However, stress and axiety can definitely increase your blood pressure and undermine your health thru lack of sleep and being too sedentary. It's thought that an embolism is often caused when someone at risk sits for too long, without getting up and walking around (WSers take note). He may have recently driven back from Vegas and been sitting around in ZP's house.
Truckers at risk for deep vein thrombosis
Most importantly, IMO, he was afraid to go to a doctor or the hospital or call 911 when he experienced the symptoms of shortness of breath, chest pain and so on, that ZP reported he'd had.
He may have confused these symptoms with the panic he was experiencing, or he might have been afraid police would track him down if he tried to get help.
MOO