Supersize Me?
Brian W. Zagol, M.D.
Dan Dishmon, M.D.
Department of Cardiology
University of Tennessee
The Good, the Fat, and the Ugly
Introduction
• We have all been taught that obesity is bad.
• Movies, television, and magazines all preach
that obesity in this country is an epidemic and
that there are many health problems associated
with its condition.
• The medical literature also supports that obesity
is a problem.
Definition
• Based upon observations by the National Health
and Nutrition Examination Survey (NHANES),
the National Center for Heath Statistics defines
the following:
•
•
•
•
Underweight: BMI < 18.5 kg/m2
Normal weight: BMI 18.6 kg/m2 to 24.9 kg/m2
Overweight: BMI 25 kg/m2 to 29.9 kg/m2
Obese: BMI > 30 kg/m2
Introduction
• Obesity has been implicated as a risk factor for
the following medical conditions:
-
Decreased life expectancy
Hypertension
Hypercholesterolemia
Diabetes Mellitus
Gout
Coronary disease
Heart Failure
Atrial fibrillation
Stroke
- Hepatobiliary Disease
- Osteoarthritis
- Cancer (esophogus, colon,
rectum, liver, gallbladder,
pancreas, kidney,
non-Hodgkins lymphoma,
multiple myeloma, stomach,
prostate, endometrial, breast
- Kidney Stones
- Psychosocial disorders
i.e. Lonely Saturday nights
Relative Risk of All-cause Mortality and
Cardiovascular Mortality Based upon
Weight (Obese = BMI > 25) and Fitness
Level
Lee C D, et al. Am J Clin Nutr. 1999; 69:373.
Relative Risk of Certain Conditions in Overweight
Individuals (BMI>27.8)
Age 20 to 44
years
Age 45 to 74
years
Age 20 to 74
years
5.6
1.9
2.9
2.1
1.1
1.5
3.8
2.1
2.9
Hypertension
Hypercholesterolemia
Diabetes Mellitus
Van Itallie TB, et al. Ann Int Med. 1985; 103:983.
Relative Risk of Certain Conditions as BMI
Increases
Dietz W H, et al. NEJM. 1999; 341:427.
The Advantage of Obesity?
• It is evident by large, observational studies that
obesity contributes to a number of conditions
which are known to lead to atherosclerotic
disease and also to the development of coronary
artery disease itself.
• However once CAD has developed and these
patients require revascularization, the picture is
not as clear cut. In fact, FAT PEOPLE DO
BETTER!!!
The Obesity Paradox
• In the 1980’s, the bias of both cardiologists and
cardiothoracic surgeons persisted and
overweight and obese patients were believed to
carry a higher risk to revascularization than their
non-overweight counterparts.
• This bias persisted despite conflicting data on
the subject.
• The bias was so evident that an editorial in the
Canadian Journal of Surgery, published in 1985
questioned whether obese patients should
receive CABG surgery at all!
Koshal A, et al. Can J Surg. 1985. 28:331.
The Obesity Paradox
• However, in the late 1990’s and early 2000’s
retrospective analysis of large revascularization
studies were finding surprising results in
overweight and obese patients – they had fewer
complications.
• These results applied to both percutaneously
revascularized patients and to those surgically
revascularized.
Percutaneous Complications
• Obese patients undergoing coronary
angiography would seemingly have higher
procedural complication rates:
• Difficulty gaining femoral arterial access
• Difficulty achieving post-procedural hemostasis
• Delayed recognition of vascular complications
Percutaneous Complications
• In an article by Nicholas Cox, et al. published in
the American Journal of Cardiology in 2004, the
group collected data on 5234 consecutive
patients undergoing cardiac catheterization at
