Objective To study the effect of primary PCI of culprit artery on epicardial flow in Nonculprit Artery in patients with STEMI.

Methods Enrolled 401 Anterior STEMI patients underwent primary PCI and the culprit artery is LAD (the test group) enrolled 100 patients that Coronary artery angiography suggesting normal as the control group. To observe the differences of CTFC and MBG pre and post primary PCI in both culprit and nonculprit artery, and to observe CTFC and MBG in the control group.

Results Nonculprit artery (LCX)'sCTFC and MBG level in patients with Anterior STEMI were different from those in the control group before primary PCI, and after primary PCI, nonculprit artery (LCX)'sCTFC and MBG level were improved, but still not recovery to normal level.

Conclusion Nonculprit artery's perfusion May be impaired in patients with STEMI, nonculprit artery's perfusion May be improved after primary PCI, but still lower than those in the control group.