spontaneous dissection of left anterior corinary artery

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?

[Cleveland Clinic]

Stress plays a significant role.  She has coronary artery disease and must change her lifestyle and start taking meds including statins and beta blockers and ASA and plavix.  There was probably some minor plaque there related to the stress and the HTN and it became unstable leading to a rupture which then led to a dissection.  Her prognosis depends on her residual heart function as measured by echocardiography.  If close to 50%, her prognosis is relatively good.  If closer to 30%, her prognosis isn't as good and she will need to be on chronic meds and may benefit from receiving a cardiac device.

[tickertock]

I think the good doctor here in replying is speaking in terms of ejection fraction when stating a prognosis of 50% is good, an innocent reading error happenes to the best of us, you were stating 50% blockage not 50% EF.

[tickertock]

Then again after rereading I think the doctor is saying after an echo if her reading is of EF is close to 50% that is good if 30% an ICD might be considered what he meant can be interpreted both ways but I'll give the good doctor the benefit of the doubt.