Resting and Stress Coronary Sinus Flow and Coronary Flow Reserve. Bar graphs demonstrate median values and 25th-75th percentiles (error bars) for resting CSF (left), stress CSF (middle) and CFR (right) for each group. Values for PAH patients are shown in blue, those for SSc non-PAH patients in red and those for the control group in green. PAH patients demonstrated a trend toward higher resting and lower stress CSF as well as a significantly lower CFR (*p=0.008) compared to healthy controls. The Non-PAH group demonstrated values in-between those for PAH patients and controls.