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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 29, No 1, January/February 2018
40
AFRICA
smoking acted in concert with these factors to result in CAD.
Our study supports the finding that clustering of major
cardiovascular risk factors predominates in young patients with
CAD.
47,48
In addition to smoking, dyslipidaemia (80%) and a
positive family history of CAD (74%) were the most frequent
risk factors identified.
Analysis of the lipid profile showed that elevated LDL-C
was present in 90% of the 87 subjects in whom it could be
calculated. The atherogenic lipid profile of raised triglycerides
and low HDL-C levels was present in 30% of the sample, and
30% were classified as obese. Major risk factors including
hypertension and diabetes mellitus (28 and 26%, respectively)
were frequently present in this young cohort of subjects with
PCAD, compared to previous studies of older subjects in this
population.
49
Of importance, we have noticed the emergence of
illicit drug use (cannabis, heroin, cocaine and the local street
drug ‘sugars’ containing a mixture including cocaine residue) as
a contributory risk factor in 8% of subjects.
The third most prevalent risk factor among our subjects
was a positive family history of CAD (74%), which influenced
both the extent and severity of CAD (
p
=
0.045 and
p
=
0.002,
respectively). It is well documented that young subjects with
CAD more often have a positive family history than middle-aged
or elderly patients,
50-53
with contributions to this increased risk
from both genetic and environmental factors. In a cohort similar
to ours, Ranjith
et al
. found a family history of premature CAD
in 54% of South African Indians with MI.
11
Parental CAD was a
strong predictor of MI in offspring in the INTERHEART study,
suggesting that in addition to possible genetic factors, similar
environmental exposure contributed to type 2 diabetes mellitus,
hypertension and obesity and the increased cardiovascular
risk.
46,51
Our findings of high prevalence of visceral obesity, high
triglyceride and low HDL-C levels, together with elevated
LDL-C and dysglycaemia, suggest environmental factors as
a major contributor to the emergence of PCAD in young
adults in their third decade of life. The combination of subtle
abnormalities of glucose metabolism
12
with clustering of other
risk factors that comprise the MetS has been recognised as a
significant predictor of CAD.
54
The prevalence of the MetS has been documented to differ
significantly among ethnic groups
54
and between age groups,
rising from less than 10% in the 20–29-year age group to between
38 and 67% in the 60–69-year age group.
55
Almost half the
subjects in our study (48%) met the modified IDF criteria
27
for
the MetS.
In a previous study, Ranjith
et al
.
assessed the prevalence
of the MetS among young (
<
45 years) South African Indian
subjects with MI using the NCEP ATP III and IDF criteria,
and found between 57 and 60% of subjects met the criteria
respectively.
56
This study suggested that use of the modified
IDF ethnic-specific waist circumference cut-off points as the
determinant of abdominal obesity was more useful to accurately
identify patients in this population group. Waist circumference
was the main driver (44/48) for the MetS in our study, reflecting
visceral adipose tissue as a major contributor to the increased
risk of hyperinsulinaemia, insulin resistance, diabetes and
dyslipidaemia in this population.
55
Our finding of higher coronary artery severity (CAS) scores
in association with a positive family history of PCAD and
dyslipidaemia (low HDL-C in particular) is in agreement with
earlier observations.
57
A strong association has been shown
between dyslipidaemia and the presence of occlusive CAD (
p
=
0.004), as well as severity of disease (
p
=
0.002). Although type
2 diabetes mellitus is known to be a strong predictor of CAD,
particularly among groups usually considered ‘low risk’, such as
young patients, women and non-smokers,
58
it did not influence
the extent (
p
=
0.56) or severity of disease (
p
=
0.88) in our study,
probably due to the shorter duration of diabetes in our cohort
of younger subjects, less than 35 years. In contrast to previous
studies that have shown the MetS to be associated with extensive
(three-vessel) disease,
56
neither smoking nor the presence of the
MetS contributed significantly to the severity of CAD.
Multi-vessel involvement was a characteristic angiographic
pattern in our study, with only a third of subjects having
single-vessel disease, in contrast to the findings of the CASS
study, which found a higher frequency of non-occlusive and
single-vessel disease in young subjects,
37
The LAD was the most
frequently involved coronary vessel in both groups, as noted in
a previous study.
59
Limitations
Our study was limited to a specific geographical area and, more
specifically, to a single tertiary referral centre but cases were
referred from throughout the province of KwaZulu-Natal. We
found a much higher prevalence of PCAD among Indians, and
although this ethnic group does not represent a majority in the
province concerned, the community is largely concentrated in
the Durban area. Because of a small sample size, we could not
undertake age and gender matching across race groups, limiting
comparisons on gender and ethnic differences in risk factors.
Fewer ‘conventional’ cardiovascular risk factors, common in the
older population, were found to have a statistically significant
relationship with PCAD in very young patients. Among the
factors that may have contributed to this indeterminate result
include the age range studied and the sample size, which was not
gender matched.
Conclusion
This study shows that over two-thirds of young subjects referred
to a tertiary centre for coronary angiography due to acute
ischaemic chest pain symptoms had atherosclerotic multi-vessel
disease. The predominance of major modifiable risk factors
suggests high environmental exposure in young adults and calls
for early lifestyle changes, beginning at school-going age.
References
1.
Mohammad AM, Jehangeer HI, Shaikhow SK. Prevalence and risk
factors of premature coronary artery disease in patients undergoing
coronary angiography in Kurdistan, Iraq.
BMC Cardiovasc Disord
2015;
15
(1): 1.
2.
Ranjith N, Pegoraro R, Naidoo D. Demographic data and outcome of
acute coronary syndrome in the South African Asian Indian population.
Cardiovasc J S Afr
2004;
16
(1): 48–54.
3.
Klein LW, Nathan S. Coronary artery disease in young adults.
J Am Coll
Cardiol
2003;
41
(4): 529–531.
4.
Tuzcu EM, Kapadia SR, Tutar E,
et al
. High prevalence of coronary