High-risk plaques were more frequent in patients with ACS and remained a significant predictor of ACS ( odds ratio [ OR ] : 8.9 ; 95 % CI : 1.8 to 43.3 ; p = 0.006 ) after adjustment for 50 % stenosis ( OR : 38.6 ; 95 % CI : 14.2 to 104.7 ; p < 0.001 ) and clinical risk assessment ( age , sex , number of cardiovascular risk factors ) .