Association of total Q/R ratio with myocardial scar in patients with chronic total occlusion.

INTRODUCTION: Myocardial scar is associated with adverse outcomes in patients with chronic total occlusion (CTO). Electrocardiography (ECG) is a simple and widely available tool that provides valuable information on myocardial ischaemia and scar. AIM: We aimed to evaluate the value of the ECG-derived total Q/R ratio for identifying myocardial scar in patients with CTO and ischaemia on myocardial perfusion scintigraphy (MPS). MATERIAL AND METHODS: In this retrospective study, 283 consecutive patients with myocardial ischaemia on MPS and CTO on coronary angiography were included. Baseline clinical, imaging, and electrocardiographic data were analysed, and multivariate logistic regression and ROC analyses were performed. Myocardial scar was defined as severe fixed perfusion defects on MPS. RESULTS: The total Q/R ratio and left ventricular ejection fraction (LVEF) were independently associated with myocardial scar in multivariate analysis (OR = 2.53, 95% CI: 1.13-5.63, p = 0.02; OR = 0.93, 95% CI: 0.89-0.97, p < 0.001; respectively). The total Q/R ratio demonstrated moderate discriminative ability for myocardial scar (AUC = 0.705, 95% CI: 0.639-0.770, p < 0.001), while LVEF showed higher discriminative performance (AUC = 0.779, 95% CI: 0.719-0.839, p < 0.001). Likelihood ratio analysis supported the dominant contribution of LVEF and total Q/R ratio. CONCLUSIONS: The total Q/R ratio is independently associated with myocardial scar and may provide clinically relevant information for identifying myocardial scar in patients with CTO and ischaemia on MPS.