Sublingual nitrates during head-up tilt testing for the diagnosis of vasovagal syncope

Teste de inclinação (Tilt-test): do necessário ao imprescindível

“…After administration of 300 mg of sublingual nitroglycerin, a positive response was observed in more than 26% of the patients and in 6% of the control group, resulting in a specificity of 94%. Similar data were presented by other authors in subsequent years 9,15,18 (Table 1). …”

“…In the analysis of five studies that evaluated the result of exposure to passive orthostasis, lasting at least 40 minutes, the sensitivity rates noted were 13%, 25%, 31%, 35% and 75% (median of 31%) [9][10][11][12] . In contrast to the low sensitivity, the specificity was 100%, 100%, 95%, 92% and 89%, respectively (mean of 95%).…”

“…In the several studies conducted, the sensitivity of the test with nitrate ranged between 57.5% and 87%, and the specificity between 70% and 100%, while the test with isoproterenol showed variations between 42% and 69% and between 70 and 90%, respectively 9,11,[13][14][15] . Isoproterenol is being abandoned due to the lower sensitivity, inconvenience of intravenous access and side effects, especially in patients with ischemic heart disease 16 (Table 1).…”

“…Since then, it is recommended that the HUTT should consist of 20 minutes of passive phase and 20 19 . In three studies that evaluated the use of this drug during the HUTT, the sensitivity ranged from 57 to 87%, and specificity from 70 to 100% 9,14,15 . The dose of 1.25 mg was evaluated in only one of these studies and it was the one related to the highest specificity (100%) 15 .…”

“…Likewise, when one analyzes more recent studies, it is possible to notice a significant decrease in specificity when, in sensitized protocols, the duration of the passive phase is equal to or more than 30 minutes. Protocols with shorter passive phases, or even without a passive phase, followed by sensitization with nitrate or isoproterenol, are linked with specificities that range from 84 to 97% 18,28,38 , whereas, in studies that used a more prolonged passive phase, there was a decrease in specificities (48 to 70%) 9,11,15 . Therefore, limiting the total duration of the examination seems to guarantee good specificity.…”