Assessment of patients with low-risk chest pain in the emergency department: Head-to-head comparison of exercise stress echocardiography and exercise myocardial SPECT.

OBJECTIVES: The aim of the study was to compare head-to-head the performance of exercise tolerance test-stress echocardiography (ex-Echo) and exercise stress-perfusion nuclear imaging (exercise-single-photon emission computed tomography [ex-SPECT]) for the diagnosis of coronary artery disease (CAD) in patients evaluated at the chest pain unit with delay from chest pain (CP) onset.

BACKGROUND: As an early triage strategy for CAD in emergency medicine, ex-Echo could have the advantage of widespread availability and low costs.

METHODS: In the years 2000-2002, 503 consecutive patients (mean age 60 years) with recent (<24 hours) CP and nonischemic electrocardiogram (ECG), in whom CAD remained undiagnosed after first line 6-hour work-up including serum markers of myocardial injury and resting echocardiogram, underwent ex-Echo and ex-SPECT within 24 hours. Patients with (+)ex-Echo or (+)ex-SPECT or (+)ex-ECG or abnormal troponin I were referred to coronary angiography; otherwise, they were discharged and followed up. End points were coronary stenosis > or =50% and cardiovascular events at 6-month follow-up.

RESULTS: Ninety-nine patients (20%) had (+)ex-Echo and 121 (24%) (+)ex-SPECT; CAD was diagnosed in 81% and 67%, respectively; positive tests were concordant in 69%. In negative ex-Echo and ex-SPECT, final evidence of CAD emerged in 14 and 13, respectively. Ex-Echo demonstrated higher accuracy than ex-SPECT (93% +/- 1% vs 89% +/- 1%), optimal specificity (95% +/- 5% vs 90% +/- 5%), and positive predictive value (81% +/- 4% vs 67% +/- 4%); moreover, in the case of (-)ex-ECG, observed effective likelihood ratio indicates a (+)synergy between ex-ECG and ex-Echo.

CONCLUSIONS: Ex-Echo can be an effective diagnostic strategy in the early triage of CP patients, improving diagnosis in case of (-)ex-ECG and reducing unnecessary angiography number. Its drawback is represented by the 5% of missed diagnosis.