Eric J. Feldmann MD, Presenter: Nothing to Disclose

Melissa Ann Daubert MD, Abstract Co-Author: Nothing to Disclose

Cheng Ting Lin MD, Abstract Co-Author: Nothing to Disclose

Michael Poon MD, Abstract Co-Author: Nothing to Disclose

Jeffrey Craig Hellinger MD, Abstract Co-Author: Nothing to Disclose

To assess the incremental clinical value of performing CCTA following a CAC score of zero, when evaluating the ER patient with acute chest pain.

Retrospective review was undertaken of 250 consecutive emergency department (ED) patients (54% female; mean age 47; BMI 29.6) who underwent CAC scoring and CCTA (80% prospectively-triggered; 11% triple rule-out protocol) on a 64-channel CT scanner January 1 – June 30, 2009. All patients presented with acute chest pain, normal initial cardiac enzymes, and no ECG evidence of ischemia. Risk factors included a family history of premature cardiac event (40%), hypertension (37%) tobacco use (33%), hyperlipidemia (26%), BMI > 35 (14%) and diabetes (6%). Scan interpretation was performed by a blinded two reader review. Atheromatous plaque was scored as follows: non-obstructive (<50% average diameter stenosis), possible obstructive (50-70%) and obstructive (>70%). Discrepancies between initial and retrospective interpretations were resolved by a two reader consensus. Chart review was undertaken to determine patient management in and triage from the ED.  

99.6% (249/250) of scans were available for review. 75% (184/249) had a negative CAC score. CCTA detected CAD in an additional 15% (28/184). In this subcohort, lesions were non-calcified in 64% (18/28) and calcified in 36% (10/28) with a calcium burden below the threshold for CAC quantification. The majority (93% [26/28]) of these lesions was nonobstructive; 7% (2/28) were possibly obstructive, resulting in an incremental clinical value of 1% (2/184) for significant disease and an alteration of patient triage from the ED. However, 77% (20/26) of those with non-obstructive disease did not have traditional CAD risk factors, increasing CCTA incremental clinical value to 12% (22/184) following a negative CAC scan.  

In the low-intermediate risk ED patient with acute chest pain, when the CAC score is zero, the prevalence for CAD on CCTA is 15% (28/184). CCTA has low incremental value for detecting obstructive disease (1%), and has a greater benefit (11%) for detecting subclinical CAD in patients who may benefit from the initiation of lipid lowering therapy and aspirin.  

Since it is customary practive to perform a calcium score before cardiac CTA, it is important to assure there is incremental value for the latter.

Feldmann, E, Daubert, M, Lin, C, Poon, M, Hellinger, J, Incremental Value of Coronary CT Angiography (CCTA) after an Initial Negative Coronary Artery Calcium (CAC) Score in the Low to Intermediate Risk Emergency Room (ER) Patient with Acute Chest Pain .  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11012582.html