Download The Influence of Gender on the Outcome of Coronary Artery Bypass

The influence of gender on the outcome of coronary artery bypass surgery
Dan Abramov, Miguel G. Tamariz, Jeri Y. Sever, George T. Christakis, Gopal
Bhatnagar, Amie L. Heenan, Bernard S. Goldman and Stephen E. Fremes
Ann Thorac Surg 2000;70:800-805
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The Influence of Gender on the Outcome of
Coronary Artery Bypass Surgery
Dan Abramov, MD, Miguel G. Tamariz, MD, Jeri Y. Sever, George T. Christakis, MD,
Gopal Bhatnagar, MD, Amie L. Heenan, Bernard S. Goldman, MD, and
Stephen E. Fremes, MD
Division of Cardiovascular Surgery, Sunnybrook and Women’s College Health Sciences Center, University of Toronto, Toronto,
Ontario, Canada
Background. To assess the impact of gender as an
independent risk factor for early and late morbidity and
mortality following coronary artery bypass surgery.
Methods. Perioperative and long-term data on all 4,823
patients undergoing isolated coronary bypass operations
from November 1989 to July 1998 were analyzed. Of these
patients, 932 (19.3%) were females.
Results. During the years 1989 to 1998 there was a
progressive increase in the percentage of women undergoing coronary artery bypass surgery. The following
preoperative risk factors were more prevalent among
women than men: age above 70, angina class 3 or 4,
urgent operation, preoperative intraaortic balloon pump
usage, congestive heart failure, previous percutaneous
transluminal coronary angioplasty, diabetes, hypertension, and peripheral vascular disease (all p < 0.05). Men
were more likely to have an ejection fraction less than
35%, three-vessel disease, repeat operations, and a recent
history of smoking. Women had a statistically significant
smaller mean body surface area than men (1.72 ⴞ 0.18
versus 1.96% ⴞ 0.26% m2).
On average, women had fewer bypass grafts constructed than men (2.9% ⴞ 0.8% versus 3.2% ⴞ 0.9%) and
were less likely to have internal mammary artery grafting
(76.2% versus 86.1%), multiple arterial conduits (10.1%
versus 19.8%), or coronary endarterectomy performed
(4.9% versus 8.6%).
The early mortality rate in women was 2.7% versus
1.8% in men (p ⴝ 0.09). Women were more prone to
perioperative myocardial infarction (4.5% versus 3.1%
p < 0.05). After adjustment for other risk variables,
female gender was not an independent predictor of early
mortality but was a weak independent predictor for the
prespecified composite endpoint of death, perioperative
myocardial infarction, intraaortic balloon counterpulsation pump insertion, or stroke (8.55 versus 5.9%; odds
ratio, 1.30; 95% confidence interval, 0.99 to 1.68; p ⴝ 0.05)
Recurrent angina class 3 or 4 was more frequent in
female patients (15.2% ⴞ 4.0% versus 8.5% ⴞ 2.0% at 60
months, p ⴝ 0.001) but not repeat revascularization procedures (percutaneous transluminal coronary angioplasty, redo) (0.6% ⴞ 0.3% versus 4.1% ⴞ 0.8% at 60
months). Actuarial survival at 60 months was greater in
women then men (93.1% ⴞ 1.7% versus 90.0% ⴞ 1.0%),
and after adjustment for other risk variables, female
gender was protective for late survival (risk ratio, 0.40;
95% confidence interval, 0.16 – 0.74; p < 0.005).
Conclusions. Perioperative complications were increased and recurrent angina more frequent in women.
Despite this, late survival was increased in women compared with men after adjustment for other risk variables
T
rates [2–3]. Other investigators have documented an
underutilization of noninvasive and invasive testing in
women compared with men that may influence perioperative results [7].