the Brigham and Women’s Hospital in Boston,
Massacusetts as well as the Western Hospital in
Fottscray, Victoria, Australia between January
2002 and July 2003.
• They retrospectively looked at complication rates
of those patients in comparison to their body
mass indices.
Cox N, et al. Am J Card. 2004; 94:1174.
Percutaneous Complications
• Cardiac catheterization was performed using
standard methods with site of access
determined by operator preference and patient
suitability.
• Obesity was defined as a BMI > 30kg/m2
• Vascular complications were defined as need for
surgical repair, transfusion, the development of
arteriovenous fistula, pseudoaneurism, or large
hematoma (>8cm)
Cox N, et al. Am J Card. 2004; 94:1174.
Percutaneous Complications –
Baseline Demographics
Cox N, et al. Am J Card. 2004; 94:1174.
Distribution of Patients Undergoing
Catheterization by BMI
Cox N, et al. Am J Card. 2004; 94:1174.
Vascular Complication Rate Based
Upon BMI
Cox N, et al. Am J Card. 2004; 94:1174.
Vascular Complications by Obesity
Group
Cox N, et al. Am J Card. 2004; 94:1174.
Vascular Complications by BMI
Looking at Approach Used
Cox N, et al. Am J Card. 2004; 94:1174.
Discussion
• The authors of this study speculated that the
lower rate of vascular complications seen in
obese people may be accounted for by the
following variables:
• Obese patients have larger arterial size : sheath size ratio
• Obese patients, at least in this study, more frequently
received device closure.
• The perceived increased risk of vascular complications in
obese people may lead to increased diligence in vascular
access and in obtaining hemostasis at the end of the
procedure.
Cox N, et al. Am J Card. 2004; 94:1174.
Percutaneous Results
• It is clear that overweight and obese patients have
fewer complications from percutaneous cardiac
interventions during the actual procedure, but how do
they do long-term?
• My colleague, I am sure, will point out that there are
multiple studies associating increased restenosis rates
in obese patients.
• The medical literature documents that obesity,
independent of blood pressure and diabetes status, is
a risk factor for repeat target lesion revascularization,
that some speculate is due to increased inflammation
and insulin resistance.
Percutaneous Results
• However it appears with drug-eluting stents, the
increased risk of restenosis may also no longer
be a problem.
• In a review of the data from the Taxus-IV trial,
Eugenia Nikolsky, et al. published a study in the
American Journal of Cardiology in March, 2005
looking at the impact of obesity on restenosis
rates in the era of drug-eluting stents versus
bare metal stents.
Nikolsky E, et al. Am J Card. 2005; 95:709.
Taxus-IV Baseline Characteristics
Nikolsky E, et al. Am J Card. 2005; 95:709.
Taxus-IV Clinical Outcomes at 1 Year
Nikolsky E, et al. Am J Card. 2005; 95:709.
Taxus-IV Freedom from TVR or
MACE
Nikolsky E, et al. Am J Card. 2005; 95:709.
Taxus-IV Restenosis Rates
Nikolsky E, et al. Am J Card. 2005; 95:709.
CABG and Obesity
• It is clear that obese patients undergoing
percutaneous interventions have fewer periprocedural complications AND with the advent of
drug-eluting stents increased restenosis rates no
longer seem to be a problem.
• But what about obese patients who require
surgical revascularization?
CABG – Procedural Results
• Obesity is frequently cited as a risk factor for
adverse outcomes with CABG surgery.
• Nancy Birkmeyer, et al. in a study published in
