Morbidity and mortality from atherosclerosis is largely due to type IV and type V lesions in which disruptions of the lesion surface, hematoma or hemorrhage, and thrombotic deposits have developed. Type IV or V lesions with one or more of these additional features are classified as type VI and may also be referred to as complicated lesions. Type VI may be subdivided by the superimposed features. Thus, disruption of the surface may be labeled type VIa; hematoma or hemorrhage, type VIb; and thrombosis, type VIc. Type VIabc indicates the presence of all three features.