- Email: [email protected]
Internal thoracic artery for coronary artery grafting in octogenarians
Internal Thoracic Artery for Coronary Artery Grafting in Octogenarians Rohinton J. Morris, MD, Michael D. Strong, MD, Karl E. Grunewald, MD, M. L. Ray Kuretu, MD, Louis E. Samuels, MD, J. Yasha Kresh, PhD, and Stanley K. Brockman, MD Department of Cardiothoracic Surgery, Hahnemann University Hospital Philadelphia, Pennsylvania
Background. Use of the left internal thoracic artery as a bypass graft has been shown to result in better long-term patency and improved survival. In elderly patients, the internal thoracic artery has been used less often for coronary artery bypass grafts because of the belief that greater morbidity and mortality are associated with this procedure. This study was undertaken to test this premise in the octogenarian population. Methods. Over an 8-year period, 474 consecutive patients 80 years of age and greater had coronary artery bypass grafting. The left internal thoracic artery was used in 188 patients (39.7%) (group 1) and saphenous vein grafts only (group 2), in 286 (60.3%). The mean age was 82.6 years (range, 80 to 95 years). There were 312 men (65.8%) and 162 women (34.2%).
Results. Use of the internal thoracic artery as a graft has risen steadily each year, as has the number of patients who are octogenarians. The hospital mortality rate was 7.8%. Patients in group 1 had a mortality rate of 9.0% and patients in group 2, a mortality rate of 7.0%. The mortality rate among survivors at I year was 6.7%. Long-term survival was significantly greater in group 1. Conclusions. On the basis of this study, we conclude that the internal thoracic artery is the bypass graft of choice, especially in regard to long-term mortality, and should not be denied to this high-risk group.
he number of cardiac operations in elderly patients has been rising steadily over the past two decades. A number of studies have shown this group of patients to be at higher risk because of the presence of concomitant diseases [1, 2]. The term elderly has been used to describe an increasingly older population. Projections by the Census Bureau [3] estimate a steady increase in the proportion of Americans exceeding the age of 80 years. The internal thoracic artery (ITA) has been shown to be of increased benefit in younger patients undergoing coronary artery bypass grafting (CABG) [4-6]. The assumption has been that ITA grafting in the elderly population is associated with increased morbidity and mortality. The reasons for this are longer time of operation, increased invasiveness of tissue, wide exposure of the pleural space, and greater pulmonary dysfunction. The present study was undertaken to elucidate more fully the degree to which use of the ITA in the elderly affects morbidity and mortality. Two cohorts of patients were studied to demonstrate the effects of ITA grafting on morbidity and mortality compared with saphenous vein grafts (SVGs) alone.
Patients a n d M e t h o d s
(Ann Thorac Surg 1996;62:16-22)
T
Patient Population
Presented at the Thirty-secondAnnual Meeting of The Societyof Thoracic Surgeons,Orlando, FL, Jan 29-31, 1996. Address reprint requests to Dr Morris, Hahnemann UniversityHospital, Broad and Vine Sts, MS 111,Philadelphia, PA 19102.
Four hundred seventy-four consecutive patients 80 years of age or older underwent CABG at Hahnemann University Hospital from January 1, 1987, to December 31, 1994. They constituted 5.5% of the 8,629 patients who had CABG during the same period. All 474 patients were entered into a retrospective study, and a longitudinal follow-up was obtained to assess results between patients who received an ITA graft to the left anterior descending coronary artery and those who received only SVGs. There were 312 men (65.8%) and 162 women (34.2%). The age range was from 80 to 95 years with a mean of 82.5 + 2.9 years. The age distribution is shown in Figure 1. Patients who received an ITA conduit (n = 188, 39.7%), were classified as group 1, and patients who received only SVGs (n = 286, 60.3%), were classified as group 2. The patient profile distribution for the two groups is shown in Table 1. The preoperative group profiles were compared and found to be similar. There was a 1.5:1 ratio (312:162) of men to women, and there were slightly more men in the ITA group than in the SVG group (67.6% versus 64.7%). The mean age was comparable between the two groups (81.9 years versus 82.9 years). The risk factors present preoperatively included the following: myocardial infarction (MI), acute (<1 week) and remote (>1 week); congestive heart failure; hypertension; diabetes mellitus; renal dysfunction; peripheral vascular dis-
© 1996 by The Society of Thoracic Surgeons Published by Elsevier Science Inc
0003-4975/96/$15.00 PII S0003-4975(96)00252-4
Ann Thorac Surg 1996;62:16-22
MORRISET AL ITA FOR CABGIN OCTOGENARIANS
17
physicians. Follow-up was complete for 92% of the known survivors.
120 100
Statistical Analysis ¢'-
80
~
60
~
40 20 80
81
82
83
~
85
~
87
88
89 90 >90
Age
Fig 1. Age distribution of the 474 octogenarian patients.
Data are presented as frequency distributions and simple percentages. Significance was assumed when the p value was less than 0.05. Categoric variables were compared using X2 analysis. Continuous variables (eg, age) were compared using an unpaired Student's t test, with Bonferroni's correction where applicable. Life-table calculations and cumulative survival were estimated by the Kaplan-Meier method and plotted along with the conditional probability standard error. Comparison of the two study groups was achieved by calculating the Z statistics and referring to tables of the normal distribution. Results
ease; and cerebrovascular disease. No significant differences between the two groups could be demonstrated. The presence of stable and unstable angina was docum e n t e d preoperatively, but no significant difference between groups 1 and 2 could be detected. Angiographic data were obtained on all patients. Critical left main disease or triple-vessel disease was noted in 416 patients (88%). Although there were slightly more patients with left main disease in the SVG group (11% versus 7%), this did not reach significance. Ejection fractions for the two groups were obtained from either the left ventriculogram or the echocardiogram and were divided into three categories; greater than 0.50, between 0.30 and 0.50, and less than 0.30. Group I had 73 patients (40.1%) and group 2 had 108 patients (39.7%) in the first category, demonstrating good left ventricular (LV) function. In the second category, demonstrating moderate LV dysfunction, there were 85 patients (46.7%) from group 1 and 121 patients (44.5%) from group 2. The third category, demonstrating severe LV dysfunction, included 24 patients (13.2%) from group I and 43 patients (15.8%) from group 2. Overall, the ejection fractions between the two groups were comparable. A total of 16 patients, 6 in group 1 and 10 in group 2, underwent emergency operation. There were 21 patients (11.2%) in group I and 18 patients (6.3%) in group 2 who were having redo operations. All patients were operated on using standard cardiopulmonary bypass techniques. Ascending aortic cannulation, single two-stage or bicaval cannulation, and hypothermia to 25 ° to 28°C were routinely used. Myocardial protection was generally afforded by antegrade cold blood cardioplegia. Distal bypass grafts were constructed under a single cross-clamp time. All proximal bypass grafts were performed with a single side-biting clamp on the ascending aorta.
Data Collection All historical and perioperative data were obtained by retrospective review. Hospital charts, catheterization reports, and operative reports were used. Follow-up information was obtained from most patients by telephone interview and for the rest, from records of the personal
The n u m b e r of octogenarians we have operated on has steadily been increasing yearly, effectively doubling from
Table 1. Preoperative Profiles for Groups 1 and 2 a Characteristic
Group 1
Group 2
No. of patients Sex Male Female Mean age (y) Risk factors Prior MI Acute (<1 week) Remote (>1 week) Congestive heart failure Hypertension Diabetes mellitus Renal dysfunction Peripheral vascular disease Cerebrovascular disease NYHA class I II III IV Angina Stable Unstable Angiographic data Left main disease Triple-vessel disease Ejection fraction >0.50 0.30-0.50 <0.30 Previous CABG Emergency operation Average no of bypass grafts
188 (39.7)
286 (60.3)
127 (67.6) 61 (32.4) 81.9 + 2.9
185 (64.7) 101 (35.3) 82.9 + 3.1
180 50 (26.6) 130 (69.1) 42 (22.3) 129 (68.6) 16 (8.5) 34 (18.1) 21 (11.2) 40 (21.3)
266 83 (29.0) 183 (64.0) 68 (23.8) 206 (72.0) 36 (12.6) 57 (19.9) 27 (9.4) 54 (18.9)
3 (1.6) 12 (6.4) 90 (47.9) 83 (44.1)
5 (1.7) 14 (4.9) 138 (48.3) 129 (45.1)
90 (47.9) 55 (29.3)
126 (44.1) 100 (35.0)
13 (6.9) 152 (80.9) 182 (96.8) 73 (40.1) 85 (46.7) 24 (13.2) 21 (11.2) 6 (3.2) 3.6
3 (10.8) 220 (76.9) 272 (95.1) 108 (39.7) 121 (44.5) 43 (15.8) 18 (6.3) 10 (3.5) 3.3
a Numbers in parentheses are percentages. CABG= coronaryartery bypass grafting; M] = myocardialinfarction; NYHA = New York Heart Association.
