Coronary sinus filling time in syndrome X: A simple yet reliable marker of microvascular dysfunction

Background: Coronary sinus filling time (CSFT) has emerged as a simple, quantitative, and reproducible marker for microvascular dysfunction (MVD); however, comparative data with other angiographic parameters, such as the corrected thrombolysis in myocardial infarction (cTIMI) frame count and myocardial blush score (MBS), remain limited. Aim and Objectives: This study aimed to evaluate the efficacy of CSFT in detecting MVD and compare it with cTIMI frame count and MBS in patients with angiographically normal coronary arteries. Materials and Methods: A prospective observational study was conducted on 120 patients aged 35–70 years with non-obstructive coronary artery disease (CAD) who presented with angina, non-ST-elevation myocardial infarction, or ST-elevation myocardial infarction. The patients were divided into case (n=60) and control (n=60) groups. CSFT, cTIMI frame count, and MBS were assessed using coronary angiography. Statistical analyses included mean comparisons and relative risk calculations. Results: The case group included 63.3% females and 36.7% males. Angina was the most common presentation (75%). Mean CSFT was significantly prolonged in cases compared to controls (43.8±4.01 vs. 31.2±1.65, P<0.001). Similarly, cTIMI was higher (21.07±1.83 vs. 18.71±1, P<0.001), whereas MBS was slightly lower in the cases (2.83±0.38 vs. 3, P=0.001). CSFT showed the highest relative risk (15.4), followed by cTIMI (6.47) and MBS (1.77). Conclusion: CSFT is a sensitive and reliable marker for detecting MVD in patients with non-obstructive CAD. It outperforms cTIMI and MBS in identifying MVD and may guide early diagnosis and treatment. Larger studies with long-term follow-up are required to establish its prognostic value.