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September 25, 2018 Circulation. 2018;138:e272–e391. DOI: 10.1161/CIR.0000000000000549 e296 CLINICAL STATEMENTS AND GUIDELINES 5.4.2. VA in Patients With No Apparent Structural Heart Disease See Section 8. VA that are not associated with underlying structural heart disease or a genetic arrhythmia syndrome are commonly referred to as idiopathic. Most idiopathic VA are monomorphic and based on a focal mechanism of triggered activity or abnormal automaticity; a few are due to reentry. For patients who are symptomatic, and in whom antiarrhythmic medications are ineffective, not tolerated, or not desired by the patient, catheter ablation is a treatment option. The ablation strategy is to identify the site of origin manifested by the earliest site of electrical activation, or when this is not practical, by pace mapping. Catheter ablation of idiopathic VA is usually accomplished with endocardial catheterization, though an epicardial approach through the coronary venous circulation or a subxiphoid pericardial puncture may occasionally be required. Ablation failure for idiopathic VA is often due to inability to provoke the arrhythmia to allow mapping in the electrophysiological laboratory or origin from an inaccessible region. 5.4.3 Scar-Related VT See Section 8. For most patients with structural heart disease, sustained monomorphic VT is due to reentry through regions of surviving myocardial fibers associated with areas of fibrous scar. The ablation strategy for these reentry circuits is to identify and eliminate channels of surviving myocardium within the scar that are often associated with slow conduction facilitating reentry. For most VTs that are related to prior MI, the substrate is on the subendocardial surface of the left ventricle. In NICM, the reentrant circuits are more variable in location, often involve the epicardial surface of either ventricle and frequently extending into the midmyocardium where ablation may be difficult to achieve from either surface. In tetralogy of Fallot specific reentry paths have been defined.S5.4.3-1 Electroanatomical mapping that helps clarify the relation of electrophysiological abnormalities to cardiac anatomy is commonly employed. Areas of scar can be appreciated as regions of relatively low electrogram voltage. For scar-related VTs, hemodynamic intolerance often limits mapping during VT. Ablation is then often guided by substrate mapping, in which areas of scar and potential reentry circuit substrate are delineated in electroanatomic maps based on electrocardiographic and pacing characteristics assessed during hemodynamically stable sinus or paced rhythm. Catheter ablation of scar-related VT requires an advanced level of experience by the operator, electrophysiological laboratory staff, and anesthesiologists as well as availability of surgical back-up and specialized mapping, imaging, and ablation equipment.S5.4.3-2,S5.4.3-3 5.5 Surgery and Revascularization Procedures in Patients With Ischemic Heart Disease Recommendations for Surgery and Revascularization Procedures in Patients With Ischemic Heart Disease References that support the recommendations are summarized in Online Data Supplement 11. COR LOE Recommendations I B-NR 1. Patients with sustained VA and survivors of SCA should be evaluated for ischemic heart disease, and should be revascularized as appropriate.S5.5-1–S5.5-4 I C-EO 2. In patients with anomalous origin of a coronary artery suspected to be the cause of SCA, repair or revascularization is recommended. Recommendation-Specific Supportive Text 1. Myocardial ischemia is a cause of sustained polymorphic VT/VF, and revascularization is an effective treatment to prevent myocardial ischemia. For patients with life-threatening VA, observational studies show that patients undergoing coronary artery bypass graft (CABG) had substantially better survival after accounting for other predictors.S5.5-1,S5.5-5 The risk of SCD appears comparable for patients with complex ischemic heart disease randomized to treatment with PCI versus CABG.S5.5-6 For patients with low LVEF and ischemic heart disease amenable to CABG, the risk of SCD is lower with CABG than medical therapy.S5.5-2,S5.5-7 Observational studies show an association between a lower likelihood of death with revascularization for survivors of SCA and CABGS5.5-3 or PCI.S5.5-4 Revascularization alone is usually insufficient to prevent recurrence of sustained monomorphic VT; further evaluation for inducible VT is generally considered if ventricular function is depressed and/or scar is present. 2. Anomalous aortic origin of the coronary arteries is detected in approximately 1% of patients undergoing routine coronary angiography, and <0.2% of children and adolescents undergoing echocardiography.S5.5-8 Although ischemic heart disease is detected in as many as 24% to 55% of SCD cases in young patients <35 years of age,S5.5-9,S5.5-10 anomalous aortic origin of the coronary arteries is an important cause of SCD in the young, reported in 10% to 17% of patients included in postmortem studies.S5.5-10,S5.5-11 Anomalous origin of the coronary arteries can be identified by echocardiography, invasive coronary angiography, CT angiography or cardiac MRI. In patients with SCA or life-threatening VA presumed Downloaded from http://ahajournals.org by on October 7, 2026