18
MORRISET AL ITA FOR CABGIN OCTOGENARIANS
Ann Thorac Surg 1996;62:16-22
100
20
80
15
rOr)
60
10
¢.~
"6
E3
40 20
0
0
Fig 2. Number of octogenarians by year of study.
43 patients in the first year of the study to 85 patients in the last year (Fig 2). The percentage of patients receiving ITA grafts has also increased during this period. During the first year of the study, the frequency of ITA use was less than 5%, but it has increased dramatically to 48% for the last 2 years (Fig 3). The length of stay (LOS) for both groups is shown in Figure 4. The overall LOS during the period of the study was 12.9 days. It ranged from a high of 15.1 days in 1989 to a low of 9.9 days in 1994. Group I had an average LOS of 11.4 days and group 2, 13.9 days (p < 0.05). The average number of bypass grafts in the two groups was similar: 3.6 grafts per patient in group I and 3.3 grafts per patient in group 2. Mortality Hospital mortality was defined as death during the period of hospitalization or within 30 days after operation. There were 37 deaths in 474 patients, for an overall hospital mortality rate of 7.8%. Group 1 had a hospital mortality rate of 9.0% (171188) compared with 7.0% (20•286) for group 2 (p = 0.056). In both groups, the most common causes of death were myocardial failure (n = 18 patients) and cerebrovascular accidents (CVA) (n = 8 patients) (Table 2). The other causes of death were sepsis
100
80
Fig 4. Length of stay in hospital for patients with internal thoracic artery graft (hatched bars) versus saphenous vein graft (black bars).
(n = 4), renal failure (n = 4), respiratory failure (n = 2), and pulmonary embolism (n = 1). Morbidity Major hospital morbidity was identified in 104 (23.8%) of the 437 survivors and comprised MI, respiratory failure, acute renal failure, CVA, infection or sepsis, and postoperative bleeding (Table 3). Myocardial infarction was documented on the basis of diagnostic electrocardiographic changes and measured elevation of myocardial enzyme levels. Respiratory failure was defined as ventilatory dependence lasting longer than 48 hours from the time of operation. Acute postoperative renal failure was classified as the requirement of temporary peritoneal dialysis or hemodialysis. Cerebrovascular accident was classified as a fixed neurologic deficit at the time of discharge. Postoperative bleeding was noted as critical only if the patient was returned to the operating room. The most common complication was respiratory failure, followed by CVA and then perioperative MI. The other three complications were less common. Patient Follow-up Patient follow-up was obtained by telephone and physician office charts for 402 (92%) of the survivors. Thirtyfive patients were lost to follow-up. Follow-up ranged from I month to 96 months (mean follow-up, 46 months). Actuarial survival rates for the two groups are shown in Figure 5. Confidence intervals for survival in each group are also included. At 2 years of follow-up and beyond, the risk of dying diminished significantly in the ITA cohort
r'-
60
-0
Table 2. Causes of Hospital Mortality
40
Cause
20 0
1987 1988 1989 1990 1991 1992 1993 1994
Year Fig 3. Use of internal thoracic artery as a graft (hatched bars) versus saphenous vein graft (black bars).
Myocardial failure Cerebrovascular accident Sepsis Renal failure Respiratory failure Pulmonary embolism
Group 1
Group 2
8 5 2 1 1 0
10 3 2 3 1 1
Ann Thorac Surg 1996;62:16-22
MORRISET AL ITAFOR CABGIN OCTOGENARIANS
Table 3. Causes of Hospital Morbidity ~
Cause
Group 1 (n = 171)
Group 2 (n = 266)
Myocardial infarction Respiratory failure Acute renal failure Cerebrovascular accident Infection/sepsis Postoperative bleeding
7 (4.1) 18 (10.5) 4 (2.3) 10 (5.8) 3 (1.8) 3 (1.8)
12 (4.5) 25 (9.4) 8 (3.0) 20 (7.5) 3 (1.1) 6 (2.3)
a Numbers in parentheses are percentages.
by a factor of 0.5. Survival at 5 years and beyond remained at 80% in group I but diminished to 60% in group 2.
Comment The population of octogenarians is steadily increasing in the United States. In these elderly patients, outcomes for myocardial revascularization are indicative of enhanced survival compared with medical treatment [7-9], Internal thoracic artery grafting to the left anterior descending coronary artery by itself has been shown to be a strong predictor of event-free survival [10, 11]. Use of the ITA graft has become well accepted for younger patients, in whom its use approaches 90%. Restrictions on long-term survival, greater incidence of concomitant disease, "brittleness" of the patient, and prolonged operations have all combined to decrease use of the ITA in octogenarians. Over the 8 years of this study, the incidence of ITA use has increased tenfold, from 4.7% to 48%. This is due to a number of factors. First, confidence in the applicability of this conduit grew with greater experience and improved skills of the surgeons. Second, the number of octogenarians seen for CABG continues to grow, with a greater number of these patients having less than ideal saphe, nous veins for CABG. This may correlate with advanced age, as saphenous veins were anecdotally noted to be more friable and of poorer quality in the very elderly. The
00 T I
-..
9O
._> >
80
co 70
----0--..
~'"'"...,,
SVG
6O
50
i
i
I
i
0
1
2
3
Years
since
J 4
i S
J 6
Procedure
Fig 5. Actuarial survival rate of paffents with internal thoracic artery (ITA) graft versus saphenous vein graft (SVG).
