False-positive rates of provocative cardiac testing in chest pain patients admitted to an emergency department observation unit.

Emergency department observation units (EDOUs) typically perform routine cardiac stress testing or coronary computed tomography (CCTA) to rule out ischemic cardiac chest pain. Some have questioned the utility of routine stress testing and advanced anatomic imaging in the low-risk chest pain patients. EDOU chest pain patients undergoing stress testing or CCTA prior to cardiac catheterization between June 1, 2009 and May 31, 2012 were studied in a prospective, observational manner. Baseline data, EDOU-related outcomes, and testing results were recorded. Stress tests were treadmill echocardiogram or myocardial perfusion stress tests and were considered positive if a "positive" or "equivocal" interpretation by the reviewing cardiologist prompted cardiac catheterization. CCTA was considered positive if it led to subsequent cardiac catheterization. Cardiac catheterization was considered positive if subsequent stent placement, coronary artery bypass graft (CABG), or change in medical management occurred. Of 1276 patients evaluated, 112 (8.8%) underwent cardiac catheterization of which 56 underwent some modality of prior testing. Forty-two of 56 were subject to stress testing (30 stress echo and 12 myocardial perfusion) and 14 underwent CCTA prior to catheterization. False-positive rate overall was 62.5% (35/56, 95% CI, 48.5%-74.7%). False-positive rate for stress testing was 75% and 66.7% for perfusion and stress echo respectively. False-positive rate for CCTA was 42.9%. It must be acknowledged that while these findings do not directly impugn the utility of stress testing or CCTA, it may indicate the need for more appropriate patient selection to avoid unnecessary cardiac catheterization among EDOU chest pain patient cohorts.