Normal or near normal myocardial perfusion stress imaging in patients with severe coronary artery disease.

Background: Normal or near normal myocardial perfusion stress imaging (MPI) suggests the absence of life-threatening coronary artery disease (CAD). Nevertheless, there are instances where severe left main or three-vessel CAD may be present despite no significant perfusion abnormalities on MPI.

Methods: Review of Tl-201 or Tc-99m sestamibi MPI over a period of 5 years to ascertain the features that may prevent misdiagnosis. Out of 9171 tests, 3992 (44%) were interpreted as normal or near normal. For clinical reasons, 98 (2%) of these patients underwent coronary angiography within 6 months.

Results: A total of 3992 patients were interpreted as normal or near normal. Seventy (22 men/48 women; 58 +/- 13 years) did not have obstructive CAD. Nine (six men/three women; 64 +/- 8 years) had either left main (n = 3), three-vessel CAD with or without left main (n = 3) or severe proximal left anterior descending (n = 3) disease. Although both normal patients and patients with CAD had similar proportions of imaging artifacts, those with severe CAD had significantly more markers of CAD (increased lung Tl-201 uptake, transient ischemic cavity dilatation, stress-induced ST-segment depression, chest pain, and/or hypotension with exercise; P < 0.01; no CAD vs. severe CAD; two-tail Fisher's Exact Test). Similarly, patients with moderate CAD by coronary angiography (n = 19), and a random sample of 250 patients (82 men/168 women; 62 +/- 14 years) with normal or near normal MPI who did not undergo coronary angiography, had similar proportions of imaging artifacts but significantly fewer markers of CAD.

Conclusion: When dealing with individual patients, the referring physician and the interpreter of MPI studies should consider severe CAD when there are markers of CAD despite normal or near normal perfusion images.