Another debatable issue is long-term results after
revascularization in women. In contrast to most results,
the recent Bypass Angioplasty Revascularization Investigation (BARI) study [8] demonstrates better long-term
survival in women who have undergone revascularization techniques. This study was performed on selected
patients who were amenable both to percutaneous transluminal coronary angioplasty and CABG revascularization; the extent we can generalize from the findings is
therefore uncertain. In the current study, we have used
an extensive database containing 180 different variables
to describe each patient as well as a long-term follow-up
here is a great uncertainty regarding the impact of
gender as an independent risk factor for morbidity
and mortality following coronary artery bypass surgery.
Most studies show that women have a higher risk for
morbidity and mortality following coronary artery bypass
grafting (CABG) procedures than do their male counterparts [1– 6]. One of the key problems, however, in attempting to compare outcomes between genders is a
difference in the preoperative clinical characteristics of
men and women. Smaller body surface area and smaller
coronary arteries could also lead to reduced graft patency
Accepted for publication Mar 23, 2000.
Address reprint requests to Dr Fremes, Division of Cardiovascular
Surgery, Sunnybrook and Women’s College Health Sciences Center, 2075
Bayview Ave, Suite H405 Toronto, ON, M4N 3M5, Canada; e-mail:
[email protected].
(Ann Thorac Surg 2000;70:800 – 6)
© 2000 by The Society of Thoracic Surgeons
© 2000 by The Society of Thoracic Surgeons
Published by Elsevier Science Inc
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Ann Thorac Surg
2000;70:800 – 6
ABRAMOV ET AL
FEMALE GENDER AND CABG
801
of up to 9 years to determine the short-term and longterm results in unselected patients.
Material and Methods
Study Population
The cardiac surgical unit of Sunnybrook and Women’s
College Health Science Center of the University of Toronto opened November 27, 1989. Between November 27,
1989, and July 31, 1998, 4823 patients underwent coronary
revascularization as an isolated procedure. Of those, 932
(19.3%) were women. Data were collected prospectively
and entered into a computerized database.
Surgical Procedure: Anesthetic and Operative
Techniques
Low-dose fentanyl citrate (10 to 15 ␮g/kg), midazolam (2
to 3 mg), isoflurane (0.5 to 2%), and propofol (100 to
150 ␮g 䡠 kg⫺1 䡠 min⫺1) were used for induction and
maintenance of anesthesia. Standard median sternotomy
and aorta–right atrial cannulation were performed for
cardiopulmonary bypass. Patients were either cooled to
28°C (earlier in the study) or remained normothermic (32
to 37°C) [9]. Revascularization was performed during a
single aortic cross-clamp and cardioplegic arrest, in most
instances. Blood cardioplegic solution was delivered in a
4:1 ratio before 1996 and an 8:1 ratio after that time [10,
11]. Cold cardioplegia (10°C) was utilized in the early
years of the study, while warm or tepid (33°C) cardioplegia was used more frequently in later years [9 –11]. Blood
cardioplegic solution was delivered either antegrade, by
way of the aortic root and completed vein grafts, or
retrograde, through the coronary sinus. After cardioplegic solution induction, additional doses of 300 to 500 mL
were administered after completion of each distal and
proximal anastomoses.
Long-Term Follow-up
Follow-up information was obtained on 4460 patients
(92.5% of late survivors) by repeat patient visits, contact
with the patient’s physician, or response to a patient
questionnaire. Mean follow-up was 22 ⫾ 20 months.
Fig 1. Percentage of female patients undergoing CABG surgery, expressed as a percentage of total CABG cases per year. Over the past
decade, the relative number of women undergoing the procedure has
increase progressively. (CABG ⫽ coronary artery bypass graft)
Student’s t test, and categorical variables were compared
using ␹2 or Fischer’s exact test analysis.
Logistic multiple regression analysis using the maximum likelihood estimates was employed to determine
independent predictors of operative mortality and early
nonfatal complications. Model discrimination was evaluated by the area under the receiver operator characteristic curve [13], and the calibration was assessed with the
Hosmer-Lemeshow goodness-of-fit test [14]. To determine the effect of gender across the risk spectrum, the
predicted mortality and morbidity and mortality were
calculated for each patient according to the logistic coefficients (excluding gender) and ranked into quintiles.
