AMD3100 attenuates cardiac function and accentuates myocardial injury after coronary artery occlusion. Mice were treated chronically with AMD3100 by osmotic minipump (ALZA). Minipumps implanted 24 h prior to coronary occlusion delivered AMD3100 or vehicle for 21 days. Mice underwent coronary artery ligation or sham surgery 24 h after implantation of minipumps. LV function, ejection fraction (EF, A) and fractional shortening (FS, B), and LV morphometry, left ventricular inner dimension systolic (LVIDS, C) and diastolic (LVIDD, D),end systolic volume (ESV, E),end diastolic volume (EDV, F) were assessed 20 days after surgery in vivo by echocardiography in Sham Vehicle (n=8), Sham AMD (n=8), Ligated vehicle (n=8), and Ligated AMD (n=10) treated mice. Values are mean ± SEM *P<0.05 vs Vehicle Ligation.