A 29-year-old woman presents to the emergency department after a transient loss of consciousness. She reports feeling lightheaded shortly after beginning a presentation at an academic conference. Four minutes into her presentation, she felt a vague flushing sensation and nausea while standing at the podium. She was able to steady herself at the podium but then fell to the floor. She did not sustain any significant trauma, and her colleagues who witnessed the event reported that she was only unconscious for a "few moments." When she regained consciousness, other than feeling profoundly fatigued, she was alert and oriented to herself and her surroundings. She has no prior history of syncope or known seizure disorder, and no significant past medical history.
Vital signs upon presentation include temperature 36.2°C, heart rate 64 bpm, and blood pressure 112/72 mm Hg. She does not have orthostatic vital sign changes. Her electrocardiogram (ECG) reveals sinus rhythm with a normal QRS axis in the frontal plane, normal intervals, no evidence of pre-excitation, no suggestive signs of chamber enlargement, and no ST/T-wave abnormalities. A complete blood count and metabolic panel are within normal limits. Her echocardiogram reveals normal left ventricular (LV) size, thickness, and systolic function with no significant valvular pathology.
She reports that her 35-year-old male cousin was diagnosed with Wolff-Parkinson-White syndrome 6 months earlier, after he presented with palpitations and near-syncope and underwent catheter ablation. She is anxious about her faint and is inquiring about the next steps of her care.
Which one of the following should be pursued?
Show Answer
The correct answer is: C. Education on the diagnosis and prognosis of her condition.
Answer choice A is an incorrect choice. Tilt-table testing can be considered in patients in whom the diagnosis is not clear after initial evaluation. It can be useful in cases in which patients have recurrent syncope suspected to be vasovagal syncope (VVS), clinical features suggestive of delayed orthostatic hypotension despite the absence of orthostatic changes on initial presentation, or suspected psychogenic pseudosyncope (Class IIa). The presentation of syncope occurring while standing, with a prodrome of nausea and fatigue and accompanied by postepisodic fatigue, is highly consistent with VVS. In contrast, although there is considerable overlap in presentations, patients with cardiac syncope rarely have postevent fatigue and classical prodromes. Given that this is the patient's first episode of syncope with typical features of VVS, tilt-table testing is not indicated at this time.
Answer choice B is an incorrect choice. Midodrine acts peripherally to reduce peripheral sympathetic neural outflow that causes vasodepressor effects and venous pooling. Prior and recent randomized controlled trials have demonstrated that midodrine can reduce the recurrence of syncope in patients with VVS. Midodrine is a reasonable option for pharmacologic therapy in patients who do not have a history of heart failure, hypertension, or urinary retention. In this patient presenting with an initial episode of VVS, education on the diagnosis of VVS, avoidance of triggers, and physical counterpressure maneuvers should be considered before initiating medical therapy.
Answer choice C is the correct choice. Her prodrome of nausea and flushing, occurring in an upright position and accompanied by fatigue, are characteristic descriptors of VVS, a type of reflex syncope. VVS is mediated by reflex hypotension and bradycardia, and is often triggered by prolonged standing, emotional stress, pain, or situational stress (e.g., dental or medical procedures). Although her concern about a more significant diagnosis considering her family history is understandable, there is an alternative nonarrhythmic explanation for her syncope. Counseling about the pathophysiology and prevalence of VVS is an essential part of reassuring patients about the benign nature of their condition, especially in those who have family members with cardiac disease or a history of arrhythmias.
Answer choice D is an incorrect choice. Cardiac magnetic resonance imaging (MRI) is useful in characterizing cardiac anatomy and structure, assessing LV and right ventricular function, identifying infiltrative processes via late gadolinium enhancement, and evaluating for areas of fibrosis or scar. It is often used in patients with known or suspected ventricular arrhythmias that may be associated with structural heart disease (SHD) or sudden cardiac death. In a patient with a normal echocardiogram and clinical features of VVS, a cardiac MRI is not necessary as part of the initial diagnostic evaluation.
Answer choice E is an incorrect choice. Electrophysiologic study (EPS) can be useful in clinical scenarios in which identifying the nature of an arrhythmia (e.g., distinguishing between ventricular tachycardia or supraventricular tachycardia with aberrancy) can affect the subsequent steps of care. Although prior studies have evaluated the use of EPS in patients with syncope of suspected arrhythmic origin, the diagnostic yield is often low, even in patients with pre-existing SHD. Furthermore, EPS is often unnecessary in patients with syncope who have a pre-existing cardiomyopathy and LV systolic dysfunction (LV ejection fraction <35%) who meet indications for a primary-prevention implantable cardioverter-defibrillator. In patients with structurally normal hearts, a normal ECG, and a clinical history suggestive of a nonarrhythmic cause for syncope, regardless of family history, EPS is not recommended as part of the initial evaluation (Class III).
Educational grant support provided by: Medtronic
To visit the course page for the Assessment and Diagnosis of Syncope Project, click here!
References
Shen WK, Sheldon RS, Benditt DG, et al. 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol 2017;70:e39-e110.
Sheldon R, Faris P, Tang A, et al.; POST 4 Investigators. Midodrine for the prevention of vasovagal syncope : a randomized clinical trial. Ann Intern Med 2021;174:1349-56.
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