Abstract 557: The Utility of Serial Enzymes to Rule out Myocardial Injury in Pateints with Non-Critical Disease by CT Angiography
Coronary Computed Tomography Angiography (CCTA) is a diagnostic test shown to have a high negative predictive value for coronary artery disease and major cardiac events at three months. Many emergency department, (ED), protocols mandate serial enzymes prior to discharge to capture possible myocardial injury even with normal CCTAs. Determine the value of serial cardiac enzymes in low risk patients (TIMI Risk Score <3) presenting to the ED with chest pain who have a normal or intermediate CTA, (< 25% stenosis). 307 patients received CCTA as part of clinical trials. All patients presented to the ED with suspected acute coronary syndrome and had a TIMI Risk <3, non diagnostic ECGs and negative initial enzymes. All patients had serial enzymes sampling at least 4 hours apart per protocol. Structured telephone follow up and chart review was completed at 30 and 90 days post ED visit. All data was analyzed using descriptive statistics. 68% of all CTA patients were classified as normal < 25% stenosis, with another 8% considered intermediate < 50% stenosis. Average time between blood collection was 4:30+/−1:28. All patients had normal serial Troponin I values (Normal <0.05 ng/mL) with no appreciable delta over time. 39 patients had an increase in Myoglobin values with 10 having a delta ≥20% but <50%, none of these patients had a level above our normal range (< 98 ng/ml). Only one myoglobin values was above our normal limits, but did change over time. There were no deaths or adverse cardiac events at 90 days in this population. In this study of low risk patients with suspected cardiac ischemia (TIMI <3) and a normal or intermediate CCTA, serial cardiac enzymes have no utility.