Tilt testing potentiated with sublingual nitroglycerin in children with unexplained syncope

Aims The aim of this prospective study was to assess the diagnostic value of a sublingual nitroglycerin (NTG) potentiated head-up tilt (HUT) testing protocol in children with unexplained syncope. Methods and results One hundred and sixty-four consecutive paediatric patients with syncope of unknown origin and no evidence of organic heart disease (115 female, mean age 13 ± 3 years) and 29 control children underwent a sublingual NTG-potentiated tilt testing protocol. Paediatric patients and controls were tilted at 60° for 20 min and, if no symptom occurred, for other 15 min after sublingual 400 μg spray NTG administration. During the drug-free phase of the test, 13 patients (8%) and no controls had a positive response. After drug administration, a positive response occurred in another 88 patients (55%) and in four controls (14%), whereas an exaggerated response was observed in nine patients (5%) and in four controls (14%). Thus, the positive rate and specificity of sublingual NTG HUT test in children were 63 and 86%, respectively. No relevant adverse events were observed during the test. Conclusion Tilt testing potentiated with sublingual NTG has proved to be effective and safe in unmasking the neurally mediated origin of unexplained syncope in children. The NTG challenge greatly increased the positive rate of passive tilt, with a small decrease in specificity.