Occurrence and Risk Factors for Reintervention After

Occurrence and Risk Factors for Reintervention After

Occurrence and Risk Factors for Reintervention After
Coronary Artery Bypass Grafting
Joseph F. Sabik III, MD; Eugene H. Blackstone, MD; A. Marc Gillinov, MD;
Nicholas G. Smedira, MD; Bruce W. Lytle, MD
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Background—Reintervention after coronary artery bypass grafting (CABG) is common. We sought to determine its
occurrence and identify patient characteristics and operative techniques that influence the need or bias for reintervention.
Methods and Results—From 1971 to 1998, 48 758 patients underwent primary isolated CABG, and 1000 patients per year
were actively followed-up every 5 years (n ⫽26 927). A multivariable time-related analysis was performed to model
freedom from first coronary reintervention (either reoperation or percutaneous coronary intervention) and identify
patient and operative characteristics associated with first reintervention. A total of 3997 patients underwent coronary
reintervention, percutaneous in 1638 and reoperation in 2359. Freedom from reintervention was 99%, 96%, 88%, 73%,
60%, and 46% at 1, 5, 10, 15, 20, and 25 years, respectively. Risk of reintervention (hazard function) demonstrated a
short, rapidly declining early phase followed by a longer, slow-rising late phase. Patient variables increasing the
likelihood of coronary reintervention included younger age (P⬍0.0001), higher triglycerides (P⫽0.002), lower
high-density lipoprotein (P⫽0.006), diabetes mellitus (P⬍0.0001), and more extensive coronary artery disease
(P⫽0.0005). Increasing extent of arterial grafting performed at primary operation decreased the likelihood of coronary
reintervention (P⬍0.0001).
Conclusions—Reintervention after primary CABG is common. Risk factors for arteriosclerosis and type of bypass conduit
influence the need or bias for repeat coronary therapy. Aggressive post-CABG risk factor reduction and extensive
arterial grafting at primary operation should decrease coronary reinterventions. (Circulation. 2006;114[suppl I]:I-454–
I-460.)
Key Words: angioplasty 䡲 coronary disease 䡲 revascularization 䡲 risk factors 䡲 surgery
T
he return of myocardial ischemia after coronary artery
bypass grafting (CABG) is common.1 It has been estimated that by 15 years postoperatively, 62% of patients will
have recurrent ischemia, 36% will experience a myocardial
infarction, and 28% will undergo coronary reoperation or
percutaneous coronary intervention (PCI).2,3 The reason is
progression of arteriosclerosis in native coronary arteries and
failure of bypass grafts. To better understand the need for
repeat coronary intervention after myocardial revascularization, we determined occurrence of coronary reintervention
(both reoperation and PCI) to 25 years after primary CABG,
and patient characteristics and operative techniques driving
the need or bias for coronary reintervention.
data for clinical research has been approved by the Institutional
Review Board. Mean follow-up was 8.7⫾6.5 years, with 17 556
patients followed-up ⱖ5 years, 10 514 ⱖ10 years, 4690 ⱖ15 years,
1628 ⱖ20 years, and 234 ⱖ25 years. Six hundred seventy-one
patients (2.5%) were lost to follow-up. Total follow-up was
229 538 patient-years.
Study End Point
End point of the study was first coronary reintervention, either PCI
or isolated reoperative CABG, for recurrent myocardial ischemia.
Patients who underwent reoperative CABG with concomitant cardiac
procedures, such as valve replacement or repair, aortic replacement,
or left ventricular aneurysmectomy, were excluded.
Statistical Methods
Analysis
Patients and Methods
Time from primary CABG to first coronary reintervention was
estimated both nonparametrically, using the Kaplan-Meier method,4
and parametrically, using a multiphase hazard method.5 The latter
involved determining the number of hazard phases, appropriate form
of equation for each phase, and parameters characterizing distribution of times to coronary reintervention (for additional details, see
http://www.clevelandclinic.org/heartcenter/hazard).
