Ann Thorac Surg 1996;62:1123-1127
© 1996 The Society of Thoracic Surgeons
Original Articles: Cardiovascular
Influence of Increasing Age on Long-Term Survival After Coronary Artery Bypass Grafting
Charles C. Canver, MD,
Ronald D. Nichols, Ccp,
Stephania D. Cooler, MS,
Dennis M. Heisey, PhD,
Edward L. Murray, Cp,
George M. Kroncke, MD
Section of Cardiothoracic Surgery, William S. Middleton Memorial Veterans Hospital, University of Wisconsin School of Medicine, Madison, Wisconsin
Accepted for publication May 3, 1996.
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Abstract
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Background. Despite the steady increase in the number of elderly patients undergoing coronary artery bypass grafting (CABG), skepticism still exists as to whether this operation is justified in older people with a reduced life expectancy. The purpose of this study was to examine the effects of increasing age on outcome after CABG.
Methods. A retrospective chart review was performed on 1,689 consecutive veterans of the United States Armed Forces undergoing isolated primary CABG from January 1972 through December 1994. For better comparison, they were arbitrarily divided by age into three groups: group I, 50 years of age or less (n = 213), group II, between 51 and 70 years of age (n = 1,258), and group III, more than 70 years of age (n = 218). Long-term survival for each group was compared to that of their age-matched population derived from Wisconsin life tables.
Results. The preoperative ejection fraction was comparable in all three groups (p = 0.114). The patients older than 70 years of age had received more grafts per operation than the patients 50 years of age and younger (3.7 versus 3.3) (p = 0.0001). Although the aortic cross-clamp time was prolonged with advanced age (p = 0.0002), the cardiopulmonary perfusion time was shortest in elderly patients (p = 0.0001). The early (30-day) mortality for the entire study population was 1.3%. There was a linear correlation between increasing age and early (30-day) mortality: group I, 0.5% (1/213); group II, 1.0% (13/1,258); and group III, 3.2% (7/218). The overall 10-year actuarial survival for all patients was 67%. The 10-year survival was diminished with increasing age (p = 0.0001): 74% for group I, 68% for group II, and 47% for group III. Comparative analysis of the three groups with their age-matched counterparts demonstrated an age-related survival after CABG. In group I, reduced survival was evident 4 years after the CABG: the 10-year survival in group I was 74.2%, and the survival of their age-matched population was 93.4% (confidence interval, 67% to 81.9%). In group II a survival difference was obvious 8 years after CABG: 10-year survival of 67.5% versus 75.1% in their age-matched population (confidence interval, 64.8% to 71.6%). In the elderly group of patients, no survival difference was noted: 10-year survival of 42.7% versus 45.9% of the age-matched population (confidence interval, 29.8% to 64.6%).
Conclusions. An acceptable early mortality and long-term survival equal to those seen for an age-matched elderly population are sound outcome measures that support the justification of CABG in older patients irrespective of age.
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Introduction
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The number of older patients with coronary artery disease undergoing coronary artery bypass grafting (CABG) continues to increase steadily. Despite the concomitant systemic ailments and other disabilities frequent among older candidates for CABG, improvements in cardiopulmonary bypass, operative techniques, and perioperative care allow CABG to be performed in the aged population [1–3].
In general, satisfactory outcome measures (ie, low early mortality and prolonged survival) are used to judge the effectiveness of CABG in the treatment of patients with coronary artery disease. Three major historic randomized trials that compared the results of CABG with those of medical therapy, done in the early days of open heart operations, excluded elderly patients [4–6]. Prior nonrandomized clinical studies dealing with CABG in elderly patients [7–12] almost uniformly compared the outcome after CABG in the elderly with their younger counterparts. Conclusions extrapolated from studies performed in younger cohorts about the role of CABG might not be completely applicable to elderly patients.
