CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 6, July 2012
AFRICA
313
Association between plasma homocysteine and
myocardial SPECT abnormalities in patients referred for
suspected myocardial ischaemia
ALFRED ANKRAH, JOHN BUSCOMBE, MIKE MACHABA SATHEKGE
Abstract
Background:
Elevated plasma homocysteine level has
emerged as a relatively newly recognised risk factor for coro-
nary artery disease (CAD). However, reduction of plasma
homocysteine levels in large prospective studies did not
appear to reduce the risk for subsequent cardiac events. In
this study, we investigated the association between plasma
homocysteine levels and quantitative indices of myocardial
perfusion SPECT imaging in patients referred for myocar-
dial ischaemia.
Methods:
Quantitative myocardial perfusion SPECT indices
were obtained for 120 patients who were recruited for the
study. All patients underwent a two-day rest–stress myocar-
dial perfusion imaging. Plasma venous sampling was done on
all patients after an overnight fast. Of the 120 participants
(mean age 56 years, 53% males), 33% had elevated plasma
homocysteine levels. The plasma homocysteine level was then
compared to the results of imaging and other known risk
factors.
Results:
After adjustment for traditional risk factors of
coronary artery disease, patients with elevated homocysteine
levels had a significantly higher mean summed stress score
(SSS) (11.3 vs 6.9,
p
=
0.02) than patients with a normal
homocysteine level. This was true for both single- and multi-
vessel disease. Also, patients with elevated homocysteine
levels had a higher stress end-systolic volume (SESV) (137 vs
105 ml,
p
=
0.03) and lower post-stress left ventricular ejec-
tion fraction (SEF) (54 vs 64%,
p
=
0.02). The patients with
elevated plasma homocysteine levels also had a significantly
lower mean body mass index (BMI) (26.6 vs 30.6 kg/m
2
,
p
=
0.002). There was a significant relationship between the total
number of known risk factors in a patient with CAD and
the proportion of patients presenting with elevated plasma
homocysteine levels (
p
=
0.03). Also, the extent of infarct, as
measured by the summed rest score (SRS), was more closely
correlated with an elevated homocysteine level than with the
degree of ischaemia.
Conclusion:
There was a correlation between plasma homo-
cysteine level and the presence and extent of myocardial
perfusion abnormalities in patients with established coro-
nary artery disease, in particular those with multiple risk
factors and multi-vessel infarction.
Keywords:
plasma homocysteine, coronary artery disease,
myocardial SPECT indices, myocardial ischaemia
Submitted 15/4/11, accepted 6/9/11
Cardiovasc J Afr
2012;
23
: 313–317
DOI: 10.5830/CVJA-2011-048
In the past two decades, plasma homocysteine level has been
extensively investigated and proposed as an independent
cardiovascular disease risk factor.
1
An elevated homocysteine
level was first shown to be a risk factor for coronary artery
disease (CAD) and later an independent risk factor for
thromboembolism.
2
Elevated homocysteine level has been linked
in many studies to greater risk of adverse cardiovascular disease
outcomes, which include myocardial infarction, stroke and
cardiovascular mortality.
3-7
However, clinical trials have not been able to demonstrate a
reduction in clinical cardiovascular endpoints after therapeutic
reduction of plasma homocysteine levels.
8
This is in contrast to
the outcome with other traditional risk factors of CAD, such as
lowering plasma cholesterol levels. This is at variance with animal
studies, which have shown that elevated homocysteine level is
associated with increased cardiac dysfunction, and that lowering
plasma homocysteine levels with folic acid may have a beneficial
effect.
9
The relationship between homocysteine level and
myocardial dysfunction, and the potential therapeutic usefulness
of lowering plasma homocysteine level is still being explored.
Myocardial perfusion SPECT is a validated imaging
technique providing for both diagnosis and risk stratification
of the possibility of future cardiac events.
10
Validated automated
algorithms provide semi-quantitative assessment of myocardial
perfusion and left ventricular systolic function.
11
In this study we
aimed to assess the correlation between homocysteine level and
myocardial SPECT abnormalities in 120 patients with suspected
myocardial ischaemia.
Methods
This prospective, open-label trial, approved by the ethics
committee of the University of Pretoria, Faculty of Health
Science, was designed to evaluate the association between
homocysteine level and myocardial SPECT abnormalities. A
total of 120 patients referred to our department with suspected
myocardial ischaemia for myocardial perfusion imaging were
recruited, after giving informed consent.
Information was obtained from each patient concerning
any history of hypertension, diabetes mellitus, smoking
and dyslipidaemia. Each patient’s weight and height were
recorded. Exclusion criteria included pregnancy, use of vitamin
supplementation (for more than five days a week in the previous
three months), and renal insufficiency (defined as creatinine
Department of Nuclear Medicine, University of Pretoria and
Steve Biko Academic Hospital, Pretoria, South Africa
ALFRED ANKRAH, MD
JOHN BUSCOMBE, MB ChB, MD
MIKE MACHABA SATHEKGE, MB ChB, MMed (Nucl Med), PhD,
