9 A retrospective review of the outcomes of non invasive imaging with off-site cardiac MRI and coronary CT angiography referrals from the acute medical unit (AMU), Beaumont Hospital

Abstract

Introduction Non invasive imaging with Cardiac MRI (CMRI) and Coronary CT Angiography (CCTA) is increasingly utilised in intermediate risk patients to evaluate for the presence of coronary artery disease (CAD). Positive scans identify target lesions prior to angiography; negative scans obviate the need for angiography, with potential economic benefits through reduced length of stay (LOS) and associated cost and complications related to invasive procedures. Methods A retrospective analysis by chart review was conducted on referrals (n = 96) for CMRI and CCTA from AMU in 2015. Results Following consultation with cardiology, 76 patients with no history of CAD were referred for CMRI (34 female, mean age 57.9 years, range 29–84). 42 patients had a normal CMRI and were discharged by the AMU service to their GP without need for cardiology OPD. 23/76 (30.2%) scans were positive for inducible ischaemia (11 outpatients) and referred on to cardiology. 11 have had formal angiography to date, with 4 requiring PCI. A further 12 scans identified unexpected abnormalities (6 cardiomyopathy/HOCM; 4 myocarditis; 2 cardiac sarcoid), not apparent on Echo. 6 patients that had abnormal Echos (LV dysfunction and Regional wall motion abnormalities) had subsequent normal CMRI, obviating the need for invasive angiography. 17 patients who had a high index of suspicion for CAD but normal ECHO, had subsequent positive CMRI. 53 patients had outpatient CMRI, average time to scan from discharge 43 days. Average LOS 3.9 days. 23 patients had an inpatient CMRI, with an average of 9 days to scan from admission, average LOS 15.1 days. 20 patients were referred for CCTA (11 female, mean age 51.4 years, range 41–71). These included: assessment of chest pain with negative troponins/normal echo/intermediate risk factors with equivocal EST, patients unable to perform EST and those unsuitable for CMRI (eg claustrophobia). All patients referred for CCTA were discharged for OPD scanning; average waiting time was 73 days (range 7 to 138 days). 7/20 scans (35%) were positive showing calcium scores ranging 2–1497 and 4 showed obstructive atherosclerosis. Patients with positive scans were older (59.1 years v 45.0 years). The 13 patients with negative scans were discharged to their GP by AMU, the other 7 referred to cardiology OPD. Conclusions Non invasive imaging forpatients attending AMU had a positivity rate of 35% for CCTA and 30.2% for CMRI for CAD and other diagnoses not appreciated on initial assessment. Patients with normal imaging were discharged by AMU without need for cardiology follow up. Patients with positive imaging were referred for cardiology review. Early access to non-invasive imaging for patients presenting with chest pain and intermediate risk factors has great potential to streamline management, with potential for earlier discharges and reduced LOS, cost savings, reduced need for invasive angiography and prompt follow up in cardiology in selected cases.