Objective To investigate the effects of intracoronary alteplase infusion on acute invasive parameters on microcirculatory function during primary percutaneous coronary intervention (PCI).

Methods A total of 80 acute ST-segment elevation myocardial infarction (STEMI) patients with ischemia time ≤ 6 h who underwent emergency PCI in the Department of Cardiology were included as study objects. The patients were divided into alteplase group and control group according to method of random number table, with 40 cases in each group. In the alteplase group, 10 mg of alteplase was infused into coronary criminal lesions after reperfusionblood flow grade of thrombolysis test for myocardial infarction (TIMI) ≥ 2, followed by stent implantation. The control group was implanted with stent immediately after reperfusion (blood grade of TIMI ≥ 2). Acute invasive parameters of microcirculatory functionmicrocirculatory resistance (IMR), resistance reserve ratio (RRR), and flow reserve (CFR) were measured after PCI.

Results The IMR of the alteplase group and control group were 22.0(17.0, 42.0) and 33.0(17.0, 57.0), respectively, and there was no significant between-group difference (P>0.05). The CFR and RRR of the alteplase group were 1.4(1.1, 1.9) and 1.6(1.4, 2.6), respectively, and were 1.3(1.1, 1.8) and 1.6(1.3, 2.2), respectively in the control group, no significance between-group difference was observed (P>0.05). Subgroup analysis showed no interaction of ischemia time and alteplase with IMR(P=0.155). Interactions of ischemia time and alteplase with CFR (P=0.014) and RRR (P=0.027) were observed. In patients with ischemic times < 2 h, the CFR and RRR of the alteplase group were 2.0(1.7, 2.3) and 2.2(2.0, 2.6), respectively, which were higher than 1.2(1.1, 1.7) and 1.5(1.3, 1.9) of the control group (P < 0.05).

Conclusion Infusion of alteplase to culprit artery microvascular has no significant effect on culprit artery microvascular function (IMR, CFR or RRR) during PCI in acute STEMI with ischemia time ≤ 6 h.