Seven-Year Outcome in the Bypass
Angioplasty Revascularization Investigation
(BARI) By Treatment and Diabetic Status
The BARI Investigators*
OBJECTIVES To compare seven-year survival in the Bypass Angioplasty Revascularization Investigation
(BARI) patients randomly assigned to percutaneous transluminal coronary angioplasty
(PTCA) versus coronary artery bypass grafting (CABG).
BACKGROUND The primary results of BARI reported no significant difference in five-year survival between
CABG and PTCA groups. However, among patients with treated diabetes mellitus, a
subgroup not specified a priori, a striking difference was seen in favor of CABG.
METHODS Symptomatic patients with multivessel disease (n 5 1,829) were randomly assigned to initial
treatment strategy of CABG or PTCA and followed for an average of 7.8 years. The
intention-to-treat principle was used to extend the initial five-year BARI treatment
comparisons.
RESULTS Kaplan-Meier estimates of seven-year survival for the total population were 84.4% for CABG
and 80.9% for PTCA (p 5 0.043). This difference could be explained by the 353 patients with
treated diabetes mellitus for whom estimates of seven year survival were 76.4% CABG and
55.7% PTCA (p 5 0.0011). Among the remaining 1,476 patients without treated diabetes,
survival was virtually identical by assigned treatment (86.4% CABG, 86.8% PTCA, p 5
0.72). The PTCA group had substantially higher subsequent revascularization rates than the
CABG group (59.7% vs. 13.1%, p , 0.001); however, the changes between the five- and
seven-year rates were similar for the two groups.
CONCLUSIONS At seven years, there was a statistically significant survival advantage for patients randomized
to CABG compared with PTCA. Among patients with treated diabetes mellitus, the benefit
of CABG over PTCA seen at five years was more pronounced at seven years; among
nondiabetic patients, there was essentially no treatment difference. (J Am Coll Cardiol 2000;
35:1122–9) © 2000 by the American College of Cardiology
In 1987, The National Heart, Lung and Blood Institute
(NHLBI) initiated the Bypass Angioplasty Revasculariza-
tion Investigation (BARI) to compare long-term survival
among patients with multivessel disease and severe angina
or ischemia randomly assigned to an initial revascularization
See page 1130
strategy of percutaneous transluminal coronary angioplasty
(PTCA) versus coronary artery bypass grafting (CABG) (1).
The five-year survival rate was 89.3% in the CABG group
compared with 86.3% in the PTCA group, a statistically
nonsignificant difference (2) consistent with results from
other randomized clinical trials comparing PTCA and
CABG (3–5). However, within the subgroup of BARI
patients with treated diabetes mellitus, a subgroup not
specified a priori, a difference was observed in favor of
bypass surgery (6). The excess mortality associated with
PTCA was almost entirely attributable to cardiac causes,
and the substantial benefit of CABG was seen only in the
majority of patients who received internal mammary artery
(IMA) grafts during surgery. Since the publication of the
initial BARI results, other authors have retrospectively
compared long-term mortality among diabetic patients after
CABG and PTCA in databases from observational studies
(7,8) and randomized trials (9,10). These comparisons, each
limited by either selection biases or sample size, were
inconsistent, with some confirming and others not support-
ing the BARI diabetes finding.
This report extends the randomized treatment compari-
son in BARI to seven years and allows further evaluation of
From the National Heart, Lung and Blood Institute, Bethesda, Maryland;
Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylva-
nia; and the BARI Investigative Sites. * Please see appendix for BARI Investigators.
This study was supported by NHLBI grants: HL38493, HL38504, HL38509,
HL38512, HL38514-6, HL38518, HL38524-5, HL38529, HL38532, HL38556,
HL38610, HL38642 and HL42145.
Manuscript received April 22, 1999; revised manuscript received September 22,
1999, accepted December 17, 1999.
Journal of the American College of Cardiology Vol. 35, No. 5, 2000
© 2000 by the American College of Cardiology ISSN 0735-1097/00/$20.00
Published by Elsevier Science Inc. PII S0735-1097(00)00533-7
the initial BARI hypothesis as well as the findings in the
subgroup of treated diabetic patients.
METHODS
Patients were eligible for BARI if they had angiographically
documented multivessel coronary disease with clinically
severe angina or objective evidence of ischemia requiring
revascularization and were suitable for both CABG and
PTCA as an initial revascularization procedure. The pub-
lished protocol (1) contains a detailed description of study
aims, patient selection, exclusion criteria, procedure guide-
lines, definitions and administrative structure.
