Abstract 201: Microvascular Obstruction on Cardiovascular Magnetic Resonance Imaging Correlates With Reperfusion Injury After Coronary Angioplasty in Patients With Acute Myocardial Infarction
Introduction: Reperfusion injury occurs in patients with acute myocardial infarction (AMI) who have received coronary angioplasty. In such patients, microvascular obstruction (MO) is often observed on cardiovascular magnetic resonance (CMR) perfusion images. However, the association between reperfusion injury and MO remains unclear.
Hypothesis: We tested the hypothesis that reperfusion injury correlates with MO, and that CMR is able to visualize reperfusion injury.
Methods: Between November 2007 and April 2009, 65 consecutive patients who underwent coronary angioplasty for AMI were studied. CMR imaging was performed in all these patients between three and 14 days after revascularization. MO was defined as not only perfusion defect on perfusion image, but also subendocardial hypoenhancement within a region of hyperenhancement area on late gadolinium enhanced image. Patients were divided into two groups: with MO and without MO. The relationship of MO with variables that may influence the occurrence of reperfusion injury was analyzed. The variables include clinical findings: peak CPK, preinfarction angina, thrombolytic therapy, reperfusion time (from onset to restoration of epicardial flow) and Killip classification; electrocardiogram findings: ST re-elevation and ST resolution; and angiographical findings: TIMI grade classification (TIMI 0 or 1, 2, 3 on first shot) and slow flow phenomenon.
Results: Of 65 patients, 26 have MO. Univariate analysis showed that MO was significantly related to peak CPK (p=0.0003), presence of preinfarction angina (p=0.03), TIMI grade classification (p=0.009), ST resolution (p=0.01), presence of ST re-elevation (p=0.003) and slow flow phenomenon (p=0.03), but not to thrombolytic therapy (p=0.11), Killip classification (p=0.79) and reperfusion time (p=0.37). Multivariate analysis revealed slow flow phenomenon as the single independent predictor of the occurrence of MO (p=0.004).
Conclusion: In conclusion, MO is strongly related to reperfusion injury as microvascular flow disturbance. The present findings suggest that MO on CMR image is a good indicator of reperfusion injury, and has prognostic and therapeutic implication in patients with AMI.