39 / 82
CARDIOVASCULAR JOURNAL OF AFRICA • Volume 29, No 1, January/February 2018
AFRICA
37
As per unit policy, all young subjects diagnosed with ACS/
CAD undergo coronary angiography. Patients referred for
coronary angiography for reasons other than assessment of CAD
(such as chest trauma or prior to elective valve replacement) were
not included. Patients were identified using the Speedminer
software program, which is a Data Warehouse Management
software package, used by the hospital to manage, process and
categorise the data collected on its database. All patient charts
were accessed via the software program and data were extracted
on demographics, clinical and biochemical parameters, as well as
investigations including SestaMIBI and coronary angiography.
Clinical and biochemical parameters were assessed to
determine the risk-factor profile as well as factors that could
influence the clinical outcome of patients. In addition to the
metabolic syndrome criteria (see below), other parameters
included in the analysis were: body mass index, total cholesterol
>
4.5 mmol/l, low-density lipoprotein cholesterol (LDL-C)
>
1.8
mmol/l, glycated haemoglobin (HbA
1c
)
>
6.5%, haemoglobin
<
13 g/dl for males,
<
12 g/dl for females, microalbuminuria 30–300
mg/l and proteinuria
>
300 mg/l.
The International Diabetes Federation consensus criteria
(harmonised definition) (2006) were used to detect subjects with
the metabolic syndrome (MetS)
27
when they had at least three
of the following factors: central obesity [waist
>
94 cm in males
(90 cm in Indians) and
>
80 cm in females], triglycerides
>
1.7
mmol/l, high-density lipoprotein cholesterol (HDL-C)
<
1.03
mmol/l in males or
<
1.29 mmol/l in females, blood pressure
>
130/85 mmHg (or previously diagnosed hypertension) and
fasting plasma glucose
>
5.6 mmol/l (or previously diagnosed
type 2 diabetes mellitus).
Coronary stenosis of ≥ 50% in any of the major coronary
arteries was designated occlusive CAD, and stenosis of
<
50%
non-occlusive coronary disease (NOD). For scoring the severity
of CAD, luminal stenosis of 50% of the proximal coronary
artery was given a score of 1, 50–74% of 2, 75–99% was scored
as 3 and total occlusion was scored as 4.
28
Statistical analysis
Statistical Package for the Social Sciences (SPSS version 23.0)
was used for data analysis. A 95% confidence interval (CI)
was estimated and a global significance level of
α
=
5% was
chosen. Simple descriptive analysis was used to identify clinical
characteristics and present results as frequencies, means and
percentages.
The chi-squared test and Mann–Whitney
U
-test were used
for categorical variables to determine the relationship between
discontinuous variables or continuous variables in assessing the
significance of risk factors between subjects with and without
angiographic CAD. Binary logistic regression analysis was used
to analyse confounding factors when assessing the independent
relationships between risk factors and the outcome variable
(CAD). A two-way ANOVA analysis was used to assess the
effect of clinical criteria and other risk factors on the presence or
absence of the metabolic syndrome and the likelihood of CAD.
Results
During the 10-year study period (January 2003 to December
2012), 7 575 subjects withCADunderwent coronary angiography.
Among this group, 100 subjects were 35 years or younger,
constituting 1.3% of all subjects with coronary disease referred
for coronary angiography. These subjects (90 males, 10 females)
had a mean age of 31.9 years (median 27.5 years) and 23
were under 30 years of age. The ethnic distribution showed a
predominance of Indian subjects (79%) (Table 1).
The majority of subjects (
n
=
93) were referred from their base
hospital following a diagnosis of acute coronary syndrome. Most
(82%) presented with ‘typical’ acute ischaemic chest pain, while
atypical chest pain symptoms (sharp, stabbing pain; symptoms
suggestive of dyspepsia or heartburn) were reported in 18 cases
(18%).
Sixty-six patients (66%) had STEMI, 45 of whom received
thrombolytic therapy on admission at the base hospital prior to
referral. The reason most often cited for failure to administer
thrombolysis in the remaining 21 patients was late presentation
(
>
24 hours since onset of chest pain). A further 13 patients were
referred with NSTEMI, and 14 patients presented with unstable
angina. Six subjects presented with chronic stable angina and
were referred following positive exercise stress tests. One patient
presented with symptomatic bradycardia (complete heart block)
(Table 1).
Varying combinations of cardiovascular risk factors were
present (Table 1) in all but one subject, a 32-year-old black male
who presented with chronic stable angina, no cardiovascular risk
factors and he had single-vessel disease at angiography.
The two most common risk factors identified were smoking
(82%) and dyslipidaemia (79%) (Table 1). The dyslipidaemia
comprised hypercholesterolaemia (67.4%), hypertriglyceridaemia
(63.7%) and low HDL-C (56.5%). In the 87 patients in whom
LDL-C could be calculated by the Friedewald formula, 78 (90%)
were found to have levels greater than 1.8 mmol/l (Table 2). The
atherogenic combination of raised triglycerides (TG) and low
HDL-C was found in 30 subjects.
Table 1. Demographic profile of the patients
Characteristics
n
=
100
Median age (years)
33
Ethnicity
Indian
79
White
11
Black
7
Coloured
3
Presentation
STEMI
66
NSTEMI
13
Chronic stable angina
6
Unstable angina
14
Symptomatic bradycardia
1
Risk profile
Smoking
82
Hypertension
28
Diabetes
26
Dyslipidaemia
80
Obesity
30
Family history
74
Illicit drug use
8
Retroviral disease
2
Systemic lupus erythematosus
1
NSTEMI: non-ST-segment elevation MI; STEMI: ST-segment elevation MI
.