Well, from what happened to me, I can show some evidence that steroids can cause cardiomyopathy. About 9 yrs ago I was diagnosed with cardiomyopathy and an ejection fraction of about 25%. I told the doc I was on steroids, I had been running about 2 grams a week, and I went off immediately. Within about 10 months of being clean my heart was once again normal and ef was back up to 55%. My heart previously had walls that were akinetic, stretched out and hypertrophied. After the 10 months it looked normal enough that the cardiologist told me if he hadn't known I had cardiomyopathy at one time he would have thought my heart had always been normal.
Jump forward 4 yrs and then I had a blood clot and almost died from taking the steroids. I didn't learn my lesson.