Between August 1988 and August 1991, 1,829 patients
were randomized at 18 North American centers. Screening
results and baseline characteristics of the BARI randomized
patients have been published (11–14). Briefly, at baseline,
the average age was 61.5 years, 73% of patients were male,
64% had unstable angina, 41% had triple-vessel disease, 9%
had congestive heart failure and 19% had treated diabetes.
By protocol, initial revascularization was required to be
performed within two weeks of randomization. Scheduled
multiple stages of PTCA were counted as a single proce-
dure, and new interventional devices, such as stents, were
not used during initial revascularization. Follow-up clinic
visits were conducted at four to 14 weeks and at one, three
and five years, with telephone contacts at six months and at
two and four years. After five years, follow-up contacts were
performed annually by telephone.
Outcome ascertainment. All-cause mortality was the pri-
mary outcome measure for BARI. Each patient was con-
tacted to determine vital status as of September 15, 1997. At
each follow-up, the occurrence of myocardial infarctions
(MIs) and subsequent procedures and angina status were
assessed. All ECG’s were interpreted at a Central ECG
Laboratory. Q wave myocardial infarction (QMI) was
defined as new two-grade worsening of the Minnesota Q
wave Code (15,16) or new left bundle branch block with
abnormal cardiac enzymes. Q wave myocardial infarction
during the four-day period after a revascularization proce-
dure was diagnosed by the Q wave criterion alone.
Angiographic definitions. Angiographic definitions used
in BARI have been described previously (17). Vessel disease
was determined by the number of myocardial territories
(anterior, lateral and inferior/posterior) affected by signifi-
cant lesions (stenosis $50% in a vessel with reference
diameter over 1.5 mm). Lesion complexity was categorized
using American Heart Association/American College of
Cardiology Consensus Panel (18) criteria. Abnormal left
ventricular function was defined by ejection fraction below
50% as measured by a contrast left ventriculogram or when
ejection fraction was unavailable, as the sum of five regional
wall motion scores (each scored 1 5 normal to 5 5
dyskinetic) (19) greater than 10. Of the 1,829 randomized
patients, 1,354 had ejection fraction measures, 424 addi-
tional patients had wall motion scores and 51 patients were
missing any measure of left ventricular function at baseline.
Clinical subgroups. As with the five-year outcomes (2),
treatment comparisons were made within a priori subgroups
of patients specified by protocol (defined by severity of
angina, number of diseased vessels, left ventricular function
and lesion complexity) and the subgroups of patients with
and without treated diabetes (defined as use of insulin or
oral hypoglycemic agents at study entry). Outcome compar-
isons were also made in additional subgroups defined by age,
gender, history of congestive heart failure, peripheral vas-
cular disease, smoking history and baseline ECG results.
Statistical methods. Treatment comparisons were made
by the intention-to-treat principle. Kaplan-Meier (20) es-
timates were used to report cumulative rates of survival,
survival free of QMI and repeat revascularization. Kaplan-
Meier curves were compared using the log-rank test (21);
comparisons were stratified by clinical center for survival
and survival free of QMI. Cox regression (22) was used to
test for departure from a common relative risk across clinical
centers. For assessment of overall outcomes, 95% confidence
intervals were calculated for treatment differences. In order
to account for multiple treatment comparisons, 99% confi-
dence intervals were used within a priori subgroups in the
entire population and 99.5% confidence intervals within
other subgroups.
Angina rates were compared cross sectionally at each
follow-up for surviving patients who completed that follow-
up. Angina was classified as stable or unstable, and stable
angina was further classified according to the criteria of the
Canadian Cardiovascular Society (CCS) (23). Chi-square
statistics were computed at each follow-up for presence of
stable or unstable angina versus no stable or unstable angina.
The seven-year p values reported in this article were not
adjusted with respect to sequential evaluation of the BARI
follow-up data since there was no statistical plan for
seven-year treatment comparisons in the original five-year
BARI study.
Abbreviations and Acronyms
BARI 5 Bypass Angioplasty Revascularization
Investigation
CABG 5 coronary artery bypass grafting
CAD 5 coronary artery disease
CCS 5 Canadian Cardiovascular Society
IMA 5 internal mammary artery
LAD 5 left anterior descending coronary artery
MI 5 myocardial infarction
NHLBI 5 National Heart, Lung and Blood Institute
PTCA 5 percutaneous transluminal coronary
angioplasty
QMI 5 Q wave myocardial infarction
SVG 5 saphenous vein graft
1123JACC Vol. 35, No. 5, 2000 The BARI Investigators
April 2000:1122–9 Seven-Year Outcome in BARI
RESULTS
Vital status as of September 15, 1997 was ascertained for
1,778 patients (97%; mean follow-up 7.7 years, range 6 to 9
years). The remaining 3% were censored when they with-
drew consent or were lost to follow-up. As of September 15,
1997, 1,414 patients (77% of total) had reached their
seven-year study anniversary, of whom 83% were alive at
seven years. Subsequent procedure, QMI and angina out-
comes were included through the time of death or last
follow-up preceding September 15, 1997. The average
follow-up time for these end points was 7.2 years.
