From the Division of Cardiovascular Surgery (J.I., R.D.W., T.E.D.), The
Toronto Hospital, Toronto Ontario; The Institute for Clinical Evaluative
Sciences (C.D.N.), North York, Ontario; The University of Toronto (J.I.,
R.D.W., T.E.D., C.D.N.), Toronto, Ontario; and The Clinical Epidemiology and
Health Services Research Program (C.D.N.), Sunnybrook Health Science Centre,
North York, Ontario, Canada.
Correspondence to Dr C. David Naylor, Institute for Clinical Evaluative Sciences, G106–2075 Bayview Ave, North York, Ontario, Canada M4N 3M5. E-mail cdn{at}ices.on.ca
Methods and Results—The proportion of elderly patients rose
significantly over time (P<.001). Crude OM among the
elderly was 7.2% in 1982 to 1986, fell to 4.4% in 1987 to 1991, but
did not improve thereafter. Logistic regression analysis of OM
was used to construct relative risk groups (low, medium, or high). The
prevalence of high-risk elderly patients rose significantly over time
(P=.001) from 16.2% in 1982 to 1986 to 19.5% in 1987
to 1991 and 26.9% in 1992 to 1996. OM in high-risk patients fell
significantly (P=.044) from 17.2% in 1982 to 1986 to
9.1% in 1987 to 1991 and was 8.9% in 1992 to 1996. Contemporary
independent predictors of OM among elderly patients were poor
ventricular function (LV grade 2 to 3, odds ratio [OR],
2.6; 95% confidence interval [CI], 1.3 to 5.2; and LV grade 4, OR,
10.7; 95% CI, 4.4 to 26); previous CABG (OR, 3.7; 95% CI, 2.0 to
7.0), female sex (OR, 1.8; 95% CI, 1.1 to 2.8), peripheral
vascular disease (OR, 1.8; 95% CI, 1.1 to 2.8), and diabetes (OR, 1.7;
95% CI, 1.1 to 2.7). Previous angioplasty was protective (OR, 0.3;
95% CI, 0.1 to 0.9).
Conclusions—OM in elderly patients has declined significantly in
recent years despite an increase in the prevalence and severity of
their risk factors. A careful weighing of risk, rather than advanced
age alone, should determine who is offered surgical
revascularization. In this regard, poor
ventricular function and repeat CABG continue to have the
greatest impact on OM in elderly patients.
In Ontario, Canada's most populous province, the population-based
utilization of CABG since 1985 has doubled among persons aged 65 to 74
years, and population-based service rates more than tripled among
persons aged
Although there have been no randomized trials comparing the efficacy of
surgery with that of medical therapy for ischemic heart disease
in a targeted group of elderly patients, the lower rates of service
among elderly Ontarians do raise questions about whether some patients
are being denied procedures that may improve their quality of life.
Stason et al27 suggested that the elderly tend to
value improved quality of life more highly than prolonged longevity.
Furthermore, several studies have reported improved quality of life in
elderly patients who underwent CABG.13 17 28 29 30
However, if the vital risk of surgery is large, then the risk-benefit
ratio may be tipped toward medical therapy for the elderly.
We have accordingly examined the trends in postoperative mortality
among elderly Ontarians undergoing CABG at Canada's largest teaching
hospital. Multivariate methods have been used to
calculate risk-adjusted outcomes, thereby creating a "level playing
field" for temporal comparisons of outcomes. More specifically, we
report on (1) the temporal changes in the prevalence of elderly
patients (
Outcome and Explanatory Variables
Core baseline explanatory variables collected since the inception
of the database in 1982 included age, sex, LV grade (1, EF >60%; 2,
EF 40% to 60%; 3, EF 20% to 39%; 4, EF <20%), previous CABG,
urgency of surgery (elective, semiurgent, surgery during the same
admission as a cardiac catheterization or cardiac
event; emergent, surgery within 12 hours of a cardiac
catheterization or cardiac event), number of diseased
coronary arteries, presence of a significant stenosis
(>50% by visual evaluation of the cineangiogram) of the
left main coronary artery, severity of angina, and New York
Heart Association functional class.
