We investigated the association between hyperglycemia and the no-reflow phenomenon in patients with acute myocardial infarction (AMI).

Hyperglycemia is associated with increased risks of heart failure, cardiogenic shock, and death after AMI, but its underlying mechanism remains unknown.

A total of 146 consecutive patients with a first AMI were studied by intracoronary myocardial contrast echocardiography (MCE) after successful reperfusion within 24 h after symptom onset. Two-dimensional echocardiography was recorded on day 1 and three months later to determine the change in the wall motion score (ΔWMS; sum of 16 segmental scores; dyskinesia = 4 to normokinesia = 0).

The no-reflow phenomenon was found on MCE in 49 (33.6%) of 146 patients; their glucose level on hospital admission was significantly higher than that of patients who did not exhibit this phenomenon (209 ± 79 vs. 159 ± 56 mg/dl; p < 0.0001). There was no difference in glycosylated hemoglobin or in the incidence of diabetes mellitus between the two subsets. The no-reflow phenomenon was more often observed in the 75 patients with hyperglycemia (≥160 mg/dl) than in those without hyperglycemia (52.0% vs. 14.1%; p < 0.0001). Patients with hyperglycemia had a higher peak creatine kinase level (2,497 ± 1,603 vs. 1,804 ± 1,300 IU/l; p = 0.005) and a lower ΔWMS (3.7 ± 4.8 vs. 5.7 ± 4.3; p = 0.01) than did those without hyperglycemia. The blood glucose level was an independent prognostic factor for no reflow, along with age, gender, absence of pre-infarction angina, complete occlusion of the culprit lesion, and anterior AMI.

Hyperglycemia might be associated with impaired microvascular function after AMI, resulting in a larger infarct size and worse functional recovery.