p.15 抽出テキスト

September 25, 2018 Circulation. 2018;138:e272–e391. DOI: 10.1161/CIR.0000000000000549 e286

CLINICAL STATEMENTS AND GUIDELINES followed by spontaneous recovery if VT terminates, or SCA if VT persists and is not treated promptly. Syncope or SCA may be the first manifestation of structural or electrical heart disease,S4.1-14 and some SCA victims have preceding “sentinel” syncope episodes.S4.1-15 Syncope, or its forewarnings of dizziness, lightheadedness, or near-syncope, may constitute a risk factor for SCA and SCD.S4.1-2 The initial evaluation at any age focuses on detection or exclusion of heart disease. Syncope during exercise should prompt thorough evaluation to rule out cardiac causes. Cardiac evaluation with echocardiography, ambulatory monitoring, and exercise testing may be warranted depending on the clinical information elicited.S4.1-3,S4.1-4 Cardiac causes of syncope include sustained VT, high-grade atrioventricular block or severe sinus bradycardia or prolonged sinus pauses, supraventricular tachycardia (SVT), malfunction of pacemakers, VA from cardiac channelopathies or structural heart disease syndromes, such as hypertrophic cardiomyopathy (HCM) or congenital heart disease.S4.1-3,S4.1-4,S4.1-16 Cardiac channelopathies and HCM are particularly important to consider in adolescents and young adults. Arrhythmic causes of syncope are often associated with very short periods of premonitory symptoms, or palpitations, and known preexisting heart disease, especially a history of a low LVEF or HF.S4.1-1 Among nonarrhythmic cardiac causes, considerations should include myocardial ischemia, severe aortic stenosis, HCM, HF, and prosthetic valve malfunction, pulmonary embolism, medications, and illicit drug use.S4.1-3

4.2 Noninvasive Evaluation

4.2.1 12-lead ECG and Exercise Testing

Recommendations for 12-lead ECG and Exercise Testing Referenced studies that support the recommendations are summarized in Online Data Supplement 2.

COR LOE Recommendations

I B-NR 1. In patients with sustained, hemodynamically stable, wide complex tachycardia, a 12lead ECG during tachycardia should be obtained.S4.2.1-1–S4.2.1-3

I B-NR 2. In patients with VA symptoms associated with exertion, suspected ischemic heart disease, or catecholaminergic polymorphic ventricular tachycardia, exercise treadmill testing is useful to assess for exercise-induced VA.S4.2.1-4,S4.2.1-5

I B-NR 3. In patients with suspected or documented VA, a 12-lead ECG should be obtained in sinus rhythm to look for evidence of heart disease.S4.2.1-6 Recommendation-Specific Supportive Text

1.	 A 12-lead ECG during tachycardia is the first diagnostic test that should be done in any patient found to be in a stable wide QRS complex tachycardia on a monitor. VT is the diagnosis in most adults with wide complex tachycardia and underlying structural heart disease.S4.2.1-3 Criteria that support a diagnosis of VT include AV dissociation, a QRS complex >0.14 s, monophasic R wave in aVR, specific QRS morphologies (eg, positively or negatively concordant QRS complexes in the precordial leads), the absence of an RS complex in all precordial leads and an RS interval >100 ms in at least 1 precordial lead.S4.2.1-2 Exceptions occur, particularly in patients with advanced heart disease and with the use of certain antiarrhythmic medications.S4.2.1-1 For patients with preexisting bundle branch block, comparison of the QRS morphology during sinus rhythm with that during wide complex tachycardia is often relevant. 2.	 For exertion-related arrhythmic symptoms, exercise in a monitored setting may reproduce the symptoms and/or the related arrhythmia, allowing for diagnosis. Exercise testing is particularly important when catecholaminergic polymorphic ventricular tachycardia is a possibility. However, exertion-related symptoms and findings may not be reliably reproducible with exercise testing, and long-term electrocardiographic monitoring with external or implantable recorders may be necessary. 3.	 A 12-lead ECG may indicate the presence of structural heart disease such as prior MI or chamber enlargement that would increase the likelihood that a patient’s symptoms might be due to VA, or it may provide evidence of the underlying substrate for documented VA. An ECG may also reveal evidence of inherited arrhythmia disorders, such as long QT syndrome, Brugada syndrome, and arrhythmogenic right ventricular cardiomyopathy. In patients with structural heart disease, QRS duration and the presence of conduction abnormalities provide prognostic information.S4.2.1-7–S4.2.1-14 Data on the use of microvolt T wave alternans and the signal averaged ECG are inconclusive, as such these tests are not routinely used in clinical practiceS4.2.1-15–S4.2.1-19; the one exception is the potential use of signal averaged ECG in patients with arrhythmogenic right ventricular cardiomyopathy (see Section 7.3).

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