Circulation in 1998 prospectively looked at
11,101 consecutive patients undergoing CABG
between 1992 and 1996 at medical centers in
Maine, New Hampshire, and Vermont.
• Patients were categorized into the following
groups: non-obese (BMI<30), obese (BMI 3136), and severely obese (BMI>36) and were
evaluated for procedural and in-hospital
complications.
Birkmeyer N, et al. Circulation. 1998; 97:1689.
CABG – Procedural Results Baseline
Characteristics
Birkmeyer N, et al. Circulation. 1998; 97:1689.
CABG – Procedural Results
Birkmeyer N, et al. Circulation. 1998; 97:1689.
CABG – Procedural Results
Conclusions
• With the exception of sternal wound infections,
the perception among clinicians that obesity
predisposes to various post-operative
complications is not supported by the data.
• Furthermore, there is no difference in mortality
among these patients and obesity seems to be
protective on the risk of postoperative bleeding.
CABG – Long-term Results
• It appears safe to perform CABGs on obese
patients, but how do they do in the long-term?
• Luis Gruberg, et al. in The American Journal of
Cardiology in February, 2005 analyzed the
outcomes of coronary artery revascularization
for patients with multi-vessel CAD based upon
the data collected in the large ARTS trial (Arterial
Revascularization Therapies Study).
Gruberg L, et al. American Journal of Cardiology. 2005; 95:439.
CABG – Long-term Results
• The ARTS trial was a multicenter, randomized
trial that compared PCI plus stenting with CABG
in patients who had multi-vessel CAD.
• A total of 1205 patients from 67 participating
centers worldwide were enrolled between April
1997 and June 1998.
• The obesity analysis was based upon the 3-year
outcomes from this trial.
Gruberg L, et al. American Journal of Cardiology. 2005; 95:439.
CABG – Long-term Results Baseline
Characteristics
Gruberg L, et al. American Journal of Cardiology. 2005; 95:439.
CABG – Long-term Results
Gruberg L, et al. American Journal of Cardiology. 2005; 95:439.
CABG – Long-term Results
Kaplan-Meier Curve for Survival without
MACE (Death, CVA, MI, or Repeat
Revascularization)
N.S.
Gruberg L, et al. American Journal of Cardiology. 2005; 95:439.
CABG – Long-term Results
• In the ARTS registry, BMI had no effect on 3
year outcome of those who underwent stenting.
• Conversely, among those who underwent
CABG, those who were overweight or obese had
significantly better outcomes than did those who
had a normal BMI with regard to survival without
MACE, mainly driven by decreased need for
revascularization.
Gruberg L, et al. American Journal of Cardiology. 2005; 95:439.
Summary for the Obesity Paradox
• Obese patients requiring revascularization
procedures compared to their non-obese
counterparts:
• Have a lower procedural risk at cardiac catheterization.
• Do not have increased rates of restenosis, since the advent
of drug-eluting stents.
• Have overall equal risk of undergoing surgical
revascularization, with decreased periprocedural bleeding.
• Have better long-term outcomes after undergoing CABG in
regard to survival, free of major adverse cardiac events.
• Bring on the Bacon!!!
Paradox, Schmaradox
Obesity is known to predispose patients to
increased overall morbidity and mortality
 Obesity is associated with conventional
cardiovascular risk factors such as HTN,
DM, and HPL
 Furthermore, obesity is associated with
endothelial dysfunction, insulin resistance,
and inflammation that may contribute to
the increased risk for adverse clinical
outcomes

