Low event rate for stress-only perfusion imaging in patients evaluated for chest pain

We sought to demonstrate the safety of stress-only perfusion imaging among patients with low to medium probability of coronary disease being evaluated for chest pain.

The need for performing rest in addition to stress perfusion imaging to confirm normalcy is due largely to defects created on the stress images by attenuation artifacts. A low cardiac event rate among patients undergoing stress-only imaging with attenuation correction (AC) would validate the safety of stress-only imaging.

Patients with low to medium pretest probability for coronary artery disease (CAD) referred for chest pain evaluation from July 1, 1997 to July 1, 1999, were scheduled for a two-day stress/rest tomographic (single photon emission computerized tomography, or SPECT) perfusion imaging study with Tc-99m sestamibi. Patients were imaged on a variable angle camera with AC using Gd-153 scanning line sources (Vantage ADAC, Milpitas, California). If the stress scan was normal without AC or corrected with AC, the patient did not return for rest scan and was followed.

Seven hundred twenty-nine patients underwent stress-only imaging, and follow-up was obtained on 652 (89%) of those patients. There were 224 males and 428 females with mean age of 52 +/- 13 years. Mean follow-up was 22.3 +/- 6.4 months. The mean pretest probability was 37 +/- 24%. The non-AC images showed breast and/or diaphragmatic attenuation artifacts severe enough to have required the patient to return for rest imaging in 37% of patients, and all corrected completely with AC. During follow-up, there were two noncardiac deaths and no cardiac deaths. There was one myocardial infarction; three patients with progressive unstable angina underwent diagnostic coronary angiography showing significant CAD. The overall cardiac event rate was 0.6%.

These results support stress-only imaging in patients with low to medium probability for CAD as a safe, time- and cost-efficient imaging modality.