block or third degree [complete] AV block) or prolonged pauses are treated with permanent pacemaker placement. (See 'Arrhythmias' above.) For patients with severe aortic stenosis in whom no other etiology of syncope is identified, and the syncope is suspected to be due to the severe aortic stenosis, aortic valve replacement is indicated. Similarly, unexplained syncope (ie, not related to neurocardiogenic/vasovagal causes) in patients with hypertrophic cardiomyopathy is considered a marker for increased risk of sudden death. (See 'Obstruction to left ventricular outflow' above and "Indications for valve replacement for high gradient aortic stenosis in adults" and "Hypertrophic cardiomyopathy: Risk stratification for sudden cardiac death".) Driving restrictions are indicated for some patients at risk for recurrent syncope for the safety of themselves and others. In general, patients with untreated syncope should not drive until appropriate preventive treatment has been instituted. Following the institution of therapy for syncope, the duration of time patients should avoid driving varies significantly depending upon the underlying condition as well as the legal restrictions of the local, state, or national government ( table 4). (See 'Driving restrictions' above.) ACKNOWLEDGMENT The UpToDate editorial staff acknowledges Brian Olshansky, MD, who contributed to earlier versions of this topic review. Use of UpToDate is subject to the Terms of Use. REFERENCES https://www.uptodate.com/contents/syncope-in-adults-management-and-prognosis/print 12/26 7/6/23, 2:38 PM Syncope in adults: Management and prognosis - UpToDate 1. 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. 2. Brignole M, Moya A, de Lange FJ, et al. 2018 ESC Guidelines for the diagnosis and management of syncope. Eur Heart J 2018; 39:1883. 3. Parry SW, Tan MP. An approach to the evaluation and management of syncope in adults. BMJ 2010; 340:c880. 4. Thijs RD, Wieling W, Kaufmann H, van Dijk G. Defining and classifying syncope. Clin Auton Res 2004; 14 Suppl 1:4. 5. Thijs RD, Benditt DG, Mathias CJ, et al. Unconscious confusion a literature search for definitions of syncope and related disorders. Clin Auton Res 2005; 15:35. 6. Kapoor WN. Evaluation and outcome of patients with syncope. Medicine (Baltimore) 1990; 69:160. 7. Blanc JJ, L'Her C, Touiza A, et al. Prospective evaluation and outcome of patients admitted for syncope over a 1 year period. Eur Heart J 2002; 23:815. 8. van Dijk JG, Ghariq M, Kerkhof FI, et al. Novel Methods for Quantification of Vasodepression and Cardioinhibition During Tilt-Induced Vasovagal Syncope. Circ Res 2020; 127:e126. 9. van Dijk N, Quartieri F, Blanc JJ, et al. Effectiveness of physical counterpressure maneuvers in preventing vasovagal syncope: the Physical Counterpressure Manoeuvres Trial (PC-Trial). J Am Coll Cardiol 2006; 48:1652. 10. Krediet CT, van Dijk N, Linzer M, et al. Management of vasovagal syncope: controlling or aborting faints by leg crossing and muscle tensing. Circulation 2002; 106:1684. 11. Anand V, Benditt DG, Adkisson WO, et al. Trends of hospitalizations for syncope/collapse in the United States from 2004 to 2013-An analysis of national inpatient sample. J Cardiovasc Electrophysiol 2018; 29:916. 12. Benditt DG, Adkisson WO, Sutton R, et al. Ambulatory diagnostic ECG monitoring for syncope and collapse: An assessment of clinical practice in the United States. Pacing Clin Electrophysiol 2018; 41:203. 13. Wieling W, Dambrink JH, Borst C. Cardiovascular effects of arising suddenly. N Engl J Med 1984; 310:1189. 14. Freeman R, Wieling W, Axelrod FB, et al. Consensus statement on the definition of orthostatic hypotension, neurally mediated syncope and the postural tachycardia syndrome. Clin Auton Res 2011; 21:69. https://www.uptodate.com/contents/syncope-in-adults-management-and-prognosis/print 13/26 7/6/23, 2:38 PM Syncope in adults: Management and prognosis - UpToDate 15. Sheldon R, Talajic M, Tang A, et al. Randomized Pragmatic Trial of Pacemaker Versus Implantable Cardiac Monitor in Syncope and Bifascicular Block. JACC Clin Electrophysiol 2022; 8:239. 