High blood pressure, high total cholesterol, increased red blood cell count. This causes blood to become thick. Damage to the right atrium, the chamber that non oxygenated blood return s to. Liver disease, Kidney disease, possible cancers.
These guys are on enormous amounts of gear. Then you have all that protien consumption. This is very hard on the kidneys. You also have the effect that the heart has to pump harder to move blood around the body because of all that muscle. The left ventricle, where the heart pumps oxygenated blood, starts to stretch. This leads to left sided congestive heart failure. That thick blood I meantioned? It can cause a stroke. Thick blood can also lead to atrial fibrillation and this can cause a clot to form. An older bodybuilder just passed away sometime over the last couple of months. He complained of foot and leg pain to his roommate before she left for a couple days. She returned and he was dead. What do I think happened? Blood clot in the lower leg travelled up to the lungs and killed him. This is called a pulmonary embolism. Had he gone to the doctor or E.R. right away he might be alive today.
I am not sure if you have medical training and am not trying to argue (I am often come across as argumentative I think...working on it.).
My understanding was that atrial fibrilation causes blood clots, not that blood clots cause atrial fib? Does it work both ways?
Also, skeletal muscle I believe can make it easier on the heart to pump. I say this because of you ever see someone with paralysis, you notice they get edema because the heart has a hard time pumping due to the lack of pressure pushing blood back to the heart.
Your list has a lot of considerations though
Something I would add to this though that I think is often over looked is BMI. We often look at BMI and say, "That doesn't matter. Bodybuilders have high BMIs and they aren't fat and being fat is what matters."
What people overlook is that BMI is based on large population statistical analysis. It basically says that people of certain heights and builds over a certain weight, based on statistical analysis, have increased incidence of disease and death.
For instance, I am 5'8'' and the BMI chart shows me that I should weigh 140-160 pounds. Over 160 and I am at increased risk of disease. This is regardless of whether it is muscle or fat, statistically. Sure, in reality maybe muscle will skew that a little, but not much.
And to put that in perspective, John Grimmek was 5'8" and 180# @ 10% bodyfat and was the best bodybuilder in the world at the time. In other words, someome with my build will have a really hard time actually becoming much more than 160# and being lean unless they use drugs.
And, to medrat's point, carrying all that weight around is a strain on your heart regardless. In order to do it your heart will adapt and may become damaged in the process...since it is a constant stress.
Finally, keep in mind a lot of competitive bodybuilders don't just use traditional steroids. They use GH, insulin, diuretics, etc. The pathways that lead to death are numerous and often intermingled. Liver damage, dehydration, potential organ growth from GH (debateable), kidney damage, overdose, thickened blood, damaged blood vessels, endocrine and immune impairment...you name it. It is a high stakes game.