CARDIOVASCULAR JOURNAL OF AFRICA • Volume 34, No 2, May/June 2023 94 AFRICA The procedure of coronary angiography was performed by a team of well-established cardiologists. A Siemens machine was used (AXIOM-Artis, Siemens, Forchheim, Germany). The procedure was performed according to the standard Seldinger technique. Radial arterial access was used in 44 patients and femoral arterial access in 156 patients. Images were recorded at frames per second at a resolution of 512 × 512 pixels for analytical purposes. Standard angiographic views were used in the assessment of the coronary arteries (anteroposterior, left anterior oblique, right anterior oblique) in cranial and caudal projections. A quantitative coronary angiography software program was used to determine the severity of coronary artery stenosis (QCA Analysis, Siemens, Germany).14 The diameter of the minimum lumen was determined in projections exhibiting the most extreme narrowing. According to the absence or presence of proximal LAD stenosis, patients were divided into two groups. Significant coronary stenosis was defined by more than 50% luminal diameter reduction.15 The LM bifurcation to the LAD and LCX was assessed in spider view [left anterior oblique caudal (LAO)] at an angle of 40°, with 30° caudal projection, and in the right anterior oblique caudal (RAO) at an angle of 30°, with 20° caudal projection. The LM–LAD and LAD–LCX angles were measured using automated software (IC MEASURE) in the LAO caudal (spider) view. Still photos (screenshots) were obtained from the spider view angiographic run and lines were manually drawn corresponding to the outer edges of the LM, LAD and LCX arteries. The angles were measured twice at end-diastolic frames and the average of the angles was recorded in order to decrease inter-observer variability (Figs 1, 2). Statistical analysis Data as a whole were gathered and reviewed using the Statistical Package for Social Sciences (IBM SPSS) version 20. Qualitative data are presented as percentages and numbers; for parametric distribution, quantitative data are presented as means, standard deviations (SD) and range; and for non-parametric distribution, quantitative data are presented as medians with inter-quartile range (IQR). When comparing two groups with qualitative data, the chi-squared and Fisher’s exact tests were employed. When comparing two groups with parametric distribution of quantitative data, we used the independent t-test, whereas the Mann–Whitney test was used to compare two groups that had quantitative data but a non-parametric distribution. A receiver operating characteristic (ROC) curve was used to calculate the diagnostic cut-off value of the bifurcating angle. Logistic regression analysis was used to detect factors associated with significant LAD stenosis. The confidence interval (CI) was set at 95% while the acceptable margin of error was set at 5%. As a result, the p-value was considered significant when < 0.05. Results Patients were divided into two groups; the first included patients who had proximal LAD stenosis ≥ 50% (100 patients) and the second those with LAD stenosis < 50% (100 patients). Patients with significant proximal LAD stenosis were older and had a higher frequency of diabetes mellitus, and higher serum creatinine and low-density lipoprotein cholesterol (LDL-C) levels than those with non-significant LAD stenosis. Patients’ characteristics and laboratory data are provided in Table 1. The mean of the angles of the LM–LAD in patients with significant proximal LAD stenosis was wider than in patients with non-significant disease (60.91 ± 25.93 vs 38.91 ± 21.33°, p < 0.001). The mean of the angles of the LAD–LCX in patients with significant proximal LAD stenosis was wider than in patients with non-significant LAD stenosis (84.55 ± 32.98 vs 68.01 ± 28.12°, p < 0.001). The bifurcating coronary angles in the two groups are provided in Table 2. The validity for LM–LAD and LAD–LCX angles to predict Fig. 1. Spider view of a 63-year-old patient with significant LAD stenosis (B). The LM–LAD angle was measured at 62.7° (A). LM: left main coronary artery, LAD: left anterior descending artery. A B
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