Multicentre multi-device hybrid imaging study of coronary artery disease: results from the EValuation of INtegrated Cardiac Imaging for the Detection and Characterization of Ischaemic Heart Disease (EVINCI) hybrid imaging population

Abstract

Aims: Hybrid imaging provides a non-invasive assessment of coronary anatomy and myocardial perfusion. We sought to evaluate the added clinical value of hybrid imaging in a multi-centre multi-vendor setting.

Methods and results: Fourteen centres enrolled 252 patients with stable angina and intermediate (20-90%) pre-test likelihood of coronary artery disease (CAD) who underwent myocardial perfusion scintigraphy (MPS), CT coronary angiography (CTCA), and quantitative coronary angiography (QCA) with fractional flow reserve (FFR). Hybrid MPS/CTCA images were obtained by 3D image fusion. Blinded core-lab analyses were performed for CTCA, MPS, QCA and hybrid datasets. Hemodynamically significant CAD was ruled-in non-invasively in the presence of a matched finding (myocardial perfusion defect co-localized with stenosed coronary artery) and ruled-out with normal findings (both CTCA and MPS normal). Overall prevalence of significant CAD on QCA (>70% stenosis or 30-70% with FFR≤0.80) was 37%. Of 1004 pathological myocardial segments on MPS, 246 (25%) were reclassified from their standard coronary distribution to another territory by hybrid imaging. In this respect, in 45/252 (18%) patients, hybrid imaging reassigned an entire perfusion defect to another coronary territory, changing the final diagnosis in 42% of the cases. Hybrid imaging allowed non-invasive CAD rule-out in 41%, and rule-in in 24% of patients, with a negative and positive predictive value of 88% and 87%, respectively.

Conclusion: In patients at intermediate risk of CAD, hybrid imaging allows non-invasive co-localization of myocardial perfusion defects and subtending coronary arteries, impacting clinical decision-making in almost one every five subjects.

Keywords: CT coronary angiography; Coronary artery disease; Hybrid imaging; Myocardial perfusion scintigraphy.

Figure 1

Patient flow chart. CTCA, coronary CT angiography; ICA, invasive coronary angiography; FFR, fractional flow reserve; MPS, myocardial perfusion imaging.

Figure 2

(A) Standardized myocardial segmentation model used in this study with number codes for each segment (see Table 3). (B) Reassignment rates by hybrid imaging for the 1004 pathological segments (the intensity of colours in each segment indicates the frequency of reassignment of that segment when pathological). (C) Pie chart indicating proportion of reassignment and reassignment fate for pathological segments in each standard coronary territory. Shades of red indicate standard LAD, of green standard LCX, and of blue standard RCA territories. Standard LCX segments were most often reassigned to LAD (36%), while standard RCA segments were equally distributed between LAD and LCX.

Figure 3

A 55-year-old gentleman with atypical chest pain. (A) SPECT shows a reversible perfusion defect inferiorly with lateral extension, and in addition, there is a separate reversible perfusion defect involving the apical region and the mid-ventricular anteroseptal wall. (B) The perfusion polar maps show the SPECT core-lab interpretation (white = normal, yellow = mildly reduced, orange = moderately reduced, and red = severely reduced radiotracer uptake) with pathological segments assigned to all three coronary territories. (C) CTCA reveals two 70–90% mid LAD stenoses, a 50% proximal LCX stenosis, and a probable occlusion of the mid RCA (arrows). (D) On hybrid imaging, the entire inferolateral perfusion defect is reassigned to the RCA, effectively changing the diagnosis from three-vessel to two-vessel disease. (E) Imaging findings were confirmed on QCA showing two high-grade lesions in the mid LAD, diffuse non-significant disease in the LCX, and a chronic total occlusion of the mid RCA.

Figure 4

Accuracy analysis of stand-alone and hybrid protocols for the diagnosis of significant CAD (by QCA ± FFR) on per-vessel (A) and per-patient (B) analysis. On a per-vessel basis, when positivity was defined by the presence of at least one positive test (either matched or mismatched findings), hybrid imaging had higher sensitivity than single modalities (P < 0.001 vs. MPS and CTCA), at the price of lower specificity (P < 0.001 vs. both MPS and CTCA) and accuracy (P < 0.001 vs. both MPS and CTCA). When only matched findings were considered positive, hybrid imaging increased accuracy (P < 0.001 vs. both MPS and CTCA) driven by higher specificity (P < 0.001 vs. both MPS and CTCA) but with lower sensitivity (P < 0.001 vs. MPS and CTCA).

Figure 5

Hybrid-based ‘rule-in/rule-out’ clinical protocol.