Background: Calcified nodule (CN) is recognized as one of the pathogenic mechanisms of acute coronary syndrome (ACS) accounting for about 10% of the ACS. The aim of this study is to examine the incidence and predictors of CN in patients with coronary artery calcification.
Methods: Between January 2015 and December 2016, 236 patients (ACS; 100 patients, stable angina; 83 patients, old myocardial infarction; 9 patients, asymptomatic coronary artery disease; 44 patients) with coronary artery calcification by fluoroscopy in the culprit vessels were enrolled and studied. Severity of calcification was divided into 2 groups based on the radiopaque densities (moderate: radiopaque density noted only during cardiac motion, severe: radiopaque density noted without cardiac motion prior to contrast injection). CN was defined as distinct calcification with protruding and convex luminal shape by optical coherence tomography (OCT). Clinical and angiographic characteristics were compared between patients with CN and those without CN.
Results: CNs were observed in 87 patients (37%). The prevalence of hypertension (90.8%vs. 72.5%; P<0.001), maintenance dialysis (17.2%vs. 4.7%; P<0.01), severe calcification (49.4%vs. 13.4%, P<0.0001) and non-culprit vessel of ACS (72.4%vs. 49.0%; P<0.001) were significantly higher in patients with CN compared with those without CN. The serum level of hemoglobin (12.7±1.87mg/dl vs. 13.2±1.79 mg/dl; P=0.05) and LDL cholesterol (91.7±25.1 mg/dl vs. 103.3±34.1 mg/dl; P=0.01) were significantly lower and the serum level of phosphorus (3.51±0.82mg/dl vs. 3.24±0.76 mg/dl; P<0.01) was significantly higher in patients with CN compared with those without CN. Multivariable logistic regression analysis revealed that hypertension (HR: (HR:3.93, 95%CI 1.51-11.77), maintenance hemodialysis (HR:3.44, 95%CI 1.02-12.43), non-culprit vessel of ACS (HR:2.30, 95%CI 1.12-4.85) and severe calcification by fluoroscopy (HR:6.54, 95%CI 3.20-13.95) were independent predictors of CN.
Conclusions: CNs were observed in 37% of the patients with coronary calcification. Hypertension, maintenance hemodialysis, severe calcification by fluoroscopy and non-culprit vessel of ACS were associated with CN.