Comparing two different protocols for tilt table testing: sublingual glyceryl trinitrate versus isoprenaline infusion

Abstract

Objective-To assess the diagnostic value and safety of sublingual glyceryl trinitrate tilt testing compared with isoprenaline infusion in patients with unexplained syncope. Design-Glyceryl trinitrate and isoprenaline tilt tests were performed in two successive days on a random basis in cases and controls. Setting-Outpatient cases with syncope referred to Shahid Rajaii Heart Hospital. Subjects-65 consecutive patients with unexplained syncope after thorough work up; 20 healthy volunteers. Results-Positive responses were observed in 20 patients during the passive phase. Of the other 45 patients, positive responses occurred in 25 cases during the glyceryl trinitrate phase and in 26 cases during the isoprenaline phase. In the control group, positive responses during the passive, glyceryl trinitrate, and isoprenaline phases occurred in one, one, and two cases, respectively. The sensitivity and specificity of the protocols were 55% and 94.7%, respectively, for glyceryl trinitrate v 58% and 89.4% for isoprenaline. Owing to discordant responses in 75% of the cases, the sequential use of the tests (if one was negative) would increase the sensitivity to 84% while decreasing the specificity slightly (to 84%). Side eVects were less frequent with glyceryl trinitrate. Conclusions-Sublingual glyceryl trinitrate tilt testing is an eVective and safe alternative to the isoprenaline infusion test and can be used as a complementary test. (Heart 1999;81:603-605)

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

“…When this phase lasted between 40 and 45 minutes, the sensitivities found were 13%, 25%, 31% and 35% [9][10][11]26 . It was only when the duration was 60 minutes that the positivity increased to 75% yet the specificity decreased to 89% 12 .…”

“…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).…”

“…Many authors consider that it is enough to stop the HUTT when the doctor believes that the loss of consciousness is imminent -phase called presyncope -, and there is no reason to subject the patient to the huge discomfort resulting from hypotension or bradycardia, which will allow defining the vasovagal response 1,26,27 . More recent studies have considered that the positivity criterion is the induction of syncope or presyncope, when associated with bradycardia or hypotension 11,13,14,18,26,28 .…”

“…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.…”