Acute myocardial infarction is thought to occur at sites of minor coronary stenosis. Recent data challenge this and also propose a role for coronary artery movement (CAM) in plaque instability. We examined the relationship between coronary stenosis severity, CAM pattern, and infarct-related lesions (IRLs) in acute myocardial infarction.

We investigated 203 consecutive patients with ST-segment elevation myocardial infarction after successful fibrinolysis. Quantitative coronary angiography, CAM pattern, and extent score (atheroma burden) analysis was performed for each coronary artery segment.

The IRL stenosis was at least moderate (>50%) and severe (>70%) in 78% and 31% of patients, respectively. Culprit arteries were associated with higher atheroma extent scores (25.2 vs 21.6, P < .001). Analysis of 2,228 coronary segments showed that stenosis severity and IRLs were highly correlated, such that the likelihood of being a culprit segment progressively increased with worsening stenosis (odds ratio [OR] 30.0, 95% confidence interval [CI] 19.0-47.6, P < .001, for >70% vs <30% stenosis). Compression CAM was also strongly associated with culprit segments (OR 3.4, 95% CI 2.6-4.5, P < .001). In addition, compression CAM and stenosis severity were strongly correlated, with the likelihood of a coronary segment having compression CAM progressively increasing with worsening stenosis (OR 56.4, 95% CI 37.9-83.8, P < .001, for >70% vs <30% stenosis).

In patients with ST-segment elevation myocardial infarction, there is a strong relationship between stenosis severity and IRLs. Our study also raises the hypothesis that compression CAM may accelerate atherosclerosis and predispose to plaque vulnerability.