Patients
From 1971 to 1998, 48 758 patients underwent primary isolated
CABG at Cleveland Clinic. The first 1000 patients of each year were
actively followed-up every 5 years (n ⫽26 927) and comprise the
study population. Patient, operative, and follow-up variables were
obtained from the Cardiovascular Information Registry; use of these
From the Department of Thoracic and Cardiovascular Surgery, Cleveland Clinic, Cleveland, Ohio.
Presented at the American Heart Association Scientific Sessions, Dallas, Tex, November 13–16, 2005.
Correspondence to Joseph F. Sabik III, Department of Thoracic and Cardiovascular Surgery, Cleveland Clinic, 9500 Euclid Avenue/Desk F24,
Cleveland, OH 44195. E-mail [email protected]
© 2006 American Heart Association, Inc.
Circulation is available at http://www.circulationaha.org
DOI: 10.1161/CIRCULATIONAHA.105.001149
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Coronary Artery Bypass Grafting
I-455
To identify which patient characteristics and operative techniques
(Appendix) were associated with coronary reintervention, multivariable analyses were performed in the hazard-function domain. Bootstrap aggregation (bagging) using the median rule was used for
variable selection, including selecting appropriate transformations of
continuous and ordinal variables.6,7 Interactions among selected
variables were also sought by bagging. The P value criterion for
retention of variables in the final model was 0.05.
Presentation
Categorical variables are presented as frequencies and percentages.
Continuous variables are summarized by mean and standard deviation. Asymmetric confidence limits are equivalent to ⫾1 standard
error (68%).
Variables and Definitions
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Values of patient characteristics and operative techniques used in the
multivariable analyses were obtained at primary CABG. Left ventricular function was graded as normal (ejection fraction [EF]
ⱖ60%), mild dysfunction (EF 40% to 59%), moderate dysfunction
(EF 25% to 39%), and severe dysfunction (EF ⬍25%).
A coronary artery system was considered importantly stenotic if it
contained ⱖ50% diameter obstruction. Incomplete revascularization
was defined as failure to graft any system containing ⱖ50% stenosis,
or both left anterior descending coronary artery (LAD) and circumflex systems for ⱖ50% left main trunk stenosis.
The authors had full access to the data and take full responsibility
for their integrity. All authors have read and agree to the manuscript
as written.
Results
Nonrisk-Adjusted Freedom from Reintervention
A total of 3997 patients underwent coronary reintervention,
percutaneous in 1638 and reoperation in 2359. Nonriskadjusted freedom from reintervention was 99%, 96%, 88%,
73%, 60%, and 46% at 1, 5, 10, 15, 20, and 25 years,
respectively (Figure 1A). A 2-phase hazard model was
identified, consisting of a short, rapidly declining early phase
followed by a long, slow-rising late phase that began ⬇1.5
years after primary CABG (Figure 1B). Two hundred five
patients underwent coronary reintervention during the early
phase and 3792 during the late phase.
Risk Profiles of Reintervention Versus
No-Reintervention Patients
Preoperative characteristics of patients who underwent reintervention were different from those who did not (Table 1).
Patients who underwent reintervention were younger, more
likely to be male, more symptomatic, and had higher serum
triglycerides and total cholesterol, better left ventricular
function, more incomplete revascularization, and less internal
thoracic artery (ITA) grafting.
Multivariable analysis identified four general categories of
factors associated with likelihood of undergoing reintervention: patient demography, noncardiac comorbidity, cardiac
comorbidity, and operative technique at primary CABG
(Table 2). Because the early hazard phase was small and late
phase large, factors influencing the late phase had a greater
impact on likelihood of reintervention.
Patient Demography
Older patients were less likely than younger ones to undergo
repeat coronary intervention (P⬍0.0001; Figure 2). However,
with greater surgical experience, likelihood of an older
Figure 1. Freedom from reintervention after primary isolated
CABG for all patients (n ⫽27 968). A, Parametric and actuarial
estimates. Solid line represents parametric estimates enclosed
within dashed 68% confidence limits (⫾1 standard error). Symbols represent actuarial estimates at yearly intervals, and error
bars represent 68% confidence limits. Numbers in parentheses
are number of patients at risk. B, Hazard function (instantaneous risk). Dashed lines are 68% confidence limits.
patient undergoing coronary reintervention increased
(P⫽0.003).
