With the rest of the findings, it’s totally within reasonable possibility. Tbh almost anything could have sent his body into a regal fatal behavior, looking at the combination of illnesses and meds on board.

Ketamine in therapeutic doses won’t often do it by itself. You can OD on enough of it, with death as a possibility. As you said, not common, and not at normal doses. But what would be a pleasant trip down the k hole for the average person isn’t a good idea for someone with pretty much any cardiovascular disease. Hell, some anaesthesiolgists won’t use it without a cardiac workup, though that’s also pretty rare from what I’ve been told.

He’d abused his body for decades. It sucks, I wish anybody struggling with addiction gets a chance to overcome it and live well. But as much as it sucks, it wouldn’t be surprising that his body just gave out under a therapeutic dose. At higher doses, it was inevitable