16. Santini M, Castro A, Giada F, et al. Prevention of syncope through permanent cardiac pacing in patients with bifascicular block and syncope of unexplained origin: the PRESS study. Circ Arrhythm Electrophysiol 2013; 6:101. 17. Sakaguchi S, Adkisson WO. Driving and flying: US and European recommendations. In: Sync ope: An Evidence-Based Approach, 2nd ed, Brignole M, Benditt DG (Eds), Springer Nature 20 20. p.319. 18. Num AK, Gislason G, Christiansen CB, et al. Syncope and Motor Vehicle Crash Risk: A Danish Nationwide Study. JAMA Intern Med 2016; 176:503. 19. Dischinger PC, Ho SM, Kufera JA. Medical conditions and car crashes. Annu Proc Assoc Adv Automot Med 2000; 44:335. 20. Redelmeier DA, Yarnell CJ, Thiruchelvam D, Tibshirani RJ. Physicians' warnings for unfit drivers and the risk of trauma from road crashes. N Engl J Med 2012; 367:1228. 21. Staples JA, Erdelyi S, Merchant K, et al. Syncope and the Risk of Subsequent Motor Vehicle Crash: A Population-Based Retrospective Cohort Study. JAMA Intern Med 2022; 182:934. 22. Soteriades ES, Evans JC, Larson MG, et al. Incidence and prognosis of syncope. N Engl J Med 2002; 347:878. 23. Saklani P, Krahn A, Klein G. Syncope. Circulation 2013; 127:1330. 24. Kenny RA, O'Shea D, Walker HF. Impact of a dedicated syncope and falls facility for older adults on emergency beds. Age Ageing 2002; 31:272. 25. Shenthar J, Prabhu MA, Banavalikar B, et al. Etiology and Outcomes of Syncope in Patients With Structural Heart Disease and Negative Electrophysiology Study. JACC Clin Electrophysiol 2019; 5:608. 26. Ruwald MH, Hansen ML, Lamberts M, et al. Prognosis among healthy individuals discharged with a primary diagnosis of syncope. J Am Coll Cardiol 2013; 61:325. 27. Yasa E, Ricci F, Magnusson M, et al. Cardiovascular risk after hospitalisation for unexplained syncope and orthostatic hypotension. Heart 2018; 104:487. 28. Francisco-Pascual J, Rodenas-Alesina E, Rivas-G ndara N, et al. Etiology and prognosis of patients with unexplained syncope and mid-range left ventricular dysfunction. Heart Rhythm 2021; 18:597. 29. Ricci F, Sutton R, Palermi S, et al. Prognostic significance of noncardiac syncope in the general population: A systematic review and meta-analysis. J Cardiovasc Electrophysiol https://www.uptodate.com/contents/syncope-in-adults-management-and-prognosis/print 14/26 7/6/23, 2:38 PM Syncope in adults: Management and prognosis - UpToDate 2018; 29:1641. Topic 1032 Version 39.0 https://www.uptodate.com/contents/syncope-in-adults-management-and-prognosis/print 15/26 7/6/23, 2:38 PM Syncope in adults: Management and prognosis - UpToDate GRAPHICS Algorithm for syncope/collapse This algorithm poses key questions about a collapse episode, including whether and when LOC occurred. However, in the absence of a credible witness, information about such episodes is often limited, as the affected individual may not have accurate recall of the event. Some causes have more than one possible type of presentation. LOC: loss of consciousness; BLS: basic life support; ACLS: advanced cardiac life support; SAH: subarachnoid hemorrhage; TIA: transient ischemic attack. This includes actual LOC as well as apparent LOC. Accidental falls without LOC often have multiple causes, including gait, posture, or balance impairment, environmental hazard, vertigo, focal seizure, TIA, stroke, and presyncope. https://www.uptodate.com/contents/syncope-in-adults-management-and-prognosis/print 16/26 7/6/23, 2:38 PM Syncope in adults: Management and prognosis - UpToDate These conditions result in apparent transient LOC, although consciousness may be preserved. Other causes of collapse may cause secondary head trauma. Most TIAs and strokes are not associated with LOC. An SAH may cause transient or prolonged LOC. A rare cause of LOC is a brainstem stroke. Graphic 131146 Version 1.0 https://www.uptodate.com/contents/syncope-in-adults-management-and-prognosis/print 