Browsing by Author "Aldous, Colleen"

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    A comparison of coronary angiography and myocardial perfusion studies, using quantitative scoring systems
    (South African Heart Association, 2021) Premsagar, Preesha; Aldous, Colleen; Esterhuizen, Tonya
    Background: Results of myocardial perfusion for screening coronary artery disease (CAD), and angiography for diagnosing CAD, can be quantified using summed difference score (SDS) and Synergy between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery (SYNTAX) score, respectively. Aim: The aim is to quantitatively compare myocardial perfusion studies with angiography amongst South African patients using scoring systems. Methods: SDS on myocardial perfusion and SYNTAX score on angiography were compared. Regional scores within each vessel (left anterior descending (LAD), circumflex and right coronary artery (RCA)) were also compared. Scores were further risk categorised and evaluated. Results: The weak correlation between SDS and SYNTAX score (rs=0.210, p=0.015), became slightly negative when SYNTAX scores were stratified into low and intermediate-high risk groups. Regionally, LAD had very slight positive correlation (rs=0.171, p=0.048), circumflex (rs=0.164, p=0.058), and RCA (rs=0.116, p=0.184) no correlation. Conversely, comparison of scores categories was signifi cant (p=0.001). Conclusions: Inherent differences in the design of 2 scoring systems that evaluate the LAD territory may explain these findings. These differences were dominance, regional blood flow distribution and significant luminal diameter reduction. This study highlights the need to interpret myocardial perfusion results contextually during CAD screening.
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    The value of exercise stress testing in prediction of angiography amongst South African patients using quantitative scoring systems
    (South African Heart Association, 2021) Premsagar, Preesha; Aldous, Colleen; Esterhuizen, Tonya
    Background: Accurate pre-test assessment of high risk patients may increase positive yield on angiography. Exercise stress testing (EST) prediction of angiography, may be evaluated by Duke Treadmill Score (DTS), and Synergy between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery (SYNTAX) score, respectively. Aim: To investigate the value of EST in prediction of angiography amongst South African patients using quantitative scoring systems. Methods: The DTS and SYNTAX score were compared in patients with high risk pre-test assessments selected for angiography. Logistic regression modelling determined the odds ratio of abnormal angiograms using EST as a predictor. Results: Pre-test assessment of 525 suspected coronary artery disease patients, indicated angiography in 131 high risk individuals. The positive yield of abnormal angiograms was 58.0%, with no correlation between DTS and SYNTAX scores (Pearson’s correlation coefficient = 0.113, p=0.200). There was low predictive probability on receiver-operator-curve for DTS when compared to angiogram results (area under curve (AUC)=0.529, p=0.574), and SYNTAX categories (AUC=0.432, p=0.378). Chi-square tests had no significance between angiography and EST (all p-values >0.05). However DTS predicted abnormal angiograms with odds ratio of 1.92 when relevant cardiovascular risk factors (smoking, BMI, age) were added. Conclusion: Pre-test assessment of high risk patients represented a homogenous group with prevalent cardiovascular risk factors. However, the high risk group had no relationship between DTS and SYNTAX scores, indicating DTS alone discounts risk factors. Modelling accounted for DTS limitation by demonstrating an obese, elderly smoker with high risk category DTS is 1.92 times more likely to have an abnormal angiogram.