50 seconds. Coumadin, when administered for this indication, was used to achieve an international normalized ratio of 2.0 to 3.0. The short-acting anesthetic agents given included fentanyl, midazolam hydrochloride, pancuronium bromide, and isoflurane. Sedation early postoperatively was achieved with continuous infusion of propolol. These agents facilitated early extubation, that is, within 4 to 18 hours after operation.

Results are expressed as the mean ± the standard error of the mean. Fisher's exact test or an equivalent ² test was used to compare sample proportions. Student's t test or the Mann-Whitney U test was employed to compare mean lengths of hospitalization. Multiple logistic regression models were utilized to evaluate the impact of age on mortality risk adjusted for other patient factors.

	Results

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
The 30-day mortality for the group of patients 70 years of age and older was 5 (1.8%) of 285 patients. Four of the 285 patients who survived 30 days died in the hospital. Thus, the overall hospital mortality for the elderly patients was 9 (3.2%) of 285. The 30-day mortality by age group is shown in Table 4. Thirty-day mortality for the patients who underwent isolated CABG was 2 (1.0%) of 209. For patients who underwent a valve operation, 30-day mortality was 1 (2.9%) of 35 and for patients who underwent valve CABG ± other procedure, 1 (3.3%) of 30. There were no deaths among the 22 patients having reoperation. The causes of death varied and included the following: low cardiac output in a 77-year-old patient who underwent CABG for acute myocardial infarction with shock; sudden asystole on postoperative day 2 in an 81-year-old patient who underwent aortic valve replacement for severe aortic stenosis; ventricular hemorrhage in a 72-year-old patient in cardiogenic shock as a result of acute myocardial infarction/ventricular septal defect and right ventricular rupture who underwent repair; left atrial hemorrhage in a 76-year-old patient who underwent aortic and mitral valve replacement and CABG; and intrapulmonary hemorrhage in a 76-year-old patient with congestive heart failure and myocardial infarction who underwent CABG. The three late deaths were due to arrhythmia, respiratory failure, and hepatic failure.

The frequency of major complications is shown in Table 6. Mean length of postoperative stay in all surviving patients 70 years old and older was 11.2 ± 0.6 days compared with 9.1 ± 0.3 days in patients less than 70 years old (p < 0.001). Over the 5-year study period, mean length of stay decreased from 12.5 ± 1.5 days to 8.9 ± 0.9 days for the elderly group and from 11.5 ± 0.1 days to 6.4 ± 0.3 days for the younger group. Table 7 shows the length of stay for all patients according to the Parsonnet risk category. For the entire time of the study, the ratio of the mean hospital charges in patients aged 70 years and older to the charges in patients less than 70 years old was 1.13.

	Comment

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
An increasing number of elderly patients are being considered for cardiovascular operations. With the recent widespread concerns about cost containment in health care, cardiac operations in elderly patients are being scrutinized in regard to early results, long-term benefits, and costs compared with medical treatment and less invasive techniques.

Past studies [1–4] have demonstrated increased risks for elderly patients undergoing cardiac surgical procedures. Models of risk stratification have also reflected the effect of age on risk. For example, in the system described by Parsonnet and colleagues [8] in 1989, a weight of 7 (equivalent to a 7% operative risk) was added to the patient's weighted score if he or she was 70 to 74 years old. A weight of 12 was given to patients 75 to 79 years old, and patients 80 years and older were assigned a weight of 20 (equivalent to a 20% operative mortality). This model was based on results of a retrospective analysis of 3,500 consecutive operations performed from 1982 to 1987 and was tested prospectively in three centers in more than 2,000 patients. More recently, Tsai and associates [5] and Sahar and colleagues [6] reported encouraging results for octogenarian patients, and our medical center [7] presented favorable results for cardiac operations in patients 70 years old and older. Mortality in this last series was increased in the elderly patients, but the results seemed to represent an improvement from studies published several years previously. The present study was undertaken to determine whether age is still an important determinant of surgical results.

Our selection of 70 years as the age to define elderly patients was based on past studies. We recognize that selection of this age is somewhat arbitrary and that as operations are performed more frequently for patients in the ninth and tenth decades, the age to dichotomize results may be advanced to 80 or 85.

The mortality and the incidence of major complications in the elderly patients in this study were not significantly different from those in the younger patients (30-day mortality, 1.8% versus 1.8%, and hospital mortality, 3.2% versus 2.5%). These favorable results and those from other centers for cardiac surgical procedures in elderly patients may be a reflection of recent intraoperative technical advances and refinements in intensive care. Probably the most important modern refinements in neutralizing the age factor relate to myocardial preservation. Elderly patients seem to be at particular risk for the complications of low cardiac output, such as renal failure, stroke, and mesenteric infarction. The cardioplegic technique employed included the use of warm as well as cold solutions and retrograde as well as antegrade infusions.

It has been well recognized that atherosclerotic emboli are an important cause of morbidity and mortality in cardiac surgical patients [10, 11]. In this series, epicardial echocardiography was employed liberally, and cannulation and clamping techniques were modified in accordance with the findings. The ascending aorta was replaced because of severe calcification in 1 elderly patient. Stroke was recognized in 4 of 285 patients, or 1.4%. None of these patients had concomitant carotid endarterectomy.

