Cardiovascular Journal of Africa: Vol 28 No 2 (March/April 2017)

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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 28, No 2, March/April 2017 AFRICA 81
The role of coronary artery collaterals in the preservation
of left ventricular function: a study to address a long-
standing controversy
NO Ajayi, EA Vanker, KS Satyapal
Abstract
Introduction: The functional significance of coronary artery
collateral (CAC) vasculature in humans has been debated for
decades and this has been compounded by the lack of a stand-
ard, systematic, objective method of grading and document-
ing CAC flow in man. CACs serve as alternative conduits for
blood in obstructive coronary artery disease. This study aimed
to evaluate the impact of CACs on left ventricular function in
the presence of total coronary arterial occlusion.
Methods: The study group included the coronary angiograph-
ic records of 97 patients (mean age: 59 ± 8 years). CACs were
graded from 0–3 based on the collateral connection between
the donor and recipient arteries. Left ventricular function was
computed from the ventriculogram and expressed as ejection
fraction (EF).
Results: The mean EF of the patients with grades 0, 1, 2 and 3
CACs were calculated as 50.4, 47, 60.5 and 70%, respectively.
A significant difference was recorded in the mean EF calcu-
lated for the different CAC grades (p = 0.001). There was a
significant positive correlation (p < 0.001; r = 0.478) between
the mean EF and the CAC grades.
Conclusion: The patients with better coronary collateral
grades had a higher mean EF. Therefore, as the grade of
CACs increased, there was an improvement in their ability to
preserve left ventricular function.
Keywords: coronary artery obstruction, coronary collateral
artery, left ventricular function
Submitted 29/5/15, accepted 16/4/16
Cardiovasc J Afr 2017; 28: 81–85
DOI: 10.5830/CVJA-2016-054
Controversy has existed for decades regarding the functional
significance of coronary artery collaterals (CACs) in humans,1
and this has been compounded by the lack of a standard
systematic method for determining CAC flow in man.2,3 These
CACs are reported to have a protective effect on myocardial
perfusion and contractile function, and to prevent left ventricular
(LV) aneurysm formation in the presence of severe coronary
artery obstruction.4,5 The presence of collateral vessels may play
a major role in determining whether the patient will develop
symptoms of myocardial ischaemia and vulnerability of the
myocardium to myocardial infarction.6
The use of coronary angiography allows correlation of the
extent of development of CACs with the severity of coronary
arterial disease.7,8 The presence of functional collateral vessels
can be of important prognostic value and can also assist
in determining the need for intervention and the type of
interventional procedure to be performed.9,10 Indeed, the presence
of well-developed coronary collateral vasculature and flow has
been correlated with the absence of ischaemic symptoms in
patients with established coronary artery disease (CAD).11
Meier and colleagues,12 in an analysis of previous studies on
the effect of coronary collaterals on mortality, reported that
well-developed collaterals reduced the mortality rate in the order
of 35%. The presence of adequately developed collateral supply
limits the degree of myocardial necrosis during myocardial
infarction.8,13 The area at risk of myocardial infarction is
inversely related to the collateral supply to that region, and
therefore becomes zero in the presence of well-developed
functional collaterals.14-16 In cases of unsuccessful intra-coronary
thrombolytic therapy after the onset of symptoms in acute
myocardial infarction, the improvement in LV function and
wall motion in the infarct region have been associated with
the presence of collateral flow to the region perfused by the
obstructed vessel. 5,17
However, some reports have cast doubt on the value of CACs.
Banerjee reported that the presence of CACs had no protective
role on the incidence of LV aneurysm formation following
myocardial infarction.18 Ilia et al .19 also reported that there
was no correlation between the characteristics of CACs and
the presence or absence of LV systolic abnormality in patients
with significant CAD. Furthermore, Turgut et al.20 stated that
coronary collaterals did not have a protective role on preservation
of LV function in the presence of severe left anterior descending
artery stenosis. Meier et al. also reported that the development
of good CACs increased the risk of restenosis after percutaneous
coronary intervention.21 In view of these controversies, our study
was undertaken to evaluate the effect of CACs on LV function
in the setting of a totally occluded coronary artery demonstrated
on angiogram.
Methods
The study group was selected from the reviewed angiographic
records of 2 029 consecutive patients (mean age: 59 ± 12
Department of Clinical Anatomy, School of Laboratory
Medicine and Medical Sciences, College of Health
Sciences, University of KwaZulu-Natal, Westville, Durban,
South Africa
NO Ajayi, MB BS, MMed Sc, PhD
KS Satyapal, LRCP, LRCS, LM, MD, FICA (USA), FRCP (Irel), LLM
(Medical Law),
St Augustine’s Hospital, Chelmsford Medical Centre,
Durban, South Africa
EA Vanker, MB ChB, FRCS