Mortality. There was a steady divergence between the
survival curves for the 914 patients assigned at random to
CABG and the 915 patients assigned to PTCA (p 5 0.043;
Fig. 1A). Seven-year survival rates for the total population
were 84.4% for CABG and 80.9% for PTCA. Results did
not vary significantly among clinical centers (p 5 0.55).
The observed treatment difference could be attributed to
a substantial and statistically significant treatment difference
in the subgroup of the 353 patients with treated diabetes
mellitus (p 5 0.0011, Fig. 1B). Estimates of seven-year
survival were 76.4% for diabetic patients assigned to CABG
and 55.7% for those assigned to PTCA. Compared with the
five year survival rates, the seven-year survival rates were
4.1% lower in the CABG group and 10.8% lower in the
PTCA group.
Among the 1,476 patients without treated diabetes at
time of entry, cumulative survival was virtually identical;
seven-year survival was 86.4% for the CABG group and
86.8% for the PTCA group (Fig. 1C).
Among the subgroups analyzed (column 1, Figs. 2 and 3),
the subgroup of treated diabetic patients was the only one
with a significant treatment difference at seven years. While
statistical power is limited to detect differences in subgroups
of a subgroup, it is noted that among the 1,476 patients
without treated diabetes at baseline, no treatment effects
were observed for any subgroup (column 3, Figs. 2 and 3).
In contrast, among the 353 patients with treated diabetes, a
uniform advantage of CABG was seen overall and among
all subgroups (column 2, Figs. 2 and 3) although the results
were not always statistically significant. Thus, it appears that
the CABG advantage was consistently confined to all
treated diabetic patients in BARI and not confounded by
differences in other patient characteristics.
For diabetic patients who were assigned to and received
CABG, those who received at least one IMA graft had
better seven-year survival (83.2%, n 5 140) compared with
those who received only saphenous vein grafts (SVGs)
(54.5%, n 5 33). The survival rate in the diabetic SVG
group was almost identical to that for diabetic patients who
received PTCA (55.5%, n 5 170). Among the nondiabetic
patients who received their assigned treatment, these three
groups had nearly identical survival rates (86.5% IMA vs.
85.2% SVG only vs. 86.8% PTCA).
Freedom from death or QMI. The survival rates for
freedom from death and QMI were not significantly differ-
ent for the two treatment groups (p 5 0.46); seven-year
rates were 75.3% and 73.5% for the CABG and PTCA
groups, respectively. Among diabetic patients, there was a
statistically significant difference favoring CABG for sur-
vival free of QMI (65.2% CABG vs. 50.0% PTCA, p 5
0.049), while among nondiabetic patients, these rates were
similar (77.8% CABG vs. 78.9% PTCA, p 5 0.57).
Repeat revascularization. After the initial procedure, the
estimated seven-year repeat revascularization rates were
13.1% for patients initially assigned to CABG and 59.7%
for patients initially assigned to PTCA (p , 0.001; Table
1). Repeat revascularization rates were not statistically
different for CABG patients who received at least one IMA
graft and those who received only SVG (13.2% IMA vs.
10.9% SVG). After initially higher repeat revascularization
rates for the PTCA arm during the first year, cumulative
repeat revascularization rates increased at a similar pace over
subsequent years. Compared with the five-year rates, the
seven-year estimates for the percentage of patients having at
least one repeat revascularization were 5.0% and 5.7%
higher for the CABG and PTCA groups, respectively.
As seen in Table 1, bypass surgery was used as a repeat
revascularization procedure among 1.7% of patients as-
signed to CABG and 35.5% of those assigned to PTCA,
and PTCA was used as a repeat revascularization procedure
among 12.1% of patients assigned to CABG and 37.3% of
those assigned to PTCA. Twelve percent of patients as-
signed to PTCA received both PTCA and CABG after
their initial procedure.