19
search for alternative conduits to SVGs led us to reexamine use of the ITA in these high-risk patients. A number of studies have shown that CABG in elderly patients is associated with increased morbidity and mortality compared with younger cohorts [12, 13, 14]. We found this to be true in our older subgroup as well. The hospital mortality rate for the total cohort of 474 patients was 7.8%. During the same period, the mortality rate was only 3.5% in 8,155 patients less than 80 years old undergoing CABG. This finding is similar to findings in other reports on octogenarians having CABG [15-17]. The underlying differences are multifactorial in origin. Elderly patients have a greater incidence of concomitant disease processes. Also, the elderly are referred for operation at a later stage of the disease than younger patients and with more severe symptomatology. In fact, more than 90% of our patients were in New York Heart Association class III or W preoperatively, a finding consistent with other studies [16,17]. In addition, an inherent bias may be present among referringphysic~ans because of the often reported increased mortality with advanced age. Early in the evaluation of this cohort laopulation, it was also more likely for octogenarians only in the best physical shape to be referred for operation. As greater numbers of elderly patients were seen with angina, referrals for operation increased. The Society of Thoracic Surgeons database [18] reports an increase in the mean age of CABG patients in each of the last three decades. The average age has increased from 58.5 years to 64 years in just the 10-year period 1980 to 1990. The average age of the patient undergoing CABG at our institution during the time period of this study has increased to 72.3 years. Importantly, a retrospective examination of the preoperative characteristics of the two groups reveals very little difference between them. An overview of the preoperative risk factors shows that elderly patients do indeed have a plethora of concomitant diseases. However, this should not be a deterrent to their referral for operation. It is tempting to speculate that most of these disease processes have not progressed to end-organ damage; otherwise the patients would not have made it to the ninth decade. Referral of the elderly patient for CABG was a decision that was not lightly made. The incidence of emergency operations in patients less than 80 years old in our institution is 11%. Comparatively, the low incidence of emergency operations in these two groups of patients, 3.2% and 3.5%, respectively, reflects an intense effort to maximally optimize the preoperative state of the patient. A substantial number of patients, 42 (22.3%) in group 1 and 68 (23.8%) in group 2, were seen with symptoms of congestive heart failure. The presence of mild to moderate congestive heart failure preoperatively has been shown not to be a strong predictor of poor outcome [14, 16]. The fact remains that hospital (operative) mortality remains the gold standard by which surgical procedures are deemed successful. Hospital mortality was slightly higher in the ITA group than the SVG group, 9.0% versus 7.0%, but did not reach significance (p > 0.1). We did not note any decrease in mortality rate by year of study; the
20
MORRISET AL ITA FOR CABGIN OCTOGENARIANS
rate ranged from 6% to 12%. Myocardial failure was the most common cause of death. The Coronary Artery Surgery Study [19] and others have shown convincingly that compromised LV function is a strong independent predictor of operative mortality. Approximately 15% of our patients had severely impaired LV function, and another 45% had moderate impairment of LV function by preoperative ventriculography. Preoperatively, more than 25% of patients in each group had a proven acute MI, and two thirds of the patients had a history of one or more previous MIs. Postoperatively, it was recognized that 4.1% and 4.5% of patients in groups 1 and 2, respectively, had sustained a perioperative MI. The frequency of perioperative MI is comparable to rates reported elsewhere for CABG and is also similar to rates in younger patients [14, 19]. We believe the lower rate of perioperative MI is due to improved techniques for cardiopulmonary bypass, better myocardial preservation techniques, and safer anesthesia management. Cerebrovascular accident, the second most common cause of hospital mortality, occurred in greater frequency than in younger patients. Five patients in group 1 and 3 patients in group 2 died secondary to a CVA. In all, 10 patients (5.8%) in group I and 20 patients (7.5%) in group 2 sustained a CVA. The incidence of CVA has clearly been shown to increase with advancing age after CABG [17, 20]. The incidence of CVA in patients younger than 80 years during this same period was less than 2%. Preoperatively, 40 patients (21.3%) in group 1 and 54 (18.9%) in group 2 were noted to have cerebrovascular disease, defined as one or more neurologic events. This is much higher than in the general group of patients undergoing CABG before the ninth decade of life. Preoperative assessment of carotid artery disease by Doppler should be routinely performed in this elderly group of patients. It is now our policy for elderly patients found to have critical carotid disease to undergo carotid endarterectomy before CABG. Sepsis was the cause of death in 2 patients in each group. In contrast, sternal infection was rare, less than 2% in both groups, although mortality was very high when it did occur. Williams and colleagues [16] showed sternal wound infection has a positive predictive value for hospital mortality and wrote that they "use the left internal m a m m a r y artery only in selected cases where the quality of sternal tissue is good." In our experience, most octogenarians appear to have weak sternums and rather friable tissue but are endowed with good mammary arteries. Four patients died secondary to renal failure, 1 in the ITA group and 3 in the SVG group. Twelve patients experienced acute renal failure requiring hemodialysis postoperatively. Hence, the mortality rate was 33% in patients requiring hemodialysis postoperatively. The incidence of preoperative renal dysfunction in groups 1 and 2 was 18.1% and 19.9%, respectively. No patient who required long-term hemodialysis preoperatively underwent operation. Several groups [21-23] have shown renal dysfunction to be an important factor in postoperative morbidity and mortality. Our protocol for patients with
Ann Thorac Surg 1996;62:16-22
Table 4. Postoperative N e w York Heart Association Class a
Class
Group 1
Group 2
I II III IV
82 (48.0) 72 (42.1) 11 (6.4) 6 (3.5)
130 (48.9) 118 (44.4) 18 (6.8) 8 (3.0)
a Numbers in parentheses are percentages.
preoperative renal dysfunction dictates minimal contrast medium use for angiography, hydration, forced diuresis, and renal-dose dopamine hydrochloride. Only 1 patient in each group died secondary to respiratory failure. Both patients had development of pneumonia, compromising marginal lung function. The second important criterion by which a surgical procedure is considered successful and is recommended as treatment is acceptable morbidity. No discernible difference in complications was noted between the two groups. One of the greatest concerns noted with ITA use in the past has been respiratory compromise. This is thought to occur secondary to pleural dissection, which may cause increased chest wall pain, postoperative pleural effusion, and a resultant underlying atelectasis. Considerable morbidity was noted secondary to respiratory difficulties. Although ventilatory dependence was slightly greater in the ITA group, 18 patients (10.5%) compared with 25 (9.4%) in the SVG group, no significant difference existed. One might think that opening the pleural space and chest wall dissection would increase postoperative respiratory difficulty, but this was found not to be the case. A separate study in younger patients having CABG at this institution shows no significant delay in extubation in patients having an ITA as a graft (personal communication). Historical concerns over adequacy of ITA flow seem to be unfounded. Certainly the absence of any increase in perioperative MIs in group 1 is reassuring. In no patient in the SVG group was a m a m m a r y artery taken and not used because of poor flows. It has been shown that takedown of single ITA grafts has not been associated with a greater incidence of sternal infections [24, 25]. Our elderly cohort confirms this finding as evidenced by a very low incidence of infection in groups 1 (1.8%) and 2 (1.1%). No patient in either group received bilateral ITA grafts. Tremendous improvement in the patients' symptoms was also noted. Preoperatively, 92.0% of patients in group 1 and 93.4% of patients in group 2 were classified in NYHA class III or W. Postoperatively a complete reversal was noted, with 90.1% of patients in group I and 93.2% of patients in group 2 classified in NYHA class I and II (Table 4). Contemporary discussions of morbidity are not complete without true scrutiny of LOS. Length of stay was markedly increased in both groups compared with that of the general population undergoing CABG. Octogenarians required an LOS nearly 3 days longer than patients younger than 80 years. The mean LOS for group 1 was
Ann Thorac Surg 1996;62:16-22
11.4 days and for group 2, 13.9 days. The LOS for group 1 was significantly lower in each year of the study, thus reaching significance. This could be attributed in part to selection bias of the surgeon, who must have chosen to use the ITA graft on healthier patients. The preoperative profiles of the two groups do not distinguish any characteristic with greater prevalence in either cohort. Nonetheless, LOS has steadily decreased during the last 6 years, dropping on average by 3 days. A n u m b e r of factors, such as better anesthesia management, early extubation and ambulation, improved pain control home health-care nursing, and pressure from managed-care groups for early discharge are responsible for the reduced LOS. Similar pressures have reduced LOS significantly a m o n g all our CABG patients. As the n u m b e r of octogenarians increases, it will remain a difficult challenge to continue decreasing LOS. The third standard of success for surgeons, and perhaps the one of greatest importance, remains the longterm benefit of such an operation. The actuarial survival rates were calculated for the two groups with follow-up as long as 7 years for those operated on early in the study (Fig 5). Significance between the two groups is reached at a point b e y o n d the 2-year follow-up. The ITA group continues to show a greater actuarial survival throughout the remaining follow-up period. Survival for the ITA cohort beyond 5 years remains approximately 80%, but the n u m b e r of patients in this group (n = 11) is too small to derive conclusive clinical significance. Survival for the SVG group mirrors that of other groups reporting on octogenarians. Survival data from the Cleveland Clinic [5] indicated that improvement in survival is conferred by ITA grafting as early as 4 to 5 years postoperatively. The fact that we could note a difference as early as 3 years points to differing conduit characteristics in the very elderly. It is conceivable that the saphenous vein is a poorer conduit in very elderly patients and therefore does not confer protection from early graft closure. Late survival benefit with use of the ITA in the elderly has not been shown by other studies [2, 22, 24]. The incidence of ITA use was fairly low in previous studies, and it remains to be seen whether with increasing use, long-term survival improves. It is inherently obvious that long-term studies in this group of patients (ie, >10 years) is difficult because of natural attrition rates. It is apparent from this study and others that the incidence of CABG procedures in octogenarians is rising. Substantial quality of life m a y be restored by surgical intervention, as shown by the improvement in NYHA class in both the ITA group and the SVG group. We conclude from the data presented here that an ITA graft to the left anterior descending coronary artery can be used without fear of greater morbidity or mortality in patients 80 years of age and older. The ITA graft has no increased morbidity than and comparable hospital mortality as the SVG. With others, we tended to assume that use of the ITA graft would cause increased respiratory failure, increased bleeding, more sternal infections, and a longer operation. On the contrary, we found no substantial difference in morbidity with use of the ITA compared
MORRISET AL ITA FOR CABGIN OCTOGENARIANS
21
with use of the SVG alone. In addition, we observed, with some surprise, that LOS was significantly lower in patients having ITA grafts. The hospital mortalities were similar, and the long-term follow-up showed decreased mortality in patients with the ITA graft. Most notably, the difference in survival is apparent within 2 years of followup, m u c h earlier than that observed in younger patients. The ITA was found to be a good-quality vessel in octogenarians, and we are not aware of a single instance of inadequate flow or perioperative MI secondary to decreased flow. We believe that there are m a n y advantages to using the ITA graft and few disadvantages in elderly patients. We therefore have made it our policy to use the ITA graft as much as possible in octogenarians.
