Abstract 12214: A Zero Calcium Score is Not Sufficient to Exclude Acute Coronary Syndrome in ED Chest Pain Patients
Objectives: To compare the performance of coronary calcium scoring and coronary CT angiography (CCTA) as methods for excluding acute coronary syndrome (ACS) in low to intermediate risk patients presenting to emergency departments (ED) with chest pain, and determine if either method allows exclusion of ACS with 99% confidence.
Methods: Retrospective review of 1191 patients who presented to the ED with chest pain and TIMI score 0–3 who underwent both calcium scoring and CCTA at a single center from January 2006-July 2009. Results of each study were compared to a final adjudicated diagnosis obtained after 30-day medical record review or telephone contact. The performance, ACS event rate and relative risk of each test result was evaluated for several thresholds.
Results: In 923 patients with calcium score of zero, 1.7% had >=70% stenosis, 4.3% >=50% stenosis, 11.1% >=25% stenosis, and 14.9% had any stenosis at CCTA. For patients with nonzero calcium score (n=268), 13.4% had stenosis >=70%, 36.9% >=50%, 66.9% >=25%, and 77.6% had any stenosis. 38/1191 patients were diagnosed with ACS (33 unstable angina (USA) and 5 acute myocardial infarction (AMI)). 29% (11/38) of ACS diagnoses were in patients with zero calcium score, with an ACS rate of 1.2% (11/923, CI 0.67–2.1%) in those with no coronary calcium. By contrast, only 1/1191 patients with no coronary stenosis was diagnosed with ACS (0.08%, CI 0.0–0.25%). The ACS rate using a 50% stenosis cut-off was 0.19% (2/1052, CI 0.0–0.45%), and 0.88% (10/1139, CI 0.34–1.42%) using a 70% stenosis cut-off. Performance of calcium scoring and CCTA using several thresholds is shown in the Table. The relative risk of ACS with nonzero calcium score was 11.9, and 136 with a >=50% stenosis.
Conclusions: 29% of ACS diagnoses occur in patients with no coronary calcium. A calcium score of zero does not exclude ACS with 99% confidence in low to intermediate risk ED chest pain patients. CCTA does allow reliable exclusion of ACS using a 50% stenosis threshold.
- © 2010 by American Heart Association, Inc.