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Circulation. 2018;138:e272–e391. DOI: 10.1161/CIR.0000000000000549 September 25, 2018 e289 CLINICAL STATEMENTS AND GUIDELINES desmosomal mutation positive individuals do not develop disease, indicating that additional mutations and environmental interactions likely influence the clinical development of disease.S4.2.6-13–S4.2.6-16 Importantly, the absence of an identified disease-causing genetic mutation does not exclude the presence of disease, and as such, ongoing monitoring and decision-making are done based on the clinical phenotype. Genotyping is frequently most useful when a pathogenic mutation is identified in the proband, such that screening can be applied to relatives who are in a preclinical phase, allowing institution of lifestyle changes, therapy, or ongoing monitoring for those who are gene mutation positive.S4.2.6-7 Refer to Section 7.9 for disease-specific recommendations. In young patients (<40 years of age) without structural heart disease who have unexplained cardiac arrest, unexplained near drowning, or recurrent exertional syncope, genetic testing may be important to identify an inherited arrhythmia syndrome as a likely cause.S4.2.6-17–S4.2.6-23 Recommendation-Specific Supportive Text 1. The decision to proceed with genetic testing requires discussion regarding the clinical use of genetic information to be obtained for both the proband and family members, as well as consideration of the important psychological, financial, employment, disability, and life insurance implications of positive genotyping.S4.2.6-17,S4.2.6-18,S4.2.6-20,S4.2.6-24 Balancing privacy of health care information for the proband with the “right to know” for family members, and the ability to provide appropriate communication of information to all potentially affected family members can be challenging on many levels, including family dynamics, geographic proximity, and access to health care.S4.2.6-25 For these reasons, genetic counseling generally occurs before proceeding with genetic testing, and, from a patient’s perspective, is optimally provided by genetic counselors, if available, in collaboration with physicians.S4.2.6-26,S4.2.6-27 A combined approach of genetic counseling with medical guidance may appropriately balance the decision as to whether genetic testing would be beneficial on an individual basis. 4.3 Invasive Testing 4.3.1 Invasive Cardiac Imaging: Cardiac Catheterization or CT Angiography Recommendation for Invasive Imaging: Cardiac Catheterization COR LOE Recommendation I C-EO 1. In patients who have recovered from unexplained SCA, CT or invasive coronary angiography is useful to confirm the presence or absence of ischemic heart disease and guide decisions for myocardial revascularization. Recommendation-Specific Supportive Text 1. Although randomized studies are unavailable, coronary angiography has an important role in establishing or excluding the presence of significant obstructive ischemic heart disease in patients with SCA or those with life-threatening VA.S4.3.1-1–S4.3.1-4 Recurrent polymorphic VT or VF can be due to ongoing myocardial ischemia that resolves with coronary revascularization. Presence of ST-elevation on preresuscitation or early postresuscitation ECG suggests ischemia and potential ACS warranting urgent angiography and revascularization.S4.3.1-5 ST-elevation can also result from coronary spasm or DC shocks. The absence of ST-elevation after cardiac arrest does not exclude obstructive or thrombotic coronary lesions. A coronary angiogram may not be warranted if a nonischemic cause of SCA is established. Coronary and CT angiography also have an important role excluding the presence of anomalous origin of the coronary arteries that may cause SCD. 4.3.2 Electrophysiological Study for VA Recommendations for Electrophysiological Study References that support the recommendations are summarized in Online Data Supplements 8 and 9. COR LOE Recommendations IIa B-R 1. In patients with ischemic cardiomyopathy, NICM, or adult congenital heart disease who have syncope or other VA symptoms and who do not meet indications for a primary prevention ICD, an electrophysiological study can be useful for assessing the risk of sustained VT.S4.3.2-1–S4.3.2-7 III: No Benefit B-R 2. In patients who meet criteria for ICD implantation, an electrophysiological study for the sole reason of inducing VA is not indicated for risk stratification.S4.3.2-8–S4.3.2-11 III: No Benefit B-NR 3. An electrophysiological study is not recommended for risk stratification for VA in the setting of long QT syndrome, catecholaminergic polymorphic ventricular tachycardia, short QT syndrome, or early repolarization syndromes.S4.3.2-12–S4.3.2-16 Synopsis Electrophysiological study can be used to induce sustained VA in patients with known or suspected VA. With the advent of the ICD and its proven benefit in the primary and secondary prevention of SCD, there are fewer indications for programmed stimulation to provoke VA. Patients with HF and LVEF ≤35% generally will have an indication for an ICD and specific induction of VT/VF before implantation is not necessary. Patients with LVEF >35% and unexplained syncope or near-syncope may benefit from an electrophysiological study to determine Downloaded from http://ahajournals.org by on October 7, 2026