Quantitative detection of myocardial ischaemia by stress echocardiography; a comparison with SPECT

Aims: Real-time perfusion (RTP) adenosine stress echocardiography (ASE) can be used to visually evaluate myocardial ischaemia. The RTP power modulation technique angio-mode (AM), provides images for off-line perfusion quantification using Qontrast (R) software, generating values of peak signal intensity (A), myocardial blood flow velocity (beta) and myocardial blood flow (Ax beta). By comparing rest and stress values, their respective reserve values (A-r, beta-r, Ax beta-r) are generated. We evaluated myocardial ischaemia by RTP-ASE Qontrast (R) quantification, compared to visual perfusion evaluation with Tc-99m-tetrofosmin single-photon emission computed tomography (SPECT). Methods and Results: Patients admitted to SPECT underwent RTP-ASE (SONOS 5500) using AM during Sonovue (R) infusion, before and throughout adenosine stress, also used for SPECT. Visual myocardial perfusion and wall motion analysis, and Qontrast (R) quantification, were blindly compared to one another and to SPECT, at different time points off-line. We analyzed 201 coronary territories (left anterior descendent [LAD], left circumflex [LCx] and right coronary [RCA] artery territories) in 67 patients. SPECT showed ischaemia in 18 patients and 19 territories. Receiver operator characteristics and kappa values showed significant agreement with SPECT only for beta-r and Ax beta-r in all segments: area under the curve 0.678 and 0.665; P < 0.001 and < 0.01, respectively. The closest agreements were seen in the LAD territory: kappa 0.442 for both beta-r and Ax beta-r; P < 0.01. Visual evaluation of ischaemia showed good agreement with SPECT: accuracy 93%; kappa 0.67; P < 0.001; without non-interpretable territories. Conclusion: In this agreement study with SPECT, RTP-ASE Qontrast (R) quantification of myocardial ischaemia was less accurate and less feasible than visual evaluation and needs further development to be clinically useful.