Impact of plaque rupture on infarct size in ST-segment elevation anterior acute myocardial infarction.

Objective: We sought to assess whether coronary plaque rupture at culprit lesions is associated with infarct size in patients with anterior acute myocardial infarction (AMI).

Background: Some patients with AMI have large infarcts despite early reperfusion. Whether culprit plaque morphology impacts infarct size or not remains unknown.

Methods: Patients who had a first anterior AMI with reperfusion within 6 hours after onset were enrolled and divided into 2 groups according to the presence or absence of plaque rupture at the culprit lesion as defined by preintervention intravascular ultrasound (IVUS): patients with rupture (n = 54) and without rupture (n = 37).

Results: Patients with plaque rupture had a higher incidence of no-reflow phenomenon (15% vs. 3%; p = 0.08) and a lower myocardial blush grade (1.5 vs. 2.3; p < 0.05) after percutaneous coronary intervention. The IVUS analysis showed that patients with plaque rupture had a higher incidence of soft plaque and positive remodeling. Peak creatine kinase levels were higher (4,707 vs. 2,309 IU/l; p < 0.0001) and left ventricular ejection fraction in the chronic phase was lower (54% vs. 63%; p < 0.01) in patients with plaque rupture. A multivariate logistic regression analysis revealed that plaque rupture and the proximal lesion site correlated with a left ventricular ejection fraction of <50% in the chronic phase (odds ratios 6.5 and 17.5, respectively; p < 0.05).

Conclusions: Plaque rupture is associated with morphologic characteristics of vulnerable lesions, as well as with larger infarcts and a higher incidence of no-reflow phenomenon, suggesting that plaque embolism contributes to the progression of myocardial damage in patients with anterior AMI.