【Abstract】Objective To determine the effect of early heparin therapy on blood flow of infarct-related arteries and heart function in patients with acute anterior myocardial infarction. Methods One hundred patients suffering from acute anterior myocardial infarction admitted to our hospital from April 2017 to November 2018 were enrolled in this study. They were randomly divided into observation group and control group, with 50 cases in each group. The patients of the observation group were given intravenous injection of 4 000 U unfractionated heparin immediately after diagnosis of ST-segment elevation myocardial infarction (STMEI). While the same dose of heparin was injected intravenously to the patients from the control group after insertion of sheath. Then all of the patients underwent percutaneus coronary intervention (PCI). The heparin administration time, activated coagulation time (ACT), blood flow of infarct-related arteries by coronary angiography, hospital door to balloon (D-to-B) time, vessel opening time, peak high-sensitive troponin T (hs-TnT) value, peak pro-brain natriuretic peptide (pro-BNP) value, pump failure during hospital stay, left ventricular ejection fraction, and length of hospital stay were observed and recorded in the 2 groups. SPSS statistics 13.0 was used to perform the statistical analysis. Student′s t test or Chi-square test was employed for comparison between the groups based on different data types. Results The observation group had significantly shorter heparin administration time [(7.5±1.8) vs (47.4±8.6)min], lower ratio of TIMI flow grade 0(28% vs 38%), shorter D-to-B time [58.4±13.0) vs (63.9±12.9)min], shorter vessel opening time [(29.2±5.9) vs (32.5±5.4)min], lower ratio of high thrombosis burden (30% vs 52%), lower value of peak hs-TnT [(2 915.4±1 845.9) vs (3 987.4±2 018.8)ng/ml], lower value of peak pro-BNP [(3 096.4±1 965.2) vs (4 770.5±2 073.5)pg/ml], lower ratio of pump failure (4% vs 16%), and shorter length of hospital stay [(9.0±1.8) vs (10.1±2.0)d] when compared with the control group (P<0.05). What′s more, longer activated coagulation time [(213.2±13.7) vs (67.7±5.1) s], higher ratio of TIMI flow grade 2-3(40.0% vs 18.0%), and higher LVEF [(56.5±7.7)% vs (51.3±7.0)%] were observed in the observation group (P<0.05). Conclusion Early heparin therapy promotes recanalization of infarct-related arteries, shortens vessel opening time, and improves heart function in acute anterior myocardial infarction patients.