Noncardiac Comorbidity
Diabetes mellitus was associated with having a coronary
reoperation or PCI (Figure 3). Patients treated with insulin or
oral medications had a similar and elevated risk of undergoing reintervention (P⬍0.0001). Patients with diet-controlled
diabetes also had an increased risk of reintervention, but not
as great as those treated pharmacologically (P⫽0.005). Risk
associated with pharmacologically treated diabetes decreased
with greater surgical experience (P⫽0.005).
Increased serum lipid levels were also associated with
repeat coronary intervention (Figure 4). Higher total cholesterol (P⫽0.007) and triglycerides (P⫽0.0006) increased the
likelihood of reintervention, whereas higher high-density
lipoprotein lowered risk (P⫽0.0001).
History of smoking was associated with lower likelihood
of coronary reintervention (P⬍0.0001).
Cardiac Comorbidity
Coronary artery disease of the LAD (P⫽0.002), circumflex
(P⫽0.003), or right coronary artery (P⫽0.008) increased the
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July 4, 2006
TABLE 1.
Baseline Patient Characteristics (nⴝ26 968)
TABLE 2. Risk Factors for Reintervention After Primary
Isolated CABG: Direction of Influence on Early and Late Hazard
Phase by Multivariable Analysis Is Indicated
Reintervention
No
(n⫽22 971)
N (%)
Characteristic
Yes
(n⫽3997)
N (%)
Hazard Phase
P
Demography
60⫾10
18 730 (82)
54⫾8.7
3445 (86)
⬍0.0001
⬍0.0001
Noncardiac Comorbidity
Older age
Late
3553 (17)
11 428 (54)
291 (9)
⬍0.0001
1730 (50)
⬍0.0001
Laboratory Values (mean ⫾ SD)
Decreases
and later date of operation
Male
Diabetes mellitus (medically treated)
History of smoking
Early
Demography
Age (years, mean ⫾ SD)
Male
Factor
Increases
Decreases
Symptoms
Higher NYHA class
Increases
Noncardiac Comorbidity
Total cholesterol
240⫾52
250⫾53
⬍0.0001
LDL
149⫾41
148⫾44
0.6
HDL
37⫾11.8
37⫾13.0
0.9
Diabetes mellitus
Increases
and later date of operation
Decreases
History of smoking
Decreases
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Triglycerides
191⫾122
208⫾130
⬍0.0001
Laboratory Values
Blood urea nitrogen
18.7⫾9.8
18.1⫾13.5
0.3
Higher HDL
Decreases
Higher total cholesterol
Increases
Higher triglycerides
Increases
Symptoms
⬍0.0001
NYHA class
I
4005 (18)
487 (12)
II
7778 (34)
1420 (36)
III
2380 (10)
393 (10)
IV
8791 (38)
1695 (43)
Cardiac Comorbidity
History of myocardial infarction
Decreases
Any LAD stenosis
⬍0.0001
Left ventricular dysfunction
Any circumflex stenosis
Increases
6649 (30)
1102 (28)
Any RCA stenosis
Increases
3536 (16)
421 (11)
Severe
1818 (8)
139 (3)
12 826 (56)
1881 (47)
Greater degree of RCA stenosis
⬍0.0001
ITA graft to LAD
Decreases
ITA graft to LCx
Decreases
Decreases
LMT
3384 (15)
419 (11)
⬍0.0001
ITA graft to RCA
LAD
21 018 (92)
3562 (89)
⬍0.0001
Postoperative Support
LCx
17 370 (76)
2766 (69)
⬍0.0001
RCA
18 736 (82)
3045 (76)
⬍0.0001
⬍0.0001
N of diseased systems (ⱖ50% stenosis)
0
146 (1)
15 (1)
1
2358 (10)
608 (15)
2
6611 (29)
1357 (34)
3
13 848 (60)
2007 (51)
24 (1)
⬍0.0001
4735 (21)
879 (22)
0.05
12 752 (56)
1949 (49)
⬍0.0001
2000 (9)
174 (4)
⬍0.0001
LAD
13 572 (59)
1898 (48)
⬍0.0001
LCx
2169 (9)
189 (5)
⬍0.0001
RCA
636 (3)
70 (2)
0.0002
Single ITA grafting
Bilateral ITA grafting
IABP postoperatively
Increases
Experience
Later date of operation
Increases
Decreases
IABP indicates intra-aortic balloon pump.
