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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 30, No 6, November/December 2019
AFRICA
333
defects. Global hypokinesia was evident in 52.5% of patients.
There were 183 (77.5%) patients with a left ventricular ejection
fraction (LVEF) less than 40%. One hundred and thirty-one
patients (55.5%) had viable myocardium exceeding 10% of the
total myocardium. This translated to a perfusion–metabolism
mismatch pattern (hibernating myocardium) seen in 586 of the
1 862 segments with perfusion defects (31.5%).
Predictors of myocardial viability: The univariable analysis
showed an association between myocardial viability and
hypertension, diabetes mellitus, oral beta-blocker therapy,
aspirin, statins and the resting LVEF. Aspirin intake and
hypertension were the only independent predictors of viable
myocardium in the multivariable regression model (Tables 2, 3).
Discussion
In our pilot study, the prevalence rate of myocardial viability was
55.5%. Auerbach
et al
. previously reported a myocardial viability
prevalence rate of 55.0% (using a 19-segment model) in patients
with ischaemic heart disease.
8
Schinkel
et al
. also used PET to
assess the prevalence of myocardial hibernation in 104 patients
with ischaemic heart disease and reported a prevalence of 61%.
9
Unlike our study, Schinkel
et al
. used a 16-segment model and
functionally significant myocardial viability was defined as the
presence of viability in four or more myocardial segments.
Despite different cut-off values to define functionally significant
myocardial viability, our study cohort had similar demographic
and clinical characteristics to the two European study populations
mentioned above. These similarities included age, gender, ethnicity
and the extent of left ventricular systolic dysfunction.
8,9
PET is a well-established, non-invasive tool for evaluation
of myocardial viability in patients with coronary artery disease.
Patients with segments of the myocardium demonstrating
reduced or absent perfusion and preserved F18-FDG uptake
are subsequently selected for coronary revascularisation.
Percutaneous coronary intervention or coronary artery bypass
grafting have been associated with an improvement in left
ventricular function.
10
Fig. 2.
Resting technetium-99m sestamibi gated single-photon emission computed tomography (SPECT) perfusion images in the
first, third and fifth rows. Fluorine-18 fluorodeoxyglucose positron emission tomography (F18-FDG PET) cardiac images
(second, fourth and sixth rows). All segments of the myocardium with reduced perfusion demonstrate a perfusion–metabo-
lism mismatch pattern (myocardial viability) (red arrows), except the apex with matched perfusion and metabolism (infarcted
tissue) (white arrows).