Unexplained syncope evaluated by electrophysiologic studies and head-up tilt testing.
OBJECTIVE
To determine the clinical characteristics of subgroups of patients with unexplained syncope having electrophysiologic studies and head-up tilt testing and to assess the efficacy of various therapies.


METHODS
Retrospective study.


METHODS
Inpatient services of a tertiary referral center.


METHODS
Eighty-six consecutively referred patients with unexplained syncope.


METHODS
All patients had electrophysiologic examinations. Patients with negative results subsequently had head-up tilt testing.


RESULTS
Twenty-nine (34%) patients (group 1) had abnormal electrophysiologic results, with sustained monomorphic ventricular tachycardia induced in 72%. Thirty-four (40%) patients (group 2) had syncope provoked by head-up tilt testing. The cause of syncope remained unexplained in 23 (26%) patients (group 3). Structural heart disease was present in 76%, 6%, and 30% of groups 1, 2, and 3, respectively. In group 1, pharmacologic or nonpharmacologic therapy was recommended based on electrophysiologic evaluation. All group 2 patients had negative results on head-up tilt testing while receiving oral beta blockers (27 patients) or disopyramide (7 patients). Group 3 patients did not receive any specific therapy. During a median follow-up period of 18.5 months, syncope recurred in 9 (10%) patients.


CONCLUSIONS
The combination of electrophysiologic evaluation and head-up tilt testing can identify the underlying cause of syncope in as many as 74% of patients presenting with unexplained syncope. Therapeutic strategies formulated according to the results of these diagnostic tests appear to prevent syncope effectively in most patients.
Sra
J S
JS
Sinai Samaritan Medical Center, Milwaukee, Wisconsin.
Anderson
A J
AJ
Sheikh
S H
SH
Avitall
B
B
Tchou
P J
PJ
Troup
P J
PJ
Gilbert
C J
CJ
Akhtar
M
M
Jazayeri
M R
MR
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001145:Arrhythmias, Cardiac / Q000150:complications / Q000175:diagnosis*; D001919:Bradycardia / Q000175:diagnosis; D002648:Child; D004568:Electrodiagnosis / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007545:Isoproterenol; D008297:Male; D008875:Middle Aged; D011187:Posture; D013575:Syncope / Q000209:etiology*; D013610:Tachycardia / Q000175:diagnosis; D013617:Tachycardia, Supraventricular / Q000175:diagnosis
D007545:Isoproterenol