Operative Procedure
340 (2)
Decreases
Previous operative procedure
Coronary artery disease (ⱖ50% stenosis)
Incomplete revascularization
Increases
2306 (58)
Moderate
Intra-aortic balloon pump
Increases
and later date of operation
10 368 (46)
Mild
Previous myocardial infarction
Increases
Coronary Artery Stenosis
Cardiac Comorbidity
None
Better left ventricular function
ITA graft to
HDL indicates high-density lipoprotein; ITA, internal thoracic artery; LAD, left
anterior descending coronary artery; LCx, left circumflex coronary artery; LDL,
low-density lipoprotein; LMT, left main trunk; NYHA, New York Heart Association; RCA, right coronary artery; SD, standard deviation.
likelihood of coronary reintervention. Risk associated with
LAD disease also increased with greater surgical experience
(P⫽0.02). Better left ventricular function (P⫽0.0001) increased the likelihood of reintervention, whereas history of a
myocardial infarction decreased it (P⫽0.0002). The more
symptomatic a patient at primary operation, the greater was
the risk of reintervention (P⬍0.0001).
Operative Procedure
More extensive ITA grafting reduced the risk of reintervention (Figure 5). ITA grafts to the LAD (P⬍0.0001), circumflex (P⫽0.002), and right coronary artery (P⫽0.02) lowered
the likelihood of repeat coronary intervention. Intra-aortic
balloon pump insertion at primary operation increased the
risk of early reintervention (P⫽0.0001). Patients who underwent operation later in the series were less likely to undergo
reintervention (P⬍0.0001).
Sabik et al
Coronary Artery Bypass Grafting
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Figure 2. Predicted freedom from coronary reintervention after primary isolated CABG stratified by
age. Format is as in Figure 1.
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Discussion
Background
Coronary artery bypass grafting is effective in prolonging
survival and relieving angina.8 –15 However, its effectiveness
in eliminating myocardial ischemia is transient, with only
22% of patients free of ischemic events 15 years postoperatively.2 Return of myocardial ischemia is caused by progression of arteriosclerosis in native coronary arteries and failure
of the primary operation. Coronary reintervention, by either
percutaneous methods or reoperation, is often performed to
relieve patients’ recurrent symptoms. To better understand
coronary reintervention after CABG, we determined its occurrence and identified patient characteristics and operative
techniques that influence need or bias for reintervention.
Principal Findings
Coronary reintervention after CABG is common, with less
than half of patients free of reintervention 25 years after
surgery. Patient characteristics as well as operative techniques influenced need or bias for reintervention. Some
patient characteristics increased the likelihood of reintervention (eg, arteriosclerosis risk factors), whereas others decreased it. Operative factors influencing the likelihood of
reintervention were conduit choice and success of primary
CABG. These findings are similar to those we recently
reported for likelihood of undergoing coronary reoperation
after primary CABG.16
Risk Factors for Arteriosclerosis
Diabetes mellitus, elevated triglycerides, and total cholesterol
were associated with increased risk of coronary reintervention. These are known risk factors for arteriosclerosis that
likely increase the need for reintervention by accelerating
arteriosclerosis in coronary arteries and saphenous vein bypass grafts. In contrast, elevated high-density lipoprotein
decreased risk of reintervention, probably by slowing development and progression of arteriosclerosis.