17/26 7/6/23, 2:38 PM Syncope in adults: Management and prognosis - UpToDate Conditions incorrectly diagnosed as syncope Disorders with partial or complete LOC but without global cerebral hypoperfusion Epilepsy Metabolic disorders including hypoglycaemia, hypoxia, hyperventilation with hypocapnia Intoxication Vertebrobasilar TIA Disorders without impairment of consciousness Cataplexy Drop attacks Falls Functional (psychogenic pseudosyncope) TIA or carotid origin LOC: loss of consciousness; TIA: transient ischaemic attack. Reproduced with permission from: European Heart Rhythm Association (EHRA), Heart Failure Association (HFA), Heart Rhythm Society (HRS), et al. Guidelines for the diagnosis and management of syncope (version 2009): the Task Force for the Diagnosis and Management of Syncope of the European Society of Cardiology (ESC). Eur Heart J 2009; 30:2631. Copyright 2009 Oxford University Press. Graphic 76023 Version 6.0 https://www.uptodate.com/contents/syncope-in-adults-management-and-prognosis/print 18/26 7/6/23, 2:38 PM Syncope in adults: Management and prognosis - UpToDate Major cardiovascular causes of syncope Reflex-mediated* Vasovagal Orthostatic vasovagal syncope: usually after prolonged standing, frequently in a warm environment, etc Emotional vasovagal syncope: secondary to fear, pain, medical procedure, etc Unknown trigger Situational Micturition, defecation Swallowing Coughing/sneezing Carotid sinus syndrome Orthostatic hypotension* Medication-related Diuretics (eg, thiazide or loop diuretics) Vasodilators (eg, dihydropyridine calcium channel blockers, nitrates, alpha blockers, etc) Antidepressants (eg, tricyclic drugs, SSRIs, etc) Volume depletion Hemorrhage Gastrointestinal losses (ie, vomiting or diarrhea) Diminished thirst drive (primarily in older patients) Autonomic failure Primary: pure autonomic failure, Parkinson disease, multiple system atrophy, Lewy body dementia Secondary: diabetes mellitus, amyloidosis, spinal cord injuries, autoimmune neuropathy (eg, Guillain-Barr ), paraneoplastic neuropathy Cardiac Tachyarrhythmias Ventricular tachycardia Supraventricular tachycardias Bradyarrhythmias (with inadequate ventricular response) Sinus node dysfunction Atrioventricular block Structural disease https://www.uptodate.com/contents/syncope-in-adults-management-and-prognosis/print 19/26 7/6/23, 2:38 PM Syncope in adults: Management and prognosis - UpToDate Severe aortic stenosis Hypertrophic cardiomyopathy Cardiac tamponade Prosthetic valve dysfunction Congenital coronary anomalies Cardiac masses and tumors (eg, atrial myxoma) Cardiopulmonary/vascular Pulmonary embolus Severe pulmonary hypertension Aortic dissection SSRI: selective serotonin reuptake inhibitor. Reflex-mediated syncope and syncope due to orthostatic hypotension are more likely to occur, or are more severe, when other factors may also be contributing, such as medication(s) causing low blood pressure, volume depletion, pulmonary diseases causing reduction in brain oxygen supply, alcohol use, and/or environmental factors (excessive heat or humidity). Adapted from: Brignole M, Moya A, de Lange FJ, et al. 2018 ESC Guidelines for the diagnosis and management of syncope. Eur Heart J 2018; 39:1883. Graphic 118175 Version 4.0 https://www.uptodate.com/contents/syncope-in-adults-management-and-prognosis/print 20/26 7/6/23, 2:38 PM Syncope in adults: Management and prognosis - UpToDate Examples of medications that may cause or exacerbate orthostatic hypotension Mechanism of hypotension and Drug group comments Diuretics Extracellular fluid volume depletion. Loop diuretics (eg, furosemide, torsemide) or thiazides Adrenergic antagonists Alpha-1-adrenergic blockers produce vasodilation Alpha-1-adrenergic blockers (eg, alfuzosin, tamsulosin, terazosin) via direct effect in vascular smooth muscle. Beta-adrenergic blockers reduce cardiac output and renin release. May also reduce vascular peripheral resistance. Beta-adrenergic blockers (eg, propranolol) Alpha-2-adrenergic agonists (eg, tizanidine, clonidine) Vasodilation via central inhibition of sympathetic efferent activity. Nitric oxide-mediated vasodilators Vasodilation via direct effect in vascular smooth muscle. Nitroglycerin, hydralazine Phosphodiesterase-5-inhibitors (eg, sildenafil) Renin-angiotensin system (RAS) inhibitors (eg, lisinopril, valsartan) Vasodilation via RAS inhibition. Calcium-channel blockers (eg, verapamil, diltiazem) Reduction of cardiac output, vasodilation via direct effect in vascular smooth muscle. Dopamine antagonists Vasodilation via central inhibition of sympathetic efferent activity. Phenothiazines (eg, chlorpromazine) Atypical antipsychotics (eg, olanzapine, risperidone, quetiapine) Antidepressants (eg, trazodone, amitriptyline) Vasodilation via central and peripheral inhibition of sympathetic efferent activity through stimulation of adrenergic receptors. Selective serotonin receptor reuptake inhibitors (eg, paroxetine) Unknown mechanism, possibly via central and peripheral inhibition of sympathetic efferent activity through stimulation of alpha-2-adrenergic receptors. Sodium-glucose co-transporter 2 inhibitors (eg, Volume depletion via osmotic diuresis. empagliflozin, canagliflozin) https://www.uptodate.com/contents/syncope-in-adults-management-and-prognosis/print 21/26 7/6/23, 2:38 PM Syncope in adults: Management and prognosis - UpToDate Graphic 130809 Version 5.0 https://www.uptodate.com/contents/syncope-in-adults-management-and-prognosis/print 22/26 7/6/23, 2:38 PM Syncope in adults: Management and prognosis - UpToDate Recommendations for resuming driving after syncope Condition Symptom-free waiting time* OH 1 month [1] VVS, no syncope in prior year No restriction [2] VVS, 1 to 6 syncope per year 1 month [1,2] VVS, >6 syncope per year 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 [1] Carotid sinus syncope, untreated Not fit to drive Carotid sinus syncope, treated with permanent pacemaker 1 week [1] [1] Syncope due to nonreflex bradycardia, untreated Not fit to drive Syncope due to nonreflex bradycardia, treated with [1,3] permanent pacemaker 1 week [1] Syncope due to SVT, untreated Not fit to drive [1] Syncope due to SVT, pharmacologically suppressed 1 month [1] Syncope due to SVT, treated with ablation 1 week Syncope with LVEF <35% and a presumed arrhythmic [4,5] etiology without an ICD Not fit to drive Syncope with LVEF <35% and presumed arrhythmic etiology with an ICD 3 months [6,7] 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 therapy 3 months [6,7] Syncope presumed due to VT with a genetic cause, Not fit to drive untreated Syncope presumed due to VT with a genetic cause, treated 3 months with an ICD or guideline-directed drug therapy Syncope presumed due to a nonstructural heart disease VT, such as RVOT or LVOT, untreated Not fit to drive https://www.uptodate.com/contents/syncope-in-adults-management-and-prognosis/print 23/26 7/6/23, 2:38 PM Syncope in adults: Management and prognosis - UpToDate Syncope presumed due to a nonstructural heart disease VT, such as RVOT or LVOT, treated successfully with ablation or 3 months [1] suppressed pharmacologically Syncope of undetermined etiology 1 month OH: orthostatic hypotension; VVS: vasovagal syncope; SVT: supraventricular tachycardia; LVEF: left ventricular ejection fraction; ICD: implantable cardioverter-defibrillator; VT: ventricular tachycardia; VF: ventricular fibrillation; RVOT: right ventricular outflow tract; LVOT: left ventricular outflow tract. It may be prudent to wait and observe for this time without a syncope spell before resuming driving. References: 1. Epstein AE, Miles WM, Benditt DG, et al. Personal and public safety issues related to arrhythmias that may a ect consciousness: implications for regulation and physician recommendations. A medical/scienti c statement from the American Heart Association and the North American Society of Pacing and Electrophysiology. Circulation 1996; 94:1147-66. 2. Tan VH, Ritchie D, Maxey C, et al. Prospective assessment of the risk of vasovagal syncope during driving. JACC Clin Electrophysiol 2016; 2:203. 