(Circulation. 1995;92:8-13.)
© 1995 American Heart Association, Inc.
Articles |
From the Vancouver Hospital and Health Sciences Centre, University of British Columbia, Vancouver, Canada.
Correspondence to Dr W.R. Eric Jamieson, Department of Surgery, 910 W 10th Ave, Vancouver, BC, V5Z 4E3 Canada.
| Abstract |
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60 years and >60 years, on patient survival,
ischemic-related events, and interventional management was
studied in 1142 patients who had coronary artery bypass graft
surgery between 1984 and 1992.
Methods and Results UL
revascularization was performed in 765 (67%) and
BL in 377 (33%) patients with supplemental vein grafts. The overall
early and hospital mortality rate was 2.7%. For UL in the age group
60 years, it was 1.1%; for BL
60 years, 1.3% (P=NS);
for UL >60 years, 4.3%; and for BL >60 years, 2.8%
(P=NS). Twenty-five preoperative patient characteristics
representing demographics, extent of disease, concomitant
disease, ventricular dysfunction, previous surgery, and
status did not differentiate the patient groups (P=NS).
Patient survival at 5 years was not different: 94% for UL
60 years,
95% for BL
60 years, 91% for UL >60 years, and 86% for BL >60
years (P=NS). The freedom from ischemic-related
events was not different at 5 years (P=NS). The freedom from
recurrent angina was 78% for UL
60 years, 88% for BL
60 years,
82% for UL >60 years, and 83% for BL >60 years (P= NS).
The myocardial infarction freedom was 98% for UL
60 years, 96% for
BL
60 years, 99% for UL >60 years, and 97% for BL >60 years
(P=NS). The freedom from sudden unexpected death and cardiac
death did not differentiate the groups (P=NS). The freedom
from angioplasty and reoperation did not differentiate the groups
(P=NS). The freedom from all ischemic-related
and interventional events was 76% for UL
60 years, 84% for BL
60
years, 81% for UL >60 years, and 79% for BL >60 years
(P=NS). A trend exists for less angina pectoris in the
bilateral population
60 years, which reflects in the trend in the
freedom from overall events.
Conclusions UL and BL mammary artery revascularizations have the same early mortality regardless of age but do not reveal any advantage for BL revascularization at 5 to 7 years.
Key Words: bypass risk factors mortality grafting
| Introduction |
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We did not begin using BL IMA revascularization until 1984. There has been no concerted opinion or pattern of practice for the use of single or double IMA grafting. In the present study, we document our experience and provide the results of 5 and 7 years, including age evaluation, of the use of single or double IMA revascularization.
| Methods |
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60 years of age, and
702 (61.5%) were >60 years of age (mean age of the
60 group, 52.0
years; range, 31.8 to 60.0 years; mean age of the >60 group, 67.5
years; range, 60.0 to 82.9 years).
The distribution of use of IMA
grafts by vessel of insertion is
demonstrated for both the UL and BL populations in Tables 1
and
2
. There were 853 IMA grafts (1.12 per
patient) in the UL population of 765 patients and 823 (2.18 per
patient) in the BL population of 377 patients. The total number of
grafts per patient for the UL group were 3.57 per patient (
60, 3.50;
>60, 3.52) and for the BL group were 3.9 per patient (
60, 3.79;
>60, 4.0). There was a minimal number of free IMA grafts and
gastroepiploic artery grafts (Table 3
).
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Clinical Presentation
Twenty-five preoperative
characteristics of the patients
were used to distinguish the groups. The characteristics are part of
the Society of Thoracic Surgeons National Cardiac Surgery Database
collection form that was used for collection of data in this
retrospective evaluation. The definitions of the terms are defined and
published by the Society of Thoracic Surgeons. The most important
parameters of the total patient population are illustrated
in Tables 4
and 5
. Of the total, 18.8%
had diabetes mellitus, 6.5% had previous coronary artery
bypass graft surgery, 27.9% had left main coronary artery
stenosis (>50%), and 60.8% had moderate-to-severe
wall motion abnormalities with ejection fraction below 45%. Of the
total, 87.0% had elective or urgent operation, whereas of the
remainder, 12.6% were classified as low emergent and 0.4% as high
emergent. The majority of the patients, 93.2%, were having a first
operative procedure, with 6.5% having a first reoperation and 0.4%
having a second reoperation.