References
1. Merrill WH, Stewart JR, Frist WH, et al. Cardiac surgery in patients age 80 years or older. Ann Surg 1990;211:772-5. 2. Salomon NW, Page US, Bigelow JC, et al. Coronary artery bypass grafting in elderly patients. J Thorac Cardiovasc Surg 1991;101:209-18. 3. US Bureau of the Census. Current population reports: projections of the population of the USA by age, sex and race. 1988-2080. Series P-25, no. 1018. Washington, DC: US Department of Commerce, 1989. 4. Lytle BW, Loop FD, Cosgrove DM, et al. Long-term (5 to 12 years) serial studies of internal mammary artery and saphenous vein coronary bypass grafts. J Thorac Cardiovasc Surg 1985;89:248-58. 5. Loop FD, Lytle BW, Cosgrove DM, et al. Influence of the internal mammary artery graft on 10 year survival and other cardiac events. N Engl J Med 1986;314:1-9. 6. Gardner TJ, Greene PS, Rykiel MF, et al. Routine use of the left internal mammary artery graft in the elderly. Ann Thorac Surg 1990;49:188-94. 7. Naunheim KS, Kern MJ, McBride LR, et al. Coronary artery bypass surgery in patients aged 80 years or older. Am J Cardiol 1987;59:804-7. 8. Krumholz HM, Forman DE, Kuntz RE, et al. Coronary revascularization after myocardial infarction in the very elderly: outcomes and long-term follow-up. Ann Intern Med 1993;119:1084-90. 9. Horvath KA, DiSesa VJ, Peigh PS, et al. Favorable results of coronary bypass grafting in patients older than 75 years. J Thorac Cardiovasc Surg 1990;99:92-6. 10. Tector AJ, Schmahl TM, Janson B, et al. The internal mammary artery graft. JAMA 1981;246:2181-4. 11. Okies JE, Page US, Bigelow JC, et al. The left internal mammary artery: the graft of choice. Circulation 1984; 70(Suppl 1):213-21. 12. Kupfer J, Khan S, Matioft JM, Tsai TP, Nessim S, Gray R. Heterogeneous mortality rates of elderly patients undergoing coronary bypass surgery. Circulation 1992;86(Suppl 1): 437-44. 13. Mohan R, Amsel BJ, Walter PJ. Coronary artery bypass grafting in the elderly: a review of studies on patients older than 64, 69 or 74 years. Cardiology 1992;80:215-23. 14. Grover FL, Johnson RR, Marshall G, et al. Factors predictive of operative mortality among coronary artery bypass subsets. Ann Thorac Su.rg 1993;56:1296-307. 15. Weintraub MS, Clements SD, Ware J, Craver JM, Cohen CL, Jones EL. Coronary artery surgery in octogenarians. Am J Cardiol 1991;68:1530-4. 16. Williams DB, Carrillo RG, Traad EA, et al. Determinants of operative mortality in octogenarians undergoing coronary bypass. Ann Thorac Surg 1995;60:1038-43. 17. Cane ME, Chen C, Bailey BM, et al. CABG in octogenarians:
22
18.
19.
20.
21.
MORRISET AL ITA FOR CABG IN OCTOGENARIANS
early and late events and actuarial survival in comparison with a matched population. Ann Thorac Surg 1995;60:1033-7. Edwards FH, Clark RE, Schwartz M. Coronary artery bypass grafting: The Society of Thoracic Surgeons national database experience. Ann Thorac Surg 1994;57:12-9. Kennedy JW, Kaiser GC, Fisher LD, et al. Multivariate discriminant analysis of the clinical and angiographic predictors of operative mortality from the Collaborative Study on Coronary Artery Surgery (CASS). J Thorac Cardiovasc Surg 1980;80:876-87. Horneffer PJ, Gardner TJ, Reitz BA, et al. The effects of age on outcome after coronary bypass surgery. Circulation 1987; 76(Suppl 5):6-12. Tsai T-P, Nessim S, Kass RM, et al. Morbidity and mortality
Ann Thorac Surg 1996;62:16-22
22. 23.
24. 25.
after coronary artery bypass in octogenarians. Ann Thorac Surg 1991;51:983-6. Ennabli K, Pelletier LC. Morbidity and mortality of coronary artery surgery after the age of 70 years. Ann Thorac Surg 1986;42:197-200. Higgins TL, Estafanous FG, Loop FD, et al. Stratification of morbidity and mortality outcome by pre-operative risk factors in coronary artery bypass patients: a clinical severity score. JAMA 1992;267:2344-8. Saldanha RF, Raman J, Esmore DS, et al. Myocardial revascularization in patients over seventy-five years. J Cardiovasc Surg (Torino) 1988;29:624-8. Dewar LRS, Jamieson WRE, Janusz MT, et al. Unilateral versus bilateral mammary revascularization: survival and event-free performance. Circulation 1995;92(Suppl 2):8-13.
DISCUSSION DR CARY W. AKINS (Boston, MA): Obviously the patient population is loaded at the front end by patients having largely saphenous vein grafting and at the back end by more patients having internal mammary grafting, which can have some impact when looking at late results. Particularly when talking about long-term survival, one has to account for a surgeon's selection of patients in whom to use internal mammary grafting. Have you looked at risk factors to be able to predict what caused late death and whether the internal mammary was actually a predictor of better survival by multivariate analysis? D R MORRIS: We have not looked at late survival in terms of
DR CONSTANTINE E. ANAGNOSTOPOULOS (New York, NY): Following the lead of Dr George Green, our three teams at St. Luke's Hospital have been doing exactly what Dr Morris and Dr Brockman have been doing, and we have noticed actually slightly improved results when looking at deaths and complications. In fact, The Society of Thoracic Surgeons showed last year (if I remember correctly) for the first time that use of the internal mammary artery, even in emergency operation, resulted in improved survival. I suspect that as we speak, The Society and the national database will have the answer as to whether the internal thoracic artery is the graft of choice in patients who are in their ninth decade. Do you have access to that information?
multivariate analysis. However, we looked at cohorts between the two groups and found that there was no significant selection bias on the part of the surgeon. It was presumed that the surgeon may have selected a healthier patient, but we found that not to be so, and we did not find a single predictor indicating that.
D R MORRIS: I am sorry, sir, but I do not have access to the information for The Society database. However, we do operate on patients in the ninth decade of life and use the internal mammary arteries. In our experience, these arteries actually made a better graft than the saphenous vein.
Bound
volumes
available to subscribers
Bound volumes of the 1995 issues of The Annals of Thoracic Surgery are available only to subscribers from the Publisher. The cost is $99.00 (outside US add $25.00 for postage) for volumes 59 and 60. Each bound volume contains a subject and author index, and all advertising is removed. The binding is durable buckram with the name of the journal, volume number, and year stamped on the spine. Payment must accompany all orders. Contact Elsevier Science Inc, 655 Avenue of the Americas, New York, NY 10010; or telephone (212) 633-3950 (facsimile: (212) 633-3990).
