Assessing coronary artery disease severity through transient ischemic dilation: evidence from MPS and SYNTAX scoring

Introduction The Transient Ischemic Dilation (TID) ratio, derived from the ratio of left ventricular (LV) volumes during stress and rest phases in Myocardial Perfusion SPECT (MPS), is a reliable marker of severe coronary artery disease (CAD). It reflects global myocardial hypoperfusion caused by extensive CAD and may manifest even in patients with atypical angina. Method This retrospective cohort study analyzed patients with chronic coronary syndrome (CCS) who underwent MPS using Tc-99m sestamibi with an adenosine pharmacologic stress test and coronary angiography between January 2022 and April 2023. MPS and angiography were performed in any sequence, provided no revascularization procedure occurred between the two examinations. Patients were categorized into mild and moderate-severe CAD groups based on the Syntax score. An unpaired t-test was conducted to compare mean TID values between groups. Results A total of 93 patients (mean age: 55.87 ± 7.44 years) were included. TID values were significantly higher in the moderate-severe CAD group compared to the mild CAD group (1.03 ± 0.11 vs. 0.906 ± 0.13; p < 0.001). Bivariate analysis revealed that the TID ratio was significantly associated with LV end-systolic volume (ESV) and end-diastolic volume (EDV) during the stress phase of MPS (p = 0.001). Conclusion The TID ratio is strongly correlated with CAD severity, as determined by the Syntax score, with elevated values indicating moderate-to-severe CAD. This supports the concept that the TID ratio reflects LV volume changes during stress and rest phases and is proportional to the severity of myocardial hypoperfusion.