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The UL and BL patient parameters did not
distinguish the
groups (P=NS). The predominant 14 characteristics and
percentages for both groups are shown in Table 6
. There
were no distinguishing features between the two groups.
|
The patient
population was divided into two subgroups: 440 (38.5%)
were
60 years of age, and 702 (61.5%) were >60 years of age. The
mean age of the
60 group was 52.0 years (range, 31.8 to 60.0 years)
(mean: UL, 52.2 years; BL, 51.7 years) and of the >60 group was 67.5
years (range, 60.0 to 82.9 years) (mean: UL, 67.6 years; BL, 67.1
years).
Data Management and Statistical Analysis
All data were
compiled and stored on the Society of Thoracic
Surgeons (Summit Medical Systems Inc) computerized database.
Univariate analysis (
2 and
grouped t tests) was used to compare the characteristics of
the groups of patients. Multivariate logistic
regression analysis was not applied because the
univariate analysis had shown no statistical
significance. Actuarial life tables or the Cutler-Ederer method was
used to evaluate overall survival and freedom from ischemic
events such as angina pectoris, myocardial infarction, and death and
interventions, percutaneous transluminal
coronary angioplasty (PTCA), and reoperation for repeat
revascularization. A set level of significance
(
=.05) was chosen for decision making.
| Results |
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60 years was 1.1% (5 patients) and for the
group >60 years it was 3.7% (26 patients) (P=NS). For the
group
60 years, the early mortality for the UL patients was 1.1% (3
patients) and for BL was 1.3% (2 patients) (P=NS). For the
group >60 years, the early mortality for UL was 4.3% (20 patients)
and for BL was 2.8% (6 patients) (P=NS). The predominant
causes of early mortality were perioperative myocardial
infarction, cerebrovascular accident, low output syndrome, cardiac
arrest, and sternal infection and mediastinitis.
Patient survival by age groups for UL and BL mammary
revascularization is illustrated in Fig 1
. The 5- and 7-year
survival is indicated, showing no
difference within age groups for UL and BL mammary artery use or
between groups (P=NS). The 5-year survival for
60 years UL
is 94.4±1.5% and for BL is 94.8±2.2%; the rates for >60 years
are
90.8±1.7% and 85.8±3.6%, respectively, for UL and BL
(P=NS).
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The incidence of exploration for postoperative bleeding and tamponade was 6% (70 patients); for UL, 5.1% (39 patients); and for BL, 8.2% (31 patients) (P<.05). There were 2 deaths for which bleeding and tamponade were contributing factors.
There were 11 cases of deep sternal wound infection and mediastinitis
(1.0%; UL, 8; BL, 3). In the
60 year group, the rate was 1.1% (3
patients) for UL and 0.6% (1 patient) for BL (P=NS). In the
>60 year group, the rate was 1.0% (5 patients) for UL and 0.9% (2
patients) for BL (P=NS). Of the 11 patients, there were 2
deaths (18%).
The freedom from ischemic-related events is demonstrated in
Figs 2 through 5![]()
![]()
![]()
.
The
freedom from recurrent angina pectoris was not different
(P=NS); 77.8±3.0% for UL
60 years, 88.1±2.6%
for BL
60 years, 81.8±2.2% for UL >60 years, and 83.0±3.5% for
BL >60
years (Fig 2
). The freedom in the
60 year group indicated a
trend
toward less angina with BL rather than UL mammary
revascularization.
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The freedom from myocardial infarction did not differentiate the groups
at 5 and 7 years (P=NS). The freedom for UL
60 years was
98.2±0.9%; for BL
60 years, 96.2±2.0%; for UL >60 years,
98.8±0.6%; and for BL >60 years, 96.8±2.0%
(P=NS) (Fig 3
). The freedom from sudden
unexpected death did not differentiate the
groups (P=NS), with freedom ranging between 97.8±1.8%
and
100% (Fig 4
).
The freedom from cardiac-related death did not reveal any
difference between the groups at 5 and 7 years (P=NS) (Fig
5
). The freedom was 96.1±1.3% for UL
60 years,
98.0±1.2% for BL
60 years, 96.5±0.8% for UL >60 years, and 92.0±2.8% for
BL >60
years at 5 years (P=NS).