Background. Use of the left internal thoracic artery as a bypass graft has been shown to result in better long-term patency and improved survival. In elderly patients, the internal thoracic artery has been used less often for coronary artery bypass grafts because of the belief that greater morbidity and mortality are associated with this procedure. This study was undertaken to test this premise in the octogenarian population. Methods. Over an 8-year period, 474 consecutive patients 80 years of age and greater had coronary artery bypass grafting. The left internal thoracic artery was used in 188 patients (39.7%) (group 1) and saphenous vein grafts only (group 2), in 286 (60.3%). The mean age was 82.6 years (range, 80 to 95 years). There were 312 men (65.8%) and 162 women (34.2%).
Results. Use of the internal thoracic artery as a graft has risen steadily each year, as has the number of patients who are octogenarians. The hospital mortality rate was 7.8%. Patients in group 1 had a mortality rate of 9.0% and patients in group 2, a mortality rate of 7.0%. The mortality rate among survivors at I year was 6.7%. Long-term survival was significantly greater in group 1. Conclusions. On the basis of this study, we conclude that the internal thoracic artery is the bypass graft of choice, especially in regard to long-term mortality, and should not be denied to this high-risk group.
he number of cardiac operations in elderly patients has been rising steadily over the past two decades. A number of studies have shown this group of patients to be at higher risk because of the presence of concomitant diseases [1, 2]. The term elderly has been used to describe an increasingly older population. Projections by the Census Bureau [3] estimate a steady increase in the proportion of Americans exceeding the age of 80 years. The internal thoracic artery (ITA) has been shown to be of increased benefit in younger patients undergoing coronary artery bypass grafting (CABG) [4-6]. The assumption has been that ITA grafting in the elderly population is associated with increased morbidity and mortality. The reasons for this are longer time of operation, increased invasiveness of tissue, wide exposure of the pleural space, and greater pulmonary dysfunction. The present study was undertaken to elucidate more fully the degree to which use of the ITA in the elderly affects morbidity and mortality. Two cohorts of patients were studied to demonstrate the effects of ITA grafting on morbidity and mortality compared with saphenous vein grafts (SVGs) alone.
Patients a n d M e t h o d s
(Ann Thorac Surg 1996;62:16-22)
T
Patient Population
Presented at the Thirty-secondAnnual Meeting of The Societyof Thoracic Surgeons,Orlando, FL, Jan 29-31, 1996. Address reprint requests to Dr Morris, Hahnemann UniversityHospital, Broad and Vine Sts, MS 111,Philadelphia, PA 19102.
Four hundred seventy-four consecutive patients 80 years of age or older underwent CABG at Hahnemann University Hospital from January 1, 1987, to December 31, 1994. They constituted 5.5% of the 8,629 patients who had CABG during the same period. All 474 patients were entered into a retrospective study, and a longitudinal follow-up was obtained to assess results between patients who received an ITA graft to the left anterior descending coronary artery and those who received only SVGs. There were 312 men (65.8%) and 162 women (34.2%). The age range was from 80 to 95 years with a mean of 82.5 + 2.9 years. The age distribution is shown in Figure 1. Patients who received an ITA conduit (n = 188, 39.7%), were classified as group 1, and patients who received only SVGs (n = 286, 60.3%), were classified as group 2. The patient profile distribution for the two groups is shown in Table 1. The preoperative group profiles were compared and found to be similar. There was a 1.5:1 ratio (312:162) of men to women, and there were slightly more men in the ITA group than in the SVG group (67.6% versus 64.7%). The mean age was comparable between the two groups (81.9 years versus 82.9 years). The risk factors present preoperatively included the following: myocardial infarction (MI), acute (<1 week) and remote (>1 week); congestive heart failure; hypertension; diabetes mellitus; renal dysfunction; peripheral vascular dis-
© 1996 by The Society of Thoracic Surgeons Published by Elsevier Science Inc
0003-4975/96/$15.00 PII S0003-4975(96)00252-4
Ann Thorac Surg 1996;62:16-22
MORRISET AL ITA FOR CABGIN OCTOGENARIANS
17
physicians. Follow-up was complete for 92% of the known survivors.
120 100
Statistical Analysis ¢'-
80
~
60
~
40 20 80
81
82
83
~
85
~
87
88
89 90 >90
Age
Fig 1. Age distribution of the 474 octogenarian patients.
Data are presented as frequency distributions and simple percentages. Significance was assumed when the p value was less than 0.05. Categoric variables were compared using X2 analysis. Continuous variables (eg, age) were compared using an unpaired Student's t test, with Bonferroni's correction where applicable. Life-table calculations and cumulative survival were estimated by the Kaplan-Meier method and plotted along with the conditional probability standard error. Comparison of the two study groups was achieved by calculating the Z statistics and referring to tables of the normal distribution. Results
ease; and cerebrovascular disease. No significant differences between the two groups could be demonstrated. The presence of stable and unstable angina was docum e n t e d preoperatively, but no significant difference between groups 1 and 2 could be detected. Angiographic data were obtained on all patients. Critical left main disease or triple-vessel disease was noted in 416 patients (88%). Although there were slightly more patients with left main disease in the SVG group (11% versus 7%), this did not reach significance. Ejection fractions for the two groups were obtained from either the left ventriculogram or the echocardiogram and were divided into three categories; greater than 0.50, between 0.30 and 0.50, and less than 0.30. Group I had 73 patients (40.1%) and group 2 had 108 patients (39.7%) in the first category, demonstrating good left ventricular (LV) function. In the second category, demonstrating moderate LV dysfunction, there were 85 patients (46.7%) from group 1 and 121 patients (44.5%) from group 2. The third category, demonstrating severe LV dysfunction, included 24 patients (13.2%) from group I and 43 patients (15.8%) from group 2. Overall, the ejection fractions between the two groups were comparable. A total of 16 patients, 6 in group 1 and 10 in group 2, underwent emergency operation. There were 21 patients (11.2%) in group I and 18 patients (6.3%) in group 2 who were having redo operations. All patients were operated on using standard cardiopulmonary bypass techniques. Ascending aortic cannulation, single two-stage or bicaval cannulation, and hypothermia to 25 ° to 28°C were routinely used. Myocardial protection was generally afforded by antegrade cold blood cardioplegia. Distal bypass grafts were constructed under a single cross-clamp time. All proximal bypass grafts were performed with a single side-biting clamp on the ascending aorta.
Data Collection All historical and perioperative data were obtained by retrospective review. Hospital charts, catheterization reports, and operative reports were used. Follow-up information was obtained from most patients by telephone interview and for the rest, from records of the personal
The n u m b e r of octogenarians we have operated on has steadily been increasing yearly, effectively doubling from
Table 1. Preoperative Profiles for Groups 1 and 2 a Characteristic
Group 1
Group 2
No. of patients Sex Male Female Mean age (y) Risk factors Prior MI Acute (<1 week) Remote (>1 week) Congestive heart failure Hypertension Diabetes mellitus Renal dysfunction Peripheral vascular disease Cerebrovascular disease NYHA class I II III IV Angina Stable Unstable Angiographic data Left main disease Triple-vessel disease Ejection fraction >0.50 0.30-0.50 <0.30 Previous CABG Emergency operation Average no of bypass grafts
188 (39.7)
286 (60.3)
127 (67.6) 61 (32.4) 81.9 + 2.9
185 (64.7) 101 (35.3) 82.9 + 3.1
180 50 (26.6) 130 (69.1) 42 (22.3) 129 (68.6) 16 (8.5) 34 (18.1) 21 (11.2) 40 (21.3)
266 83 (29.0) 183 (64.0) 68 (23.8) 206 (72.0) 36 (12.6) 57 (19.9) 27 (9.4) 54 (18.9)
3 (1.6) 12 (6.4) 90 (47.9) 83 (44.1)
5 (1.7) 14 (4.9) 138 (48.3) 129 (45.1)
90 (47.9) 55 (29.3)
126 (44.1) 100 (35.0)
13 (6.9) 152 (80.9) 182 (96.8) 73 (40.1) 85 (46.7) 24 (13.2) 21 (11.2) 6 (3.2) 3.6
3 (10.8) 220 (76.9) 272 (95.1) 108 (39.7) 121 (44.5) 43 (15.8) 18 (6.3) 10 (3.5) 3.3
a Numbers in parentheses are percentages. CABG= coronaryartery bypass grafting; M] = myocardialinfarction; NYHA = New York Heart Association.
