Relationship of clinical presentation and calcification of culprit coronary artery stenoses

Coronary artery calcification is increased in the presence of atheroscleros is. However, there is great variability in the calcification of individual coronary stenoses, and the clinical significance of this finding remains un known. We tested the hypothesis that culprit lesions associated with myocar dial infarction or unstable angina are less calcified than are stenoses ass ociated with stable angina. The study consisted of 78 patients who underwen t intravascular ultrasound imaging of culprit stenoses after the placement of a stent. Seventeen patients presented with stable angina; 43, with unsta ble angina; and 18, with myocardial infarction. The extent of coronary calc ification was measured by the angle of its are and was quantified with a co mputer-based protractor. The are of calcium was measured in the stented are a at the point of maximal calcification and also as an average of the calci fication found at proximal, middle, and distal stent segments. The maximal arc of calcium decreased progressively from patients with stable angina (91 +/- 10 degrees) to those with unstable angina (59 +/-8 degrees) and to tho se with myocardial infarction (49 +/- 11 degrees, P=0.014). Similarly, the average arc of calcium was greatest (32 +/-7 degrees) in patients with stab le angina, less (15 +/-4 degrees) in patients with unstable angina, and lea st (10 +/-5 degrees) in patients with acute myocardial infarction (P=0.014) . These associations remained significant after adjustment for other factor s that potentially affect arterial calcification. Acute coronary syndromes are associated with a relative lack of calcium in the culprit stenoses comp ared with stenoses of patients with stable angina. These findings have impl ications for the understanding of the biology of acute coronary syndromes a s well as for the identification of coronary stenoses by methods that rely solely on the presence of calcium.