The achievement of a low early mortality and improved late survival results after CABG in young patients is generally presupposed in all hospitals nationwide where open heart operations are performed. As expected, the results of CABG in the elderly are not the same as those in young patients [13]. Comparison of the elderly with their age-matched population offers a more precise way of determining a true longevity benefit for aged patients. Therefore, the purpose of this study was to perform an age-matched comparative analysis of patients of increasing age who had undergone CABG in an effort to justify performing CABG in elderly patients.
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Patients and Methods
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This nonrandomized, retrospective study group consisted of 1,689 patients who underwent isolated primary CABG at the William S. Middleton Memorial Veterans Hospital of Madison, Wisconsin, between 1972 and 1994. For comparison purposes, patients were arbitrarily divided into three age groups: group I, 50 years of age and younger (n = 213; range, 33 to 50 years); group II, between 51 and 70 years of age (n = 1,258), and group III, more than 70 years of age (n = 218; range, 71 to 82 years). We did not include in this analysis patients who had undergone repeat CABG or patients who had undergone CABG along with heart valve repair or replacement, resection of a ventricular aneurysm, or other surgical procedures.
Most patients had class III or IV angina according to the Canadian Cardiovascular Society. The indications for CABG included unstable angina or angina after recent (<6 weeks) myocardial infarction. Most of the patients had three-vessel disease at angiography. Most operations were performed by one of two cardiac surgeons (C.C.C. or G.M.K.). In the early years, a bubble oxygenator was used to establish cardiopulmonary bypass; since 1984, however, a membrane oxygenator has been employed. Cold blood cardioplegia was predominantly adopted in the past decade. Saphenous vein grafts were primarily used at the beginning; in recent years, the use of an internal thoracic artery graft has steadily increased.
Because of the retrospective nature of the study, only the following variables were complete for each patient: age, sex, body surface area, preoperative ejection fraction, number of grafts, the use of an internal thoracic artery graft, ischemia time, perfusion time, early mortality (defined as death between 30 and 90 days after CABG), and current status (dead or alive). This information was strictly recorded by one of the authors (R.D.N.) from the beginning of the open heart operation program at this institution. The average follow-up time for young patients was 104 ± 5 months; it was 87 ± 1 month for patients between 51 and 70 years old; and it was 43 ± 2 months for elderly patients. Current status was confirmed for 94.4% of all patients as of January 1994. The proof of survival was one of the following: a signed and dated postcard, a hospital admission date, a visit to the outpatient clinic, a drug pickup from the pharmacy, a personal visit, or a phone call. The proof of death was established by the hospital computer, documentation from the family members, or a search in the HINQ system at the Veterans Affairs Regional Office.
Data for the age- and sex-matched populations were derived from Wisconsin life tables [14]. Statistical analysis was performed by using a Statistical Analysis Systems software program (SAS Institute, Cary, NC), and values were expressed as the mean ± the standard deviation. Nonparametric analysis of the data was performed using the Kruskal-Wallis one-way analysis of variance. Actuarial survival estimates were calculated according to the method of Kaplan and Meier. The 95% confidence intervals for the survival differences between the study groups and their age-matched populations are also given. Significance was assumed when the calculated p value was 0.05 or less.
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Results
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The average age of patients undergoing CABG at this institution has increased gradually over the years (Fig 1
). The mean preoperative ejection fraction was comparable for all three age groups (p = 0.114) (Table 1), but older patients tended to receive more grafts during CABG (p = 0.0001) and the aortic-cross clamp time was prolonged in the elderly patients (p = 0.0002), though the cardiopulmonary perfusion time was shorter (p = 0.0001). This discrepancy was perhaps due to the fact that we have recently started using more efficient heat exchangers that reduced the rewarming time despite the longer cold ischemic interval.
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Fig 1. . Numbers of patients in three age groups who underwent coronary artery bypass grafting, by year, showing increasing average age at operation.
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The 30-day mortality rate for the entire study population was 1.3%, and the 90-day mortality rate was 2.0% (Table 2). Increasing age was associated with higher early mortality and reduced 10-year survival rates. However, when the study groups were compared with their age-matched counterparts, there were age-related differences in the survival of patients undergoing CABG. There was a significant difference in survival between group I patients and their age-matched population 4 years after CABG (Fig 2). In group II patients, survival was reduced 8 years after CABG in comparison with their age-matched population (Fig 3). There was no significant survival difference at any time point between the oldest patients and their age-matched population (Fig 4).
