my sister, age 47, recently had an MI. results of angio revealed a spontaneous dissectio of her LAD. a stent was placed. her right coronary artery showwed a 50% blockage, but collateral circulation precluded any intervention for this, aside from meds. Her lipid profile is normal. No hx of usual cad signs and symptoms. type a personality; walks 3-7 miles most days. hx of htn, treated with meds, all vital signs within normal limits. all other coronary arteries patent with no plaque seen. my question is this- what may have caused this, what is long-term outlook-does stress play any role in this?