Some very confusing data overall, lots of terms thrown around, but from what I can gather...
The researchers exposed endothelial cells to testosterone, the testosterone precursor androstenedione, and two precursors of nandrolone. They then recorded the concentration at which half of the cells stopped growing. The results are presented below.
The more an anabolic steroid reduces growth of blood vessel cells, the more dangerous the anabolic steroid is for the heart and blood vessels.
They appear to be measuring "heart damage" on the basis of how much it takes to make blood vessel cells stop growing.
However, this doesn't tell us how much it actually matters in the real context. Let's say you run a 16 week cycle per year. Accounting for the time it takes for blood concentration to maximize, around 11 weeks.
Add in the "damage" done during the "loading phase" and it's around ~13 weeks out of the year.
So essentially, you are slowing the growth of blood vesssel cells for ~1/4 of the year (and likely only for a portion of your life) if it's a drug of choice.
The real question here is this:
does it matter?
Is that enough to make a significant impact overall?
Can you fully recover in the down time?
Can the increased health benefits of staying active through weight training put your net cardio system actually above that of a sedentary individual?
As XELFLEC already alluded to: "define heavy and long term."