This is streptokinase. It was first isolated from bacteria in the 1930s and in the lab was shown to breakdown blood clots (by converting plasminogen to plasmin). When a purified version became available in the 1950s there was great interest to find out if it might increase survival if given after a person had suffered a heart-attack. This resulted in the first randomised trials being undertaken at the end of the 1950s, so what did they show? If streptokinase was given after a person had a heart-attack was survival increased?