Head-up tilt testing in patients with suspected vasovagal syncope: A meta-regression modelling

Head-up tilt testing (HUT) is a useful diagnostic tool for patients with suspected reflex syncope. We conducted a meta-regression analysis to evaluate the influence of age and instrumental parameters on HUT outcome.

Searching in multiple databases, 97 articles were identified until July 2024 among studies enrolling at least 100 patients with history of syncope or 50 subjects without (controls) who underwent to passive HUT (60 or 70 degree) eventually potentiated with isoproterenol or nitroglycerin.

The pooled positivity rate of patients was 34 % (95 % confidence interval: 29-39 %) in 8362 drug-free HUT, 53 % (45-60 %) in 2121 with isoproterenol and 62 % (59-66 %) in 14,054 with nitroglycerin. The pooled negativity rate of controls was 86 % (81-91 %) in 876 drug-free HUT, 83 % (76-91 %) in 276 with isoproterenol and 88 % (83-94 %) in 806 with nitroglycerin. In patients, a greater HUT positivity rate was associate to younger age for the passive stage and overall, and to pharmacological provocation that showed, during the active phase, a significant higher diagnostic yield of nitroglycerin than isoproterenol. A longer duration of passive stage increased the rate of syncope during the unmedicated phase but reduced probability during the active one. In controls, older age was associated to a greater proportion of negative response.

In HUT used in clinical practice, tilt angle is less important than patient's age and methodology with shorter protocols requiring pharmacological provocation to improve positivity rate. The diagnostic role of HUT modifies with age, being more relevant in older patients whether potentiated with nitroglycerin.