Actual results were then compared between men and
women by risk quintile and analyzed by Fischer’s exact
test.
Actuarial techniques using the life-table method were
employed to assess late events. Survival curves were
compared between groups by the log rank method and
multivariate analysis by the Cox proportional hazards
method. A p value is depicted for each comparison.
Results
Demographics and Preoperative Risk Factors
Study Endpoints
The prespecified outcomes of interest to the investigators
were early mortality (⬍ 30 days postoperatively) and
cardiovascular morbidity (perioperative myocardial infarction (MI), perioperative low output syndrome necessitating intraaortic balloon counterpulsation pump
usage, and perioperative cerebrovascular accident). Follow-up endpoints included late mortality, late MI, repeat
interventions (redo CABG, PTCA) and Canadian Cardiovascular Society angina class 3 or 4.
Statistical Analysis
Statistical analysis was facilitated with SAS for PC software (SAS Institute, Cary, NC) [12]. Clinical and catheterization features were analyzed by descriptive statistical methods. Continuous variables were compared by
During the years 1989 to 1998 there was a progressive
increase in the percentage of women undergoing CABG
(Fig 1). A comparison of risk factors for women and men
shows that there were statistically significant differences
in the two populations (Table 1). Women were older and
a larger percent of them were older than 70 years (Fig 2).
The female population had a greater prevalence of Canadian Cardiovascular Society angina class 3 or 4,
needed more urgent surgery, and required preoperative
intraaortic balloon counterpulsation pump insertion
more often than men. Women were more likely to have
congestive heart failure preoperatively and had greater
incidence of prior PTCA. Comorbidities such as diabetes
mellitus, hypertension, and peripheral vascular disease
or carotid artery stenosis were significantly more prevalent among women. Women had a statistically significant
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ABRAMOV ET AL
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Ann Thorac Surg
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Table 1. Clinical Characteristics of Female and Male
Patients
Variable
Age (y)
Age ⱖ 70 y
CCS Class 3– 4
Urgent
Preop IABP
Preop CHF
Prior PTCA
Diabetes
Hypertension
PVD/CVA
COPD
Current smoker
⫹ve GXT
SVD/DVD/TVD
LVEF ⬍ 35%
Redo CABG
BSA (m2)
Women
Men
p Value
65.2 ⫾ 9.0
31.3%
89.8%
47.3%
4.4%
7.2%
8.6%
31.4%
59.7%
18.6%
3.8%
14.5%
51.3%
8.6/29.0/62.4%
14.8%
1.6%
1.72 ⫾ 0.18
61.9 ⫾ 10.0
19.2%
74.8%
32.7%
3.0%
3.2%
5.8%
21.8%
45.0%
13.9%
5.0%
17.1%
59.5%
5.7/26.5/67.9%
18.1%
3.0%
1.96 ⫾ 0.26
⬍ 0.001
⬍ 0.001
⬍ 0.001
⬍ 0.001
0.031
⬍ 0.001
0.002
⬍ 0.001
⬍ 0.001
⬍ 0.001
0.105
0.057
⬍ 0.001
⬍ 0.001
0.018
0.027
⬍ 0.001
BSA ⫽ body surface area;
CABG ⫽ coronary artery bypass grafting;
CCS ⫽ Canadian Cardiovascular Society;
CHF ⫽ congestive heart
failure;
COPD ⫽ chronic obstructive lung disease;
IABP ⫽ intraaortic balloon pump;
PVD ⫽ peripheral vascular disease;
SVD/DVD/TVD ⫽ single, double and triple vessel disease;
⫹veGTX
⫽ positive exercise stress test.
smaller body surface area than men (Fig 3). There was no
difference in body mass index (p ⫽ 0.34), although the
distribution of values was broader in women than in
men. Men, on the other hand, were more likely to have
an ejection fraction of less than 35%, three-vessel disease,
redo operations, and a recent history of smoking.
