<qa>  What is the 2 agonist clenbuterol?The hypothesis of this study is that patients with dilated nonischemic cardiomyopathy who require support with an implanted left ventricular assist device LVAD for chronic refractory heart failure can, with a specific two-staged medical regimen designed to enhance maximal reverse remodeling an angiotensin converting enzyme inhibitor, beta blocker, angiotensin receptor blocker, aldosterone antagonist and digoxin stage 1 and preventreverse myocardial atrophy the β2 agonist clenbuterol stage 2, recover adequate left ventricular systolic function to allow LVAD explantation and subsequent intermediate-term survival without need for mechanical circulatory support or heart transplantation. 