18
MORRISET AL ITA FOR CABGIN OCTOGENARIANS
Ann Thorac Surg 1996;62:16-22
100
20
80
15
rOr)
60
10
¢.~
"6
E3
40 20
0
0
Fig 2. Number of octogenarians by year of study.
43 patients in the first year of the study to 85 patients in the last year (Fig 2). The percentage of patients receiving ITA grafts has also increased during this period. During the first year of the study, the frequency of ITA use was less than 5%, but it has increased dramatically to 48% for the last 2 years (Fig 3). The length of stay (LOS) for both groups is shown in Figure 4. The overall LOS during the period of the study was 12.9 days. It ranged from a high of 15.1 days in 1989 to a low of 9.9 days in 1994. Group I had an average LOS of 11.4 days and group 2, 13.9 days (p < 0.05). The average number of bypass grafts in the two groups was similar: 3.6 grafts per patient in group I and 3.3 grafts per patient in group 2. Mortality Hospital mortality was defined as death during the period of hospitalization or within 30 days after operation. There were 37 deaths in 474 patients, for an overall hospital mortality rate of 7.8%. Group 1 had a hospital mortality rate of 9.0% (171188) compared with 7.0% (20•286) for group 2 (p = 0.056). In both groups, the most common causes of death were myocardial failure (n = 18 patients) and cerebrovascular accidents (CVA) (n = 8 patients) (Table 2). The other causes of death were sepsis
100
80
Fig 4. Length of stay in hospital for patients with internal thoracic artery graft (hatched bars) versus saphenous vein graft (black bars).
(n = 4), renal failure (n = 4), respiratory failure (n = 2), and pulmonary embolism (n = 1). Morbidity Major hospital morbidity was identified in 104 (23.8%) of the 437 survivors and comprised MI, respiratory failure, acute renal failure, CVA, infection or sepsis, and postoperative bleeding (Table 3). Myocardial infarction was documented on the basis of diagnostic electrocardiographic changes and measured elevation of myocardial enzyme levels. Respiratory failure was defined as ventilatory dependence lasting longer than 48 hours from the time of operation. Acute postoperative renal failure was classified as the requirement of temporary peritoneal dialysis or hemodialysis. Cerebrovascular accident was classified as a fixed neurologic deficit at the time of discharge. Postoperative bleeding was noted as critical only if the patient was returned to the operating room. The most common complication was respiratory failure, followed by CVA and then perioperative MI. The other three complications were less common. Patient Follow-up Patient follow-up was obtained by telephone and physician office charts for 402 (92%) of the survivors. Thirtyfive patients were lost to follow-up. Follow-up ranged from I month to 96 months (mean follow-up, 46 months). Actuarial survival rates for the two groups are shown in Figure 5. Confidence intervals for survival in each group are also included. At 2 years of follow-up and beyond, the risk of dying diminished significantly in the ITA cohort
r'-
60
-0
Table 2. Causes of Hospital Mortality
40
Cause
20 0
1987 1988 1989 1990 1991 1992 1993 1994
Year Fig 3. Use of internal thoracic artery as a graft (hatched bars) versus saphenous vein graft (black bars).
Myocardial failure Cerebrovascular accident Sepsis Renal failure Respiratory failure Pulmonary embolism
Group 1
Group 2
8 5 2 1 1 0
10 3 2 3 1 1
Ann Thorac Surg 1996;62:16-22
MORRISET AL ITAFOR CABGIN OCTOGENARIANS
Table 3. Causes of Hospital Morbidity ~
Cause
Group 1 (n = 171)
Group 2 (n = 266)
Myocardial infarction Respiratory failure Acute renal failure Cerebrovascular accident Infection/sepsis Postoperative bleeding
7 (4.1) 18 (10.5) 4 (2.3) 10 (5.8) 3 (1.8) 3 (1.8)
12 (4.5) 25 (9.4) 8 (3.0) 20 (7.5) 3 (1.1) 6 (2.3)
a Numbers in parentheses are percentages.
by a factor of 0.5. Survival at 5 years and beyond remained at 80% in group I but diminished to 60% in group 2.
Comment The population of octogenarians is steadily increasing in the United States. In these elderly patients, outcomes for myocardial revascularization are indicative of enhanced survival compared with medical treatment [7-9], Internal thoracic artery grafting to the left anterior descending coronary artery by itself has been shown to be a strong predictor of event-free survival [10, 11]. Use of the ITA graft has become well accepted for younger patients, in whom its use approaches 90%. Restrictions on long-term survival, greater incidence of concomitant disease, "brittleness" of the patient, and prolonged operations have all combined to decrease use of the ITA in octogenarians. Over the 8 years of this study, the incidence of ITA use has increased tenfold, from 4.7% to 48%. This is due to a number of factors. First, confidence in the applicability of this conduit grew with greater experience and improved skills of the surgeons. Second, the number of octogenarians seen for CABG continues to grow, with a greater number of these patients having less than ideal saphe, nous veins for CABG. This may correlate with advanced age, as saphenous veins were anecdotally noted to be more friable and of poorer quality in the very elderly. The
00 T I
-..
9O
._> >
80
co 70
----0--..
~'"'"...,,
SVG
6O
50
i
i
I
i
0
1
2
3
Years
since
J 4
i S
J 6
Procedure
Fig 5. Actuarial survival rate of paffents with internal thoracic artery (ITA) graft versus saphenous vein graft (SVG).