Operative Procedure
On average, women, in contrast to men, had significantly
fewer bypass grafts (2.9 ⫾ 1.0 versus 3.2 ⫾ 0.9), internal
mammary artery grafts (76.2% versus 86.1%), multiple
arterial conduits (10.1% versus 19.8%) and coronary endarterectomies (4.9% versus 8.6%) (all p ⬍ 0.001). Average
cross-clamp and cardiopulmonary bypass times were
Fig 3. Comparison of female and male study patients’ body surface
area. Female patients were significantly smaller then male patients,
according to body surface area calculations.
shorter in women than in men (58.1 ⫾ 23.4 and 87.2 ⫾ 31.3
versus 63.2 ⫾ 25.5 and 92.6 ⫾ 30.1, respectively) (all p ⬍
0.001).
Early Results
Perioperative results are summarized in Table 2. Early
mortality (2.7%, versus 1.8% p ⫽ 0.09) and perioperative
MI (4.5% versus 3.1% p ⬍ 0.05) occurred more frequently
in female than male patients. The cluster of early mortality and cardiovascular complications was significantly
more common in women (p ⬍ 0.01). The incidences of
low output syndrome (15.8% versus 10.9% p ⬍ 0.001),
ventilation for greater than 24 hours (6.0% versus 4.5%
p ⫽ 0.06), and sternal wound infections (2.8% versus 1.7%
p ⬍ 0.05) were increased in women. Women were more
likely to require transfusion of any blood product; 90.5%
underwent transfusion, compared with only 46.6% of
men (p ⬍ 0.001). Transfusion of homologous red cells was
required in 89.8% of women (2.7 ⫾ 2.6 U) compared with
43.0% of men (1.2 ⫾ 2.4 U). Chest reopening for bleeding
was performed in 1.5% of women and 1.9% of men.
Though the intensive care unit stay was not significantly
different between women and men (45.5 ⫾ 72.7 versus
42.8 ⫾ 77.6 hours), the postoperative stay was significantly longer for women (7.5 ⫾ 7.0 versus 6.8 ⫾ 6.5 days).
The results of stepwise logistic regression analysis are
presented in Tables 3 and 4. Female gender did not prove
to be an independent predictor for early postoperative
Table 2. Operative Results in Male and Female Patients
Results
Fig 2. Percentage of male or female patients older then 70 years undergoing CABG. For each of the later years of the study, approximately 35% of female patients were elderly, compared with less then
25% of men. (CABG, coronary artery bypass graft)
Mortality (%)
Perioperative MI (%)
Postoperative LABP (%)
CVA (%)
Any of the above (%)
Women
Men
p Value
2.7
4.5
3.0
2.4
8.4
1.8
3.1
3.4
1.8
5.9
0.088
0.043
0.611
0.230
0.007
MI ⫽ myocardial infarction;
IABP ⫽ intra-aortic balloon pump;
CVA ⫽ cerebral vascular accident;
ICU ⫽ intensive care unit.
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ABRAMOV ET AL
FEMALE GENDER AND CABG
Table 3. Multivariate Predictors of Early Mortality
Table 5. Comparison of Early Mortality by Predicted Risk
Variable
OR
95% CI
p
Value
Preop IABP
Redo CABG
Renal insufficiency
LVEF ⬍ 35%
Left main
Age ⱖ 70 years
LIMA
5.01
4.07
2.37
3.11
2.08
1.77
0.60
2.79 –9.00
2.04 – 8.12
1.24 – 4.53
2.01– 4.81
1.31–3.04
1.13–2.78
0.37– 0.97
⬍ 0.001
⬍ 0.001
0.003
⬍ 0.001
0.002
0.017
0.050
Goodness-of-fit statistic, p ⫽ 0.972; receiver operating characteristic ⫽
0.759.
Results of stepwise logistic regression of 4839 patients who underwent
coronary revascularization procedure between 1990 and 1998. Response
variable analyzed is early mortality. Female gender was not a significant
predictor of mortality after adjustment of other risk variables (OR 1.31,
95% CI 0.79 –2.15, p ⫽ 0.290).
