Prevalence and Clinical Correlates of TIMI Flow Grade Zero Culprit-artery Occlusion in Patients with NSTEMI Undergoing Early Percutaneous Coronary Intervention

Background: A substantial proportion of patients with non-ST-elevation myocardial infarction (NSTEMI) have an acutely occluded culprit artery despite the absence of diagnostic ST-segment elevation on the presenting electrocardiogram.Objective: To determine the prevalence of thrombolysis in myocardial infarction (TIMI) flow grade 0 total culprit-artery occlusion in percutaneous coronary intervention (PCI) treated NSTEMI and to identify its clinical, laboratory, echocardiographic, and angiographic correlates.Materials and Methods: This prospective single-center observational study included consecutive patients with NSTEMI who underwent coronary angiography within 24 hours of presentation and culprit-vessel PCI at Kirkuk Cardiac Centre, Iraq, from September 2023 to September 2025. NSTEMI was diagnosed by ischemic symptoms, absence of persistent ST-segment elevation, and cardiac troponin I above the 99th-percentile upper reference limit (0.04 μg/L) with a serial rise/fall pattern. Patients were classified into the TIMI 0 and TIMI ≥1 groups based on pre-PCI culprit-vessel flow. Echocardiography was performed within 24 hours of admission and repeated before discharge. Group comparisons and multivariable logistic regression were performed.Results: Among 225 patients, TIMI 0 total occlusion was present in 78 (34.7%). Compared with TIMI ≥1, TIMI 0 was associated with male sex, higher body mass index (BMI), smoking, arrhythmia, family history of coronary artery disease, higher troponin, lower high-density lipoprotein (HDL) cholesterol, lower left ventricular ejection fraction, and more frequent left circumflex culprit lesions. In multivariable analysis, higher BMI, family history of coronary artery disease, higher admission troponin, lower HDL cholesterol, and lower admission ejection fraction remained independently associated with TIMI 0, whereas diabetes mellitus showed an inverse association.Conclusion: TIMI 0 total occlusion was common in PCI-treated NSTEMI and was associated with a distinct clinical and angiographic profile, including higher BMI and troponin levels, lower HDL cholesterol and left ventricular ejection fraction, and more frequent left circumflex culprit lesions.