Publication: The Australian perspective on premature coronary artery disease: prevalence and risk factors

The Australian perspective on premature coronary artery disease: prevalence and risk factors.
Gilhotra RG, Gunnarsson RG, Sutcliffe SS.
Boston, MA, USA: 12th Annual Cardiometabolic Health Congress 2017; 2017.


Purpose: Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in the world as reported by the World Health Organization. CVD is a group of disorders encompassing Coronary Artery Disease (CAD), cerebrovascular disease, and peripheral arterial disease. Shifting our attention to CAD, CAD claimed the lives of over 20,000 Australians in 2012. Not only is the incidence of CAD on the rise, it is also estimated that about 4–10% of individuals with documented CAD are below the age of 45, referring to this phenomenon as Premature Coronary Artery Disease (PCAD). Whilst there is a relatively good understanding of CAD in Australia, there is very limited amount of research conducted in the field of PCAD. The reported prevalence of PCAD ranges from 25% to 31% in other countries and as far as we know there is no study in Australia that elaborates on the prevalence of PCAD, let alone the risk factors for PCAD. Furthermore, the true prevalence of PCAD is also believed to be underestimated, as symptomatic CAD at a young age is relatively uncommon. The primary outcome of this study was to gain a greater understanding of the prevalence and risk factors for PCAD. The secondary outcomes included the development of a prediction model that could be used to predict the outcome of the coronary angiogram based on an individual’s risk factor profile. Furthermore, this study aimed to determine the factors that correlate to a normal coronary angiogram; in other words, to determine the protective factors against PCAD. Methods: Patients who underwent coronary angiography at the Cairns Hospital between 1 January 2014 and 31 December 2016 were included in the study. The patients had to be equal to or less than the age of 50 years at the time of the procedure. Patients were excluded from the study if they had multiple coronary angiograms conducted in the time frame (between 1 January 2014 and 31 December 2016). Only the first coronary angiogram conducted on a particular individual in the given time frame was included in the study. A National Ethical Application Form (NEAF) was applied to the Far North Queensland Human Research Ethics Committee (HREC). The HREC approval number is HREC/16/QCH/4-1022. Furthermore, a Public Health Act application (PHA) and Site-Specific Application (SSA) was also completed and approved. A total of 635 coronary angiograms were conducted at the Cairns Hospital between 1 January 2014 and 31 December 2016 on patients who were ≤50 years of age at the time of the procedure. Eighty-two cases were excluded from the study due to repeated angiograms during this time frame. The final number included in the study was 553 patients. Demographic factors included in this study were age, gender, and ethnicity. Clinical risk factors included were history of diabetes mellitus (DM), hypercholesterolemia, smoking, hypertension, family history of CAD, and body mass index (BMI). The biochemical or laboratory risk factors that were included were blood glucose levels, red blood cell count, white blood cell count, neutrophil to lymphocyte ratio, and hemoglobin and creatinine levels. Results: We identified a high prevalence of 64% of PCAD amongst Australian patients undergoing coronary angiography at the Cairns Hospital. Half of the recruited individuals were of Aboriginal and/or Torres Strait Islander background. Furthermore, 57% of the individuals with PCAD in the study were of Aboriginal and/or Torres Strait Islander background. However as per the 2011 census, only 9% of the population in the Cairns region was represented by people with an Aboriginal and/or Torres Strait Islander background. We investigated for protective factors against PCAD and identified factors such as increasing age (5-year intervals) (odds ratio (OR) = 0.67 (0.55–0.81; p = 0.000026), male gender (OR = 0.40 (0.25–0.65); p = 0.00023), Aboriginal and/or Torres Strait Islander background (OR = 0.49 (0.29–0.81); p = 0.005), hypercholesterolemia (OR = 0.41 (0.25–0.66); p = 0.00027), smoking (OR = 0.45 (0.28–0.73); p = 0.001), white cell count (OR = 0.92 (0.86–0.99); p = 0.042), and blood glucose levels (OR = 0.91 (0.83–0.99); p = 0.032) to be statistically significant after multivariate forward stepwise logistic regression. Furthermore, we identified that when comparing the group with pathological coronary angiogram results to the group with normal coronary angiogram results, there was a mean age difference of 2 years, with the pathological group being 2 years older. Similarly, when comparing mean glucose levels within the two groups, the pathological angiogram results group had a mean glucose level of 8.6 mmol/L as compared to a lowly 6.7 mmol/L in the normal results group. The pathological results group also had worse renal function, with a mean creatinine level of 110 umol/L as compared to 85 umol/L in the normal angiogram group. Lastly, the mean neutrophil to lymphocyte ratio, a marker for systemic inflammation, was also higher in the pathological coronary angiogram results group, 8.6 as compared to 6.7 in the normal coronary angiogram results group. Conclusions: We concluded that there is a high prevalence of PCAD within the Cairns region and also amongst the Australian Indigenous patients undergoing coronary angiography at the Cairns Hospital. Other strongly associated risk factors with PCAD include increasing age, male gender, hypercholesterolemia, smoking, white cell count, and blood glucose levels.

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