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Circulation. 2017;136:e60–e122. DOI: 10.1161/CIR.0000000000000499 August 1, 2017 e97 CLINICAL STATEMENTS AND GUIDELINES

12.2 Risk Stratification and Clinical

Outcomes

At a patient’s presentation, several key questions follow: What is the likely cause of syncope? Does the pa- tient have significant underlying heart disease and/or comorbid medical illnesses? If the cause of syncope is determined, is there an effective therapy to prevent recurrent syncope, prevent syncope-related nonfatal outcomes (injury, diminished healthcare–related QoL, lost workdays), or improve survival? What are the predictors of short- and long-term clinical outcomes? What are the key outcomes relevant to patients with syncope, including recurrent syncope? When the cause of syncope is unknown, what is the standard of care for this group of patients?

•	 Studies are needed to determine whether syncope is an independent predictor of nonfatal or fatal outcomes in selected patient populations. •	 Studies are needed to develop risk scores to be prospectively validated in a given clinical setting with predefined endpoints from short- and longterm follow-up. •	 Prospective and well-designed studies are needed to define relevant clinical outcomes with regard to recurrent syncope, nonfatal outcomes such as injury, and fatal outcomes. Future studies should incorporate QoL, work loss, and functional capacity as additional clinical endpoints. •	 Prospective studies are needed to differentiate cardiac and noncardiac clinical outcomes in different clinical settings and with different follow-up durations. •	 Among patients without identifiable causes of syncope, studies are needed to determine short- and long-term outcomes to guide the overall management of these patients.

12.3 Evaluation and Diagnosis

Because of the concerns that patients presenting with syncope are at higher risk for an impending catastrophic event, overuse and inappropriate use of testing and hospital admission are common. Answers to the following question will improve the effectiveness of patient evaluation: How should the initial evaluation and subsequent follow-up vary by risk (low, intermediate, or high) to assess clinical outcomes?

•	 Studies are needed to better understand the interaction and relationships among the presenting symptom of syncope, the cause of syncope, the underlying disease condition, and their effect on clinical outcomes. •	 Investigations are needed to understand the key components of clinical characteristics during the initial evaluation and to develop standardization tools to guide the evaluation by healthcare team. •	 RCTs are needed to develop structured protocols to evaluate patients with syncope who are at intermediate risk without an immediate

Table 10.  Avoidance of Private Driving After an Episode of Syncope: Suggested Symptom-Free Waiting Times for Various Conditions

Condition Symptom-Free Waiting Time* OH 1 month V VS, no syncope in prior year698 No restriction V VS, 1–6 syncope per year694 1 month V VS, >6 syncope per year694,698 Not fit to drive until symptoms resolved Situational syncope other than cough syncope 1 month Cough syncope, untreated Not fit to drive Cough syncope, treated with cough suppression 1 month Carotid sinus syncope, untreated698 Not fit to drive Carotid sinus syncope, treated with permanent pacemaker698 1 week Syncope due to nonreflex bradycardia, untreated698 Not fit to drive Syncope due to nonreflex bradycardia, treated with permanent pacemaker12,698 1 week Syncope due to SVT, untreated698 Not fit to drive Syncope due to SVT, pharmacologically suppressed698 1 month Syncope due to SVT, treated with ablation698 1 week Syncope with LVEF <35% and a presumed arrhythmic etiology without an ICD699,700 Not fit to drive Syncope with LVEF <35% and presumed arrhythmic etiology with an ICD701,702 3 months Syncope presumed due to VT/VF, structural heart disease, and LVEF ≥35%, untreated Not fit to drive Syncope presumed due to VT/VF, structural heart disease, and LVEF ≥35%, treated with an ICD and guideline-directed drug therapy701,702 3 months Syncope presumed due to VT with a genetic cause, untreated Not fit to drive Syncope presumed due to VT with a genetic cause, treated with an ICD or guideline-directed drug therapy 3 months Syncope presumed due to a nonstructural heart disease VT, such as RVOT or LVOT, untreated Not fit to drive Syncope presumed due to a nonstructural heart disease VT, such as RVOT or LVOT, treated successfully with ablation or suppressed pharmacologically698 3 months Syncope of undetermined etiology 1 month *It may be prudent to wait and observe for this time without a syncope spell before resuming driving. ICD indicates implantable cardioverter-defibrillator; LVEF, left ventricular ejection fraction; LVOT, left ventricular outflow tract; OH, orthostatic hypotension; RVOT, right ventricular outflow tract; SVT, supraventricular tachycardia; VF, ventricular fibrillation; VT, ventricular tachycardia; and V VS, vasovagal syncope.

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