Diagnosis and management challenges of in-stent restenosis in coronary arteries

Table 1 ACC/AHA lesion-specific classification of the primary target stenosis

Lesion type	Lesion characteristic according to AHA/ACC classification
Type A lesions	Discrete (< 10 mm length)	Concentric	Readily accessible	Non angulated segment < 45°	Smooth contour	Little or no calcification
	Less than totally occlusive	Not ostial in location	No major branch involvement	Absence of thrombus
Type B1 lesions	Tubular (10-20 mm length)	Eccentric	Moderate tortuosity of proximal segment	Moderately angulated segment, 45°-90°	Irregular contour	Moderate to heavy calcification
	Total occlusion < 3-mo-old	Ostial in location	Bifurcation lesions requiring double Guidewires	Some thrombus present
Type B2 lesions	Two or more “B” characteristics
Type C lesions	Diffuse (> 2 cm length)	Total occlusion > 3-mo-old	Excessive tortuosity of proximal segment	Extremely angulated segments, > 90°	Inability to protect major side branches	Degenerated vein grafts with friable lesions