Detection of coronary artery disease with perfusion stress echocardiography using a novel ultrasound imaging agent: Two Phase 3 international trials in comparison with radionuclide perfusion imaging

Aims: To determine if perfusion stress echocardiography (PSE) with Imagify™ (perflubutane polymer microspheres) is comparable to stress perfusion imaging using ^99mTc single photon emission computed tomography (SPECT) for coronary artery disease (CAD) detection. PSE is a novel technique for evaluating myocardial perfusion. RAMP (real-time assessment of myocardial perfusion)-1 and -2 were international, Phase 3 trials that evaluated the ability of PSE with Imagify, to detect CAD. Methods and results: Chronic, stable, chest pain patients (n = 662) underwent Imagify PSE and gated SPECT imaging at rest and during dipyridamole stress. Independent blinded cardiologists [three PSE readers per trial, and four SPECT readers (one for RAMP-1, three for RAMP-2)] interpreted images. CAD was defined by quantitative coronary angiography or 90-day outcome with clinical review. Accuracy, sensitivity, and specificity were evaluated using non-inferiority analysis (one-sided alpha = 0.025) compared with SPECT. SPECT results for RAMP-1 and -2 were: accuracy (70%, 67%), sensitivity (78%, 61%), and specificity (64%, 76%). Accuracy of all six PSE readers was non-inferior to SPECT (66-71%, P ≤ 0.004). Four demonstrated non-inferior sensitivity (68-77%, P ≤ 0.002), three demonstrated non-inferior specificity (72-88%, P ≤ 0.013). Three PSE readers (RAMP-2) were superior for sensitivity. Two PSE readers (RAMP-1) were superior for specificity. Area under the multi-reader receiver operating characteristics curve (0.72) was equal for both modalities. Majority of adverse events followed dipyridamole dosing, and were mild, transient, and required no treatment. Conclusions: Imagify PSE was well-tolerated. Its diagnostic performance in chest pain patients is comparable with SPECT perfusion imaging.