In 1990, the database was expanded to more fully characterize our
patients by adding information such as recent myocardial infarction,
diabetes, peripheral vascular disease, previous angioplasty
or stent, history of hypertension, renal failure (dialysis),
preoperative stroke or transient ischemic attack, body size,
and chronic obstructive lung disease, among others.. Details of this
database have been published elsewhere.31
Analysis
Evaluation of Temporal Trends
The data before 1990 lacked the full range of potential predictors of
postoperative mortality. Thus, any temporal comparative
analysis required a simple predictive rule that included only
key predictors. To this end, we started from the previously-validated
predictive algorithm developed by Tu and
colleagues37 as a template. That algorithm was
designed for both valve surgery and CABG and therefore included type of
surgery (isolated CABG, isolated valve, or valve plus CABG) as a
variable. Other validated models for predicting isolated CABG
outcomes have included left mainstem disease as a prognostic
variable; hence this item was added to the model instead of type of
surgery.
To recalibrate the resulting six-variable algorithm for this
one-center temporal analysis, we performed a logistic
regression analysis in the entire 1982-to-1996 cohort of
patients. The resulting adjusted odds ratios for six explanatory
variables—age (<65, 65 to 74,
Next, data from 15 years were divided into three 5-year time cohorts
based on date of operation: 1982 to 1986, 1987 to 1991, and 1992 to
1996. Patients were further divided into a younger cohort (<70 years)
and an elderly cohort (
As a complementary method, logistic regression analysis for OM
was performed solely for the elderly cohort (1982 to 1996). This
allowed us to generate elderly-specific odds ratios for the six
explanatory variables, as well as the risk reduction in OM
associated with time after adjustment for those variables.
Contemporary Predictors of OM
Generalizability
Increasing Prevalence of Elderly CABG Patients
Changing Risk Severity and OM
The predictive rule, recalibrated in the 1982-to-1996 dataset of
19 009 patients, had a ROC area of 0.70 and a Hosmer-Lemeshow p-value
of 0.53. Table 2
Table 3
Overall mortality and risk group–specific mortality data are
presented in Table 4
For the overall logistic regression, we set aside the risk scores based
on rounded odds ratios and used the ß-coefficients, calculating exact
adjusted odds ratios and related CIs for all explanatory factors. Among
3330 elderly patients operated on between 1982 and 1996, there were 165
deaths. Compared with 1982 to 1986, operations in 1986 to 1991 and 1992
to 1996 were each associated with a significant
Contemporary Predictors of OM in the Elderly
Our analysis has provided a 15-year perspective on 19 009
consecutive isolated CABG procedures at Canada's largest hospital, and
includes >3300 patients aged
Given the enthusiasm for outcomes "scorecards," it is also
noteworthy that an improvement in outcomes was already evident in the
1987-to-1991 period for both older and younger patients. This occurred
well before the current program of systematic outcomes monitoring was
embarked on in Ontario, as described
elsewhere.40
Because patients' characteristics were not as exhaustively documented
in earlier as in later years, we cannot absolutely rule out the
possibility that the recent improvements in outcomes are partly an
epiphenomenon of unmeasured changes in case selection. However, the
model for mortality of elderly patients between 1982 and 1996 had an
ROC curve area similar (0.69 versus 0.71) to that for elderly patients
in the 1991-to-1996 model, which drew on additional risk factor data,
and the trends to inclusion of higher-risk elderly patients are
temporally consistent. Therefore, it is exceedingly unlikely
that our findings are explained by unmeasured changes in patient
characteristics working in the opposite direction, that is, toward
lower-risk case selection.
Another hypothetical confounder is declining length of stay. Because
patients in recent years would be discharged earlier, some who might
otherwise have died in hospital would die at home and not be counted.
However, this also is an implausible explanation for the observed
trends. The mortality decrement was already evident for the
1987-to-1991 period, which antedates the contemporary move to much
shorter lengths of stay after CABG. Second, postoperative stays among
the elderly undergoing CABG remain relatively long; for our
1992-to-1996 cohort, the mean was 11.3 days (95% CI, 10.8, 11.8).
Third, we have tracked patients after discharge in a major randomized
trial.41 Deaths occurring between discharge and
30 days from the date of surgery were uncommon; >95% of deaths
occurred on the index admission. Thus, any minor decrements in lengths
of stay occurring from 1982 through 1986 to 1987 through 1991 are most
unlikely to account for the dramatic decline in postoperative mortality
observed in the same period.
The reasons for the improved outcomes nevertheless remain speculative.
