To determine the impact of inflammatory reaction levels and the culprit plaque characteristics on preprocedural Thrombolysis in Myocardial Infarction (TIMI) flow grade in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI).

The is a retrospective study. A total of 1 268 STEMI patients who underwent pre-intervention optical coherence tomography (OCT) examination of culprit lesion during emergency PCI were divided into 2 groups by preprocedural TIMI flow grade (TIMI 0-1 group (n =964, 76.0%) and TIMI 2-3 group (n =304, 24.0%)). Baseline clinical data of the 2 groups were collected; blood samples were collected for the detection of inflammatory markers such as high sensitivity C-reactive protein (hsCRP), myocardial injury marker, blood lipid, etc.; echocardiography was used to determine left ventricular ejection fraction; coronary angiography and OCT were performed to define the lesion length, diameter stenosis degree of the infarct-related arteries, presence or absence of complex lesions, culprit lesion type, area stenosis degree and vulnerability of culprit plaques. Multivariable logistic regression analysis was performed to identify independent correlation factors. The receiver operating characteristic (ROC) curve of continuous independent correlation factors was analyzed, and the best cut-off value of TIMI 0-1 was respectively determined according to the maximum value of Youden index.

The mean age of 1 268 STEMI patients were (57.6±11.4) years old and 923 cases were males (72.8%). Compared with TIMI 2-3 group, the patients in TIMI 0-1 group were older and had higher N-terminal-pro-B-type natriuretic peptide level, lower cardiac troponin I (cTnI) level, lower left ventricular ejection fraction, and higher hsCRP level (5.16(2.06, 11.78) mg/L vs. 3.73(1.51, 10.46) mg/L). Moreover, the hsCRP level of patients in TIMI 0-1 group was higher in the plaque rupture subgroup (all P<0.05). Coronary angiography results showed that compared with TIMI 2-3 group, the proportion of right coronary artery (RCA) as the infarct-related artery was higher, the angiographical lesion length was longer, minimal lumen diameter was smaller, and diameter stenosis was larger in TIMI 0-1 group (allP<0.05). The prevalence of plaque rupture was higher (75.8% vs. 61.2%) in TIMI 0-1 group. Plaque vulnerability was significantly higher in TIMI 0-1 group than that in TIMI 2-3 group with larger mean lipid arc (241.27°±46.78° vs. 228.30°±46.32°), more thin-cap fibroatheroma (TCFA, 72.4% vs. 57.9%), more frequent appearance of macrophage accumulation (84.4% vs. 70.7%) and cholesterol crystals (39.1% vs. 25.7%). Minimal flow area was smaller [1.3(1.1-1.7)mm² vs. 1.4(1.1-1.9)mm², all P<0.05] and flow area stenosis was higher (78.2%±10.6% vs. 76.3%±12.3%) in TIMI 0-1 group. Multivariable analysis showed that mean lipid arc>255.55°, cholesterol crystals, angiographical lesion length>16.14 mm, and hsCRP>3.29 mg/L were the independent correlation factors of reduced preprocedural TIMI flow grade in STEMI patients.

Plaque vulnerability and inflammation are closely related to reduced preprocedural TIMI flow grade in STEMI patients.