Comorbidity
Smoking, older age, and worse left ventricular function were
all associated with decreased occurrence of reintervention. A
possible explanation is that these factors increase the risk
associated with reintervention and therefore may bias treatment in favor of medical therapy.
Symptoms
Patients who were more symptomatic at primary operation
were more likely to require reintervention. This may be
Figure 3. Predicted freedom from coronary reintervention after primary isolated CABG stratified by
diabetes mellitus and its treatment by either diet or
medicine. Format is as in Figure 1.
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July 4, 2006
Figure 4. Predicted freedom from coronary reintervention after primary isolated CABG stratified by
elevated and normal serum lipid levels. Elevated
lipids⫽triglycerides of 300 and total cholesterol of
350. Normal lipids⫽triglycerides of 100 and total
cholesterol of 150. Format is as in Figure 1.
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because they had a lower symptom threshold to myocardial
ischemia and thus were more likely to present with recurrent
symptoms and undergo coronary reintervention to relieve
them.
ITA Grafts
More extensive ITA grafting at primary operation reduced the
need for coronary reintervention. Because of their resistance
to arteriosclerosis, ITA grafts are more likely to remain patent
than saphenous vein grafts.17 Therefore, they should have a
longer-lasting effect on prevention of myocardial ischemia
than saphenous vein grafts. Sergeant et al similarly found that
likelihood of coronary reoperation or PCI was reduced by
more extensive ITA grafting at primary operation.3 The
incremental benefit of 1 and then 2 ITA grafts on both
survival and freedom from reoperation has been previously
reported.18 –20
Another reason ITA grafting may reduce coronary reintervention is that physicians and surgeons may be reluctant to
intervene in patients with patent ITA grafts. Supporting this
hypothesis is Sergeant et al’s finding that ITA grafting did not
decrease risk of return of angina after CABG.2,3 It is therefore
surprising that, despite a similar likelihood of experiencing
recurrent angina, patients with previous ITA grafting are less
likely to undergo coronary reintervention than patients with
saphenous vein grafts alone. This bias against reintervening
when ITA grafts are present may be appropriate. Patients with
recurrent ischemia and patent ITA grafts are less likely to
derive a survival benefit from reintervention than patients
without patent ITA grafts.
Success of Primary Operation
Placing an intra-aortic balloon pump at primary CABG was
associated with increased likelihood of early (⬍18 months
after primary CABG) reintervention. Need to insert an intraaortic balloon at primary operation suggests ineffective revascularization, possibly because of incomplete revascularization or early graft failure. An ineffective operation will not
relieve myocardial ischemia, and therefore early coronary
reintervention for symptom relief may be required.
Surprisingly, incomplete revascularization was not found
by multivariable analysis to increase the likelihood of coronary reintervention. This may be because of incomplete
revascularization being highly correlated with another factor
(such as intra-aortic balloon pump insertion) found by multivariable analysis to be associated with reintervention; if that
is the case, incomplete revascularization would not appear to
be a risk factor per se for reintervention.
Figure 5. Predicted freedom from reintervention
after primary isolated CABG stratified by single,
double, or no ITA grafting at primary operation.
Format is as in Figure 1.
Sabik et al
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Limitations
Noncardiac Comorbidity
This study analyzes the clinical practice of coronary reintervention after primary CABG; it does not analyze the actual
need for coronary reintervention. Because many factors go
into the decision to proceed with coronary reintervention,
including patient comorbidities, amount of ischemic myocardium, risk of reintervention, and benefits of the procedure,
our findings on the occurrence and risk factors for coronary
reintervention may be biased.
Another limitation is that 3 decades of coronary surgery
were included in this study, during which both surgical and
medical therapy for coronary artery disease changed. However, a long observation period has advantages as well,
including many years of follow-up data available for analysis
and ability to evaluate the effect of surgical strategies that
were common early in the series but not today, such as
saphenous vein revascularization of the LAD.
