My husband had steriod injections in his feet. Within hours his heart beat from 51 per minute went to over 100. They took him in saying he had had a  heart attack, though subsequent tests including an angiogram, showed no blockages etc.BP. 132 over 72.He was put on clopidrogel to thin his blood and now it is so thin if he cuts himself he cant stop the bleeding. He was to have an op to repair the bones in his feet and because of this drug they cannot operate.They say he has to stay on this for a year (7months to go). Meanwhile he is on crutches. Never ever before had these problems till the steroids.
You have brought up a common problem for people who have had a brush with the heart. Even if no severe narrowing was uncovered, if there was evidence of heart injury, the medicine may be valuable to prevent another one. They are usually used for up to one year but when faced with a curable disability, I will usually discuss the risks and suggest a one-month hiatus to have surgical repair and begin recovery. Other medicines that don't affect blood clotting, like beta blockers, may also be used to protect the heart. It is not possible to know for sure what role the steroid may have played in all of this.