19
search for alternative conduits to SVGs led us to reexamine use of the ITA in these high-risk patients. A number of studies have shown that CABG in elderly patients is associated with increased morbidity and mortality compared with younger cohorts [12, 13, 14]. We found this to be true in our older subgroup as well. The hospital mortality rate for the total cohort of 474 patients was 7.8%. During the same period, the mortality rate was only 3.5% in 8,155 patients less than 80 years old undergoing CABG. This finding is similar to findings in other reports on octogenarians having CABG [15-17]. The underlying differences are multifactorial in origin. Elderly patients have a greater incidence of concomitant disease processes. Also, the elderly are referred for operation at a later stage of the disease than younger patients and with more severe symptomatology. In fact, more than 90% of our patients were in New York Heart Association class III or W preoperatively, a finding consistent with other studies [16,17]. In addition, an inherent bias may be present among referringphysic~ans because of the often reported increased mortality with advanced age. Early in the evaluation of this cohort laopulation, it was also more likely for octogenarians only in the best physical shape to be referred for operation. As greater numbers of elderly patients were seen with angina, referrals for operation increased. The Society of Thoracic Surgeons database [18] reports an increase in the mean age of CABG patients in each of the last three decades. The average age has increased from 58.5 years to 64 years in just the 10-year period 1980 to 1990. The average age of the patient undergoing CABG at our institution during the time period of this study has increased to 72.3 years. Importantly, a retrospective examination of the preoperative characteristics of the two groups reveals very little difference between them. An overview of the preoperative risk factors shows that elderly patients do indeed have a plethora of concomitant diseases. However, this should not be a deterrent to their referral for operation. It is tempting to speculate that most of these disease processes have not progressed to end-organ damage; otherwise the patients would not have made it to the ninth decade. Referral of the elderly patient for CABG was a decision that was not lightly made. The incidence of emergency operations in patients less than 80 years old in our institution is 11%. Comparatively, the low incidence of emergency operations in these two groups of patients, 3.2% and 3.5%, respectively, reflects an intense effort to maximally optimize the preoperative state of the patient. A substantial number of patients, 42 (22.3%) in group 1 and 68 (23.8%) in group 2, were seen with symptoms of congestive heart failure. The presence of mild to moderate congestive heart failure preoperatively has been shown not to be a strong predictor of poor outcome [14, 16]. The fact remains that hospital (operative) mortality remains the gold standard by which surgical procedures are deemed successful. Hospital mortality was slightly higher in the ITA group than the SVG group, 9.0% versus 7.0%, but did not reach significance (p > 0.1). We did not note any decrease in mortality rate by year of study; the
20
MORRISET AL ITA FOR CABGIN OCTOGENARIANS
rate ranged from 6% to 12%. Myocardial failure was the most common cause of death. The Coronary Artery Surgery Study [19] and others have shown convincingly that compromised LV function is a strong independent predictor of operative mortality. Approximately 15% of our patients had severely impaired LV function, and another 45% had moderate impairment of LV function by preoperative ventriculography. Preoperatively, more than 25% of patients in each group had a proven acute MI, and two thirds of the patients had a history of one or more previous MIs. Postoperatively, it was recognized that 4.1% and 4.5% of patients in groups 1 and 2, respectively, had sustained a perioperative MI. The frequency of perioperative MI is comparable to rates reported elsewhere for CABG and is also similar to rates in younger patients [14, 19]. We believe the lower rate of perioperative MI is due to improved techniques for cardiopulmonary bypass, better myocardial preservation techniques, and safer anesthesia management. Cerebrovascular accident, the second most common cause of hospital mortality, occurred in greater frequency than in younger patients. Five patients in group 1 and 3 patients in group 2 died secondary to a CVA. In all, 10 patients (5.8%) in group I and 20 patients (7.5%) in group 2 sustained a CVA. The incidence of CVA has clearly been shown to increase with advancing age after CABG [17, 20]. The incidence of CVA in patients younger than 80 years during this same period was less than 2%. Preoperatively, 40 patients (21.3%) in group 1 and 54 (18.9%) in group 2 were noted to have cerebrovascular disease, defined as one or more neurologic events. This is much higher than in the general group of patients undergoing CABG before the ninth decade of life. Preoperative assessment of carotid artery disease by Doppler should be routinely performed in this elderly group of patients. It is now our policy for elderly patients found to have critical carotid disease to undergo carotid endarterectomy before CABG. Sepsis was the cause of death in 2 patients in each group. In contrast, sternal infection was rare, less than 2% in both groups, although mortality was very high when it did occur. Williams and colleagues [16] showed sternal wound infection has a positive predictive value for hospital mortality and wrote that they "use the left internal m a m m a r y artery only in selected cases where the quality of sternal tissue is good." In our experience, most octogenarians appear to have weak sternums and rather friable tissue but are endowed with good mammary arteries. Four patients died secondary to renal failure, 1 in the ITA group and 3 in the SVG group. Twelve patients experienced acute renal failure requiring hemodialysis postoperatively. Hence, the mortality rate was 33% in patients requiring hemodialysis postoperatively. The incidence of preoperative renal dysfunction in groups 1 and 2 was 18.1% and 19.9%, respectively. No patient who required long-term hemodialysis preoperatively underwent operation. Several groups [21-23] have shown renal dysfunction to be an important factor in postoperative morbidity and mortality. Our protocol for patients with
Ann Thorac Surg 1996;62:16-22
Table 4. Postoperative N e w York Heart Association Class a
Class
Group 1
Group 2
I II III IV
82 (48.0) 72 (42.1) 11 (6.4) 6 (3.5)
130 (48.9) 118 (44.4) 18 (6.8) 8 (3.0)
a Numbers in parentheses are percentages.
preoperative renal dysfunction dictates minimal contrast medium use for angiography, hydration, forced diuresis, and renal-dose dopamine hydrochloride. Only 1 patient in each group died secondary to respiratory failure. Both patients had development of pneumonia, compromising marginal lung function. The second important criterion by which a surgical procedure is considered successful and is recommended as treatment is acceptable morbidity. No discernible difference in complications was noted between the two groups. One of the greatest concerns noted with ITA use in the past has been respiratory compromise. This is thought to occur secondary to pleural dissection, which may cause increased chest wall pain, postoperative pleural effusion, and a resultant underlying atelectasis. Considerable morbidity was noted secondary to respiratory difficulties. Although ventilatory dependence was slightly greater in the ITA group, 18 patients (10.5%) compared with 25 (9.4%) in the SVG group, no significant difference existed. One might think that opening the pleural space and chest wall dissection would increase postoperative respiratory difficulty, but this was found not to be the case. A separate study in younger patients having CABG at this institution shows no significant delay in extubation in patients having an ITA as a graft (personal communication). Historical concerns over adequacy of ITA flow seem to be unfounded. Certainly the absence of any increase in perioperative MIs in group 1 is reassuring. In no patient in the SVG group was a m a m m a r y artery taken and not used because of poor flows. It has been shown that takedown of single ITA grafts has not been associated with a greater incidence of sternal infections [24, 25]. Our elderly cohort confirms this finding as evidenced by a very low incidence of infection in groups 1 (1.8%) and 2 (1.1%). No patient in either group received bilateral ITA grafts. Tremendous improvement in the patients' symptoms was also noted. Preoperatively, 92.0% of patients in group 1 and 93.4% of patients in group 2 were classified in NYHA class III or W. Postoperatively a complete reversal was noted, with 90.1% of patients in group I and 93.2% of patients in group 2 classified in NYHA class I and II (Table 4). Contemporary discussions of morbidity are not complete without true scrutiny of LOS. Length of stay was markedly increased in both groups compared with that of the general population undergoing CABG. Octogenarians required an LOS nearly 3 days longer than patients younger than 80 years. The mean LOS for group 1 was
Ann Thorac Surg 1996;62:16-22
11.4 days and for group 2, 13.9 days. The LOS for group 1 was significantly lower in each year of the study, thus reaching significance. This could be attributed in part to selection bias of the surgeon, who must have chosen to use the ITA graft on healthier patients. The preoperative profiles of the two groups do not distinguish any characteristic with greater prevalence in either cohort. Nonetheless, LOS has steadily decreased during the last 6 years, dropping on average by 3 days. A n u m b e r of factors, such as better anesthesia management, early extubation and ambulation, improved pain control home health-care nursing, and pressure from managed-care groups for early discharge are responsible for the reduced LOS. Similar pressures have reduced LOS significantly a m o n g all our CABG patients. As the n u m b e r of octogenarians increases, it will remain a difficult challenge to continue decreasing LOS. The third standard of success for surgeons, and perhaps the one of greatest importance, remains the longterm benefit of such an operation. The actuarial survival rates were calculated for the two groups with follow-up as long as 7 years for those operated on early in the study (Fig 5). Significance between the two groups is reached at a point b e y o n d the 2-year follow-up. The ITA group continues to show a greater actuarial survival throughout the remaining follow-up period. Survival for the ITA cohort beyond 5 years remains approximately 80%, but the n u m b e r of patients in this group (n = 11) is too small to derive conclusive clinical significance. Survival for the SVG group mirrors that of other groups reporting on octogenarians. Survival data from the Cleveland Clinic [5] indicated that improvement in survival is conferred by ITA grafting as early as 4 to 5 years postoperatively. The fact that we could note a difference as early as 3 years points to differing conduit characteristics in the very elderly. It is conceivable that the saphenous vein is a poorer conduit in very elderly patients and therefore does not confer protection from early graft closure. Late survival benefit with use of the ITA in the elderly has not been shown by other studies [2, 22, 24]. The incidence of ITA use was fairly low in previous studies, and it remains to be seen whether with increasing use, long-term survival improves. It is inherently obvious that long-term studies in this group of patients (ie, >10 years) is difficult because of natural attrition rates. It is apparent from this study and others that the incidence of CABG procedures in octogenarians is rising. Substantial quality of life m a y be restored by surgical intervention, as shown by the improvement in NYHA class in both the ITA group and the SVG group. We conclude from the data presented here that an ITA graft to the left anterior descending coronary artery can be used without fear of greater morbidity or mortality in patients 80 years of age and older. The ITA graft has no increased morbidity than and comparable hospital mortality as the SVG. With others, we tended to assume that use of the ITA graft would cause increased respiratory failure, increased bleeding, more sternal infections, and a longer operation. On the contrary, we found no substantial difference in morbidity with use of the ITA compared
MORRISET AL ITA FOR CABGIN OCTOGENARIANS
21
with use of the SVG alone. In addition, we observed, with some surprise, that LOS was significantly lower in patients having ITA grafts. The hospital mortalities were similar, and the long-term follow-up showed decreased mortality in patients with the ITA graft. Most notably, the difference in survival is apparent within 2 years of followup, m u c h earlier than that observed in younger patients. The ITA was found to be a good-quality vessel in octogenarians, and we are not aware of a single instance of inadequate flow or perioperative MI secondary to decreased flow. We believe that there are m a n y advantages to using the ITA graft and few disadvantages in elderly patients. We therefore have made it our policy to use the ITA graft as much as possible in octogenarians.
