Let History and Physical Examination Guide Your Testing in Patients with Syncope
A structured comprehensive history and physical examination focusing on orthostatics and a cardiac and neurologic examination will identify the cause of syncope in almost half of patients. Patients who are admitted without a clear low-risk etiology for syncope should be considered for imaging to rule out pulmonary embolism (PE) with a positive D-dimer, said Daniel Dressler, MD.
Sixty percent of syncope is reflex mediated, such as that with vasovagal episodes, situational syncope, and, less commonly, carotid sinus syncope, while 15% of cases can be attributed to orthostatic phenomena.1 Higher-risk syncope has cardiovascular causes, either rhythm disturbances or structural heart disease, and is responsible for about 15% of syncope.
The history and physical examination has a diagnostic yield of about 45%.2 In an additional 8%, the history and physical examination provides suggestive findings that confirm the diagnosis on subsequent testing. “Probably every patient deserves an electrocardiogram [ECG],” said Dr. Dressler, professor of medicine, Emory University School of Medicine, Atlanta.
Key components of the physical examination are a recording of vital signs, including assessment of orthostatic hypotension; a complete neurologic examination; and a complete cardiac examination.
Features that are suggestive of seizure rather than syncope are tongue biting (specificity of 96%);3 head turning during temporary loss of consciousness; no memory of abnormal behavior before, during, or after the event; prolonged limb jerking; and confusion after the event.
The ECG is abnormal in about 50% of patients with syncope, but it is only diagnostic in about 5%.
Estimating the risk of pulmonary embolism
The multicenter cross-sectional PESIT trial enrolled 560 patients who were admitted following presentation to the emergency department (ED) for a first episode of syncope.4 Patients were assessed for the presence or absence of PE using the simplified Wells score plus a D-dimer assay. Pulmonary embolism was ruled out in two-thirds based on the simplified Wells score and a negative D-dimer assay, and one-third required imaging. Of the original 2,584 patients who presented to the ED with syncope, only 3.8% had PE. Two-thirds of those diagnosed with PE had large-vessel PE, or 2.5% of those who presented to the ED. One-fourth of patients diagnosed with PE had no clinical manifestations of PE.
In a systematic review/meta-analysis of 12 retrospective studies, the pooled prevalence of PE was 0.8%, and the PE prevalence in hospitalized syncope was 1.0%.5 In a separate retrospective cohort of 1.6 million unselected patients with syncope who presented to the ED, the prevalence of PE ranged from 0.06% to 0.55% (0.15% to 2.1% for hospitalized patients) and the prevalence of venous thromboembolism was 0.3% to 1.37% (0.75% to 3.86% for hospitalized patients).6 A 2019 multicenter prospective cohort study of patients presenting to the ED with syncope found a PE prevalence of 0.6%.7
“What I think we should be doing in the ED is continuing with a thorough workup with no change in imaging ordering. When patients get admitted to the hospital, if we’ve done a workup and we think they’re low risk, we should just discharge them,” said Dr. Dressler. “If we work them up and find something high risk, like an arrhythmia, then we should manage that situation.” Without a clear etiology after the workup, he advises checking the simplified Wells score and D-dimer level. If the D-dimer assay is positive or the simplified Wells score is ≥4, consider imaging for PE.
Risk stratification
The Canadian Syncope Risk Score identifies patients at risk for serious adverse events within 30 days of ED disposition.8 The rate of serious outcomes increases from <1.0% in those with very low-risk scores to up to 50% in those with very high-risk scores.8,9
Clinical findings should guide the ordering of tests. Left bundle branch block (BBB) can be diagnosed from the evaluation in about one-third of patients with syncope; the remainder deserve electrophysiologic study and potentially an implantable loop recorder.
The diagnostic yield of neurologic tests (ie, brain imaging, carotid Doppler ultrasound, electroencephalogram) is 1.5%.10 The yield increases to >30% if neurologic studies were directed only at patients with neurologic findings on the history or physical examination, he said. According to the ACP, American Academy of Neurology, and American College of Emergency Physicians, brain imaging studies are not indicated in the evaluation of simple syncope and a normal neurologic examination.
An echocardiogram is recommended only if underlying heart disease is suspected and the physical examination and ECG do not provide a diagnosis.
Indications for exercise stress testing are suspected ischemia, exertion-related syncope, exertion-induced tachyarrhythmias, and bradyarrhythmia with BBB. Echocardiography may be necessary prior to stress testing to exclude structural heart disease.
A carotid sinus massage is indicated in older patients with unexplained history or a suggestive history. In such patients, the complication rate is low and the yield can be as high as 46%.11
Electrophysiologic studies are indicated in patients with organic heart disease in whom the suspicion for arrhythmia is high or who have a clinically normal heart but are at high risk for bradyarrhythmia.
Tilt table testing evaluates the predisposition to vasovagal syncope and is indicated in patients with recurrent unexplained syncope without evidence of organic heart disease or with a negative cardiac work-up.
Disclosure
Nothing to disclose.
References
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- Schnipper JL, Kapoor WN. Diagnostic evaluation and management of patients with syncope. Med Clin North Am 2001;85:423-56.
- Brigo F, Nardone R, Bongiovanni LG. Value of tongue biting in the differential diagnosis between epileptic seizures and syncope. Seizure 2012;21:568-72.
- Prandoni P, Lensing AWA, Prins MH, et al. Prevalence of pulmonary embolism among patients hospitalized for syncope. N Engl J Med 2016;375:1524-31.
- Oqab Z, Ganshorn H, Sheldon R. Prevalence of pulmonary embolism in patients presenting with syncope: A systematic review and meta-analysis. Am J Emerg Med 2018;36:551-5.
- Costantino G, Ruwald MH, Quinn J, et al. Prevalence of pulmonary embolism in patients with syncope. JAMA Intern Med 2018;178:356-62.
- Thiruganasambandamoorthy V, Sivilotti MLA, Rowe BH, et al. Prevalence of pulmonary embolism among emergency department patients with syncope: a multicenter prospective cohort study. Ann Emerg Med 2019;73:500-10.
- Thiruganasambandamoorthy V, Kwong K, Wells GA, et al. Development of the Canadian Syncope Risk Score to predict serious adverse events after emergency department assessment of syncope. CMAJ 2016;188:E289-98.
- Thiruganasambandamoorthy V, Sivilotti MLA, Le Sage N, et al. Multicenter emergency department validation of the Canadian Syncope Risk Score. JAMA Intern Med 2020;180:737-44.
- Pires LA, Ganji JR, Jarandila R, Steele R. Diagnostic patterns and temporal trends in the evaluation of adult patients hospitalized with syncope. Arch Intern Med 2001;161:1889-95.
- Pasquier M, Clair M, Pruvot E, Hugli O, Carron P-N. Carotid sinus massage. N Engl J Med 2017;377:e21. Doi:10.1056/NEJMvcm1313338.