A 72-year-old man presents to the emergency department after having abrupt syncope while hiking in Sedona, Arizona. He states that he has never passed out before. He was walking through a shaded grove up a hill when he had 1-2 sec of his vision darkening followed by abrupt loss of consciousness. His spouse rushed to his side and he regained consciousness in a few seconds. He denies any other symptoms such as flushing, nausea, or sweats. He denies any new medications.
On physical examination, he is oriented to person, place, and time but notably worried about having passed out. His neurological examination shows unremarkable findings. His cardiac examination shows regular rhythm with a systolic murmur. His electrocardiogram (ECG) shows sinus rhythm at 65 bpm, P-R interval 225 msec, left bundle branch block (LBBB), and normal axis. He is admitted overnight and telemetry shows unremarkable findings.
Which one of the following would be an appropriate test to evaluate his syncope further?
Show Answer
The correct answer is: A. Exercise stress testing.
This patient has a probable cardiac cause of syncope. Risk factors for cardiogenic syncope include him being a man >60 years of age without any prior syncope. The syncope event was preceded with a very brief prodrome. He had an outflow tract murmur and LBBB on his ECG. The most important piece of history was that the syncope event occurred during exertion. For patients with exertional syncope, exercise stress testing can evaluate for several structural issues, such as aortic stenosis and hypertrophic cardiomyopathy, especially considering that there was a systolic murmur on examination. Combining an imaging evaluation such as echocardiography to the stress test can be useful. Stress ECG can be helpful for signs of rate-dependent heart block in a patient with LBBB on baseline ECG (such as this patient), long QT syndrome type 1, and catecholaminergic polymorphic ventricular tachycardia in younger patients.
Carotid ultrasonography is not indicated. Carotid artery disease causing syncope without any neurological sequalae is unlikely. At this point, an electrophysiology study would be premature, but is reasonable in selected patients with a suspected arrhythmia etiology for the syncope. With this patient having an LBBB, an electrophysiology study can be considered if syncope remains unexplained after exercise stress testing. The diagnostic yield of a short-term Holter monitor is low in his presentation with an isolated syncope when the frequency of recurrence is unknown. If one were to choose monitoring at this point for suspected cardiogenic syncope, a longer-duration monitor, including an implantable loop recorder, would provide higher yield to make a diagnosis.
For his treatment, the guidelines recommend (Class IIa, Level of Evidence C-LD) that exercise stress testing can be useful to establish the cause of syncope in selected patients who experience syncope or presyncope during exertion.
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.
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