Acute Coronary Syndrome (ACS) remains a leading cause of mortality worldwide. Several studies have demonstrated a role for Coronary Computed Tomographic Angiography (CCTA) to predict the vulnerability of the plaque. Recent works suggest a role for calcification in this vulnerability.

To assess if the CCTA study of the calcium component of plaques can predict plaque vulnerability defined by intracoronary OCT analysis in patients with non-ST elevation myocardial infarction (NSTEMI).

Prospective study of consecutive patients with NSTEMI and elevated high-sensitivity cardiac troponin I level>50ng/ml from January to October 2018. CCTA was performed before coronary angiography. When CCTA demonstrated significant lesions, coronary angiography was performed with OCT study of three coronary arteries. Apart culprit plaques, vulnerable plaques were defined in OCT by a fibrous screed thickness <65microns. Calcified plaques were analysed and classified into 3groups: vulnerable culprit plaque (VCP), vulnerable non-culprit plaque (VNCP) and stable plaque (SP).

Of 1478patients with chest pain, 257 (17%) had NSTEMI. Among them 44(17%) were without known CAD and among these patients 29(66%-mean age 59±13years, 73%men) had received coronary angiography and OCT. A total of 123calcified plaques were identified. Among them, OCT allowed to identify 77 (63%) SP and 47 (37%) calcified vulnerable plaques with 28VNCP and 19VCP. After CCTA analysis, predictive factors of vulnerability were identified: longer calcification length, larger calcification volume, higher plaque's Agatston score, lower sphericity index, more spotty calcifications, a more intimal position in the wall (P<0.001 for all) and lower calcium mass (P=0.003). No significant differences were observed comparing VNCP and VCP (Fig. 1).

CCTA study of the calcium component of plaque allows to identify predictors of plaque vulnerability defined by OCT in patients with NSTEMI.