AIM  To explore the relationship between QFR microcirculation resistance index (Angio-IMR, AMR) and the prognosis of patients with acute ST-segment elevation myocardial infarction (STEMI) after primary percutaneous coronary intervention (pPCI).

METHODS One hundred and ninety-seven patients diagnosed with STEMI and undergoing pPCI treatment from January 1, 2021, to April 30, 2022 at the Lianyungang First People’s Hospital were included for this study. All patients were followed up postoperatively and the occurrence of major adverse cardiovascular events (MACE) during the follow-up period was used as the prognosis standard. Based on the follow-up results, the patients were divided into two groups: 143 cases without MACE and 54 cases with MACE. To explore the influencing factors during the occurrence of MACE in the follow-up period, relevant indicators compared between the two groups included preoperative related indicators (general patient information, initial blood routine, electrolytes, liver and kidney functions, and other biochemical indicators), intraoperative related indicators (number of stents, stent length and slow blood flow) and postoperative related indicators (LVEF, left atrial and left ventricular diastolic diameters measured by transthoracic echocardiography and retrospective measurement of AMR, QFR, MLD, MDS, MAS and blood flow velocity using the Shanghai RADI Medical QFR system. Additionally, the predictive value of AMR for the occurrence of MACE in STEMI patients after pPCI was evaluated and a model for comprehensive use of line charts to assess the predictive value of joint predictive factors was established.

RESULTS Among 197 STEMI patients treated with pPCI, the incidence of MACE was 27.4%. There was no statistical difference in age, sex, smoking history, diabetes history and hypertension history between two groups. Compared with the group without MACE, the group with MACE had a larger average platelet volume 9.5 (8.8,10.2) vs. 9.8 (8.6,10.8), P<0.05, higher CRP levels 1.5 (0.7,5.6) vs. 6.0 (1.8,16.8), P<0.05, and higher Lp (a) levels 163 (91,65.4) vs. 235 (128,493), P<0.01. The AMR value is higher (P<0.01), the proportion of postoperative lower QFR value is higher (P<0.05), the proportion of microcirculation deterioration is higher (P<0.05), MLD is lower (P<0.05), MDS is higher (P<0.05), MAS is larger (P<0.05), and blood flow velocity is slower (P<0.05). Multivariate logistic regression analysis showed that serum CRP (P<0.05), high levels of Lp (a) (P<0.01), lower postoperative QFR (P<0.01), and AMR values (P<0.05) were associated with poor prognosis in AMI patients after PCI. The area under the curve (AUC) predicted by AMR in the ROC curve for MACE events in STEMI patients within 1 year of discharge was 0.633 (95%CI: 0.543~0.723, P<0.01). The AUC for predicting MACE events in STEMI patients within 1 year was 0.769 (95%CI: 0.691~0.847, P<0.01) when combined with CRP, lipoprotein a, and lower postoperative QFR. On this basis, the AUC for combining AMR was 0.776 (95%CI: 0.705~0.847, P<0.01), indicating that combining AMR with risk factors can increase the accuracy of predicting MACE events in STEMI patients within 1 year. A column chart prediction model was constructed based on the above risk factors, and the model was validated with an AUC of 0.822, sensitivity of 0.746, specificity of 0.898, and good discrimination. This further proves that the column chart proposed in this paper can accurately predict the risk of MACE in STEMI patients after pPCI, and can also be applied to other STEMI patients after pPCI. CONCLUSION The AMR value derived from coronary angiography is closely related to the post-procedural prognosis of STEMI patients undergoing pPCI and it has certain value in assessing patient prognosis. Monitoring post-procedure AMR values may help in the early prediction of post-procedure risk for STEMI patients.