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^TM (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 noninferior 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.