CABG ⫽ coronary artery bypass grafting;
CI ⫽ confidence interval;
IABP ⫽ intraaortic balloon pump;
LIMA ⫽ left internal mammary
artery;
LVEF ⫽ left ventricular ejection fraction;
OR ⫽ odds ratio.
mortality after adjustment for other risk variables (odds
ratio. 1.31; 95% confidence interval, 0.79 to 2.15; p ⫽
0.296). Female gender was found to be a weak independent predictor of early mortality and cardiovascular complications, with an odds ratio of 1.30 and a 95% confidence interval of 0.99 to 1.68, which was only of
borderline significance (p ⫽ 0.053). Tables 5 and 6 present
the female-male comparisons according to the predicted
risk for early mortality as well as for early mortality and
cardiovascular complications. The increased risk of early
mortality and complications associated with female gen-
Redo CABG
Preop IABP
Endarterectomy
LVEF ⬍ 35%
Recent MI
Age ⱖ 70 y
Left main
Female
Hypertension
LIMA
Arterial conduits ⱖ 2
Warm cardioplegia
Women
Quintile
No.
Mortality
Rate
1 and 2
3
4
5
369
175
206
184
1.1%
1.7%
1.0%
8.2%
Men
No.
Mortality
Rate
p
Value
1856
496
797
739
0.7%
1.0%
1.4%
5.6%
0.51
0.44
1.00
0.23
p ⬍ 0.0001, gender versus quintile.
Female and male results of early mortality are presented according to the
predicted risk expressed as the quintile from the logistic models. The
presence of ties for the predicted event rates is the reason for unequal
numbers of patients in each quintile and why quintiles 1 and 2 are
reported together.
der was present in the moderate and highest risk
quintiles.
Late Results
Recurrent angina class 3 or 4 was more frequent in
women than in men (15.2% ⫾ 4.0% versus 8.5% ⫾ 2.0% at
60 months, p ⫽ 0.001, Fig 4), as was late MI (5.1% ⫾ 2.6%
versus 1.9% ⫾ 1.3%, p ⫽ 0.36). That was not true of repeat
revascularization procedures (PTCA, redo) (0.6% ⫾ 0.3%
versus 4.1% ⫾ 0.8% at 60 months, p ⫽ 0.13). Actuarial
survival at 60 months was greater in women then men
(93.1% ⫾ 1.7% versus 90.0% ⫾ 1.0%) (Fig 5) whereas
freedom from death or MI was less (80.5% ⫾ 2.6% versus
83.3% ⫾ 1.3%) (Fig 6). After adjustment for other risk
variables, female gender was protective for late survival
(risk ratio, 0.40; 95% confidence interval, 0.16 to 0.74; p ⬍
0.005) (Table 7).
Comment
Table 4. Multivariate Predictors of Early Mortality or
Complications
Variable
803
Odds
Ratio
95% CI
p
Value
5.25
2.28
2.18
1.59
1.47
1.39
1.38
1.30
1.26
0.66
0.66
0.57
3.48 –7.83
1.46 –3.50
1.58 –2.96
1.23–2.05
1.07–1.99
1.08 –1.77
1.05–1.79
0.99 –1.68
1.01–1.56
0.51– 0.86
0.45– 0.95
0.46 – 0.71
⬍ 0.0001
⬍ 0.0002
⬍ 0.0001
0.0004
0.0146
0.0095
0.0169
0.0526
0.0392
0.0020
0.0296
⬍ 0.0001
Goodness-of-fit statistic, p ⫽ 0 8943; Receiver operating characteristic ⫽
0.695.
Results of stepwise logistic regression of 4839 patients who underwent
coronary revascularization procedures between 1990 and 1998. Response
variable analyzed is the prespecified composite endpoint of early mortality or complications, such as death.
