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SA JOURNAL OF DIABETES & VASCULAR DISEASE
RESEARCH ARTICLE
VOLUME 14 NUMBER 1 • JULY 2017
31
The severity of CAD was measured by the SYNTAX and Duke
jeopardy scores. For the SYNTAX score, the mean ± SD of the
patients’ scores was 17.7 ± 9.6 (range 0–64) and for the Duke score,
it was 3.2 ± 1.7 (range 0–12). There was a negative correlation
between the SYNTAX and Duke scores (severity of CAD) and the
patients’ BMI (
p
= 0.01 and
p
= 0.001, respectively).The correlation
between the patients’ BMI and the severity of CAD (SYNTAX and
Duke scores) is presented in Table 2.
There was an inverse relationship between obesity and the
severity of CAD, according to the SYNTAX and Duke criteria, which
has been defined as the ‘obesity paradox’. In order to rule out the
impact of other cardiovascular risk factors, multivariate regression
analysis was performed. Regression analysis revealed a
β
-coefficient
of –0.14 for the Duke score and –0.17 for the SYNTAX score. This
means that for every unit increase in BMI there would be a 0.14
and 0.17 decrease in the severity of CAD according to the Duke
and SYNTAX scores, respectively. After adjusting for confounding
factors, there was still a significantly negative correlation between
BMI and severity of CAD (
p
= 0.028 and 0.01, respectively).
Meanwhile multivariate analysis revealed a positive correlation
between severity of CAD and cardiovascular risk factors (Table 3).
On the other hand, our findings regarding the relationship
between WHR and severity of CAD, based on the Duke myocardial
jeopardy score, showed a positive correlation between the two
variables (
p
= 0.03). With increasing WHR, the Duke score also
increased. The relationship between severity of CAD (Duke score)
and WHR is presented in Table 4.
Discussion
In this study, there was a paradoxical relationship between BMI and
severity of CAD but not between WHR and severity of CAD. Based
on the SYNTAX and Duke scores,
β
-coefficients between BMI and
severity of CAD before multivariate analysis were –0.2 and –0.18,
respectively. After multivariate analysis, they were –0.17.and –0.14,
respectively. This shows an inverse relationship between BMI and
severity of CAD.
Controversy regarding the correlation between obesity and
CAD, which surfaced a few decades ago, was the motivation for
us to conduct this study. Although it seems logical that obesity or
adiposity should be accompanied by more accumulation of fat cells
everywhere in the body, including vascular walls (atherosclerotic
plaques), it must be clarified that first of all, obesity per se is not
adiposopathy, and second, the process of atherosclerosis is not a
simple process of fat accumulation.
19,20
The process of atherosclerosis is inflammation as a result of the
response to injury in the milieu of high intravascular LDL cholesterol,
especially oxidised LDL. It seems that visceral adipose tissue is
metabolically more active and pathological than subcutaneous
adipose tissue, and induces immunity processes that contribute
to atherosclerotic cardiovascular disease.
21-24
The answer to the
question raised from the obesity paradox is that atherosclerotic
disease does not result from the accumulation of adipose tissue per
se but is as a result of adipose tissue dysfunction, or ‘sick fat’.
19,23,24
Rubinshtein and colleagues (2006), in their study on 928 patients
with CAD, showed that obesity had an inverse relationship with the
severity of CAD but other risk factors such as DM, hyperlipidaemia
and male gender were correlated with the severity of CAD.
11
In
another study, published in 2007 by Niraj and colleagues, which was
similar to our study, the relationship between severity of CAD and
BMI according to the Duke score was also paradoxical.
10
Although
there are similarities between our study and theirs regarding the
inverse relationship between patients’ BMI and the severity of CAD,
in our study the relationship between WHR and severity of CAD
was evaluated simultaneously. Surprisingly, in our study, WHR was
correlated with the severity of CAD based on the Duke score.
Table 2.
Correlation between BMI and severity of CAD (SYNTAX and
Duke scores)
BMI
(kg/m²)
Number of
patients (%)
SYNTAX score
(mean ± SD)
Duke score
(mean ± SD)
20–24
169 (40.8)
22.3 ± 17.2
4.01 ± 3.3
25–29
154 (37.2)
16.1 ± 14.6
3.05 ± 2.5
30–34
83 (20.1)
12.1 ± 9.2
2.3 ± 1.1
35–39
8 (1.9)
10.8 ± 7.04
1.8 ± 1.04
p
-value
–
0.01
0.001
BMI = body mass index
Table 3.
Correlation between cardiovascular risk factors and severity of
CAD (Duke and SYNTA X scores)
Risk factors
Duke score
(mean ± SD)
p
-value
SYNTAX score
(mean ± SD)
p
-value
Hypertensives
3.6 ± 1.7
0.04 19.1 ± 13.1
0.03
Normotensives
2.4 ± 1.9
14.9 ± 9.5
Cigarette
smokers
3.8 ± 1.2
0.02 20.8 ± 17.4
0.03
Non-smokers
3.07 ± 1.4
16.6 ± 14.2
Hyperlipidaemics
3.9 ± 1.5
0.001 31.5 ± 18.05 0.001
Normolipidaemics
2.8 ± 1.2
15.3 ± 11.02
Diabetics
4.1 ± 3.6
0.002 21.5 ± 18.4 0.008
Non-diabetics
2.9 ± 1.3
16.3 ± 9.2
FH positive
4.5 ± 3.1
0.07 21.9 ± 14.2
0.4
FH negative
3.1 ± 2.3
17.5 ± 10.4
FH = family history.
Table 4.
Relation between WHR and severity of CAD based on the Duke
score
WHR (mean ± SD)
Number of patients
Duke score
0.951 ± 0.07
165
0
0.954 ± 0.06
62
2
0.957 ± 0.07
58
4
0.962 ± 0.05
54
6
0.971 ± 0.05
44
8
0.979 ± 0.02
24
10
0.987 ± 0.05
6
12
p
-value
0.03
WHR = waist-to-hip ratio.