The value of stress single photon emission computed tomography in patients without known coronary artery disease presenting with dyspnea

Background Dyspnea is a complex system with multiple etiologies, including myocardial ischemia ("anginal equivalent"). Few studies have examined the utility of stress testing to detect coronary artery disease in this setting. The purpose of this study was to examine the prevalence, severity, and prognostic value of perfusion defects detected by stress single photon emission computed tomography (SPECT) imaging in patients with dyspnea. Methods SPECT imaging was performed in 1864 patients (age 65.8 +/- 10.2 years, 52% male, 23% diabetic, 89% overweight/obese) without known coronary artery disease referred for evaluation of dyspnea. Dyspnea was rated mild, moderate, or severe. SPECT scans were categorized low, intermediate, or high risk. The associations of stress SPECT imaging results with clinical variables and mortality were analyzed. Results An abnormal perfusion SPECT image was present in 45% of patients and a high-risk scan in 11%. Male sex, diabetes, and clinical severity of dyspnea were the strongest predictors of both an abnormal and high-risk SPECT scan. A high-risk scan was present in 5% of nondiabetic women with mild dyspnea versus 22% of diabetic men with dyspnea of any severity. At 10 years, survival by SPECT scan category was low risk 75%, intermediate risk 68%, and high risk 53% (P < .001). Conclusions In this population of older overweight patients refer red for evaluation of dyspnea, there was a high prevalence of abnormal (45%) and high-risk (11%) SPECT scans. High-risk scans were associated with much worse 10-year survival.