Weight lifting is a form of isometric exercise which can lead to thickening of the heart muscle, which is not good. Given that you have had a prior heart attack and cardiac arrest this may not be a good idea whether on beta blockers or not. I would consult with your doctor and review all of your prior heart studies and discuss this issue. Light weight lifting may not be a problem, but one would need to thoroughly review your history. I probably would not recommend it.
There are many natural supplements on the markert today. I am not aware of any "natural substance" which improves survival in a person with your medical conditions. I treat patients having a similar medical history to you with an aspirin, beta blocker, ACE inhibitor and statin(cholesterol lowering medication). Many of these natural supplements may not cause harm but I don't think they help.
Thanks for your question,
CCF-MD-KE