Not a human study, but toxicology RCTS rarely are…
Levosimendan – a calcium sensitiser with inotropic properties, was superior to dobutamine and to saline placebo in the end points of survival, cardiac output, and mean arterial pressure in anaesthetised pigs with propranolol overdose.
Levosimendan as a Rescue Drug in Experimental Propranolol- Induced Myocardial Depression: A Randomized Study
Ann Emerg Med. 2009 Dec;54(6):811-817