Beneficial effect of residual anterograde flow on tissue viability as assessed by positron emission tomography in patients with myocardial infarction.

With the advent of therapeutic interventions to restore blood flow in patients with acute infarction, early identification of salvageable myocardium has gained clinical importance. It was the purpose of this study to define regional blood flow and glucose metabolism in patients with acute myocardial infarction as assessed by positron emission tomography (PET) and to correlate these findings with coronary anatomy. In 15 patients blood flow as determined by N-13 ammonia was reduced in 37 left ventricular segments. In 20 segments there was a similar decrease in FDG uptake, consistent with tissue necrosis. In contrast, 17 segments with reduced blood flow revealed maintained FDG uptake suggesting residual viability in the electrocardiographically defined 'infarct segment'. PET viability and necrosis was significantly associated with presence or absence of anterograde flow in the infarct artery. Evaluation of regional wall motion did not distinguish segments with PET criteria for viability from segments with necrosis. Thus, in patients without thrombolytic therapy during evolving myocardial infarction, spontaneous reperfusion appears to be beneficial for tissue survival. PET offers the unique possibility to assess tissue viability early after the ischaemic injury where evaluation of wall motion fails to identify salvageable myocardium.