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Circulation. 2017;136:e60–e122. DOI: 10.1161/CIR.0000000000000499 August 1, 2017 e95 CLINICAL STATEMENTS AND GUIDELINES

Table 9.  Conditions Uncommonly Associated with Syncope

Condition Clinical Characteristics Notes Cardiovascular and Cardiopulmonary Cardiac tamponade Hypotension, tachycardia, cardiogenic shock. Often tachycardia and hypotension; may be hypotensive and bradycardic acutely. Constrictive

pericarditis533–535 Severe HF symptoms, including edema, exertional dyspnea, orthopnea. May be associated with cough syncope. LV noncompaction536–539 Cardiomyopathy characterized by prominent LV trabeculae and deep intertrabecular recesses, due to embryologic perturbation. Syncope reported in 5%–9% of both adult and pediatric patients. The mechanism may be a tachyarrhythmia. Takotsubo

cardiomyopathy540,541 Apical ballooning and basal hypercontractility, often due to stress. Chest pain and ECG changes consistent with ischemia are commonly seen. Syncope is uncommon and may be multifactorial. Pulmonary embolus128,542,543 Hypoxemia, tachycardia; hypotension and shock leading to pulseless electrical activity cardiac arrest in severe cases. Syncope due to bradycardia and/or hypotension. One study showed higher prevalence of pulmonary embolus in older patients with first episode of syncope after admission to the hospital. Further confirmation of this finding in the older populations is warranted. Pulmonary arterial

hypertension Occurs more often during exertion in younger patients. Syncope due to inability to augment or sustain cardiac output during exertion, followed by vasodilatation. Infiltrative Fabry disease544,545 Lysosomal storage disorder with neuropathic pain, renal failure concentric LVH, and HF. Syncope usually due to AV block. Amyloidosis546,547 Systemic disease due to amyloid deposition. Light chain amyloidosis affects the kidneys, heart, and peripheral and autonomic nervous systems. Syncope may be due to conduction system disease, arrhythmias, impaired cardiac output from restrictive cardiomyopathy, or neurological involvement. AV block is the likely cause, although VA may occur with myocardial involvement. Hemochromatosis548 Systemic iron deposition causing liver disease, skin pigmentation, diabetes mellitus, arthropathy, impotence, and dilated cardiomyopathy. Myocardial involvement more common than sick sinus syndrome and AV conduction disease. Infectious Myocarditis413,549–553 Chest pain, arrhythmias, or profound LV systolic dysfunction. Hemodynamic collapse may occur. VT and AV block are the likely causes of syncope; transient hemodynamic collapse is possible. Lyme disease554 Lyme myocarditis with classical features of Lyme disease, including erythema migraines and neurological manifestations. Syncope may be due to AV block, but many patients manifest V VS.554,555 Chagas disease556–559 Chagasic cardiomyopathy caused by trypanosomiasis. Syncope and sudden death associated with ventricular tachyarrhythmias. AV block also occurs. Neuromuscular Myotonic dystrophy12,560,561 Autosomal dominant inheritance with multiple organ systems affected. Grip myotonia, weakness, temporal wasting, alopecia, cataracts, glucose intolerance, and daytime somnolence. Both bradyarrhythmia and tachyarrhythmias. Friedreich ataxia562,563 Autosomal recessive inheritance with limb and gait ataxia, bladder dysfunction, and daytime somnolence. Diffuse interstitial fibrosis and HCM. Syncope can be bradycardic or tachycardic. SCD is known to occur. Kearns-Sayre

Syndrome564,565 Mitochondrial myopathy. Chronic progressive external ophthalmoplegia; pigmentary retinopathy. Many patients develop significant His-Purkinje disease. Erb dystrophy566 Limb girdle muscular dystrophy, manifesting as scapulohymeral and/or pelvifemoral weakness and atrophy. AV conduction disease, dilated cardiomyopathy. Anatomic Lenègre-Lev disease567–571 Progressive fibrosis and sclerosis of cardiac conduction system, including the cardiac skeleton, including the aortic and mitral rings. Syncope is usually due to high-grade AV block. Cardiac tumors572 Triad of obstruction, embolic, and systemic signs and symptoms. Syncope is often due to obstruction to blood flow. Prosthetic valve

thrombosis573–575 Ranges from asymptomatic to profound HF. May have similar presentation to a cardiac tumor, with a high risk of embolic phenomenon and obstruction. Anomalous coronary

artery576–579 Common cause of exertional syncope or SCD, classically in young athletes. Syncope can be due to Bezold Jarisch reflex, hypotension, VT, or AV block.

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