Obesity and PCI
Clinical outcome in the 1st year after coronary
stenting is determined primarily by restenosis,
manifested clinically as recurrent ischemia
prompting repeat revascularization of the
original target lesion (target lesion
revascularization [TLR])
 HTN and DM have been associated with an
increased risk for TLR after coronary stent
placement
 Any effect of obesity on TLR may be influenced
by the increased prevalence of these obesity
related diseases

No Paradox Here
Fat Needs No Friends
These findings are consistent with an
obesity effect that is not mediated by DM
or HTN
 Insulin resistance and endothelial
dysfunction are independent predictors of
early restenosis after coronary stenting
 Neointimal proliferation after stent
implantation in patients with IGT has been
shown to be greater than in patients with
normal glucose tolerance


Products of
adipocytes include IL6, TNF-a, and CRP

Inflammation has
been implicated to
play a central role in
neointimal
hyperplasia
Correlation between levels of inflammatory
markers and propensity for restenosis has
also been demonstrated
 Previous reports of an obesity paradox
after PCI are possibly explained by
inadequate adjustment for high-risk
patients at lower extremes of BMI and
focus on mortality outcomes

Obesity and CABG
Obesity is often thought
to be a risk factor for
perioperative morbidity
and mortality with
cardiac surgery
 Factors predisposing and
contributing to severity
of CAD as well as the
technical difficulties in
surgical and postsurgical
care of the obese likely
contribute to these
perceptions

Many previous attempts to study the
association between obesity and outcomes
with cardiac surgery have suffered from
limitations caused by sample size and lack
of data about potential confounders
 In most studies, those classified as obese
or severely obese were on average
younger, more likely to be female, more
likely to have other CAD risk factors, had a
greater incidence of L main disease, and
higher LVED pressure

Patient Characteristics
Birkmeyer, et al. Obesity and Risk of
Adverse Outcomes Associated with CAB
Surgery. Circulation.
Morbidity of Obesity

It has been demonstrated that obese patients
undergoing cardiac surgery have a higher
incidence of peri- and postoperative MI’s,
arrhythmias, respiratory infections, infections of
the leg donor site, and sternal dehiscence
Post-CABG Morbidity in the Obese
Pathophysiology

Myocardial Infarction, Arrhythmias
– Greater cardiac workload?
– Inadequate myocardial protection of fatty or
hypertrophied hearts?
– O2 supply/demand mismatch?

Pneumonia
– Decreased mechanical ventilatory functions
– Longer mechanical ventilation times
More Pathophysiology

Wound Infections
– Poor wound healing
– Diabetes
– Excessive adipose tissue with low regional
oxygen tension
– Inadequate serum levels of prophylactic abx
– Technical difficulties in maintaining sterility of
tissue folds
Infectious Implications
Infection in the setting of cardiac surgery
increases morbidity and mortality
 In a study by Fowler et al, patients with
major infection had significantly higher
mortality (17.3% vs 3.0%, p<0.0001) and
postoperative length of stay >14 days
(47.0% vs 5.9%, p<0.0001)
 Most common risk factors for infection
included BMI of 30 to 40 kg/m2, DM,
previous MI, and HTN

Fat and Fib/Flutter
Obesity is a risk factor for atrial fibrillation
and atrial flutter in the cardiac surgery
setting
 Postoperative atrial dysrhythmias may be
complicated by significant symptoms,
hemodynamic instability, and an increased
risk of stroke
 Postop fib/flutter is also associated with
increased length of stay and incurs
additional costs

Lose the Weight and Do Great?
In patients encouraged to undergo
preoperative weight reduction, there was
a trend of better postoperative recovery
 They had a shorter time in the ICU (1.5 vs
2.1 days), a lower incidence of MI (4.7%
vs 6.7%) and arrhythmias (25.7% vs
30.4%), and fewer respiratory infections
(3.8% vs 4.2%)


Preoperative weight reduction and
subsequent postoperative weight control
should reduce perioperative complications
and improve patients’ long term results
References



Rana, JS, et al. Obesity and Clinical
Restenosis after Coronary Stent Placement.
Am Heart Journal. 2005; 150: 821-826.
Fowler, VG, et al. Clinical Predictors of Major
Infections After Cardiac Surgery. Circulation.
112 [I] 358-365.
Martinez, EA, et al. ACCP Guidelines for
Prevention and Management of Postop A-fib
After Cardiac Surgery. Chest. 2005; 128: 4855.
References Cont’d



Fasol, R. et al. The Influence of Obesity on
Perioperative Morbidity. Thoracic and
Cardiovascular Surgeon. 1992. 40: 126-129.
Birkmeyer, NJ, et al. Obesity and Risk of
Adverse Outcomes Associated with CAB
Surgery. Circulation. 1998; 97: 1689-1694.
Gurm, HS, et al. The Impact of BMI on Shortand Long-Term Outcomes in Patients
Undergoing Coronary Revascularization.
JACC. 2002; 39: 834-840.
References Cont’d

Prasad, US, et al. Influence of Obesity on
the Early and Long Term Results of
Surgery for CAD. Eur J Cardiothorac Surg.
1991. 5: 67-73.