[Analysis using scintigraphy with thallium-201 of the perfusion picture before and after myocardial...

The present study was undertaken to investigate the effects of coronary artery bypass surgery on myocardial perfusion analyzed by thallium-201 scintigraphy. In 34 patients early thallium-201 imaging, repeated 4 hours later at rest, was performed 2-3 days before and within 1 year following myocardial revascularization. Before surgery, exercise ECGs were positive in 22/34 patients, with scintigraphic perfusion defects in 33/34 patients; thallium-201 imaging showed reversible in 77 and irreversible perfusion defects in 51 myocardial segments. After surgery, exercise ECGs were positive in 3/34 patients, while thallium-201 perfusion data improved in 27, were unchanged in 4 and worsened in 3 patients. After surgery, thallium-201 imaging showed a remarkable improvement, with decreased number of reversible (8 segments) and irreversible (32 segments) perfusion defects. Ten of the 22 patients with previous myocardial infarction had improved irreversible perfusion defects in myocardial segments that were infarcted. Qualitative thallium-201 scintigraphy showed that myocardial revascularization exerted a clear favorable influence on reversible perfusion defects and in part on irreversible perfusion defects, suggesting that persistent defects are compatible not only with scar tissue, but also may represent hypoperfusion of viable myocardium.