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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 29, No 1, January/February 2018
AFRICA
39
(
n
=
32) and anteroseptal (
n
=
24). Thirty per cent presented
with inferior (
n
=
15), inferolateral (
n
=
13) or inferoposterior (
n
=
2) involvement. Fully evolved Q waves were identified in 63%
of subjects, likely indicative of late presentation as none had a
previous history of coronary events.
Echocardiography revealedregionalwallmotionabnormalities
in 83% of subjects; the ejection fraction (EF) was
<
50% in 42%,
with evidence of left ventricular thrombus in nine patients.
Reversible ischaemia was identified in 19/29 (65%) subjects who
underwent technetium (99mTC) SestaMIBI scanning.
Coronary angiography revealed occlusive CAD (
>
50%
stenosis) in 78 subjects, while 20% had non-occlusive disease
and the remaining two subjects had normal epicardial vessels.
Single-vessel disease was present in 36 subjects, with the LAD
artery being the most commonly involved vessel (
n
=
33, 92%).
Multi-vessel disease was found in 42 subjects; of whom 27 had
two-vessel disease (19 with LAD involvement) and 15 had three-
vessel disease.
Among the 26 subjects with diabetes mellitus, angiography
revealed most (
n
=
12) had multi-vessel disease, followed by single-
vessel (
n
=
7) and non-occlusive disease (
n
=
6). Atherosclerotic
coronary disease was present in five of the eight subjects with
a history of illicit drug use. There were two subjects who had
normal epicardial vessels at coronary angiography: one was
the 25-year-old black male who had a history of illicit drug use
including cocaine, and the second was a 34-year-old HIV-positive
black male. Both subjects presented with anterior STEMI and
received thrombolysis at their base hospitals prior to referral.
To determine the association of various risk factors on the
severity of stenosis or number of vessels affected, we conducted
a Mann–Whitney
U
-test with stenosis severity or number of
vessels as the dependent variable and major risk factors as the
independent variable. Dyslipidaemia was associated with severity
of stenosis (
p
=
0.002) as well as the number of vessels involved
(
p
=
0.039). Low HDL-C was particularly associated with disease
severity (
p
=
0.004). A positive family history was also found to be
associated with both severity of stenosis (
p
=
0.002) and number
of vessels involved (
p
=
0.001). Hypertension (
p
=
0.36), diabetes
(
p
=
0.88), the MetS (
p
=
0.80) and smoking (
p
=
0.70) were not
associated with disease severity. An association with severity and
increased waist circumference (
p
=
0.08) and generalised obesity
(
p
=
0.08) was shown but this was not significant.
To determine the relationship between risk factors and
occlusive CAD, a chi-squared test was conducted with
dyslipidaemia, obesity, smoking, family history, hypertension,
diabetes or the MetS as independent factors and occlusive
CAD as the dependent factor. On bivariate analysis, a strong
association between dyslipidaemia and occlusive CAD was
observed (
χ
2
=
11.717,
p
=
0.001, RR
=
5.52) while major risk
factors such as hypertension (
p
=
0.30), diabetes (
p
=
0.59)
smoking (
p
=
0.14), family history (
p
=
0.16) and the MetS (
p
=
0.93) were not associated with occlusive CAD.
To determine the effect of the MetS in combination with
other risk factors on the severity of CAD, a two-way ANOVA
analysis was conducted with the coronary artery score as the
dependent variable and the MetS as the grouping variable, along
with various risk factors. Generalised obesity (BMI
>
30 kg/m
2
)
in combination with the MetS appeared to influence severity
of stenosis (
p
=
0.004); however, a strong association was not
demonstrated with smoking (
p
=
0.85) or family history of
CAD (
p
=
0.591). When assessed independently of the MetS, the
combination of raised triglycerides and low HDL-C influenced
severity of stenosis (
p
=
0.05) but not number of vessels involved
(
p
=
0.33).
To further assess the association of various risk factors with
significant CAD, a binomial regression analysis was conducted
with significant CAD as the dependent variable and gender,
ethnicity, cardiovascular risk factors and the presence or absence
of the MetS as covariates. For ethnicity, three dummy variables
were created and compared with Indians as the baseline;
similarly with regard to age, an age range of 20−24 years was
taken as baseline for comparison, and 25−30 and 31−35 years
were assigned dummy variables. Only dyslipidaemia showed a
significant association with occlusive CAD (
p
=
0.008, OR: 0.21,
95% CI: 0.670–0.672).
Discussion
In this study, young adults comprised 1.3% of subjects with
CAD referred for coronary angiography, and the majority
presented with acute coronary syndrome. While often regarded
as a disease of advancing age, atherosclerotic changes in the
coronary vessels have been documented early in adolescence,
29
with changes in lifestyle and dietary habits
30-32
contributing to
CAD becoming clinically manifest early in the third decade of
life,
8
particularly among certain ethnic groups such as the Indian
population.
8-10
The observation that CAD prevalence differs significantly
among ethnic groups is in agreement with earlier studies
that
have shown a 50% higher risk of CAD among expatriate Indians
compared to other ethnic groups such as Hispanics and blacks,
33
even after adjusting for lifestyle factors.
34
The majority of
subjects in our study were of Indian origin (79%), of whom 53
(81%) were diagnosed with occlusive CAD. The data are also in
agreement with the CADI study, which estimated a higher risk
of CAD among Indians.
35
Our findings suggest that young patients are less likely to
present with symptoms of stable angina,
36
their first manifestation
of CAD being most often an ACS, which untreated or
unrecognised, progressed rapidly to MI, STEMI in particular.
37,38
Up to two-thirds of young subjects deny a history of chest pain
prior toMI;
39
when present, angina symptoms have been reported
to occur most often in the week preceding the event.
37
A study
of 200 subjects under 45 years of age with angiographic CAD
found a lower incidence of stable angina (24%) and a higher
incidence of ACS (76%) compared to subjects over 60 years, with
a higher likelihood of complex lesions on angiogram.
38
Similar to previous studies in young subjects,
40-43
smoking was
highly prevalent in our sample, and conferred a greater risk (OR
2.9) among Indian and white subjects. Our findings also confirm
a male preponderance in young subjects with CAD,
37,44,45
which
has been attributed the higher prevalence of smoking among
young men and to non-modifiable factors such as the protective
effect of oestrogen in women.
25
The 82% prevalence of smoking
in our study is in keeping with registry data of patients with
STEMI undergoing percutaneous coronary intervention (PCI)
where smoking rates were highest among the age range of 18–34
years (78%) compared both to older age groups and the general
population of similar age (23%).
46
Since other cardiovascular risk
factors were also highly prevalent in our study, it is likely that