Comparison of coronary flow reserve feasibility in different stress echocardiography protocols: dobutamine, dipyridamole, exercise and rapid pacing

INTRODUCTION: The assessment of coronary flow velocity reserve (CFVR) may improve the diagnostic and prognostic value of stress echocardiography (SE). OBJECTIVES: The aim of the study was to compare the feasibility of CFVR assessment in the left anterior descending artery (LAD) in 4 modalities of SE: dobutamine, dipyridamole, rapid cardiac pacing, and exercise using cycle ergometer. PATIENTS AND METHODS: We performed SE in 369 patients (mean [SD] age, 67 [11] years) with dobutamine (n = 230), dipyridamole (n = 73), rapid cardiac pacing (n = 22), or exercise (n = 44) between June 2017 and June 2020. We measured CFVR as the ratio of peak diastolic coronary flow velocity during exercise, pharmacological stress, or pacing to peak diastolic coronary flow velocity at rest in the distal or mid LAD. RESULTS: The feasibility of CFVR was excellent during rapid cardiac pacing (100%), dobutamine (95%), and dipyridamole (95%) and was lower during exercise (73%; P <⁠0.01 vs other groups). In multivariable analysis, the exercise protocol was a predictor of the loss of blood flow in the LAD during SE (odds ratio, 7.89; 95% CI, 2.17–31.33; P = 0.002). The median (interquartile range) CFVR was lower with rapid cardiac pacing (1.7 [1.4–2.0]) as compared with dobutamine (2.1 [1.7–2.5]), dipyridamole (2.1 [1.8–2.5]), and exercise (2.0 [1.7–2.3]) (P <⁠0.05 for all). CONCLUSIONS: CFVR in the LAD can be obtained during all forms of SE, but the feasibility is significantly higher with rapid cardiac pacing and pharmacological tests as compared with exercise, which was identified in our study as an independent predictor of the loss of blood flow during a blood flow recording in the LAD at the peak of stress test.