The freedom for interventional management in the patient subgroups is
shown in Figs 6
and 7
. The freedom from
PTCA was not different at 5 years: 91.0±2.2% for UL
60 years,
95.5±1.9% for BL
60 years, 96.3±1.1% for UL >60 years,
and
98.4±0.9% for BL >60 years (P=NS) (Fig
6
). Reoperation
was performed infrequently during the observation period; the freedom
was 98.2±0.9% for UL
60 years, 99.4±0.6% for BL
60
years,
98.0±1.1% for UL >60 years, and 99.4±0.6% for BL >60 years
(P=NS) (Fig 7
).
|
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The demonstration of freedom from all ischemic-related and
management interventional events is presented in Fig 8
. The
freedom from overall events was 75.7±3.0% for
UL
60 years, 83.9±3.2% for BL
60 years. 80.9±2.2% for UL
>60
years, and 79.0±3.9% for BL >60 years at 5 years
(P=NS).
The trend toward reduced freedom for the bilateral
revascularization group
60 years is related to
the noted trend in greater freedom from recurrent angina pectoris.
|
The results for the total UL and BL mammary
revascularization groups, regardless of age
groupings, for patient survival, ischemic-related events,
and interventional management are presented at the 5-year
interval (Table 7
). There also was no difference
considering the two populations as a whole without consideration of age
groupings (P=NS).
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| Discussion |
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The use of arterial revascularization with the IMA became more common practice after the 1984 reports by Grondin et al1 and Okies et al.2 The report from the Montreal Heart Institute by Grondin et al1 compared survival and patency of IMA grafts with those of SV grafts at 10 years. The patient survival at 10 years for IMA grafts was 84% compared with 70% for SV grafts. The patency at 1 year was 89% and 76% and at 10 years was 84% and 53%, respectively, for IMA and SV grafts. In the same year, Okies et al2 identified the left IMA as the graft of choice to the anterior descending coronary artery in a nonrandomized study. The study revealed, at 10 years, survival rates of 82% and 69%, event-free survival rates of 61% and 48%, and patency rates of 83% and 48%, respectively, for IMA and SV grafts.2 The 5-year survival rate of Okies et al2 was 92% for IMA compared with our overall IMA survival rate of the same value. Their event-free survival was 61%2 compared with our event-free survival rate including a reoperation rate of 80%. This fact could be explained by advanced myocardial preservation techniques with minimal ventricular muscle compromise at surgery became congestive heart failure was a factor, together with recurrent angina, myocardial infarction, and death in their event-free survival rate.
Additional reports3 4 5 7 documented comparisons between the performance of IMA and SV grafts. Barner et al,3 reporting in 1985, revealed a 5-year survival rate of 93% (comparable to our survival rate of 91%) and 10-year survival rate of 84%. The patency rate in this study was 88% at 5 and 10 years for IMA grafts and 74% at 5 years and 41% at 10 years for SV grafts. Cameron et al4 (including Green) revealed a 5-year survival rate for IMA and SV grafts of 91% and 86%, respectively, and, at 10 years, of 82% and 72%. Loop et al5 from the Cleveland Clinic Foundation reported on an extensive series of patients and found survival rates at 10 years for management of three-vessel disease with IMA grafts of 83% and with SV grafts of 71%. Survival was higher for one- and two-vessel disease.
In 1994, Edwards et al7 reported on the Society of Thoracic Surgeons database, which showed improved early survival with IMA grafts: 2.0% for IMA grafts and 4.5% for SV grafts. The early mortality from several reports4 7 8 9 10 11 ranges from 1.9% to 2.8% for UL IMA grafts and from 1.3% to 3.7% for BL IMA grafts. The early mortality in the authors' series, expanding over 8 years from 1984, was not different for UL and BL IMA grafts: 3.0% and 2.1%, respectively. The early mortality for SV grafting in comparison reports has ranged from 4.1% to 4.5%.1 2 3 7 This may be due to more compromised and elderly patients receiving SV grafts. There appears to be no difference in early mortality with use of UL and BL IMA grafts. There remains concern that BL IMA grafting may still increase morbidity, ie, sternal infections and mediastinitis, bleeding requiring reexploration, and the need for prolonged ventilation. In the authors' series, BL IMA grafting did not increase the incidence of deep sternal infections and mediastinitis (P=NS) but did increase the incidence of reexploration for bleeding and tamponade (P<.05).