Possible factors include better myocardial protection during surgery
(eg, by use of blood rather than crystalloid cardioplegia or warm/tepid
rather than cold cardioplegia temperatures), greater use of left
internal thoracic artery conduits, and improved
cardiovascular anesthetic techniques. For that matter,
most centers reporting temporal trends in overall CABG outcomes have
noted improvements over the past decade. We found no evidence for
further significant changes in outcomes for 1992 to 1996. However,
ongoing improvements may be masked by the increasing prevalence of
high-risk patients who are incompletely characterized by the simplified
risk-adjustment algorithm used for the 15-year trend
analysis.
Analysis of the 1982-to-1996 dataset obviously was not ideal
for delineating predictors in current practice for two reasons. First,
a richer set of variables did not become available until 1990; and
second, as noted above, outcomes have been improving over time. Thus,
to determine the contemporary predictors of OM in the elderly, a
logistic regression analysis was performed on a database of
2002 well characterized elderly patients undergoing CABG between 1991
and 1996. Strong risk factors were presence of a grade 4 ventricle
(odds ratio, 10.7; 95% CI, 4.4 to 26) or previous CABG (odds ratio,
3.73; 95% CI, 2.0 to 7.0). Some expected predictors—such as age of
The protective effect of previous angioplasty/stenting in the algorithm
is strikingly large. This finding is almost counterintuitive because
one would expect individuals at higher risk from CABG to be more likely
to undergo angioplasty as a temporizing measure, rather than proceeding
directly to open heart surgery. There are two plausible explanations
for the effect, which are not mutually exclusive. The first is that
previous angioplasty/stenting is directly protective by reducing one or
more of the critical coronary arterial
stenoses before CABG. The second is that the prior occurrence
of angioplasty/stenting is actually a proxy for less extensive or
severe coronary atherosclerosis, independent of
the number of diseased vessels. In the latter scenario, patients with a
limited number of discrete lesions would be more likely to undergo a
prior angioplasty than those with diffuse atheroma and
distal vessel involvement.
Limitations of this analysis are those that apply in any
observational outcomes analysis. First, miscoding of key risk
factors is always a concern. The database in question is very well
established and subject to systematic logic and range checks.
Definitions for risk factors have remained unchanged since 1982 in some
cases and since 1990 for those factors added later. Furthermore, the
data are subject to random audits, which have consistently
shown raw interabstractor agreement on major variables to be
>98%. The dataset also is acceptably complete in terms of core
variable information, with only 1.8% of patients missing one or
more key data elements.
Second, we have demonstrated the improving outcomes of isolated CABG in
the presence of growing numbers of procedures on high-risk elderly
patients, but, in contrast to the accumulated trial data on younger
persons, the risk-benefit ratios of surgery for the elderly are not
precisely defined.23 42 The elderly are a very
diverse group in terms of their physical and mental health, work
capacity, and economic status. Prudent case selection obviously must
take into account the baseline functional capacities and preferences of
elderly patients. Furthermore, our results show that high-risk elderly
patients still have a significantly increased OM rate (8.9%); those
with poor ventricular function or previous CABG are at
particularly high risk of postoperative mortality. These latter
findings may help clinicians in counseling elderly patients about the
risks of isolated CABG surgery.
Third, as noted in "Methods," the predictive algorithm for the most
recent period is based on consecutive patients from a single center,
without independent validation. With only 92 deaths among the 2002
elderly patients undergoing isolated CABG at our center between 1991
and 1996, it was not feasible to split the cohort into derivation and
validation samples. That said, most risk-adjustment algorithms in the
literature have been validated only in the centers from which they were
derived. Other centers should ideally use their own outcomes data to
validate and recalibrate the risk factors identified here.
Fourth, we focused exclusively on mortality as a postoperative
complication. Additional work is needed to delineate trends in
postoperative morbidity, not the least of which is stroke, an outcome
particularly feared by the elderly. Furthermore, we do not have data on
long-term life expectancy gains or quality of life enhancement. Linkage
to provincial statistics is planned to address life-expectancy gains,
but in the absence of prospective data collection, quality of life
improvements cannot be quantified.
In conclusion, CABG surgery may sometimes be the best of the
unattractive options for elderly patients who have a progression of
disease and symptoms. OM after isolated CABG in the elderly declined
significantly starting in the late 1980s for this important and growing
group of patients, despite an increase in the prevalence and severity
of their risk factors, and has been stable since the early 1990s at
<5% overall for patients aged
Received June 9, 1997;
revision received October 8, 1997;
accepted October 21, 1997.
© 1998 American Heart Association, Inc.
