Plaque rupture and calcified nodules: major contributors to out-of-hospital cardiac arrest in acute myocardial infarction.

Since patients with cardiac arrest associated with acute myocardial infarction (MI) may not be successfully resuscitated, the underlying mechanisms of acute MI leading to out-of-hospital cardiac arrest (OHCA) have not been elucidated. This study evaluated whether there are differences in the plaque characteristics of infarct-related lesions between acute MI patients with OHCA and those without OHCA. This study analyzed 604 consecutive patients with a diagnosis of acute MI who underwent intravascular ultrasound (IVUS) evaluation of the infarct-related lesion before coronary intervention. All study patients were divided into two groups based on whether they presented with OHCA. The underlying mechanisms of acute MI were classified into four categories according to pre-interventional angiographic and IVUS images: plaque rupture, plaque erosion, calcified nodule, and embolization. Of the 604 patients diagnosed with acute MI, 69 (11%) suffered from OHCA. The OHCA group had a higher frequency of plaque rupture and calcified nodules than the non-OHCA group. Multivariate logistic regression analysis showed that an infarct-related lesion in the left main artery, the underlying plaque morphology of a calcified nodule, and plaque rupture were significantly associated with OHCA. In patients with acute MI, plaque morphology of infarct-related lesions with plaque rupture or a calcified nodule has a higher risk of leading to OHCA than other morphological types.