Re: Relation of Body Mass Index to Outcome in Patients With Known or Suspected Coronary Artery Disease

Here's part of the discussion. The bottom line seems to be that they
really don't know the reason for their results, although they have
some theories. I should note that although they mention smokers
having a lower BMI, they were controlling for smoking status in their
statistical analysis. This idea of "peripheral adiposity" is new to
me. I have heard before that lower BMI and cholesterol is associated
with a worse prognosis in heart failure.

"The paradoxic relation, a “protective effect,” of obesity on survival
had been observed recently in several patient populations, such as
patients with chronic HF or renal disease.[5], [9] and [11] Curtis et
al11 examined a cohort of 7,767 outpatients with an established
history of HF controlled under digitalis treatment. Higher BMIs were
associated with a lower mortality.11 These data confirmed previous
survival data of 4,700 hospitalized patients with congestive HF
associating an increased BMI with lower mortality (p <0.0001).9
Recently, Gruberg et al12 studied patients who underwent percutaneous
coronary intervention or coronary artery bypass grafting. The long-
term mortality risk was similar across all BMI categories irrespective
of type of revascularization procedure. Thus, overweight or obesity
had no effect on crude survival at 3 years.12 Sierra-Johnson et al13
followed 389 patients undergoing cardiac rehabilitation and found an
inverse relation between BMI and total and cardiovascular mortalities,
although only the relation with cardiovascular mortality was
statistically significant after adjustment for age and gender.
Kragelund14 examined the effect of BMI on survival in 6,676
consecutive patients with acute MI during 10-year follow-up. Overall
obesity was inversely related to mortality from all causes, There was
no association between obesity assessed as BMI and mortality (men,
adjusted relative risk 0.90, 95% confidence interval 0.85 to 1.14, p =
0.3; women, adjusted relative risk 0.90, 95% confidence interval 0.74
to 1.10, p = 0.2).14 Similar results were reported by Kennedy et al15
who had examined BMI for all-cause mortality and cardiac death in
5,388 patients with complicated AMI. Comparable results were assessed
in patients with renal disease.[5] and [16] When a large cohort of
patients with renal failure requiring dialysis (n = 418,021) was
examined for survival, overweight and obese patients using dialysis
had longer survival than did those with lower BMI.7

The reason for the paradoxic relation of BMI with mortality in the
aforementioned patient populations is not understood. Although this
pathomodulatory phenomenon is quite obscure, several influences can be
suggested in our study. It had been previously demonstrated that
peripheral adiposity (i.e., gynoid obesity) poses cardiovascular
benefits due to secretion of adiponectin, which has anti-inflammatory,
insulin-sensitizing, and antiatherogenic effects in addition to an
association with lower total body fat content and the fact that
subcutaneous body fat is relatively “inert” in metabolic and
inflammatory/mediation terms.17 Abdominal obesity is associated with
higher total body fat content, more insulin-resistance, more other co-
morbid associations, and more metabolic activity and inflammatory
cascading influences. Thus, an obesity paradox might be reflected from
a higher prevalence of 1 obesity type (i.e., peripheral) over another
(i.e., central), with its decelerating influences becoming more
manifest as BMI increases to reach higher levels (i.e., >30 kg/m2). It
had been suggested that hypercholesterolemia and high levels of serum
low-density lipoproteins associated with obesity serve a scavenging
action against unbound circulating lipopolysaccharides with consequent
anti-inflammatory response and improved long-term outcomes.18 In the
other extreme, it can be inferred from our population characteristics
that active smokers were mostly in the normal BMI and underweight
groups, an unsurprising finding knowing that those were the 2 groups
with lowest survival. Loss of weight in geriatric patients, which
might be related to malnutrition, multiorgan dysfunction, or
unidentified occult malignancies (especially in the smoking
population), had been identified as a significant predictor of
mortality.[19] and [20] In this instance, those patients who presented
at the time of evaluation with a BMI <18.5 kg/m2 at ≥60 years of age
represented a subcohort of patients at a higher risk of mortality.
Most offending coronary risk factors were associated with a BMI >25 kg/
m2. Those patients with symptomatic co-morbidities were expected to
have had consulted medical care, with a high probability that they
were maintained on drugs proved to improve survival in a CAD
population such as β blockers, statins, α2 agonists and angiotensin-
converting enzyme inhibitors.

One limitation of the study is its retrospective design. Due to time
limits, we could not extend our follow-up beyond the date of
conclusion. Data regarding waist circumference and waist/hip ratio
that measures abdominal obesity were not routinely available. A more
precise differentiation between peripheral adiposity and central
compartment adiposity would have served to support the suggested
hypothetical explanation about the role of a high BMI in prolonging
survival in our patient population. Regarding the detection of our end
points, a number of nonfatal asymptomatic MIs might have not been
reported, especially if these occurred outside the hospital.
Unfortunately, we have no data regarding a particular cause of cardiac
death."








Marilyn

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