Diagnosis and Management of Reflex Syncope

Indications for Tilt Table Testing

The European Society of Cardiology recommends tilt table testing for reflex syncope when the diagnosis is suspected but not confirmed by initial evaluation, and in specific clinical scenarios with high-risk implications, such as unexplained single syncopal episode in high-risk settings, recurrent episodes of unexplained syncope, and to demonstrate susceptibility to reflex syncope to the patient 1
Tilt table testing is indicated for patients with unexplained single syncopal episode in settings with potential for physical injury, occupational implications, or potential risk to others, according to the European Society of Cardiology 1
The test is also recommended to discriminate between reflex and orthostatic hypotension syncope, to differentiate syncope with jerking movements from epilepsy, to evaluate patients with recurrent unexplained falls, and to evaluate patients with frequent syncope and psychiatric disease 1

Isoproterenol tilt testing is contraindicated in patients with ischemic heart disease, uncontrolled hypertension, left ventricular outflow tract obstruction, or significant aortic stenosis, according to the European Society of Cardiology 1
Tilt table testing is not recommended for assessment of treatment efficacy, as stated by the European Society of Cardiology 1
Pacemakers should be avoided in vasovagal syncope with asystole in young patients due to the transient and benign nature of the condition 1

The European Society of Cardiology recommends low-dose intravenous isoproterenol test and sublingual nitroglycerin protocol, both having similar positive response rates (61-69%) and high specificity (92-94%) 1
Patients should fast for 4 hours prior to testing, with a tilt angle between 60-70 degrees, and a passive phase of 20-45 minutes, as per the European Society of Cardiology guidelines 1
For nitroglycerin, 300-400 μg should be administered sublingually in upright position, and for isoproterenol, incremental infusion up to 3 μg/min should be used, according to the European Society of Cardiology 1

A positive diagnosis is made when reflex hypotension/bradycardia is induced with reproduction of syncope, a probable diagnosis is made when reflex hypotension/bradycardia is induced without reproduction of syncope, and a negative tilt test does not exclude the diagnosis of reflex syncope, as per the European Society of Cardiology guidelines 1
The European Heart Journal classification characterizes a Type 3 (vasodepressor) response as a heart rate that does not fall more than 10% from peak at the time of syncope, with a blood pressure drop without significant bradycardia 2

Reflex syncope can be diagnosed based on a thorough clinical history and physical examination, without additional testing, when characteristic triggers, prodromal symptoms, and event characteristics are present, and the physical examination and ECG are normal, as stated by the European Society of Cardiology (ESC) guidelines 1
Characteristic triggers for reflex syncope include pain or emotional distress, prolonged standing, hot or crowded environments, post-prandial state, seeing blood or medical procedures, and coughing, swallowing, or micturition 1
Prodromal symptoms of reflex syncope include nausea/vomiting, feeling warm, sweating, pallor, visual blurring, and dizziness 1
Event characteristics of reflex syncope include brief loss of consciousness (typically <1-2 minutes), rapid recovery, and no significant post-event confusion 1

The European Society of Cardiology (ESC) guidelines recommend education and reassurance about the benign nature of the condition, avoidance of triggers when possible, and physical counterpressure maneuvers such as leg crossing with muscle tensing, hand gripping and arm tensing, and squatting for patients diagnosed with reflex syncope 3, 2
Volume expansion through increased fluid intake (2-3 liters daily) and salt intake (8-10g/day) unless contraindicated is also recommended 3, 2
Pharmacological therapy such as fludrocortisone (0.1-0.2 mg daily) and midodrine (2.5-10 mg three times daily) may be considered in refractory cases 3, 2
Beta-blockers such as low-dose propranolol (10-20 mg twice daily) or metoprolol can be used for predominant tachycardia, with monitoring for worsening of orthostatic hypotension 2
Physical training with a gradual autonomic reconditioning program, regular aerobic exercise (30 minutes, 3-4 times weekly), and lower extremity resistance training can help improve symptoms 2

Regular follow-up visits at 1, 3, and 6 months, home blood pressure and heart rate monitoring in different positions, and a symptom diary to track frequency and severity of episodes are recommended 1
Repeat tilt table testing is not recommended for assessing treatment efficacy, and a negative tilt table response does not exclude reflex syncope, according to the European Heart Journal 1