From the Guidelines
Cardiac syncope is a medical emergency that requires immediate evaluation and treatment, as it can be a symptom of a life-threatening underlying cardiac condition, such as arrhythmias, structural heart disease, or cardiac ischemia, as outlined in the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1.
Causes of Cardiac Syncope
The causes of cardiac syncope are diverse and can be categorized into several groups, including:
- Cardiovascular and cardiopulmonary conditions, such as cardiac tamponade, constrictive pericarditis, and pulmonary embolus, which can lead to syncope due to hypotension, tachycardia, or bradycardia 1.
- Infiltrative diseases, such as Fabry disease, amyloidosis, and hemochromatosis, which can cause syncope due to AV block, conduction system disease, or restrictive cardiomyopathy 1.
- Infectious diseases, such as myocarditis, Lyme disease, and Chagas disease, which can lead to syncope due to VT, AV block, or ventricular tachyarrhythmias 1.
- Neuromuscular diseases, such as myotonic dystrophy, Friedreich ataxia, and Kearns-Sayre Syndrome, which can cause syncope due to bradyarrhythmia, tachyarrhythmias, or AV conduction disease 1.
- Anatomic abnormalities, such as Lenègre-Lev disease, cardiac tumors, and prosthetic valve thrombosis, which can lead to syncope due to high-grade AV block, obstruction to blood flow, or embolic phenomena 1.
Diagnosis and Treatment
Diagnosis of cardiac syncope typically involves a thorough history, physical examination, ECG, echocardiogram, and possibly Holter monitoring or electrophysiology studies 1. Treatment depends on the underlying cause and may include medications, such as beta-blockers or antiarrhythmics, device implantation, surgical intervention, or coronary revascularization.
Management and Prognosis
Patients experiencing syncope should lie down immediately if they feel warning symptoms, avoid triggers like prolonged standing, ensure adequate hydration, and rise slowly from lying positions. The prognosis varies significantly based on the underlying cardiac condition, with some arrhythmic causes carrying a high risk of sudden cardiac death if untreated, making prompt diagnosis and appropriate management essential 1.
From the Research
Definition and Diagnosis of Cardiac Syncope
- Cardiac syncope is a type of syncope that is caused by a cardiac condition, such as an arrhythmia or a structural heart disease 2, 3.
- Syncope is defined as a transient loss of consciousness due to cerebral hypoperfusion with spontaneous return to baseline function without intervention 2, 3.
- The diagnosis of cardiac syncope can be challenging, as most patients are asymptomatic at the time of presentation, and a thorough history and physical examination, including orthostatic assessment, are crucial for making the diagnosis 2.
Evaluation and Management of Cardiac Syncope
- A short-term risk assessment should be performed to determine the need for admission, and if the short-term risk is high, inpatient evaluation is needed 2, 4.
- In patients with suspected cardiac syncope, monitoring is indicated until a diagnosis is made, and syncope units have been shown to improve the rate of diagnosis while reducing cost 2.
- Risk-stratifying patients into low, moderate, and high-risk groups can assist in medical decision making and help determine the patient's disposition 4, 3.
Treatment and Prevention of Cardiac Syncope
- Beta-blockers have been shown to have anti-arrhythmic effects and can be used to prevent sudden cardiac death in patients with heart failure 5, 6.
- Guideline-directed medical therapy, including beta-blockers, angiotensin receptor-neprilysin inhibitors, and mineralocorticoid receptor antagonists, has been shown to reduce the risk of sudden cardiac death in patients with heart failure with reduced ejection fraction 6.
- Emerging treatments, such as sodium-glucose cotransporter 2 inhibitors, show promise in reducing the risk of sudden cardiac death, but further research is needed to clarify their anti-arrhythmic benefits 6.