CARDIOVASCULAR JOURNAL OF AFRICA • Volume 34, No 2, May/June 2023 96 AFRICA relationship between the LAD–LCX angle measured by coronary CT angiography and the severity of LAD coronary stenosis. Patients with angles more than 75° had more significant LAD stenosis than those with smaller angles. Sun et al.19 also used CT coronary angiography and they reported an LAD–LCX angle of 94 ± 19° in patients with significant LAD stenosis, versus 75 ± 19° in patients with a normal LAD. Similarly, RodriguezGranillo et al.20 reported a cut-off value of 88.5° could predict significant ostial to mid LAD and LCX disease, and they concluded that the left main bifurcation angle and severity of the plaques are closely related. In our study, we assessed the LM bifurcation angle during coronary angiography using automated software (IC MEASURE), and to our knowledge, the association between bifurcation angle and the severity of proximal LAD stenosis has not been investigated before by invasive coronary angiography in patients who had no previous PCI. The angles of LM–LAD and LAD–LCX in our report were wider in patients with significant proximal LAD disease than in those with non-significant disease (60.91 ± 25.93 vs 38.91 ± 21.33° and 84.55 ± 32.98 vs 68.01 ± 28.12°, respectively). The cut-off value of 42° of the LM–LAD angle had a sensitivity of 73% and specificity of 70% to predict significant proximal LAD stenosis. The cut-off value of 68° of the LAD–LCX angle had a sensitivity of 68% and specificity of 62% to predict significant proximal LAD stenosis. The bifurcation angles retained statistical significance in a multivariate logistic regression analysis. In this study, patients with significant proximal LAD stenosis were older than those with non-significant disease. Age has a role in worsening of vascular functionality, increasing the risk of cardiovascular disease. There is a direct relationship between age and prevalence of cardiovascular disease.21,22 In addition, in this study, patients with significant LAD stenosis demonstrated higher LDL-C values and higher prevalence of diabetes mellitus than those with non-significant LAD stenosis. Diabetes mellitus and dyslipidaemia are risk factors for cardiovascular disorders.23 Studies have shown that the administration of statins and thiazolidinedione (pioglitazone and rosiglitazone) causes a significant regression of the coronary atherosclerotic plaques and they can be used in the secondary prevention of cardiovascular disease.24-26 A wide angle between the LM and LAD could predict in-stent restenosis after stenting of the proximal LAD, as reported by Konishi et al.27 The effect of the bifurcation angle on 12-month outcome after stenting of the LM–LAD was investigated by Amemiya et al.28 The angle was evaluated by three-dimensional quantitative coronary angiography analysis. They reported a significant relationship between the pre-procedure bifurcation angle and adverse cardiac events. In a sub-study of the SYNTAX trial, the bifurcation angle had an impact on five-year outcome after stenting of the main left coronary artery.29 A LM–LAD angle of more than 152° during LM bifurcation stenting was associated with a greater risk of target lesion failure in the crush technique.30 Our study had some limitations. It had a limited sample size and was conducted at a single medical centre. Its findings should be confirmed in additional centres with a larger sample size. Assessment of the severity of LAD stenosis by intravascular ultrasound was unavailable. The results should be confirmed in further investigations employing intravascular ultrasound. Conclusion Wider LM–LAD and LAD–LCX angles were associated with severity of proximal LAD stenosis. Preventative measures and close follow up are needed in such cases to improve the cardiovascular outcome. References 1. Cunningham KS, Gotlieb AI. The role of shear stress in the pathogenesis of atherosclerosis. Lab Invest 2005; 85(1): 9–23. 2. Siasos G, Sara JD, Zaromytidou M, et al. Local low shear stress and Table 4. Univariate and multivariate logistic regression analysis for the parameters affecting coronary artery disease Parameters Univariate Multivariate p-value OR (95% CI) p-value OR (95% CI) Age, years < 0.001 1.048 (1.024–1.073) 0.001 1.054 (1.022–1.088) Females 0.321 0.754 (0.431–1.317) Diabetes mellitus 0.014 2.209 (1.177–4.147) 0.366 1.502 (0.621–3.629) Hypertension 0.069 1.999 (0.948–4.215) Dyslipidaemia 0.360 1.325(0.726–2.417) Smoking 0.290 1.458 (0.725–2.935) Total cholesterol 0.039 0.991 (0.982–1.0) 0.831 0.996 (0.965–1.029) LDL-C 0.049 0.991 (0.982–1.0) 0.681 0.993 (0.960–1.027) HDL-C 0.969 1.001 (0.964–1.039) Triglycerides 0.366 0.998 (0.992–1.0) Creatinine, mg/dl < 0.001 0.090 (0.025–0.326) LVEF, % < 0.001 0.895 (0.855–0.936) 0.001 0.913 (0.866–0.963) LM–LAD angle < 0.001 1.039 (1.025–1.053) < 0.001 1.094 (1.053–1.137) LAD–LCX angle < 0.001 1.018 (1.008–1.028) 0.001 0.951 (0.924–0.978) HDL-C: high-density lipoprotein cholesterol, LDL-C: low density lipoprotein cholesterol, LVEF: left ventricular ejection fraction, LM: left main coronary artery, LAD: left anterior descending artery, LCX: left circumflex artery, OR: odds ratio, CI: confidence interval, LL: lower limit, UL: upper limit. Source of the curve LM–LAD angle LAD–LCX angle Reference line Fig. 3. ROC curve for the LM–LAD and LAD–LCX angles for prediction of LAD stenosis.
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