Significance of plaque disruption sites in acute coronary syndrome.

Coronary plaque disruption and subsequent thrombosis occur in both unstable angina (UA) and acute myocardial infarction (AMI). However, it is unclear why UA and AMI have different clinical courses. The purpose of this angiographic study was to examine whether the longitudinal plaque disruption site is a factor that can be used to distinguish these two conditions. Seventy-two patients with AMI or UA in whom ischemia- or infarct-related arteries and plaque disruption sites could be determined were enrolled. The plaque disruption sites were classified as upstream type or downstream type. The upstream type and downstream type were defined as plaque rupture site located proximal and distal, respectively, to the maximum stenosis on angiography. The frequency of the upstream type was significantly higher in patients with AMI (60.0%) than in patients with UA (18.5%). On the other hand, the frequency of the downstream type was higher in patients with UA (81.5%) in patients with AMI (40.0%; p<0.01). The longitudinal plaque disruption site may thus be a factor that can be used to distinguish these two diseases.