(A) Experimental protocol. The guinea pigs were divided into four groups: 2.5 ATU hirudin (100 µL), 4 ATU hirudin (100 µL), 5 ATU hirudin (100 µL), and vehicle (0.01% mannitol) for hirudin were locally injected in the left ventricular area 1–2 mm below the LCA ligature. The different doses of hirudin were injected 1–2 min before the LCA ligation. (B) Representative electrocardiographic recordings of different hirudin dosages at different time points after LCA ligation. (C) Summary percent of control of the ST/QRS+ at different time points for each group. Data are mean ± SEM from five animals per group. *P < 0.05, 5 ATU hirudin group versus 2.5 ATU hirudin group, 4 ATU hirudin group, and control group. #P < 0.05, 4 ATU hirudin group versus 2.5 ATU hirudin group and control group.