Comparison of a shortened isosorbide dinitrate-potentiated head-up tilt testing with the conventional protocol: tolerance and diagnostic accuracy.
BACKGROUND
The head-up tilt test (HUT) is widely used to investigate unexplained syncope; however, in clinical practice, it is long and sometimes not well tolerated.


OBJECTIVE
To compare the sensitivity, specificity, accuracy, and patients' tolerance of a conventional and shortened HUT.


METHODS
Patients with a history of vasovagal syndrome (VVS) were randomized to a conventional HUT (group I) consisting of 20-minute passive tilt followed by 25 minutes after administration of sublingual isosorbide dinitrate (ISDN), or a shortened HUT (group II) where ISDN was given immediately after tilt and observed for 25 minutes. The control group consisted of age- and gender-matched subjects without VVS symptoms. A specific questionnaire to evaluate tolerance was applied.


RESULTS
Sixty patients (29 ± 10 years, 82% female) were included. In group I, 22/30 patients had a positive HUT compared to 21/30 in group II (73% vs 70%, P = 0.77). There was also no difference in the accuracy between the two protocols (63% vs 73%, P = 0.24). The time to positivity was shorter in group II (13.2 minutes vs 30 minutes, P < 0.001). Within the control group (n = 60), the frequency of false-positives was 47% and 23% for the conventional and shortened HUT, respectively (P = 0.058). After conventional HUT, 65.2% subjects reported that the test was too long compared to 25% subjects after the shortened HUT (P = 0.002).


CONCLUSIONS
In this study, the HUT without passive phase was not inferior to the conventional HUT regarding sensitivity, specificity, and accuracy. Furthermore, the shortened ISDN-potentiated protocol allowed faster diagnosis and was better tolerated.
Department of Medical Science, Universidade de Brasília, Braslia, Brazil.
Paula G
PG
Macedo
Samuel J
SJ
Asirvatham
Leila
L
Maia
Eustáquio
E
Ferreira Neto
André
A
Zanatta
José
J
Sobral Neto
José Roberto
JR
Barreto
Henrique
H
Maia
Edna M
EM
Oliveira
Jairo M
JM
Da Rocha
Carla S
CS
Margalho
Tamer
T
Seixas
Ayrton
A
Peres
Leopoldo
L
Santos-Neto
Luiz R
LR
Leite
D000328:Adult; D003951:Diagnostic Errors; D005260:Female; D006801:Humans; D007545:Isoproterenol; D007548:Isosorbide Dinitrate / Q000009:adverse effects; D008297:Male; D005996:Nitroglycerin; D017060:Patient Satisfaction; D012680:Sensitivity and Specificity; D019462:Syncope, Vasovagal / Q000175:diagnosis*; D018667:Tilt-Table Test / Q000379:methods; D014665:Vasodilator Agents / Q000009:adverse effects; D055815:Young Adult
D014665:Vasodilator Agents; D005996:Nitroglycerin; D007548:Isosorbide Dinitrate; D007545:Isoproterenol