Feasibility of Stress-Alone Cardiac CT for Detecting Hemodynamically Significant Coronary Stenosis in the Presence of High Coronary Calcium Score and Coronary Stents

Abstract

Objective: Coronary computed tomographic angiography (CTA), including rest and stress myocardial perfusion computed tomography (CTP), allows for comprehensive assessment of flowlimiting coronary artery disease (CAD). In patients with severe coronary calcification or prior coronary stents where rest CTA had limited accuracy, stress CTP with coronary artery assessment on the same stress CTP dataset (stress-alone CTP/CTA) without rest CTA may be a valuable protocol. We assessed the diagnostic performance of stress-alone CTP/CTA with 320-slice CT compared to a combination of stress CTP/CTA and rest CTA/CTP using invasively determined fractional flow reserve (FFR) as the reference standard. Materials and Methods:Thirty-five patients with a high calcium score, stratified according to >400 Agatston units and/or prior stents, underwent CT examination starting with stress CTP/CTA and followed by rest CTA/CTP and invasive angiography. FFR <0.80 or luminal stenosis >90% was considered hemodynamically significant.Results: Fifty-six coronary vessels had flow-limiting stenoses. In our vessel-based analysis, integration of rest CTA/CTP with stress CTP/CTA significantly improved diagnostic performance to 82% sensitivity and 96% specificity, with an area under the receiver operator characteristic curve (AUC) of 0.94, compared with 0.90 for stress-alone CTP/CTA. However, according to our per-patient level analysis, stress CTP/CTA yielded its highest diagnostic performance with an AUC of 0.97, which was not an improvement on the integration of rest CTA/CTP. Mean radiation for stress-alone CTP/CTA and combined stress-rest CTA/CTP was 8.0 and 12.7 mSV, respectively. These were relatively high doses but were performed on a first-generation 320-slice CT scanner. Conclusion:A stress-alone CTP/CTA protocol can provide excellent diagnostic performance for predicting flow-limiting CAD in patients with a high calcium score and coronary stents, omitting the need for radiation and contrast medium required for rest CTA/CTP.