Clinical Investigation and Reports
Fifteen-Year Trends in Risk Severity and Operative Mortality in Elderly Patients Undergoing Coronary Artery Bypass Graft Surgery
Abstract
Top
Abstract
Introduction
Methods
Results
Discussion
References
Background—Trends in risk-severity
and operative mortality (OM) were examined in 3330 consecutive patients
aged 70 years and older who underwent isolated coronary artery
bypass graft surgery (CABG) between 1982 and 1996.
Key Words: risk factors • bypass • coronary disease • mortality • surgery
Introduction
Top
Abstract
Introduction
Methods
Results
Discussion
References
The elderly compose
the fastest growing segment of North American society, and the greatest
increases in numbers are in the oldest group (ie, persons 
85 years
old).1 2 3 4 Increasing numbers of elderly patients
now undergo CABG.3 5 6 Indeed, over the past 20
years, the definition of "elderly" in the literature on cardiac
surgical outcomes has gradually increased from persons 65 to those
80 years old.5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 This shift reflects
reductions in the risks of surgery arising from improvements in
technology, skills, and patient
selection.1 4 5 9 10 11 15 23 24 75 years.25 Despite these trends,
the 1993 CABG service rate in Ontario was about half that of New York
State for patients aged 65 to 74 and only one third the New York rate
for those 75 years of age.26 New York, in turn,
is at the low end of the US range for population-based CABG rates. 70 years of age) undergoing CABG over a 15-year period in
Toronto, (2) the risk-adjusted temporal changes in clinical
severity and in-hospital OM among these subjects, and (3) the
contemporary predictors of postoperative mortality in a 1991-to-1996
cohort of elderly patients undergoing CABG.
Methods
Top
Abstract
Introduction
Methods
Results
Discussion
References
Data Source
Clinical, operative, and outcome data were collected
prospectively in a computerized database for 19 009 consecutive
patients undergoing isolated CABG between January 1, 1982, and December
31, 1996, at The Toronto Hospital (formerly the Toronto
Western and Toronto General Hospitals). Patients undergoing
valve, congenital, aortic root, ventricular
aneurysm repair, transplantation, ventricular
mapping, etc were excluded from this study.
The outcome of interest for this study is OM, which is defined
as any postoperative, in-hospital death.
Data were collected and managed in dBASE IV datasets. The SAS
for PC32 and BMDP/DYN LR33
programs were used for statistical analyses. The
2 or Fisher's exact tests were used to
evaluate categorical data univariately.
Multivariate logistic regression methods were used to
calculate risk-adjusted mortality and calculate factor-adjusted odds
ratios. Model discrimination was evaluated by the area under the ROC
curve,34 35 and the calibration was assessed with
the Hosmer-Lemeshow goodness-of-fit statistic.36
For goodness-of-fit, the null hypothesis is that the model fits the
data. Therefore, a nonsignificant P value is desired because
P<.05 would indicate a poor fit between predicted and
observed results.
Rather than build a complex model to assess the temporal trends
in incidence, risk profiles, and outcomes of elderly versus nonelderly
patients, we used a simpler approach based on risk stratification and
contingency tables, as outlined below. 75), sex, previous CABG, urgency
of surgery, LV dysfunction (LV grade 2 to 3, LV grade 4), and left main
coronary artery disease—were rounded as in the algorithm of Tu
et al. These rounded odds ratios served as risk weights for each level
of the predictor variables. A risk score for each patient was
calculated by summing the risk weights for the variables that
described the patient's baseline characteristics. Observed mortality,
determined by frequency analysis, for each risk score was used
to construct relative risk groups (eg, low, medium, or high). 70 years). This allowed us to use contingency
table analysis to evaluate changes in the prevalence of elderly
patients, their risk factors, and OM over time and among the three risk
groups.
In the final step of the analysis, we focused on the
cohort of elderly patients undergoing CABG between 1991 and 1996, a
group that was better characterized with additional data as outlined
above. This enabled us to determine the contemporary predictors of OM
as contrasted to the six core explanatory variables used for the
temporal trend analysis. The following variables were
tested by 2 analysis for their
univariate association with OM: diabetes,
peripheral vascular disease, history of hypertension,
previous angioplasty/stent, renal failure, New York Heart Association
class, recent preoperative myocardial infarction, preoperative
stroke/transient ischemic attack, number of diseased vessels,
severity of angina, and body size. We included all variables with a
value of P<.20, as well as those found to be clinically
important in other models38 regardless of whether
they met the critical 
level for inclusion. These variables were
submitted for consideration to a stepwise logistic regression
analysis using forward selection combined with backward
elimination. The best model was determined by two criteria: the area
under the ROC curve, and the Hosmer-Lemeshow statistic. Because of the
limited number of events, we did not undertake split-sample methods to
validate the model. Such validation would in any case confirm the
model's applicability in our setting but not prove generalizability to
other centers. Thus, we simply present this set of predictors for
information and as a hypothesis for consideration and validation by
others.
