A 62 year old man presents with episodes of chest pain at rest and with exertion over the past 3 months. He has hypertension and hyperlipidemia and a family history of coronary artery disease.
He undergoes stress testing. Baseline EKG:
Baseline EKG demonstrated normal sinus rhythm with no abnormalities. Stress EKG demonstrated 3 mm horizontal ST segment elevation in leads I, II, III, and V3-V6. 3 mm ST elevation is seen in aVR.
Perfusion findings (Tc99m sestamibi SPECT):
Perfusion imaging demonstrates a possible small region of reversibility/decreased stress perfusion in the basal inferior wall, though scatter artifact on rest images may contribute to this appearance. No other perfusion defects are seen.
The patient underwent cardiac catheterization, which demonstrated: Left main 80% stenosis, proximal LAD 90% stenosis, proximal first diagonal 80% stenosis, 70% mid circumflex stenosis, 90% proximal and mid RCA stenoses.
How do we reconcile these catheterization findings with the minor/absent perfusion deficits on SPECT?
This is a patient with balanced ischemia due to 3-vessel coronary artery disease. Sestamibi SPECT imaging demonstrates the relative myocardial perfusion, i.e. impaired perfusion in abnormal myocardium relative to normally perfused sections. However in balanced ischemia there is no normally perfused myocardium, thus SPECT images may appear normal when in fact there is a global decrease.
Myocardial perfusion imaging with PET/CT is quantitative, i.e. can calculate the amount of perfusion in ml/g/min, and therefore can better detect balanced ischemia.
This patient underwent 4-vessel CABG with good results and no symptoms at last followup 4 years later.
