Background In animal models of myocardial infarction (MI), inflammatory responses compromise microcirculation during reperfusion and restrict functional recovery. To investigate cardiac inflammatory responses in patients with acute MI, we examined the cardiac release of cytokines, the expression on neutrophils of the β₂-integrin Mac-1 (CD11b/CD18) and L-selectin (CD62L), and the cardiac release of thrombomodulin as a marker of endothelial injury.

Methods and Results In 12 patients with acute anterior MI, blood samples were obtained from the coronary sinus and from the aorta immediately before and after recanalization of the coronary occlusion by balloon angioplasty. Twelve patients undergoing elective balloon angioplasty served as control subjects. Plasma concentrations of interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor-α, and thrombomodulin were determined by immunoassay, and surface expression of CD11b and CD62L was assessed by flow cytometry. Differences in coronary sinus and arterial blood were found in IL-6 before (median, 6.3 ng/L, P=.01) and after (13.4 ng/L, P=.002) recanalization and in IL-8 after recanalization (10.7 ng/L, P=.02). The cardiac release of both cytokines significantly (P≤.03) increased with reperfusion. Cytokine release after reperfusion was associated with significant transcardiac gradients in surface expression on neutrophils of CD11b (10.1 mean channel of fluorescence intensity [mean fl], P=.01) and CD62L (−8.7 mean fl, P=.007) and with a thrombomodulin release (4.5 μg/L, P=.004). Transcardiac gradients in IL-1β and tumor necrosis factor-α were not found. None of the changes found in MI were detectable in the control group.

Conclusions As evidence of cardiac inflammatory responses in reperfused acute MI, the study demonstrates cardiac neutrophil activation with signs of endothelial injury and a release of the proinflammatory cytokines IL-8 and IL-6. These findings may assist in the design of pharmacological interventions aimed at reducing microvascular reperfusion injury.