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

OBJECTIVES

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.