What is the implication of a reversible defect on SMPI?
A reversible defect implies a lack of myocardial perfusion during the stress component but normal myocardial perfusion during rest. Reversible defects can be caused by attenuation artifact but must always be assumed to be related to CAD, in which the stenotic artery cannot accommodate the extra perfusion demand during stress. The importance of a reversible defect is that the myocardium is intact but is at risk for coronary events. It typically requires a stenosis of at least 70% for perfusion to be affected during the stress test. Reversible defects also usually mandate further study with coronary angiography to assess for the extent of blockage of the artery