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

Coronary Angiography
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Lesion Complexity
ACC/AHA Lesion-Specific Classification of the Primary Target Stenosis
Preprocedural Lesion Morphology Eccentricity Irregularity Ulceration Intimal Flap Aneurysm Sawtooth Pattern Length Ostial location Angulation Proximal tortuosity Degenerated SVG Calcification Total occlusion Coronary Artery Thrombus TIMI Thrombus Grade TIMI Thrombus Grade 0 TIMI Thrombus Grade 1 TIMI Thrombus Grade 2 TIMI Thrombus Grade 3 TIMI Thrombus Grade 4 TIMI Thrombus Grade 5 TIMI Thrombus Grade 6
Lesion Morphology Quantitative Coronary Angiography Definitions of Preprocedural Lesion Morphology Irregular Lesion Disease Extent Arterial Foreshortening Infarct Related Artery Restenosis Degenerated SVG Collaterals Aneurysm Bifurcation Trifurcation Ulceration
Left ventriculography
Technique Quantification of LV Function Quantification of Mitral Regurgitation

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Rim Halaby, M.D. [2]; Vanessa Cherniauskas, M.D. [3]

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 stenosis and the probability of success of a percutaneous intervention. ACC/AHA lesion complexity system provides short-term prognostic information adjunctive to TIMI flow grade (TFG) and TIMI myocardial perfusion grade (TMPG).

ACC/AHA Lesion-Specific Classification of the Primary Target Stenosis

The lesion-specific classification was proposed by the Subcommittee on Percutaneous Transluminal Coronary Angioplasty to estimate the likelihood of a successful angioplastic procedure (defined as one in which a ≥20% change in luminal diameter is achieved, with the final diameter stenosis <50% and without the occurrence of death, acute myocardial infarction, or the need for emergency bypass operation) as well as the likelihood of developing abrupt vessel closure.

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

Type A lesions are associated with an anticipated success procedure rate of ≥85% and a low risk of abrupt closure. Type A lesions demonstrate all of the following characterisitics:

• Discreteness (<10 mm in length)
• Concentricity
• Ready accessibility
• Location in a nonangulated segment (<45°)
• Smoothness of contour
• Little or no calcification
• Absence of total occlusion
• Nonostial location
• Absence of major branch involvement
• Absence of thrombus

Type B Lesions (Moderate Success, 60 to 85%; Moderate Risk*)

Type B lesions are associated with an anticipated success procedure rate ranging from 60 to 85% or a moderate risk of abrupt closure, or both. Type B lesions include all lesions that are neither type A nor type C and are usually identified by, but not limited to, the following characterisitics:

• Tubular shape (10 to 20 mm in length)
• Eccentricity
• Accessibility influenced by moderate tortuosity of proximal segment
• Location in a moderately angulated segment (>45°, <90°)
• Irregularity of contour
• Moderate or severe calcification
• Presence of thrombus
• Ostial location
• Bifurcation lesions requiring double guide wires
• Total occlusions <3 months old

* Although the risk of abrupt vessel closure is moderate, in certain circumstances the likelihood of a major complication may be low as in dilation of total occlusions <3 months old or when abundant collateral channels supply the distal vessel.

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

Type C lesions are associated with an anticipated success procedure rate of <60% or a high risk of abrupt closure, or both. Type C lesions demonstrate any of the following characterisitics:

• Diffuseness (>20 mm in length)
• Excessive tortuosity of proximal segments
• Location in an extremely angulated segment (>90°)
• Total occlusion >3 months old
• Inability to protect major side branches
• Degeneration of older vein grafts with friable lesions

Modified ACC/AHA Lesion-Specific Classification of the Primary Target Stenosis

The standard ACC/AHA classification of the primary target stenosis is prospectively modified to subdivide type B stenoses into B1 (one adverse characteristic) and B2 (≥ two adverse characteristics) on the basis of previous studies suggesting the cumulative significance of mutiple adverse lesion characteristics.

Clinical Significance

• A greater ACC/AHA lesion complexity at 60 to 90 minutes after fibrinolytic administration was shown to be associated with poorer epicardial flow and myocardial perfusion as well as a higher risk of pulmonary edema, shock, and mortality within 30 days. However, increased lesion complexity was not associated with a higher risk of recurrent myocardial infarction.

• Independent of left anterior descending coronary artery infarct location, TIMI grade 3 flow, age, performance of rescue or adjunctive PCI, pulse, and systolic blood pressure on admission, type C lesion complexity was associated with an increased short-term mortality rate at 30 days.