THC-A does not bind to the CB1/2 receptors. It has a spike on the molecule that must be broken off by heating, actually causing the spike to break away, allowing binding and the all-important signaling processes that control a number life functions, and give the plant some of it's healing properties. And yes, all cannabinoids break down, but slowly. Referencing the chart, 98F would take days. So rule number one is your medicine should have as much THC-A converted to D9-THC as possible.