Medtronic Inc. is beginning a large, randomized trial that will examine the safety of drug-eluting stents. The 8800-patient clinical trial will compare the company's zotarolimus-eluting coronary stent system (Endeavor) with J&J'sÂ sirolimus-eluting stent (Cypher). Medtronic enrolled the first patient in the study, called Protect,Â yesterday. The trial will look at overal stent thrombosis after three years. Other points of analysis will include a composite of death and nonfatal myocardial infarction. According to an investigator of the study, the trial is designed to give doctors the long term safety data that they've been needing.