Preoperative renal dysfunction, particularly in elderly patients, is an important risk factor for morbidity and mortality. In designing their "clinical severity score," Higgins and colleagues [12] noted that moderate elevation of serum creatinine levels, 1.6 mg/dL to 1.8 mg/dL, adds only moderate risk but that preoperative creatinine values of 1.9 mg/dL or greater are associated with markedly increased risk. This is reflected in their clinical severity scoring system. Lahey and colleagues [13] reported that a creatinine level greater than 2 mg/dL was an important risk factor for prolonged hospital stay in patients older than 60 years having CABG. Although there are not data from this study to document favorable effects, when the serum creatinine level was 1.5 mg/dL or greater, intravenous fluids at or greater than maintenance levels were infused in the 8 hours preceding operation, and dopamine was infused during operation and in the early postoperative period.

The sternum of elderly patients is sometimes fragile because of osteoporosis and suboptimal nutrition. When this situation was identified in this series, additional sternal wires were placed in a pericostal fashion. There was one instance of dehiscence in both the elderly group (0.4%) and the younger group (0.2%) (p = not significant).

Elderly age has been recognized as a predictor of increased length of hospital stay after cardiac surgical procedures [13–16]. In the recent study from our medical center [7], mean length of stay for elderly patients was about 3 days longer (11.6 versus 8.5 days). In the present study, length of postoperative stay was higher by 2 days in the elderly group compared with the younger group. The increased length of hospitalization probably reflects less resilience to the stress of operation. An important challenge in the future will be to employ techniques such as minimally invasive procedures and practices such as those in rapid recovery protocols [17, 18] to facilitate a more rapid convalescence and an earlier dismissal from the hospital. Over the 5-year period of this study, length of postoperative stay decreased in both age groups probably as a result of the institution of such protocols. The increased length of stay and the greater intensity of care required for elderly patients is reflected in the 13% higher overall hospital charges compared with younger patients. This increase in charges was related to multiple factors such as longer intensive care stays and use of more laboratory tests and more pharmacologic agents. It should be emphasized that the data available were charges, not costs.

Although follow-up data in this study are limited, the early results were favorable with a 91% 2-year survival rate and most patients in New York Heart Association classes I and II. In an extensive nonrandomized study of patients aged 65 and older from the Coronary Artery Surgery Study (CASS) Registry, Gersh and colleagues [19] documented a cumulative survival rate of 79% at 6 years in the surgical group. At 5 years, 62% of the patients in the surgical group were free from chest pain. In comparison, the cumulative survival rate at 6 years was 64% in the medical group and at 5 years, only 29% of them had no chest pain. Salomon and co-workers [20] reported a 5-year survival rate of 80% for patients older than 75 years undergoing CABG. Rahimtoola and colleagues [21] documented 5- and 10-year survival rates of 81% and 65%, respectively, in patients aged 65 years and older who underwent CABG. Jaeger and associates [22] reported that most elderly patients experience a meaningful improvement in functional capacity after cardiac operations, and Kumar and colleagues [23] documented improved quality of life in octogenarians after cardiac surgical procedures.

Our findings could be interpreted as indicating that the risk of death from a cardiac operation in elderly patients can be reduced to that of younger patients with consistent and careful application of modern techniques and clinical practices. A second interpretation is that operations in elderly patients who were seen with potentially catastrophic clinical situations were avoided. In the overall series, we did select against patients with severe left ventricular dysfunction and ongoing myocardial infarction, recent stroke, ongoing gastrointestinal bleeding, and end-stage pulmonary disease. We recognize that this screening of patients for potentially catastrophic complications might have been applied differentially for elderly patients, as older patients do not seem to have as strong recuperative powers in the face of life-threatening complications. However, we do not think that patient selection factors are completely responsible for our results because detailed examination of the risk factors omitting age has shown a typical or slightly elevated risk profile for the elderly patients as a group.

In summary, (1) with present surgical techniques and clinical practices, mortality for cardiac operations in patients 70 years old and older approached that for patients less than 70 years old; (2) the frequency of complications was not significantly higher for the elderly patients; (3) mean length of hospitalization in elderly patients was approximately 2 days longer than that for younger patients; and (4) mortality and length of stay correlated with risk predicted by the Parsonnet model, but the actual risk was less than predicted. Results of this study support continued performance of cardiac surgical procedures in select elderly patients. The higher costs documented for elderly patients are a challenge to apply the latest surgical techniques and postoperative care protocols to facilitate a more rapid convalescence. Modern techniques seem to have mitigated the age factor in cardiac surgery.

	Acknowledgments

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
We thank Kerry Murphy, RN, and Evelyn Naranjo, MA, for assistance with the statistical analyses and manuscript preparation.

	Footnotes

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
Address reprint requests to Dr Katz, Department of Surgery, Georgetown University Medical Center, 3800 Reservoir Rd, NW, Washington, DC 20007.

	References

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 

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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): Nevin M. Katz Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Katz, N. M. Articles by Chase, G. A. Search for Related Content PubMed PubMed Citation Articles by Katz, N. M. Articles by Chase, G. A. Related Collections Related Article