The debate remains over the use of UL or BL IMA grafts.3 4 8 9 10 11 12 13 14 15 In 1990, Fiore et al,9 reporting on the St Louis experience, revealed that survival was extended and ischemic events were reduced with BL IMA grafts at 13 years. Survival for BL IMA grafts was 74%, and for UL grafts, 59%. The 10-year survival rate was 82% and 84%, respectively, favoring BL IMA grafting. Cameron et al4 reported survival in favor of BL IMA at 10 years: 90% versus 83%. In 1989, Johnson et al13 reported no improvement in survival between BL and UL IMA grafting. In the same year, Kirklin et al14 found improved survival with UL IMA graft. Galbut et al,8 in 1990, reporting on a 17-year experience with BL IMA revascularization in 1087 patients, revealed a 10-year survival rate of 80% and a 15-year rate of 60%. In the authors' experience, the 5-year survival rate was similar; 92% for UL IMA and 90% for BL IMA grafting.
Freedom from ischemic-related events and reoperation has also been varied. In the authors' series, there has been no difference between the UL and BL populations. The freedom from recurrent angina pectoris, at 5 years, was 80% for UL IMA and 85% for BL IMA (P=NS). The freedom from myocardial infarction rate was 99% and 97%, respectively. The overall event-free comparison, at 5 years, was 79% for UL IMA and 81% for BL IMA. Okies et al,2 reporting in 1984 on UL IMA graft to the anterior descending coronary artery, had an event-free survival of 92% at 5 years and of 61% at 10 years. This perspective is not comparable to our freedom from all ischemic-related events and cardiac death rate. Fiore et al9 reported, in 1990, differences in long-term performance between BL and UL IMA grafting. At 13 years, the freedom from myocardial infarction was 75% for BL IMA and 59% for UL IMA, the freedom from recurrent angina was 36% and 27%, and the freedom from overall ischemic events was 32% and 18%, respectively.
In other terms, ischemic events have been reported as percentage per year. In 1986, Cameron et al4 found the rate of myocardial infarction for UL IMA to be 1.8%/year and for BL IMA to be 1.1%/year compared with SV grafting (3.1%/year). Barner et al,3 reporting in 1985, had a rate of 1.5%/year for UL and BL grafting. The authors' rate is 0.7%/year over a shorter time interval. Barner et al,3 in 1985, indicated a recurrent angina rate of 6.2%/year compared with our rate of 3% to 4%/year for undifferentiated IMA grafting. The recurrence of angina is more likely to be unrelated to IMA graft status, but to progression of native vessel disease or vein graft atherosclerosis.
The reintervention rate, including PTCA and reoperation, was reported by Barner et al3 to be 0.85%/year, comparable to our rate of 1.0%/year. Recent literature deals extensively with reoperative surgery and primary operative techniques to facilitate reoperation.16 17 18 19 20 21 22 In 1994, Joyce et al16 reported that reoperations with previous BL IMA grafting can be facilitated by retrograde cardioplegia or hypothermic circulatory arrest. Lytle et al,18 in 1994, documented that IMA grafting at the primary operation does not increase the risk of reoperation, nor does use of IMA grafting at reoperation increase mortality. Navia et al17 reported a high incidence of hypoperfusion syndrome with IMA conduits between an interrupted stenotic vein graft to the anterior descending coronary artery. In a subsequent editorial, Barner21 reviewed the problem of hypoperfusion syndrome and competitive flow and the development of IMA "string sign" of an IMA graft supplemented by a vein graft. Reoperative surgery is facilitated by the right IMA traversing the transverse sinus rather than the substernal approach. In 1994, Tector et al22 reported on the formation of T grafts (proximal right IMA free to left IMA) to facilitate reoperation.
Our experience provides early to intermediate-term results with
comparable populations with UL and BL IMA grafts in two age groups. At
the reported time frame, there is no apparent benefit to BL IMA
grafting over the age of 60 years with a trend to less recurrent angina
with BL grafting in the
60 year group. There has been limited
documentation on age consideration; in 1989, Gardner et
al6 found IMA grafting in the elderly to be an independent
predictor of survival. We will continue to be selective in UL and BL
IMA use. This series requires continuing evaluation to determine the
long-term results of UL and BL IMA
revascularization to 10 and 15 years.
| References |
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