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Lawton et al 2021 ACC/AHA/SCAI Coronary Revascularization Guideline

Circulation. 2022;145:e18–e114. DOI: 10.1161/CIR.0000000000001038 January 18, 2022 e31 CLINICAL STATEMENTS AND GUIDELINES

severe stenosis. An angiographically intermediate coronary stenosis is defined as a diameter stenosis severity of 40% to 69%, and generally warrants additional investigation to assess physiological significance. There is controversy over whether visually estimated diameter stenosis or quantitative coronary angiography better predicts the functional significance of a coronary stenosis.1,2 The difference in mean diameter stenosis between quantitative coronary angiography and visual estimation varies from 10% to 20% and is dependent on stenosis severity.3-5 The use of optimal angiographic projections, multiple angiographic views, and adjunct imaging or physiology may aid in the assessment of coronary anatomy when coronary angiography is used.

4.2 Defining Coronary Artery Lesion

Complexity: Calculation of the SYNTAX (Synergy Between PCI With TAXUS and Cardiac Surgery) Score Recommendation for Defining Coronary Artery Lesion Complexity: Calculation of the SYNTAX Score Referenced studies that support the recommendation are summarized in Online Data Supplement 4.

COR LOE Recommendation

2b B-NR 1.	 In patients with multivessel CAD, an assessment of CAD complexity, such as the SYNTAX score, may be useful to guide revascularization.1-4

Synopsis The anatomic complexity of lesions, expected completeness of revascularization, predicted risk of death, and other adverse outcomes are important factors to consider for determining the type of revascularization for patients with CAD. Many factors contribute to the estimation of the complexity of CAD (Table 6). The SYNTAX score was prospectively derived from the SYNTAX trial to aid in this decision-making process by providing an objective measure to grade the anatomic complexity of CAD in patients with multivessel disease.1 Its value as an independent predictor of long-term major adverse cardiac and cerebrovascular events and death was established in the SYNTAX trial cohort and subsequently validated in external studies of patients treated with PCI but not CABG.2-4 The SYNTAX II score and the revised SYNTAX Score II 2020 was retrospectively developed from the SYNTAX trial cohort.5,6 to incorporate clinical variables in addition to the anatomic variables. These scores demonstrate modest discrimination in predicting adverse clinical events after revascularization.6

Recommendation-Specific Supporting Text

1.	 The SYNTAX score remains the most widely used and validated risk score to guide the choice of revascularization in patients with multivessel disease. Important limitations of this score include the cumbersome scoring system required for each lesion and the interobserver variability in its calculation.7,8 Additionally, the absence of clinical variables limits its use in estimating the risk of clinical events after CABG. When estimating a patient’s complexity of disease, it is important to consider variables that contribute to disease complexity which might impact the success and outcomes of revascularization (Table 6).

4.3 Use of Coronary Physiology to Guide

Revascularization With PCI Recommendations for the Use of Coronary Physiology to Guide Revascularization With PCI Referenced studies that support the recommendations are summarized in Online Data Supplement 5.

COR LOE Recommendations

1 A 1.	 In patients with angina or an anginal equivalent, undocumented ischemia, and angiographically intermediate stenoses, the use of fractional flow reserve (FFR) or instantaneous wave-free ratio (iFR) is recommended to guide the decision to proceed with PCI.1-6

3: No benefit B-R 2.	 In stable patients with angiographically intermediate stenoses and FFR >0.80 or iFR >0.89, PCI should not be performed.7-10

Synopsis FFR and iFR are 2 of the most commonly used physiological methods of assessing lesion significance. FFR is defined as the ratio of maximal blood flow in a region distal to a lesion compared with the normal maximal blood flow of an artery. iFR, an index of lesion severity, is the instantaneous wave-free ratio (in diastole) of coronary pressure distal to the coronary lesion (Pd) to the aortic pressure (Pa) The potential advantage of iFR, which is a resting physiological index, is that it obviates the use of adenosine because it does not require a state of maximal hyperemia. These 2 measures—FFR and iFR—have

Table 6.  Angiographic Features Contributing to Increasing Complexity of CAD Multivessel disease Left main or proximal LAD artery lesion Chronic total occlusion Trifurcation lesion Complex bifurcation lesion Heavy calcification Severe tortuosity Aorto-ostial stenosis Diffusely diseased and narrowed segments distal to the lesion Thrombotic lesion Lesion length >20 mm CAD indicates coronary artery disease; and LAD, left anterior descending.

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