References
1. Merrill WH, Stewart JR, Frist WH, et al. Cardiac surgery in patients age 80 years or older. Ann Surg 1990;211:772-5. 2. Salomon NW, Page US, Bigelow JC, et al. Coronary artery bypass grafting in elderly patients. J Thorac Cardiovasc Surg 1991;101:209-18. 3. US Bureau of the Census. Current population reports: projections of the population of the USA by age, sex and race. 1988-2080. Series P-25, no. 1018. Washington, DC: US Department of Commerce, 1989. 4. Lytle BW, Loop FD, Cosgrove DM, et al. Long-term (5 to 12 years) serial studies of internal mammary artery and saphenous vein coronary bypass grafts. J Thorac Cardiovasc Surg 1985;89:248-58. 5. Loop FD, Lytle BW, Cosgrove DM, et al. Influence of the internal mammary artery graft on 10 year survival and other cardiac events. N Engl J Med 1986;314:1-9. 6. Gardner TJ, Greene PS, Rykiel MF, et al. Routine use of the left internal mammary artery graft in the elderly. Ann Thorac Surg 1990;49:188-94. 7. Naunheim KS, Kern MJ, McBride LR, et al. Coronary artery bypass surgery in patients aged 80 years or older. Am J Cardiol 1987;59:804-7. 8. Krumholz HM, Forman DE, Kuntz RE, et al. Coronary revascularization after myocardial infarction in the very elderly: outcomes and long-term follow-up. Ann Intern Med 1993;119:1084-90. 9. Horvath KA, DiSesa VJ, Peigh PS, et al. Favorable results of coronary bypass grafting in patients older than 75 years. J Thorac Cardiovasc Surg 1990;99:92-6. 10. Tector AJ, Schmahl TM, Janson B, et al. The internal mammary artery graft. JAMA 1981;246:2181-4. 11. Okies JE, Page US, Bigelow JC, et al. The left internal mammary artery: the graft of choice. Circulation 1984; 70(Suppl 1):213-21. 12. Kupfer J, Khan S, Matioft JM, Tsai TP, Nessim S, Gray R. Heterogeneous mortality rates of elderly patients undergoing coronary bypass surgery. Circulation 1992;86(Suppl 1): 437-44. 13. Mohan R, Amsel BJ, Walter PJ. Coronary artery bypass grafting in the elderly: a review of studies on patients older than 64, 69 or 74 years. Cardiology 1992;80:215-23. 14. Grover FL, Johnson RR, Marshall G, et al. Factors predictive of operative mortality among coronary artery bypass subsets. Ann Thorac Su.rg 1993;56:1296-307. 15. Weintraub MS, Clements SD, Ware J, Craver JM, Cohen CL, Jones EL. Coronary artery surgery in octogenarians. Am J Cardiol 1991;68:1530-4. 16. Williams DB, Carrillo RG, Traad EA, et al. Determinants of operative mortality in octogenarians undergoing coronary bypass. Ann Thorac Surg 1995;60:1038-43. 17. Cane ME, Chen C, Bailey BM, et al. CABG in octogenarians:
22
18.
19.
20.
21.
MORRISET AL ITA FOR CABG IN OCTOGENARIANS
early and late events and actuarial survival in comparison with a matched population. Ann Thorac Surg 1995;60:1033-7. Edwards FH, Clark RE, Schwartz M. Coronary artery bypass grafting: The Society of Thoracic Surgeons national database experience. Ann Thorac Surg 1994;57:12-9. Kennedy JW, Kaiser GC, Fisher LD, et al. Multivariate discriminant analysis of the clinical and angiographic predictors of operative mortality from the Collaborative Study on Coronary Artery Surgery (CASS). J Thorac Cardiovasc Surg 1980;80:876-87. Horneffer PJ, Gardner TJ, Reitz BA, et al. The effects of age on outcome after coronary bypass surgery. Circulation 1987; 76(Suppl 5):6-12. Tsai T-P, Nessim S, Kass RM, et al. Morbidity and mortality
Ann Thorac Surg 1996;62:16-22
22. 23.
24. 25.
after coronary artery bypass in octogenarians. Ann Thorac Surg 1991;51:983-6. Ennabli K, Pelletier LC. Morbidity and mortality of coronary artery surgery after the age of 70 years. Ann Thorac Surg 1986;42:197-200. Higgins TL, Estafanous FG, Loop FD, et al. Stratification of morbidity and mortality outcome by pre-operative risk factors in coronary artery bypass patients: a clinical severity score. JAMA 1992;267:2344-8. Saldanha RF, Raman J, Esmore DS, et al. Myocardial revascularization in patients over seventy-five years. J Cardiovasc Surg (Torino) 1988;29:624-8. Dewar LRS, Jamieson WRE, Janusz MT, et al. Unilateral versus bilateral mammary revascularization: survival and event-free performance. Circulation 1995;92(Suppl 2):8-13.
DISCUSSION DR CARY W. AKINS (Boston, MA): Obviously the patient population is loaded at the front end by patients having largely saphenous vein grafting and at the back end by more patients having internal mammary grafting, which can have some impact when looking at late results. Particularly when talking about long-term survival, one has to account for a surgeon's selection of patients in whom to use internal mammary grafting. Have you looked at risk factors to be able to predict what caused late death and whether the internal mammary was actually a predictor of better survival by multivariate analysis? D R MORRIS: We have not looked at late survival in terms of
DR CONSTANTINE E. ANAGNOSTOPOULOS (New York, NY): Following the lead of Dr George Green, our three teams at St. Luke's Hospital have been doing exactly what Dr Morris and Dr Brockman have been doing, and we have noticed actually slightly improved results when looking at deaths and complications. In fact, The Society of Thoracic Surgeons showed last year (if I remember correctly) for the first time that use of the internal mammary artery, even in emergency operation, resulted in improved survival. I suspect that as we speak, The Society and the national database will have the answer as to whether the internal thoracic artery is the graft of choice in patients who are in their ninth decade. Do you have access to that information?
multivariate analysis. However, we looked at cohorts between the two groups and found that there was no significant selection bias on the part of the surgeon. It was presumed that the surgeon may have selected a healthier patient, but we found that not to be so, and we did not find a single predictor indicating that.
D R MORRIS: I am sorry, sir, but I do not have access to the information for The Society database. However, we do operate on patients in the ninth decade of life and use the internal mammary arteries. In our experience, these arteries actually made a better graft than the saphenous vein.
Bound
volumes
available to subscribers
Bound volumes of the 1995 issues of The Annals of Thoracic Surgery are available only to subscribers from the Publisher. The cost is $99.00 (outside US add $25.00 for postage) for volumes 59 and 60. Each bound volume contains a subject and author index, and all advertising is removed. The binding is durable buckram with the name of the journal, volume number, and year stamped on the spine. Payment must accompany all orders. Contact Elsevier Science Inc, 655 Avenue of the Americas, New York, NY 10010; or telephone (212) 633-3950 (facsimile: (212) 633-3990).