CABG ⫽ coronary artery bypass grafting;
CI ⫽ confidence interval;
CVA ⫽ cardiovascular accident;
IABP ⫽ intra-aortic balloon
pump;
LVEF ⫽ left ventricular ejection fraction;
MI ⫽ myocardial
infarction;
LIMA ⫽ left internal mammary artery.
Accurate risk assessment of CABG is the focus of much
investigation and increasingly demanded by patients. In
most previous studies reporting outcomes following
CABG, there has been a large preponderance of male
patients [1– 6]; the gender balance of the surgical population is changing, however. The frequency of CABG
Table 6. Comparison of Early Mortality and Complications
by Predicted Risk
Female
Quintile
No.
Mortality and
Complications
1
2
3
4
5
136
192
197
195
214
3.7%
5.7%
8.6%
9.2%
19.6%
Male
No.
Mortality and
Complications
p
Value
878
646
830
784
749
3.1%
5.3%
5.5%
7.5%
17.5%
0.61
0.86
0.14
0.46
0.48
p ⬍ 0.0001, gender vs. quintile.
Female and male incidence of early mortality and cardiovascular complications (myocardial infarction, postoperative intraaortic balloon pump, or
stroke) are presented according to the predicted risk expressed as the
quintile from the logistic models. The presence of ties for the predicted
event rates is the reason for unequal numbers of patients in each quintile.
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Fig 4. Recurrent angina, depicted in an actuarial manner, was more
frequent in the female than in the male cohort.
performed in women has increased over the past decade
in association with a gradual aging of the surgical population, as shown in Figures 1 and 2. The proportion of
female patients reported in this study is less than the
provincial average (26.5%) [4,] which in turn is less than
results reported from centers in the United States (28.2%)
[6]. The international differences may be due in part to a
younger surgical population of both men and women
treated in this institution (men ⬎ 70 years, 23% versus
29%; females ⬎ 70 years, 35% versus 42%) [6]. It is likely
that the proportion of female patients will continue to
increase coincident with the progressive aging of the
surgical population and that outcome assessment of
females will assume even greater importance.
Our study, supporting previous reports, has shown
that women have a greater prevalence of most risk
factors (old age, Canadian Cardiovascular Society angina
class 3 to 4, urgent operation, congestive heart failure,
prior PTCA, diabetes mellitus, hypertension, peripheral
vascular disease, and small body surface area). Men have
higher prevalence of left ventricular ejection fraction of
less than 35%, triple vessel disease, and history of smoking [6]. We also found that internal mammary artery
grafts and multiple arterial grafts were less frequently
used in women [6].
Operative mortality in CABG is generally greater in
women than in men [1– 6]. According to the Society of
Thoracic Surgeons (STS) database (344,914 patients operated upon between 1994 and 1996), the operative mortality rate in women is 4.52% versus 2.61% in men [6]. The
STS database study showed that operative mortality was
greater in women in 31 individual stratified analyses.
According to multivariate analysis, female gender was
found to be an independent risk factor for mortality in
low-risk and medium-risk patients groups [1], whereas
female gender had a greater influence in the mediumand high-risk quintiles according to our analysis.
The unadjusted morbidity (8.4% versus 5.9%) and
mortality (2.7% versus 1.8%) in our institution were
higher in women than in men (Table 2). Female gender
was not an independent risk factor for early mortality
and only a weak independent predictor for the combined
endpoint of early mortality and cardiovascular morbidity.
We concluded that within this study, the differences in
Ann Thorac Surg
2000;70:800 – 6
Fig 5. Actuarial survival of female patients was nonsignificantly
greater than male patients 5 years postoperatively. Both early and
late deaths were included in the calculations.
risk factor profile between men and women assumed
greater significance than female gender itself. The Working Group Panel on the Collaborative CABG Database
Project considers female gender as one of seven core
variables related to operative mortality [5]. Female gender is considered a risk factor for operative mortality in
the province of Ontario, with an adjusted odds ratio of
1.68 [4] that is similar to the crude odds ratio of the STS
investigation (1.77 [6]).