Results
Top
Abstract
Introduction
Methods
Results
Discussion
References
Knowledge to Date
Table 1
presents 18 reports
retrieved from a Medline search that demonstrate the changing
definition of "elderly" and the range of OM (5% to 20%) reported
for isolated CABG over the past 20 years.
View this table:
[in a new window]
Table 1. Incidence and Outcomes of CABG in the Elderly:
Changing Profile of Cohort Studies in the Literature
All 19 009 consecutive patients undergoing isolated CABG at The
Toronto Hospital between January 1, 1982, and December 31,
1996, were examined. As noted, the core variables for this study
were age, sex, LV grade, previous CABG, urgency of surgery, and left
main disease. There were 346 patients with one or more of these data
elements missing, making the database 98.2% complete for core
information.
There were 15 679 (OM=2.2%) patients under the age of 70 years
who underwent CABG between 1982 and 1996. "Elderly" was defined as
those patients 70 years of age at the time of surgery (3330,
OM=4.95%). Fig 1 demonstrates the yearly
increase in the prevalence of those patients aged 70 to 74 (top) and
those 75 (bottom) over the 15 years of this study. Both groups
increased significantly over time (P<.001). The absolute
numbers for patients under 70 remained fairly stable for each 5-year
time cohort (
5300), but the number of elderly patients almost
tripled from 593 in the 1982-to-1986 cohort to 1726 in the 1992-to-1996
group.
View larger version (29K):
[in a new window]
Figure 1. Significant increase in the prevalence of elderly
patients undergoing isolated CABG at The Toronto Hospital
between 1982 and 1996. The temporal change was significant
(P<.001) for those those aged 70 to 74 years and those
aged 75 years.
There was a 34% overall relative risk reduction in the OM rate
(all patients) from 1982 to 1986 (OM=3.52%) to the following time
cohorts (OM=2.34% for both 1987-to-1991 and 1992-to-1996 cohorts). shows the risk weights
for each level of the prognostic variables derived from the rounded
odds ratios and the cutpoints of the total risk score used to define
the relative risk groups.
View this table:
[in a new window]
Table 2. Odds Ratios, 95% CI, and Corresponding Risk Weights
From Logistic Regression Analysis of 19 009 Patients
Undergoing Isolated CABG Between 1982 and 1996 shows the prevalence of
individual risk factors as well as the changing distribution of overall
risk severity. Combined prevalence of medium- and high-risk patients
increased significantly (P<.001) over time for those
patients over and under 70 years of age (Fig 2).
View this table:
[in a new window]
Table 3. Distribution of Risk Factors for 19 009
Patients Undergoing Isolated CABG Between 1982 and 1996 at the
Toronto Hospital
View larger version (30K):
[in a new window]
Figure 2. Top, Prevalence of high-risk elderly patients
increased significantly (P<.001) over time. Bottom, OM
decreased significantly (P<.05 over time for both
medium- and high-risk elderly patients. and Fig 2
.
Significantly positive trends are seen for medium- and high-risk
patients and for most, albeit not all, risk factor subgroups in the
nonelderly and elderly. Age-specific mortality improved significantly
for persons <70 years of age. Even larger absolute improvements were
seen among persons aged 70 to 74 and 75 years. However, these did not
reach significance due to smaller sample sizes. We accordingly turned
to the overall logistic regression model for the elderly because this
would allow us to factor in the temporal increases in severity.
View this table:
[in a new window]
Table 4. Distribution of Outcomes for 19 009 Patients
Undergoing Isolated CABG Between 1982 and 1996 at the Toronto
Hospital 50% reduction in
relative odds of death (Table 5).
Adjusted odds ratios and their 95% CIs for all core risk factors are
also shown in Table 5. Predictive accuracy measured by the area under
the ROC curve was 0.69, and precision, measured by the Hosmer-Lemeshow
goodness-of-fit statistic was 0.232.
