Patients presenting to the emergency department (ED) with chest pain who are assessed as having an intermediate risk of coronary artery disease (CAD) pose a diagnostic and management problem. An unstructured approach to patient management may lead to either inappropriate discharge and a missed myocardial infarction (in 1%–5% patients) or unnecessary, prolonged admissions. This has resulted in the development of a Chest Pain Assessment Service (CPAS) at The Prince Charles Hospital (TPCH). Patients admitted to CPAS undergo an exercise stress test (EST) in order to further risk stratify them into either high or low risk groups. With their result from EST, patients are given a diagnosis of either low risk acute coronary syndrome (ACS), in which case they are discharged home for local doctor follow-up, or high risk ACS, in which case they are admitted to an inpatient Cardiology unit for further assessment and management. The average time to discharge of patients from CPAS is 14.5 hours.
Several recent international studies have demonstrated the potential of CT Coronary Angiogram (CTCA) to be used in the assessment of patients with acute undifferentiated chest pain without diagnostic ECG changes or serum troponin elevation. Locally, recent results from the yet to be published CT COMPARE trial have demonstrated that CTCA can potentially be utilised to facilitate early discharge of patients with chest pain thought to be at intermediate risk of ACS from TPCH ED.
The proposed study aims to identify whether patients with initial normal cardiac serum biomarkers and ECGs and a normal CT within 2 hours of presentation can be discharged early. This group represented 40% of the patients admitted to the CPAS unit in the CT COMPARE trial. It also aims to identify patients who have mild disease at CT and normal 6 hr serum cardiac biomarkers and ECGs as being suitable for discharge at 7 hours. Patients with mild disease represented a further 42% of the patients admitted to the CPAS unit in the CT COMPARE trial. This accelerated CT diagnostic pathway may potentially reduce time to diagnosis significantly.
CT will also allow for exclusion of coronary artery disease or the detection of coronary artery disease not normally identified by existing physiologic testing modalities and help guide implementation of appropriate medical therapy.
The team ran a randomized, single-centre trial involving 562 patients. ACS occurred in 24 (4%) patients. ExECG had 213 negative studies and 27 (26%) positive studies for ACS with sensitivity of 83% [95% CI: 36, 99.6%], specificity of 91% [CI: 86, 94%], and ROC AUC of 0.87 [CI: 0.70, 1]. CCTA (>50% stenosis considered positive) had 288 negative studies and 18/35 (51%) positive studies with a sensitivity of 100% [CI: 81.5, 100], specificity of 94% [CI: 91.2, 96.7%], and ROC of 0.97 [CI: 0.92, 1.0; p=0.2]. Despite CCTA having higher odds of downstream testing (OR 2.0), 30 day per-patient cost was significantly lower for CCTA ($2193 vs $2704, p<0.001). Length of stay for CCTA was significantly reduced (13.5h [95% CI: 11.2-15.7], ExECG 19.7h [95% CI: 17.4-22.1], p<0.0005), which drove the reduction in cost. No patient had post-discharge cardiovascular events at 30 days. CCTA had improved diagnostic performance compared to ExECG, combined with 35% relative reduction in length-of-stay, and 20% reduction in hospital costs. These data lend further evidence that CCTA is useful as a first line assessment in emergency department chest pain.
Hamilton-Craig, C., Fifoot, A., Hansen, M., Pincus, M., Chan, J., Walters, D.L. and Branch, K.R., 2014. Diagnostic performance and cost of CT angiography versus stress ECG—a randomized prospective study of suspected acute coronary syndrome chest pain in the emergency department (CT-COMPARE). International journal of cardiology, 177(3), pp.867-873.
Dr Allison Fifoot
Dr Mark Hanson
Dr Richard Slaughter
Dr Matthew Pincus
Dr Mark Whitby
Dr Colin Myers
Prof Paul Scuffham
Dr Harry Bartlett