3. Epstein AE, DiMarco JP, Ellenbogen KA, et al. 2012 ACCF/AHA/HRS focused update incorporated into the ACCF/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol 2013; 61:e6. 4. B nsch D, Brunn J, Castrucci M, et al. Syncope in patients with an implantable cardioverter-de brillator: incidence, prediction and implications for driving restrictions. J Am Coll Cardiol 1998; 31:608. 5. Antonelli D, Peres D, Freedberg NA, et al. Incidence of postdischarge symptomatic paroxysmal atrial brillation in patients who underwent coronary artery bypass graft: long-term follow-up. Pacing Clin Electrophysiol 2004; 27:365. 6. Thijssen J, Borle s CJ, van Rees JB, et al. Driving restrictions after implantable cardioverter de brillator implantation: an evidence-based approach. Eur Heart J 2011; 32:2678. 7. Vijgen J, Botto G, Camm J, et al. Consensus statement of the European Heart Rhythm Association: updated recommendations for driving by patients with implantable cardioverter de brillators. Europace 2009; 11:1097. Reproduced from: Shen W-K, Sheldon RS, Benditt DG, et al. 2017 ACC/AHA/HRS Guideline for the Evaluation and Management of Patients With Syncope. J Am Coll Cardiol 2017. Table used with the permission of Elsevier Inc. All rights reserved. Graphic 113080 Version 2.0 https://www.uptodate.com/contents/syncope-in-adults-management-and-prognosis/print 24/26 7/6/23, 2:38 PM Syncope in adults: Management and prognosis - UpToDate Overall survival of patients with syncope Survival was worst for patients with a cardiovascular cause of syncope. p<0.001 for the comparison between participants with and those without syncope. The category "Vasovagal and other causes" includes vasovagal, orthostatic, medication-induced, and other, infrequent cause of syncope. Sorteriades ES, Evans JC, Larson MG, et al. Incidence and prognosis of syncope. N Engl J Med 2002; 347:878. Graphic 53302 Version 4.0 https://www.uptodate.com/contents/syncope-in-adults-management-and-prognosis/print 25/26 7/6/23, 2:38 PM Syncope in adults: Management and prognosis - UpToDate Contributor Disclosures David Benditt, MD Equity Ownership/Stock Options: Medtronic [Pacemakers/event recorders and defibrillators]. Grant/Research/Clinical Trial Support: Medtronic [Pacemakers/event recorders and defibrillators]; St Jude Medical [Pacemakers/event recorders and defibrillators]. Consultant/Advisory Boards: Medtronic [Pacemakers/event recorders and defibrillators]; Zoll [Pacemakers/event recorders and defibrillators]. Other Financial Interest: Advanced CPR Solutions [Outside director]. All of the relevant financial relationships listed have been mitigated. Peter Kowey, MD, FACC, FAHA, FHRS Equity Ownership/Stock Options: VuMedi [Arrhythmias]. Consultant/Advisory Boards: Abbvie [Arrhythmias]; Acesion Pharma [Arrhythmias]; Allergan [Arrhythmias, cardiac safety of non-cardiac drugs]; Anthos [Anticoagulants]; Boehringer-Ingelheim [Arrhythmias]; Bristol-Meyers-Squibb [Arrhythmias]; Daiichi Sankyo [Arrhythmias]; Gilead [Arrhythmias]; Huya [Arrhythmias]; InCarda Therapeutics [Arrhythmias]; INSTA [Arrhythmias]; Johnson & Johnson [Arrhythmias]; Medtronic [Arrhythmias]; Milestone [Arrhythmias]; Novartis [Arrhythmias, cardiac safety of non-cardiac drugs]; Pfizer [Arrhythmias]; Sanofi [Arrhythmias]; Takeda [Arrhythmias]. All of the relevant financial relationships listed have been mitigated. Susan B Yeon, MD, JD, FACC No relevant financial relationship(s) with ineligible companies to disclose. Contributor disclosures are reviewed for conflicts of interest by the editorial group. When found, these are addressed by vetting through a multi-level review process, and through requirements for references to be provided to support the content. Appropriately referenced content is required of all authors and must conform to UpToDate standards of evidence. Conflict of interest policy https://www.uptodate.com/contents/syncope-in-adults-management-and-prognosis/print 26/26