Lack of correlation between the responses to tilt testing and adenosine triphosphate test and the mechanism of spontaneous neurally mediated syncope.
OBJECTIVE
We prospectively correlated the results of tilt testing (TT) and adenosine triphosphate test (ATP) with the findings observed during a spontaneous syncopal relapse by means of an implantable loop recorder (ILR) in patients with a clinical diagnosis of neurally mediated syncope.


RESULTS
We included patients with three or more clinically severe syncopal episodes in the last 2 years without significant electrocardiographic and cardiac abnormalities. Patients with orthostatic hypotension and carotid sinus syncope were excluded. After ILR implantation, patients were followed until the first documented syncope. Among 392 enrolled patients, 343 underwent TT, which was positive in 164 (48%), and 180 ATP test, which was positive in 53 (29%). Syncope was documented by ILR in 106 (26%) patients after a median of 3 months. Patients with positive and negative TT had similar baseline characteristics, syncopal recurrence rate, and mechanism of syncope, but those with positive TT had more frequently no or slight rhythm variations during spontaneous syncope (45 vs. 21%, P=0.02). An asystolic pause was more frequently found during spontaneous syncope than during TT (45 vs. 21%, P=0.02), but there was a trend for those with an asystolic response during TT also to have an asystolic response during spontaneous syncope (75 vs. 37%, P=0.1). Patients with positive ATP test responses showed syncopal recurrence rates and mechanism of syncope similar to those with negative ATP tests.


CONCLUSIONS
In patients with neurally mediated syncope, clinical characteristics, outcome, and mechanism of syncope are poorly correlated and not predicted by the results of TT and ATP test. Therefore, these tests are of little or no value in guiding specific therapy.
Brignole
Michele
M
Department of Cardiology, Arrhythmologic Centre, Ospedali del Tigullio, Via don Bobbio 24, 16033 Lavagna, Italy. mbrignole@ASL4.liguria.it
Sutton
Richard
R
Menozzi
Carlo
C
Garcia-Civera
Roberto
R
Moya
Angel
A
Wieling
Wouter
W
Andresen
Dietrich
D
Benditt
David G
DG
Grovale
Nicoletta
N
De Santo
Tiziana
T
Vardas
Panos
P
D000255:Adenosine Triphosphate; D000328:Adult; D000368:Aged; D015716:Electrocardiography, Ambulatory / Q000295:instrumentation; D004567:Electrodes, Implanted; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012008:Recurrence; D012680:Sensitivity and Specificity; D019462:Syncope, Vasovagal / Q000175:diagnosis*; D018667:Tilt-Table Test / Q000592:standards*
D000255:Adenosine Triphosphate