The association of preoperative risk factors and operative
techniques on the likelihood of having a coronary reintervention were evaluated in this study. However, we did not
determine how postoperative medical therapy and risk factor
modification influenced the occurrence of coronary reintervention. This information was not available.
History of cigarette smoking, peripheral vascular disease, carotid
stenosis, hypertension, diabetes mellitus (diet-controlled, oraltreated, and insulin-treated), renal insufficiency
Preoperative Laboratory Values
Total cholesterol, high-density lipoprotein, low-density lipoprotein,
triglycerides, creatinine, blood urea nitrogen, hematocrit
Coronary Artery Anatomy and Stenosis
Dominance (left, right, codominant), number of coronary artery
systems with stenosis ⱖ50% (1, 2, 3), left main trunk stenosis (any,
ⱖ50% stenosis, ⱖ70% stenosis), left anterior descending stenosis
(any, ⱖ50% stenosis, ⱖ70% stenosis), circumflex stenosis (any,
ⱖ50% stenosis, ⱖ70% stenosis), right coronary artery stenosis (any,
ⱖ50% stenosis, ⱖ70% stenosis)
Procedure
Complete revascularization; incomplete revascularization of left
anterior descending, circumflex, or right coronary artery system; any
internal thoracic artery grafting; internal thoracic artery graft to left
anterior descending, circumflex, or right coronary artery; any saphenous vein grafting; saphenous vein graft to left anterior descending,
circumflex, or right coronary artery
Experience
Date of operation
Implications
Postoperative Management
These findings suggest that reducing arteriosclerosis risk
factors and ITA grafting at primary CABG will lower the
need for repeat coronary intervention. Although we could not
determine influence of postoperative risk factor modification
on occurrence of coronary reintervention, it is logical to
suggest that such modification would be beneficial. Support
for this comes from the finding that aggressive lipid reduction
after CABG decreased both saphenous vein graft arteriosclerosis and need for coronary reintervention.21
Intra-aortic balloon pump
Summary
Coronary reintervention after primary CABG is common.
Risk factors for arteriosclerosis progression and ITA grafting
influence the need or bias for reintervention. Arteriosclerosis
risk-factor reduction and extensive ITA grafting should decrease occurrence of coronary reintervention after primary
surgical revascularization.
Appendix
Variables Considered in Analyses
Demography
Sex, age (years), height (cm), weight (kg), body surface area (m2),
body mass index (kg䡠m⫺2)
Symptoms
New York Heart Association functional class (I, II, III, IV)
Left Ventricular Function
Left ventricular function (normal; mild, moderate, and severe dysfunction), previous myocardial infarction, left ventricular segmental
wall motion abnormalities (septal, anterior, inferior, lateral, apical,
basilar, none)
Cardiac Comorbidity
Family history of coronary artery disease, atrial fibrillation, complete
heart block
Disclosures
None.
References
1. Sergeant P, Blackstone E, Meyns B. Is return of angina after coronary
artery bypass grafting immutable, can it be delayed, and is it important?
J Thorac Cardiovasc Surg. 1998;116:440 – 453.
2. Sergeant P, Lesaffre E, Flameng W, Suy R, Blackstone E. The return of
clinically evident ischemia after coronary artery bypass grafting. Eur
J Cardiothorac Surg. 1991;5:447– 457.
3. Sergeant P, Blackstone E, Meyns B, Stockman B, Jashari R. First cardiological or cardiosurgical reintervention for ischemic heart disease after
primary coronary artery bypass grafting. Eur J Cardiothorac Surg. 1998;
14:480 – 487.
4. Kaplan EL, Meier P. Nonparametric estimation from incomplete observations. J Am Stat Assoc. 1958;53:457– 481.
5. Blackstone EH, Naftel DC, Turner ME, Jr. The decomposition of timevarying hazard into phases, each incorporating a separate stream of
concomitant information. J Am Stat Assoc. 1986;81:615– 624.
