Persistent infarct-related artery occlusion is associated with an increased myocardial apoptosis at postmortem examination in humans late after an acute myocardial infarction

Background - Myocardial apoptosis persists beyond the acute phases of acute myocardial infarction (AMI) and is associated with left ventricular (LV) remodeling. Infarct-related artery (IRA) patency is considered a favorable prognostic factor after AMI and may be associated with more favorable LV remodeling because of reduced apoptosis at the site of AMI. The aim of this study was to assess the influence of IRA status on apoptotic rate (AR) in the hearts of subjects dying late after AMI. Methods and Results - We used colocalization for in situ end-labeling of DNA fragmentation and immunohistochemistry for caspase-3 to calculate the AR at time of death (12 to 62 days after AMI) in 16 hearts with persistently occluded IRAs and in 8 hearts with patent IRAs. No significant differences were found when comparing the clinical characteristics of the 2 groups. Occluded IRA was associated with significantly higher AR at site of infarction (25,8% [interquartile range 20.9% to 28.5%] versus 2.3% [interquartile range 0.6% to 5.0%], P<0.001). This strong correlation between IRA occlusion and AR remained statistically significant even after correction for clinical characteristics such as sex, age, history of previous additional AMI or heart failure, transmural AMI, anterior AMI, fibrinolytic treatment, time from AMI to death, trauma as cause of death, and multivessel coronary disease (P=0.003). Conclusions - A significantly higher AR was associated with persistent IRA occlusion late post-AMI. These data may suggest that the post-AMI benefits observed with a patent IRA (the "open-artery hypothesis") may in part be due to reduced myocardial apoptosis.