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Fig 2. . Comparison of survival between the patients 50 years of age and younger (group I), with confidence intervals of 95% (dotted lines), and their age- and sex-matched population.
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Fig 3. . Comparison of survival between the patients 51 to 70 years of age (group II), with confidence intervals of 95% (dotted lines), and their age- and sex-matched population.
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Fig 4. . Comparison of survival between the patients older than 70 years of age (group III), with confidence intervals of 95% (dotted lines), and their age- and sex-matched population.
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Comment
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Elderly patients consume over one third of all U.S. health care expenditures, although they constitute only 12% of the population [15]. Much of this cost is for treatment of cardiovascular disease, the major cause of death and disability in the elderly. It is now clear that men over 65 years of age in the United States have an average life expectancy of 15.1 years; women in this age group have an average life expectancy of 19.5 years [15]. Therefore, preventive approaches are warranted and efforts to surgically treat elderly people with coronary disease are worthwhile.
Many previous studies that have examined the effect of age on morbidity and mortality rates after CABG are retrospective and have analyzed an elderly subgroup in relation to their younger controls [7–12]. Of the three major randomized trials (the Veterans Administration Cooperative Study [4], the European Coronary Surgery Study [5], and the Coronary Artery Surgery Study [6]), only the Veterans Administration trial included patients as old as 67 years; yet the mean age, 50 years, was the same as that in the other two trials. A prior study showed that CABG appeared to improve survival and alleviate symptoms in specific higher-risk subsets of nonrandomized patients 65 years of age or older, compared with medical therapy alone [16]. A trial comparing CABG with modern medical therapy in the elderly is feasible. In such a clinical trial, the results from the aggressive control of risk factors, plus pharmacologic antianginal therapy, would be compared with the results of CABG. However, current recommendations for CABG in old patients are generally derived from nonrandomized surgical series.
Coronary artery bypass grafting is not free of risk for any age group. However, the perioperative mortality rate remains higher for older CABG patients [13]. In the present study, the early mortality after CABG for the elderly patients was 3.2%. However, it is necessary to reiterate that all patients in this analysis were veteran men with normal left ventricular function and that the results pertain solely to male patients. Conclusions drawn from this study may not be completely applicable to women or to those people with diminished left ventricular function. The morbidity associated with CABG may be higher in elderly patients [17]. Because of its design, this study was unable to evaluate the independent risk factors for morbidity. However, it did demonstrate a longevity in elderly patients after CABG comparable to that in their age-matched cohorts. In fact, long-term survival is significantly diminished in the patients younger than 70 years of age who have undergone CABG, compared with that in their age-matched population. This is more pronounced in the youngest patients (<50 years old). This finding may be related to genetic factors, lipid metabolism abnormalities, malignant progression of coronary atherosclerosis, and less compliance of the young patients with measures designed to reduce cardiac risk factors, such as smoking cessation, weight reduction, and exercise. At present, a left internal thoracic artery conduit is used routinely during every CABG at our center, irrespective of the patient's age. Coronary artery bypass grafting with a right internal thoracic artery or other alternative arterial conduits is being utilized increasingly, particularly in young patients. However, it remains unknown whether aggressive arterial revascularization of the myocardium would result in a more comparable survival relationship between patients and their age-matched population.
Because of its retrospective nature, this study does not separate the patient groups according to other incremental risks, but it does affirm that CABG in elderly patients (>70 years old) is of value, irrespective of age. Coronary artery bypass grafting should be offered to elderly patients with the same indications as younger patients. It can be part of cost-effective programs specifically dealing with elderly patients to minimize the cost of health care delivery for this subset.
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Acknowledgments
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The assistance provided by Wanda L. Stroyny in the preparation of the manuscript is greatly appreciated.
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Footnotes
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Presented in part at the Sixty-first Annual International Scientific Assembly of the American College of Chest Physicians, New York, NY, Oct 29–Nov 2, 1995.