6. Breiman L. Bagging predictors. Machine Learning. 1996;24:123–140.
7. Blackstone EH. Breaking down barriers: helpful breakthrough statistical
methods you need to understand better. J Thorac Cardiovasc Surg.
2001;122:430 – 439.
8. Eleven-year survival in the Veterans Administration randomized trial of
coronary bypass surgery for stable angina. The Veterans Administration
Coronary Artery Bypass Surgery Cooperative Study Group. N Engl
J Med. 1984;311:1333–1339.
9. Takaro T, Hultgren HN, Lipton MJ, Detre KM. The VA cooperative
randomized study of surgery for coronary arterial occlusive disease II.
Subgroup with significant left main lesions. Circulation. 1976;54:
III107–III117.
10. Prospective randomised study of coronary artery bypass surgery in stable
angina pectoris. Second interim report by the European Coronary Surgery
Study Group. Lancet. 1980;2:491– 495.
11. Varnauskas E. Twelve-year follow-up of survival in the randomized
European Coronary Surgery Study. N Engl J Med. 1988;319:332–337.
12. Passamani E, Davis KB, Gillespie MJ, Killip T. A randomized trial of
coronary artery bypass surgery. Survival of patients with a low ejection
fraction. N Engl J Med. 1985;312:1665–1671.
I-460
Circulation
July 4, 2006
13. Coronary artery surgery study. (CASS): a randomized trial of coronary
artery bypass surgery. Survival data. Circulation. 1983;68:939 –950.
14. Coronary artery surgery study. (CASS): a randomized trial of coronary
artery bypass surgery. Quality of life in patients randomly assigned to
treatment groups. Circulation. 1983;68:951–960.
15. Alderman EL, Bourassa MG, Cohen LS, Davis KB, Kaiser GG, Killip T,
Mock MB, Pettinger M, Robertson TL. Ten-year follow-up of survival
and myocardial infarction in the randomized Coronary Artery Surgery
Study. Circulation. 1990;82:1629 –1646.
16. Sabik JF, Blackstone EH, Gillinov AM, Banbury MK, Smedira NG, Lytle
BW. Influence of patient characteristics and arterial grafts on freedom
from coronary reoperation. J Thorac Cardiovasc Surg. 2006;131:90 –98.
17. Sabik JF, 3rd, Lytle BW, Blackstone EH, Houghtaling PL, Cosgrove DM.
Comparison of saphenous vein and internal thoracic artery graft patency
by coronary system. Ann Thorac Surg. 2005;79:544 –551; discussion
544 –551.
18. Lytle BW, Blackstone EH, Sabik JF, Houghtaling P, Loop FD, Cosgrove
DM. The effect of bilateral internal thoracic artery grafting on survival
during 20 postoperative years. Ann Thorac Surg. 2004;78:2005–2014;
discussion 2005–2014.
19. Lytle BW, Blackstone EH, Loop FD, Houghtaling PL, Arnold JH,
Akhrass R, McCarthy PM, Cosgrove DM. Two internal thoracic artery
grafts are better than one. J Thorac Cardiovasc Surg. 1999;117:855– 872.
20. Loop FD, Lytle BW, Cosgrove DM, Stewart RW, Goormastic M,
Williams GW, Golding LA, Gill CC, Taylor PC, Sheldon WC, Proudfit
W. Influence of the internal-mammary-artery graft on 10-year survival
and other cardiac events. N Engl J Med. 1986;314:1– 6.
21. The effect of aggressive lowering of low-density lipoprotein cholesterol
levels and low-dose anticoagulation on obstructive changes in
saphenous-vein coronary-artery bypass grafts. The Post Coronary Artery
Bypass Graft Trial Investigators. N Engl J Med. 1997;336:153–162.
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Occurrence and Risk Factors for Reintervention After Coronary Artery Bypass Grafting
Joseph F. Sabik III, Eugene H. Blackstone, A. Marc Gillinov, Nicholas G. Smedira and Bruce
W. Lytle
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Circulation. 2006;114:I-454-I-460
doi: 10.1161/CIRCULATIONAHA.105.001149
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