Evaluation and Management of Syncope in Pregnancy

Initial Assessment and Risk Stratification

The American College of Emergency Physicians recommends that the cornerstone of syncope evaluation remains history and physical examination, which identifies the cause in up to 85% of cases where a diagnosis is established 1, 2.
The European Heart Journal suggests considering pregnancy-specific etiologies while not missing cardiac causes that carry high mortality risk 3.
A history of structural heart disease or congestive heart failure is a critical element to obtain, as it increases the risk of cardiac complications 1, 6.
The American College of Cardiology recommends considering family history of sudden cardiac death as a risk factor for cardiac etiology 7.
Syncope during exertion is a high-risk feature suggesting cardiac etiology, according to the Journal of the American College of Cardiology 7.

A 12-lead ECG is warranted in all pregnant patients with syncope, as it is noninvasive, inexpensive, and can immediately identify life-threatening conditions, despite a low overall yield of 5% 1, 2.
The European Heart Journal recommends looking for evidence of myocardial infarction or ischemia, arrhythmias or conduction abnormalities, prolonged QT interval, ventricular hypertrophy, and pre-excitation patterns on the ECG 2, 4.
Orthostatic vital signs should be measured, with a decrease in systolic blood pressure of >20 mmHg or an increase in heart rate of >20 beats per minute considered abnormal 1, 8, 9.

The American College of Emergency Physicians recommends admitting patients with high-risk features, including age >45 years, history of congestive heart failure, history of ventricular arrhythmias, abnormal ECG, physical exam findings of heart failure, and cardiac murmur suggesting outflow obstruction 6.
Patients with 3-4 risk factors have a 57.6-80.4% risk of 1-year mortality or significant arrhythmia, while those with zero risk factors have 0% 72-hour cardiac mortality and 0.7% risk of arrhythmia 2, 6.
The European Heart Journal suggests that patients without structural heart disease, normal ECG, and clinical features suggesting vasovagal or orthostatic syncope can be safely discharged with outpatient follow-up 3.

Physiologic changes in pregnancy, including increased cardiac output, decreased systemic vascular resistance, and aortocaval compression, predispose to syncope 8, 9, 10.
Common benign causes of syncope in pregnancy include vasovagal syncope and orthostatic hypotension, while life-threatening causes include pulmonary embolism, cardiac arrhythmias, and amniotic fluid embolism 1, 4, 8, 11.

Continuous cardiac monitoring is appropriate for the first 24 hours if arrhythmia is suspected, according to the Annals of Emergency Medicine 2.
The Journal of the American College of Cardiology recommends arranging outpatient cardiology follow-up if any concerning features are present, and routine obstetric follow-up to monitor pregnancy 3, 7.