Head-up Tilt Testing for Diagnosing Vasovagal Syncope in the Pediatric Population: A Systematic Review and Meta-Analysis

Purpose Vasovagal syncope (VVS) is the most prevalent type of transient loss of consciousness among children and adolescents. Head-up tilt test (HUT) allows the reproduction of symptoms through prolonged orthostatic stress, thus helping to confirms the vasovagal nature of syncope. We conducted a meta-analysis to estimate diagnostic yield of HUT in the pediatric population and to evaluate the influence of age and instrumental parameters on test outcome. Methods Searching in multiple databases, 52 articles were identified among studies enrolling patients with history of syncope (mean or maximum age lower than 18 years) who underwent to HUT eventually potentiated with isoproterenol or nitroglycerin. Data were extracted for patients and also controls when included in the study. Results The pooled proportion of patients with syncope during HUT was 46% (95% confidence interval: 39-52%) in 3542 drug-free, 65% (53-77%) in 496 isoproterenol and 71% (62-80%) in1108 nitroglycerin. Pharmacological provocation induced a greater proportion of mixed and cardioinhibition response than passive methodology. In controls, the pooled proportion of syncope was 1% in 157 drug-free, 25% in 48 isoproterenol and 10% in 56 nitroglycerin. At multivariate analyses, the positivity rate in patients was associated to age in potentiated test, tilt angle and nitroglycerin usage while in controls a positive response was related to greater age and both drugs. Conclusion In children and adolescent, drug-free HUT shows an acceptable sensitivity and high specificity resulting an effective diagnostic tool for VVS. Potentiated HUT should be tailored on the diagnostic needs to enhance positivity rate.