Previous studies have shown better long-term results
after surgery in men. Men have experienced greater
relief of angina [15, 16] and higher graft patency rates [15,
16]and have had fewer complaints of congestive heart
failure and functional disability [17]. Despite less symptom relief and lower graft patency rates, long-term survival data revealed no significant differences between
sexes after CABG. A secondary analysis of the BARI
study showed similar early mortality rates after CABG in
women and men but surprisingly, better late survival and
freedom from MI in women than men after adjustment
for other risk variables [8]. The BARI study was performed in a selected group of patients (those who were
amenable for both CABG and percutaneous coronary
angioplasty).
At Sunnybrook, late survival was higher in women 4
and 5 years postoperatively and female gender was
protective according to the Cox proportional hazards
Fig 6. Freedom from death or myocardial infarction (including early
and late death or myocardial infarction) was nonsignificantly greater
in men at 5 years following surgery.
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Ann Thorac Surg
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ABRAMOV ET AL
FEMALE GENDER AND CABG
References
Table 7. Multiple Predictors of Late Mortality
Variable
Renal insufficiency
LVEF ⬍ 35%
Redo CABG
Age ⱖ 70 years
Diabetes
Female gender
Risk Ratio
95% CI
p
Value
6.866
6.668
3.520
2.093
2.059
0.399
3.979 –11.847
2.677–16.610
1.686 –7.348
1.288 –3.402
1.308 –3.241
0.155– 0.740
0.0001
0.0001
0.0001
0.0062
0.0045
0.0045
Multivariate predicators of late mortality are presented as risk ratios and
95% CI from the Cox proportional hazard analysis. Early deaths are
included in the analysis. Female gender was protective after adjustment
for other risk variables.
CABG ⫽ coronary artery bypass graft;
LVEF ⫽ left ventricular ejection fraction.
805
CI ⫽ confidence interval;
model. Life expectancy is greater in women then men in
Western countries. Could the survival advantage seen in
the female surgical patients be related to this known
difference in life expectancy? Reasons for the increased
life expectancy in women are probably associated with
differences in the prevalence of multiple health-related
covariates common to both men and women plus some
gender-specific effects. It should be emphasized that one
of the key differences between men and women is the
later onset of coronary artery disease in women. By
extrapolation, after controlling for age, female surgical
patients may have a shorter duration of coronary artery
disease, which presumably would be associated with
increased longevity.
Female patients were more likely to have postoperative
angina, as well as MI, but less likely to have repeat
intervention than men. Incomplete revascularization,
graft occlusion, and progression of coronary disease all
contribute to postoperative angina. Factors characteristic
of female operative patients—such as small coronary
size, fewer bypass grafts, and underutilization of the left
internal mammary, in association with less multivessel
disease and better ventricular function at the time of the
original operation—may be associated with a greater
incidence of postoperative angina. On the other hand,
the smaller coronary arteries of women may be less
suitable for repeat revascularization, and advanced age
may mitigate against repeat CABG.
Estrogen replacement therapy after menopause has
been shown to be protective against development of
coronary artery disease in observational studies [18, 19].
The Heart and Estrogen/progestin Replacement Study
(HERS) investigators [20] found no overall benefit from
hormone replacement but in fact noted increased cardiovascular events in the first year of therapy, although they
did observe a possible reduction in events with extended
therapy. These results suggest that starting hormone
replacement therapy perioperatively may be hazardous;
the long-term use of hormone replacement could, however, limit perioperative complications, enhance late results, or both.
The authors express their appreciation to Ms Tarja Antila for
assistance in preparation of the manuscript.
1. Kennedy JW, Kaiser GC, Fisher LD. Multivariate discriminant and angiographic predictors of operative mortality
from the collaborative study in coronary artery surgery
(CASS). J Thorac Cardiovasc Surg 1980;80:876–7.
2. Fisher LD, Kennedy JW, Davis KB. Association of sex,
physical size and operative mortality after coronary bypass
in the Coronary Artery Surgery Study (CASS). J Thorac
Cardiovasc Surg 1982;84:334– 41.
