To investigate the characteristics of coronary angiography and types of intracoronary thrombus in patients with acute myocardial infarction (AMI) who were classified according to changes of ST segment in electrocardiogram (ECG).

A total of 232 consecutive AMI patients within 24 h of symptom onset undergoing primary percutaneous coronary intervention (PCI) in Henan Provincial People’s Hospital from September 2016 to August 2018 were included. According to the changes of ST segment, patients were divided into three groups: ST-elevated group (161 cases), ST-unoffset group (28 cases) and ST-depression group (43 cases). Optical coherence tomography (OCT) during primary PCI were performed and intracoronary thrombus types were differentiated according to OCT. One-way analysis of variance, Chi-square test and Fisher exact probability test were used to analyze the clinical baselines, angiographic characteristics and intracoronary thrombus types among the three groups. A P<0.05 was considered statistically significant.

Left anterior descending coronary artery and right coronary artery were the most common infarct related arteries in the ST-elevated group and ST-depression group, while left circumflex artery was more common in the ST-unoffset group (P<0.001). The infarct sites in the ST-elevated group and ST-depression group were mostly located in the proximal and middLe segments, while those in the ST-unoffset group were mostly located in the middLe and distal segments (P=0.008). The proportion of occlusive lesion in the ST-elevated group and ST-unoffset group was higher than that in the ST-depression group (68.3% vs. 30.2%, P<0.05; 67.9%vs. 30.2%, P<0.05). The proportion of single vessel in the ST-elevated group and ST-unoffset group was higher than that in the ST-depression group (36.0%vs. 4.7%, P<0.05; 39.3%vs. 4.7%, P<0.05). The proportion of collateral circulation of infarct related artery in the ST-unoffset group and ST-depression group was higher than that in the ST-elevated group (35.7%vs. 16.1%, P<0.05; 58.1%vs. 16.1%,P<0.05). The incidence of red thrombus in the ST-elevated group and ST-unoffset group was significantly higher than that in ST-depression group (76.4%vs. 34.9%, P<0.05; 64.3%vs. 34.9%, P<0.05).

Compared with the ST-depression group, the proportions of single-vessel, occlusive lesion and red thrombus are higher in the ST-unoffset group and ST-elevated group. Therefore, in acute non ST-segment elevated myocardial infarction, those without ST-segment deviation are different from those with ST-segment depression. It is recommended to further divide acute myocardial infarction into ST segment elevation type, ST segment unoffset type and ST segment depression type according to ECG.

Acute myocardial infarction; ST segment elevation; ST segment unoffset; ST segment depression; Coronary angiography; Types of thrombus; Red thrombus; white thrombus