MYOCARDIAL RISK AREA DEFINED BY TC-99M SESTAMIBI IMAGING DURING PERCUTANEOUS TRANSLUMINAL CORONARY ANGIOPLASTY - COMPARISON WITH CORONARY ANGIOGRAPHY

Objectives. The purpose of this study was to compare the assessment of myocardial area at risk in patients with coronary artery stenosis by coronary angiography and quantitative myocardial perfusion imaging wit h technetium-99m sestamibi. Background. Decisions concerning patient m anagement frequently rely on semiquantitative angiographic estimation of the myocardial area at risk, although this approach has not been we ll validated. Technetium-99m sestamibi is a perfusion imaging agent wi th little redistribution after initial myocardial uptake. This charact eristic allows for injection during angioplasty and later imaging for visualization and quantitation of the nonperfused area at risk. Method s. Thirty-nine patients referred for coronary angioplasty were studied . Technetium-99m sestamibi was injected intravenously during angioplas ty balloon inflation. Planar (33 patients) or tomographic (6 patients) imaging was performed after completion of angioplasty. Imaging was re peated 24 to 48 h later. Myocardial risk area (perfusion defect on ang ioplasty image) was quantified as an integral using circumferential co unt distribution profiles and normal reference. Angiographic risk area was assessed using five scoring methods. Results. The scintigraphic r isk area was 14 +/- 15 on planar images and 39 +/- 16 on tomography. S cintigraphic risk area of patients with infarction was larger than in patients without (22 +/- 17 versus 7 +/- 8, p = 0.003). The left anter ior descending coronary artery had a larger mean risk area than other vessels (22 +/- 15 versus 7 +/- 11, p = 0.002). The presence of angiog raphic collateral channels was associated with smaller risk areas. Ang iographic risk scores correlated only moderately with the technetium-9 9m sestamibi risk area (r = 0.54 to 0.65), with considerable spread of data. Conclusions. Area at risk estimated from coronary angiography d oes not correlate well with that from quantitative myocardial perfusio n imaging with technetium-99m sestamibi. These findings emphasize that the functional significance of coronary artery disease is not predict ed by coronary anatomy alone.