3. O’Connor GT, Morton JR, Deihl MJ. Differences between
men and women in hospital mortality associated with coronary bypass artery graft surgery. Circulation 1993;88(Pt 1):
2104–10.
4. Tu JV, Jaglal SB, Naylor DC, Steering Committee of the
Provincial Adult Cardiac Care Network of Ontario. Multicenter validation of a risk index for mortality, intensive care
unit stay, and overall hospital length of stay after cardiac
surgery. Circulation 1995;91:677– 84.
5. Jones RH, Hannan EL, Hammermeister KE, et al. Working
group panel on the cooperative CABG database project:
identification of preoperative variables needed for risk adjustment of short-term mortality after coronary artery bypass graft surgery. J Am Coll Cardiol 1996;28:1478– 87.
6. Edwards FH, Carey JS, Grover FL. Impact of gender on
coronary bypass operative mortality. Ann Thorac Surg 1998;
66:125–31.
7. Shin AY, Jaglal S, Slaughter P, Iron K. Women and heart
disease. In: Naylor CD, Slaughter PM, eds. Cardiovascular
health & services in Ontario—an ICES Atlas. Toronto: Institute for Clinical Evaluative Sciences, 1999:335–53.
8. Jacobs AK, Kelsey SF, Brooks MM. Better outcome for
women compared with men undergoing coronary revascularization: a report from the bypass angioplasty revascularization (BARI). Circulation 1998;29:98:1279– 85.
9. By the Warm Heart Investigators. Normothermic versus
hypothermic blood cardioplegia for coronary bypass surgery: A randomized trial in 1732 patients. Lancet 1994;343:
559– 63.
10. Fremes SE, Levy SL, Christakis GT, et al. A phase I human
trial of adenosine-potassium cardioplegia. Circulation
1996;94 (Suppl II):370–75.
11. Cohen G, Feder-Elituv R, Iazetta J, et al. Phase 2 studies of
adenosine cardioplegia. Circulation 1998;98(Suppl II):II-225–
33.
12. SAS Institute. SAS language guide for personal computers.
Cary, NC: SAS Institute, 1988.
13. Hanley JA, McNeil BJ. The meaning and use of the area
under a receiver operating characteristic (ROC) curve. Radiology 1982;143:29–36.
14. Hosmer DW, Lemeshow S. Applied logistic regression. New
York: John Wiley & Sons, 1989.
15. Loop FD, Golding LR, Macmillan JP. Coronary artery surgery in women compared with men: analyses of risks and
long-term results. J Am Coll Cardiol 1983;1:383–90.
16. Johnson WD, Kayser KL, Pedraza PM. Angina pectoris and
coronary bypass surgery: patterns of prevention and recurrences in 3105 consecutive patients followed up to 11 years.
Am Heart J 1984;108:1190–7.
17. Stanton BA, Jenkins CD, Savageau JA. Functional benefits
following coronary artery bypass graft surgery. Ann Thorac
Surg 1984;32:286–90.
18. Stampfer MS, Colditz GA. Estrogen replacement therapy
and coronary heart disease: a quantitative assessment of the
epidemiologic evidence. Prev Med 1991;20:47– 63.
19. Grady D, Rubin SM, Petitti DB, et al. Hormone therapy to
prevent disease and prolong life in postmenopausal women.
Ann Intern Med 1992;117:1016–37.
20. Hulley S, Grady D, Bush T, et al. Randomized trial of
estrogen plus progestin for secondary prevention of coronary heart disease in postmenopausal women. Heart and
Estrogen/progestin Replacement Study (HERS) Research
Group. JAMA 1998;280:605–13.
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The influence of gender on the outcome of coronary artery bypass surgery
Dan Abramov, Miguel G. Tamariz, Jeri Y. Sever, George T. Christakis, Gopal
Bhatnagar, Amie L. Heenan, Bernard S. Goldman and Stephen E. Fremes
Ann Thorac Surg 2000;70:800-805
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