Endothelin release: a marker for the severity of exercise-induced ischemia

Elevated endothelin-1 levels were found in exercise-induced ischemia. To our knowledge, no attempt has been made to correlate the presence of the elevated endothelin levels with severity of ischemia. In the present study, we attempt to correlate the severity of ischemia, quantified using a bullseye visual display of scintigraphic ischemic score on SPECT technetium 99m sestamibi, with presence of endothelin at peak exercise. Twenty seven patients with documented effort angina were included in the study. All subjects underwent stress technetium 99m sestamibi and ischemic scores were evaluated on the polar map image divided into 13 segments. Endothelin levels were measured at baseline and at peak exercise. In 13 patients with elevated endothelin-1 levels, there were 88 ischemic segments, 26 of which showed severe ischemia. In the remaining 14 patients with no endothelin-1 elevation, there were 80 ischemic segments of which only four showed severe ischemia. The amount of severe ischemic segments per patient was 2+/-2.2 in the elevated endothelin positive group and 0.28+/-0.6 in the endothelin negative (P< or =0.011). When looking at ischemia as detected by sestamibi SPECT as a gold standard, we found that of 331 segments, 168 were without ischemia, 143 had mild to moderate ischemia, and 30 has severe ischemia. Endothelin levels were 1.2+/-0.6, 2.2+/-0.5, 6.2+/-0.7 pg/l (P<0.01), respectively. Thus, endothelin-1 is a marker of severity of ischemia rather than ischemia itself, and as such, may have prognostic value.