"Blood clot injections for in patients."

I recently added a reveiw of my stay in the cardiac ward on how humble I was with the lovely staff and care that I received. There was something that I found odd being a cardiac patient for two nights and confined to bed I didn`t receive an anti-clot injection until I inquired about it. At first I thought perhaps different Hospital Trusts have different procedures. The reason I`m mentioning this now is that I spent 5 wks in Morriston Hospital as an in patient with oesteo -arthritis in 2013 and every patient had this injection once a day to prevent clots. Should patients admitted with chest pains be treated as stated? Respectfully Mr M Godfrey