View this table:
[in a new window]
Table 5. Logistic Regression of 3330 Elderly Patients
Undergoing CABG Between 1982 and 1996 at the Toronto
Hospital
There were 2002 elderly patients (70 years old) who
underwent isolated CABG between 1991 and 1996. OM was 4.6% in this
group (n=92). The six core variables—age, (70 to 74 years or 75
years) sex, previous CABG, LV grade (1, 2 or 3, or 4) timing of surgery
(elective, semiurgent, or emergent), and left main disease (>50%
stenosis)—were submitted to a logistic regression
analysis along with the following additional variables:
diabetes, peripheral vascular disease, history of
hypertension, previous angioplasty/stent, renal failure, New York Heart
Association class, recent preoperative myocardial infarction,
preoperative stroke/transient ischemic attack, number of
diseased vessels, severity of angina, and body size. The contemporary,
independent, multivariate predictors of OM are
contained in Table 6. Particularly
interesting is a risk reduction associated with previous
angioplasty/stent. The Hosmer-Lemeshow goodness-of-fit was 0.932, and
the area under the ROC curve was 0.713.
View this table:
[in a new window]
Table 6. Logistic Regression of Contemporary Elderly Patients
(1991 to 1996)
Discussion
Top
Abstract
Introduction
Methods
Results
Discussion
References
Although advancing age remains a consistent
predictor of OM after isolated CABG, a variety of reports in the
literature have demonstrated that elderly patients previously thought
to be at very high risk for adverse events can now undergo this
beneficial procedure with acceptable postoperative
risk.1 4 5 9 10 11 12 15 23 24 Many of these reports
have been limited, however, either by not providing a long-term
perspective on outcome trends among the elderly or by not incorporating
risk-adjustment algorithms that take into account the temporal shifts
in risk profiles among patients receiving CABG. In the latter respect,
statistical power has been a problem for many reports of CABG in the
elderly, with the obvious exception of the study by Hannan et
al.18 Given the current convention that there
should be 10 outcome events for every explanatory variable in an
outcomes-prediction model,39 many studies have
sample sizes that permit only two or three variables to be
considered adequately for risk-adjustment purposes. 70 years. We used a previously
validated predictive rule37 as a template for
risk adjustment, added an additional explanatory variable (left
main disease), and recalibrated the rule across the entire 15-year
dataset to create a more level playing field for temporal comparisons
of risk factor profiles and outcomes. Our findings confirm that there
has been not only a time-related increase in the prevalence of older
patients undergoing isolated CABG at our center but also an increase in
the severity of the preoperative risk profile of those patients.
However, risk-adjusted OM has decreased significantly for elderly
patients. The current overall mortality rate for elderly patients is
<5% and only 3% for low- and medium-risk patients. 75 years, urgent/emergent surgery, renal failure, number of diseased
vessels, presence of left mainstem disease, or recent preoperative
myocardial infarction—fell out of the final model. This is partly a
function of statistical power, but it is instructive that other
predictors, such as diabetes and peripheral vascular
disease, took precedence in the risk-adjustment algorithm. 70 years. A careful weighing of risk,
rather than advanced age alone, should determine who is offered
surgical revascularization. In this regard, poor
ventricular function and repeat CABG continue to have the
most impact on OM in elderly patients in our center. These and other
risk factors noted here can serve as a starting point for cardiologists
and surgeons who want to counsel elderly patients about the vital risks
of isolated CABG or to delineate risk factors for adverse events in
their own practices.
Selected Abbreviations and Acronyms
CI
=
confidence interval
CABG
=
coronary artery bypass graft surgery
EF
=
ejection fraction
LV
=
left ventricular, ventricle
OM
=
operative mortality
ROC
=
receiver-operator characteristic
Acknowledgments
Ms Ivanov is supported by a fellowship from the Heart and Stroke
Foundation of Canada. Dr Naylor is a Career Scientist of the Ontario
Ministry of Health. Dr Naylor also receives personnel support from the
Institute for Clinical Evaluative Sciences, which is funded by the
Ontario Ministry of Health. The findings and views are those of the
authors; no endorsement by the supporting agencies is implied. The
authors wish to express their sincere appreciation to Susan Collins for
data collection and management. We are deeply indebted to the
contributing surgeons at The Toronto Hospital: R.J. Baird, Hugh
E. Scully, Lynda L. Mickleborough,. Christopher M. Feindel, Charles M.
Peniston, Irving H. Lipton, R.J. Cusimano, Anthony Ralph-Edwards, and
Bernard S. Goldman (currently chief of Cardiovascular
Surgery at Sunnybrook Health Science Center, Toronto, Canada).