Address reprint requests to Dr Canver, Division of Cardiothoracic Surgery, University of Wisconsin-Madison, H4/352, Clinical Science Center, 600 Highland Ave, Madison, WI 53792.
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References
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- Horvath KA, DiSesa VJ, Peigh PS, Couper GS, Collins JJ Jr, Cohn LH. Favorable results of coronary artery bypass grafting in patients older than 75 years. J Thorac Cardiovasc Surg 1990;99:92–6.[Abstract]
- Salomon NW, Page US, Bigelow JC, Krause AH, Okies JE, Metzdorff MT. Coronary artery bypass grafting in elderly patients: comparative results in a consecutive series of 469 patients older than 75 years. J Thorac Cardiovasc Surg 1991;101:209–18.[Abstract]
- Edmunds LH, Stephenson LW, Edie RN, Ratcliffe MB. Open-heart surgery in octogenarians. N Engl J Med 1988;319:131–6.[Abstract]
- The Veterans Administration Cooperative Study Group. Eleven-year follow-up in the Veterans Administration randomized trial of coronary bypass surgery for stable angina. N Engl J Med 1984;311:1333–39.[Abstract]
- Varnauskas E, The European Coronary Surgery Study Group. Twelve-year follow-up of survival in the randomized European Coronary Surgery Study. N Engl J Med 1988;319:332–37.[Abstract]
- CASS Principal Investigators. Coronary Artery Surgery Study (CASS): a randomized trial of coronary artery bypass surgery: survival data. Circulation 1983;68:939–47.[Abstract/Free Full Text]
- Montague NT, Kouchoukos NT, Wilson TAS, et al. Morbidity and mortality of coronary bypass grafting in patients 70 years of age and older. Ann Thorac Surg 1985;39:552–57.[Abstract]
- Rahimtoola SH, Grunkemeier GL, Starr A. Ten-year survival after coronary artery bypass surgery for angina in patients aged 65 years and older. Circulation 1986;74:509–17.[Abstract/Free Full Text]
- Roberts AJ, Woodhall DD, Conti CR, et al. Mortality, morbidity, and cost-accounting related to coronary artery bypass graft surgery in the elderly. Ann Thorac Surg 1985;39:426–32.[Abstract]
- Ennabli K, Pelletier LC. Morbidity and mortality of coronary artery surgery after the age of 70 years. Ann Thorac Surg 1986;42:197–200.[Abstract]
- Tsai TP, Matloff JM, Gray RJ, et al. Cardiac surgery in the octogenarian. J Thorac Cardiovasc Surg 1986;91:924–28.[Abstract]
- Cane ME, Chen C, Bailey BM, et al. CABG in octogenarians: early and late events and actuarial survival in comparison with a matched population. Ann Thorac Surg 1995;60:1033–7.[Abstract/Free Full Text]
- Canver CC, Kroncke GM, Nichols RD, Heisey DM, Murray EL, Mentzer RM. Coronary artery bypass surgery in older patients. Cardiol Elderly 1994;2:442–7.
- US Department of Health and Human Services. U.S. Decennial Life Tables for 1979–1981 Based on 1980 Census, Vol. II, State Life Tables, No. 50. Washington: US Government Printing Office, 1985 (Publication no. [PHS] 86-1151-50x).
- Wenger NK, Marcus FI, O'Rourke RA. Cardiovascular disease in the elderly. J Am Coll Cardiol 1987;10:80A–7A.[Medline]
- Gersh BJ, Kronmal RA, Schaff HV, et al. Comparison of coronary artery bypass surgery and medical therapy in patients 65 years of age or older: a nonrandomized study from the Coronary Artery Surgery Study (CASS) Registry. N Engl J Med 1985;313:217–24.[Abstract]
- Loop FD, Lytle BW, Cosgrove DM, et al. Coronary artery bypass graft surgery in the elderly: indications and outcome. Cleve Clin J Med 1988;55:23–34.[Medline]
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Abstract
Introduction
