Impact of Coronary Calcification on Clinical Management in Patients With Acute Chest Pain

Abstract

Background: Coronary artery calcification (CAC) may impair diagnostic assessment of coronary computed tomography angiography (CTA). We determined whether CAC affects efficiency of coronary CTA in patients with suspected acute coronary syndrome (ACS).

Methods and results: This is a pooled analysis of ACRIN-PA (American College of Radiology Imaging Network-Pennsylvania) 4005 and the ROMICAT-II trial (Rule Out Myocardial Infarction/Ischemia Using Computer Assisted Tomography) comparing an initial coronary CTA strategy to standard of care in acute chest pain patients. In the CTA arms, we investigated appropriateness of downstream testing, cost, and diagnostic yield to identify patients with obstructive coronary artery disease on subsequent invasive coronary angiography across CAC score strata (Agatston score: 0, >0-10, >10-100, >100-400, >400). Out of 1234 patients (mean age 51±8.8 years), 80 (6.5%) had obstructive coronary artery disease (≥70% stenosis) and 68 (5.5%) had ACS. Prevalence of obstructive coronary artery disease (1%-64%), ACS (1%-44%), downstream testing (4%-72%), and total (2337-8484 US$) and diagnostic cost (2310-6678 US$) increased across CAC strata (P<0.001). As the increase in testing and cost were lower than the increase of ACS rate in patients with CAC>400, cost to diagnose one ACS was lowest in this group (19 283 US$ versus 464 399 US$) as compared with patients without CAC. The diagnostic yield of invasive coronary angiography was highest in patients with CAC>400 (87% versus 38%).

Conclusions: Downstream testing, total, and diagnostic cost increased with increasing CAC, but were found to be appropriate because obstructive coronary artery disease and ACS were more prevalent in patients with high CAC. In patients with acute chest pain undergoing coronary CTA, cost-efficient testing and excellent diagnostic yield can be achieved even with high CAC burden.

Clinical trial registration: URL: http://www.clinicaltrials.gov. Unique identifiers: NCT01084239 and NCT00933400.

Keywords: acute chest pain; acute coronary syndrome; coronary CT angiography; coronary artery calcification; coronary stenosis; resource utilization.

Conflict of interest statement

Disclosures:

The other authors have nothing to disclose.

© 2017 American Heart Association, Inc.

Figures

Figure 1

Flow chart demonstrating study population of the two source trials (ROMICAT II and ACRIN) (n=1,234). SOC: standard of care; CCTA: coronary computed tomography angiography; CAC: coronary artery calcification

Figure 2

Prevalence of coronary artery stenosis (≥50% and ≥70%), incidence of acute coronary syndrome (ACS) during the index hospitalization and frequency of revascularization (all trends p>0.001) in relation to cost per ACS stratified by CAC score in all patients.

Figure 3

a–b: Incidence of acute coronary syndrome (ACS) and frequency of additional testing (all trends p>0.001) in relation to cost per ACS stratified by CAC score in (A) men and (B) women.

Figure 3

a–b: Incidence of acute coronary syndrome (ACS) and frequency of additional testing (all trends p>0.001) in relation to cost per ACS stratified by CAC score in (A) men and (B) women.

Figure 4

Invasive diagnostic yield of coronary CTA and cost per ACS stratified by CAC in men and women. Coronary artery calcification (CAC) may impair the diagnostic accuracy to detect obstructive CAD on coronary CTA and is thought to be associated with inefficient patient management. This pooled analysis looked at resource utilization (downstream testing including ICA and cost) across CAC strata in patents with suspected ACS undergoing coronary CTA. Disease burden, adverse health outcomes and additional testing increased with increasing extent of CAC (Table 2, trend p>0.001) but did not vary in patients with obstructive CAD across CAC strata (Table 3). The diagnostic yield of invasive angiography to detect obstructive CAD was used as measure of effectiveness for a strategy using coronary CTA. The invasive diagnostic yield increased across CAC strata and was higher in patients with CAC>400 as compared to patients with CAC of zero, similar in men and women (left). While total and diagnostic cost increased with increasing extent of CAC (Table 2, p>0.001), cost to diagnose one ACS (Cost per ACS) decreased across CAC strata and was lowest in patients with high extent of CAC, also seen in men and women (right). In conclusion, in patients undergoing a strategy with coronary CTA, cost efficient testing and excellent invasive diagnostic yield can be achieved in patients with high burden of CAC.