References
Top
Abstract
Introduction
Methods
Results
Discussion
References
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 J. L. Anderson, C. D. Adams, E. M. Antman, C. R. Bridges, R. M. Califf, D. E. Casey Jr, W. E. Chavey II, F. M. Fesmire, J. S. Hochman, T. N. Levin, et al. ACC/AHA 2007 Guidelines for the Management of Patients With Unstable Angina/Non-ST-Elevation Myocardial Infarction: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 2002 Guidelines for the Management of Patients With Unstable Angina/Non-ST-Elevation Myocardial Infarction) Developed in Collaboration with the American College of Emergency Physicians, the Society for Cardiovascular Angiography and Interventions, and the Society of Thoracic Surgeons Endorsed by the American Association of Cardiovascular and Pulmonary Rehabilitation and the Society for Academic Emergency Medicine J. Am. Coll. Cardiol., August 14, 2007; 50(7): e1 - e157. [Full Text] [PDF]
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M. J. Magee, M. A. Herbert, T. M. Dewey, J. R. Edgerton, W. H. Ryan, S. Prince, and M. J. Mack Atrial Fibrillation After Coronary Artery Bypass Grafting Surgery: Development of a Predictive Risk Algorithm Ann. Thorac. Surg., May 1, 2007; 83(5): 1707 - 1712. [Abstract] [Full Text] [PDF]
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V. Aboyans, P. Lacroix, A. Postil, J. Guilloux, F. Rolle, E. Cornu, and M. Laskar Subclinical Peripheral Arterial Disease and Incompressible Ankle Arteries Are Both Long-Term Prognostic Factors in Patients Undergoing Coronary Artery Bypass Grafting J. Am. Coll. Cardiol., September 6, 2005; 46(5): 815 - 820. [Abstract] [Full Text] [PDF]
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F. Rosenfeldt, S. Marasco, W. Lyon, M. Wowk, F. Sheeran, M. Bailey, D. Esmore, B. Davis, A. Pick, M. Rabinov, et al. Coenzyme Q10 therapy before cardiac surgery improves mitochondrial function and in vitro contractility of myocardial tissue J. Thorac. Cardiovasc. Surg., January 1, 2005; 129(1): 25 - 32. [Abstract] [Full Text] [PDF]
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J. P. Mathew, M. L. Fontes, I. C. Tudor, J. Ramsay, P. Duke, C. D. Mazer, P. G. Barash, P. H. Hsu, and D. T. Mangano A Multicenter Risk Index for Atrial Fibrillation After Cardiac Surgery JAMA, April 14, 2004; 291(14): 1720 - 1729. [Abstract] [Full Text] [PDF]
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S. Karthik, G. Musleh, A. D. Grayson, D. J. M. Keenan, D. M. Pullan, W. C. Dihmis, R. Hasan, and B. M. Fabri Coronary surgery in patients with peripheral vascular disease: effect of avoiding cardiopulmonary bypass Ann. Thorac. Surg., April 1, 2004; 77(4): 1245 - 1249. [Abstract] [Full Text] [PDF]
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C. Muneretto, G. Bisleri, A. Negri, J. Manfredi, E. Carone, J. A. Morgan, M. Metra, and L. Dei Cas Left internal thoracic artery-radial artery composite grafts as the technique of choice for myocardial revascularization in elderly patients: A prospective randomized evaluation J. Thorac. Cardiovasc. Surg., January 1, 2004; 127(1): 179 - 184. [Abstract] [Full Text] [PDF]
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P. M. Davierwala, M. Maganti, and T. M. Yau Decreasing significance of left ventricular dysfunction and reoperative surgery in predicting coronary artery bypass grafting-associated mortality: A twelve-year study J. Thorac. Cardiovasc. Surg., November 1, 2003; 126(5): 1335 - 1344. [Abstract] [Full Text] [PDF]
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L. L. Mickleborough, S. Carson, and J. Ivanov Gender differences in quality of distal vessels: effect on results of coronary artery bypass grafting J. Thorac. Cardiovasc. Surg., October 1, 2003; 126(4): 950 - 958. [Abstract] [Full Text] [PDF]
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