Review Question - QID 217231

A patient with extensive cardiac history with sudden loss of consciousness without prodromal symptoms is most likely to have suffered from a cardiac-related origin of syncope.

Syncope is defined as a sudden and transient loss of consciousness and associated postural tone. Syncope must be distinguished from seizures, which typically involve focal or generalized body movements, postictal state, and other signs such as tongue-biting or urinary incontinence. There are several forms of syncope as outlined below in Illustration A. Cardiac syncope, while a less frequent cause, is indicative of a potentially fatal underlying disease process. In fact, the one-year mortality in these individuals is 30%. The etiology is related to structural or electrical abnormalities. History can help distinguish this etiology from other syncopal causes as there are typically no prodromal symptoms, it occurs often during exertion and in patients with cardiac history. Workout entails electrocardiogram (including potential telemetry monitoring as an inpatient), echocardiogram, and cardiac enzyme cycling. Prevention relates to treating the underlying condition (e.g. pacemaker/defibrillator implant for patients with severe congestive heart failure) and/or optimizing medical management of said underlying condition.

Illustration A depicts a table characterizing the various forms of syncope and their associated symptoms and presenting features.

Runser et al. discuss the differential, workup, and management of syncope, including cardiac syncope.

Incorrect Answers:
Answer 2: Orthostatic hypotension-related syncope is due to hypoperfusion of the brain with sudden transition from seated to standing position. This typically occurs in elderly patient's and can be simulated via the gold standard tilt table test or, more frequently and conveniently, via blood pressure measurements in the seated and then standing position to assess for stark disparities in pressures (decline of ≥20mm Hg in systolic or ≥10 mm Hg in diastolic blood pressure after 3 minutes of standing).

Answer 3: Situational syncope refers to syncopal episodes that occur during specific behaviors, classically during urination. It may also occur during defecating or coughing.

Answer 4: Seizure is an important differential diagnosis in a patient presenting with loss of consciousness. It must be distinguished from syncope. Seizures typically involve focal or generalized body movements, postictal state, and other signs such as tongue-biting or urinary incontinence. An electroencephalogram is the diagnostic test of choice.

Answer 5: Vasovagal syncope is also known as neurocardiogenic syncope. It refers to a sudden drop in heart rate and blood pressure leading to fainting, often in reaction to a stressful trigger or strong emotion (e.g. the sight of blood). As such, patients often describe characteristic prodromal symptoms, such as lightheadedness or nausea.

Bullet Summary:
Patients with a history of cardiac ailments presenting with a sudden onset of syncope with prompt return to consciousness without prodromal symptoms are most likely to have suffered cardiac syncope.