Decoders on the right track again. Even though the heart itself does contain androgen receptors, I am not sure the actual extent/abundance. We do know that AAS adversly effect the cardiovascular system, these may be some proposed mechanisms: 1) an atherogenic effect involving the effects of AAS on lipoprotein concentrations ; 2) a thrombosis effect involving the effects of AAS on clotting factors and platelets; 3) a vasospasm effect involving the effects of AAS on the vascular nitric oxide system; and 4) a direct myocardial injury effect involving the effects of AAS on individual myocardial cells 5) Hypertension. These are just a few of many hypothetical models, but never the less, stand to good reasoning from what we now know. There are clearly various mechanisms which add to AAS related cardiac pathology. We know that all AAS have an effect on lipid balance to some extent. We know that AAS can cause hypertension, and the list goes on. But many other factors come into play as well, such as intensity of exercise, individual lifestyles, ie. diet etc., predisposing factors/risk factors to name a few. Most people only see what AAS do the outside of our bodies, because these are the effects we can see and feel, both good and bad. We often ignore, or don't realize what is going on inside our bodies because we don't feel this right away. Most of bad effects take time, often years, to show up. The good thing is that we can anticipate and confirm (through lab tests/physicals etc.) that these events are going to happen and take appropriate measures to help counteract. We can do things (whether through lifestyle mod.,medication,supplementation etc.) to lower blood pressure, produce a favorable lipid profile, counteract estrogen/DHT accumulation and ultimately reduce the morbidity associated with AAS use.
Anyways, I know I didn't answer your question directly. But I think you see the picture. I don't know why doing cardio while on AAS would be a bad thing, because we know of the many positive benefits it produces. Now keep this in perspective though. Most athletes in general, (the ones that do intense exercise/sports, not golfing, bowling-some of these people do consider themselves athletes) will show some degree of left ventricular hypertrophy. So if you were doing "cardio" at 90% of max HR, then yeah, I would agree this would probably not be a good thing. But I think that mild-moderate cardio is beneficial. Your heart wont blow up. You put more stress on your cardiovascular system doing intense squats(although this is not time sustained) than doing cardio. In general, doing cardio keeps the cardio vascular system happy. So why not do it? In moderation of course