Most people give an MI via left coronary ligation, or use ascending aortic constriction. On the other side are easier models that are more costly to maintain - Dahl Salt Sensitive rats, or a model of spontaneously hypertensive heart failure prone rats.
Another option for Rats is to use a model of Autoimmune Myocarditis. The animals develop a cardiomyopathy which provides a reasonable model for DCM in humans.
ligate the LAD? Maybe you can ask Prof. Dr. Steinhoff (http://www.med.uni-rostock.de/index.php?id=802). I know that his group is doing such experiments in mice in Rostock. It is not far away from Berlin.