Evaluation of Left Ventricular Function in Patients with Coronary Slow Flow by the Dobutamine Stress Echocardiography

The study aims to assess the changes to left ventricular (LV) function of patients with the coronary slow flow (CSF) in response to stress induced by low dose dobutamine.

Based on coronary angiography (CAG) results, a total of 186 patients undergoing CAG for chest pain and suspected coronary heart disease were assigned to the CSF group (n = 142) and control group (n = 44). Patients in the CSF group underwent two-dimensional speckle-tracking echocardiography (STE) during the dobutamine stress test to evaluate LV systolic and diastolic functions.

At rest, there were no statistically significant differences in LV peak systolic longitudinal strain (LS), LV peak systolic longitudinal strain rate (LSRs), LV peak early diastolic longitudinal strain rate (LSRed), LV circumferential strain (CS), or LV circumferential strain rate (CSRed) between the CSF and control groups. In the CSF group, LS and LSRs first increased as the infusion rate was increased to 10 μg/kg/min (all, p < 0.05), before decreasing at infusion rates of 15 and 20 μg/kg/min (all, p < 0.05). CS and CSRed increased in the CSF group at infusion rates of 5, 10, and 15 μg/kg/min, (all, p < 0.05), but decreased significantly at 20 μg/kg/min (all, p < 0.05).

At rest, LV systolic and diastolic functions were comparable between the CSF and control groups. However, when blood flow to the heart muscles was insufficient, LSRed decreased first, followed by LS. In terms of sensitivity to myocardial ischemia, LS is a better strain parameter than CS.