Coronary angiography ACC-AHA characteristics of type A, B, and C coronary lesions

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

The American College of Cardiology/American Heart Association (ACC/AHA) Task Force on Assessment of Diagnostic and Therapeutic Cardiovascular Procedures developed a classification scheme to characterize the complexity of coronary stenoses and the probability of success of a percutaneous intervention. This system was developed in 1988 prior to the widespread deployment of coronary stents.

Type A Lesions (High Success [> 85%]; Low Risk)

• Discrete (< 10 mm)
• Little or no calcium
• Concentric
• Less than totally occlusive
• Readily accessible
• Not ostial in location
• Nonangulated segment (< 45 degrees)
• No major side branch involvement
• Smooth contour
• Absence of thrombus

Type B Lesions (Moderate Success [60%–85%]; Moderate Risk)

• Tubular (10–20 mm length)
• Moderate to heavy calcification
• Eccentric
• Total occlusions < 3 months old
• Moderate tortuosity of proximal segment
• Ostial in location
• Moderately angulated (45-90 degrees)
• Bifurcation lesion requiring double guidewire
• Irregular contour
• Some thrombus present

Type C Lesions (Low Success [< 60%]; High Risk)

• Diffuse (> 20 mm length)
• Total occlusion > 3 months old
• Excessive tortuosity of proximal segment
• Inability to protect major side branches
• Extremely angulated segment (> 90 degrees)
• Degenerated vein grafts with friable lesions

Pathophysiology

Even in the modern era of stenting, the PERFUSE study group has shown that increasing lesion complexity is associated with impairments in both epicardial and myocardial perfusion.

Natural History, Complications and Prognosis

Increase lesion complexity is associated with a higher risk of cardiogenic shock and cardiovascular death.