Influence of preload and afterload on stroke volume response to low-dose dobutamine stress in patients with non-ischemic heart failure: a cardiac MR study.

Lack of increase in left ventricular (LV) stroke volume (SV) during low-dose dobutamine stress (LDD) is attributed to exhausted cardiac contractile reserve in failing heart. However, the role of the afterload and preload in SV changes is underestimated. The aim of the study was to investigate the effects of LDD on preload reserve and afterload in patients with non-ischemic heart failure.58 patients (age 62 years) underwent LDD (up to 20μg/kg/min) using cardiac magnetic resonance.LV-SV increased by 27% in 24 patients (p0.001) (SV+), while decreased by 19% in 22 patients (p0.001) (SV-). The LDD-to-rest reduction in preload, as defined by LV end-diastolic volume (EDV), was more pronounced in S…