Among patients initially assigned to CABG, repeat
revascularization rates were similar for those with and
without treated diabetes (11.1% vs. 13.5%, p 5 0.45). In
contrast, among patients initially assigned to PTCA, repeat
revascularization rates were higher for those with treated
diabetes than for nondiabetic patients (69.9% vs. 57.8%,
p 5 0.0078), and, in particular, the rate of subsequent
CABG was higher for diabetic PTCA patients compared
with nondiabetic PTCA patients (48% vs. 33.3%, p 5
0.014). Much of this difference can be attributed to the fifth
and sixth years of follow-up when a sharp rise in the number
of CABG procedures for diabetics occurred.
Angina. After the first three years when the CABG group
had significantly less angina, the five-year angina rates were
closer but still statistically different (20.3% PTCA vs. 15.6%
CABG, p 5 0.015, Fig. 4). Among survivors who com-
pleted their seven-year follow-up (note, 23% of the patients
had less than seven years of follow-up), the seven-year
treatment difference in angina was not statistically signifi-
cant (15.1% PTCA vs. 11.4% CABG, p 5 0.075). Within
both the PTCA group and the CABG group, the angina
rate decreased between five and seven years in the cross-
sectional analysis presented as well as in an analysis that was
limited to those patients who completed their seven year
1124 The BARI Investigators JACC Vol. 35, No. 5, 2000
Seven-Year Outcome in BARI April 2000:1122–9
follow-up. The large majority of angina reported through-
out follow-up was stable CCS class I or II.
DISCUSSION
Previous reports from BARI had demonstrated a trend
toward better survival in those assigned to CABG compared
with PTCA among symptomatic multivessel coronary ar-
tery disease (CAD) patients. We now report a statistically
significant survival benefit at seven years for all patients
assigned to CABG as compared with PTCA. However, this
treatment difference was limited to those patients with
treated diabetes mellitus. Among the remaining 1,476
patients without treated diabetes, survival rates between the
two treatment arms were virtually identical at seven years.
Diabetes results. The report of the BARI five-year out-
come among diabetic patients generated appropriate con-
Figure 1. Kaplan-Meier estimates of overall survival for all BARI randomized patients (Panel A), for randomized patients with treated
diabetes (Panel B) and for randomized patients without treated diabetes (Panel C). Solid lines indicate patients assigned to CABG and
dashed lines indicate patients assigned to PTCA. The numbers of patients at risk are shown below the graph at baseline, three years and
seven years. CABG 5 coronary artery bypass grafting; PTCA 5 percutaneous transluminal coronary angioplasty.
1125JACC Vol. 35, No. 5, 2000 The BARI Investigators
April 2000:1122–9 Seven-Year Outcome in BARI
cern about the potential of a spurious finding. While
recognizing the hazards of subgroup analysis, the BARI
diabetes result was generally accepted by investigators based
on the limited number of subgroups specified before the end
of the trial and the magnitude of the observed treatment
difference, which was clinically, as well as statistically,
substantial.
The seven-year outcome, which demonstrates a steadily
increasing advantage of CABG compared with PTCA,
provides further support for the conclusion reached after five
years of follow-up that, in the population of patients in the
BARI trial with treated diabetes, survival was significantly
better with CABG than with PTCA. It is important to
emphasize the distinctive features of those diabetics who
were randomized in BARI. As a group, the treated diabetic
patients in both treatment groups were at higher risk than
other BARI patients regarding extent of CAD, left ventric-
ular function, history of congestive heart failure, peripheral
vascular disease and prior MI; in addition, a greater pro-
portion of diabetics were women and African Americans.
Recent data from other studies have suggested that stents
(24,25) and newer antiplatelet therapy (26), neither of
which were used in BARI, may improve the prognosis of
diabetic patients after angioplasty. Critical variables regard-
ing hyperglycemia at baseline and the degree of glycemic
control are, unfortunately, not available in this study.
Other subgroup results. With the exception of the sub-
group of diabetic patients, there was no significant treat-
ment difference within any of the subgroups for all-cause
mortality. Moreover, it is striking that there was no appar-
ent trend suggesting that CABG is the preferred treatment
in other high risk subgroups (abnormal left ventricular
function, triple-vessel disease, presence of left anterior
Figure 2. Seven-year estimated survival rates for all patients, for patients with treated diabetes and for patients without treated diabetes
according to subgroups selected a priori on the basis of baseline characteristics. Ninety-nine percent confidence intervals (CI) of the
difference between the seven-year survival rates for the CABG group and the PTCA group are shown in the first column, and 99.5% CI
are shown in the second and third column. CABG 5 coronary artery bypass grafting; PTCA 5 percutaneous transluminal coronary
angioplasty; CCS 5 Canadian Cardiovascular Society; LAD 5 left anterior descending artery; LV 5
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