Combined low-dose dobutamine and exercise stress echocardiography: a new hybrid protocol to detect inducible ischaemia.

ABSTRACT

Aims: Myocardial response to stress echocardiography may be elicited physiologically, through exercise, or pharmacologically, often with dobutamine. Both have advantages but also limitations due to reduced exercise capacity or side-effects to stressor agent/lack of closeness to true pathophysiology of ischaemic cascade. We have combined low-dose dobutamine and exercise, creating a 'hybrid' protocol to utilize the advantages of both techniques and limit the drawbacks. The aim of the study was to evaluate its safety and feasibility. Methods and results: In the hybrid protocol, low-dose dobutamine infusion (up to 10 µg/kg/min) is enhanced by supine bicycle exercise at 3-min increments of workload of 25 W to achieve target heart rate (THR). We analysed safety and outcome data for all the patients who underwent this protocol from 2017 to 2022. Out of 835, 727 (87.1%) patients referred for evaluation of ischaemia underwent the hybrid protocol. The median age was 61 years old and 61% (442/727) were men. The median exercise time was 11 (9-13.5) min with a median maximum workload of 100 W (75-125). Out of 727, 670 (92.2%) achieved THR. Atropine was not used. Out of 727, 192 (26.4%) of studies were positive for ischaemia. Out of 122, 102 (83.6%) with positive stress who underwent invasive angiography had significant coronary disease. The incidence of complications was low 1/727-severe arrhythmia, 5/727 (0.7%) developed a vasovagal episode, and 14/727 (1.9%) had a hypertensive response to exercise. Conclusion: Our findings suggest that this protocol is safe, feasible, and has a high success rate in achieving THR.