Clinical Trial for the Prevention of Vasovagal Syncope

Inclusion Criteria: * Syncope as a cause of loss of consciousness according to European Society of Cardiology criteria * \> 2 lifetime syncopal spells preceding enrollment * \> or = to -2 points on the Syncope Symptom Score for Structurally Normal Hearts * Age \> 18 years with informed consent, or age \> 14 years with consent and informed parental consent Exclusion Criteria: * Other causes of syncope, such as ventricular tachycardia, complete heart block, postural (orthostatic) hypotension or hypersensitive carotid sinus syndrome * An inability to give informed consent * Important valvular, coronary, myocardial or conduction abnormality or significant arrhythmia * Hypertrophic cardiomyopathy * A known intolerance to fludrocortisone * Another clinical need for fludrocortisone that cannot be met with other drugs * A permanent pacemaker * A seizure disorder * A major chronic non cardiovascular disease * Hypertension (blood pressure ≥ 130/85 on 2 occasions) or heart failure * Renal dysfunction (baseline glomerular filtration rate reduced below 60 ml/min/1.73m2 according to the Cockroft-Gault formula) * Diabetes mellitus * Hepatic disease * Glaucoma * Any prior use of fludrocortisone acetate * A 5-minute stand test resulting in diagnosis of postural orthostatic tachycardia syndrome or orthostatic hypotension