Clinical Trial for Evaluating the Effectiveness and Safety of Online caIMR in STEMI Patients

Despite the success of restoration of epicardial blood flow by the primary percutaneous coronary intervention (PPCI), approximately a half of patients with ST-segment elevation myocardial infarction (STEMI) have failed myocardial reperfusion, as reflected by microvascular obstruction (MVO) and intramyocardial haemorrhage (IMH). There are many defects in the current measurement technology, such as non-timely, long measurement time, high price, potential risk of gadolinium contrast agent. The index of microcirculatory resistance (IMR) is a readily available, wire-based approach for assessing microvascular dysfunction immediately post-stenting for STEMI. The parameter has been used to characterize MVO, was associated with infarct size, and subsequent cardiac death and heart failure. However, the application of IMR in clinical practice remains limited, primarily due to the requirement of a pressure-temperature sensor wire and hyperaemic agents, which add complexity and time. The development of functional coronary angiography has enabled the estimation of IMR based on angiography alone. The coronary angiography-derived index of microvascular resistance (caIMR) has shown good diagnostic accuracy compared with wire-based invasive IMR. This simple alternative index showed an association with extent of MVO and was of prognostic importance. In this trial, the investigators aim to verify the safety and effectiveness of caIMR in STEMI who underwent primary PCI. The investigators will immediately measure the caIMR of patients who successfully underwent pPCI, and combine the caIMR with the long-term prognosis, to verify the prognostic performance of caIMR.