Neurally mediated syncope as a cause of syncope in patients with Brugada electrocardiogram.
BACKGROUND
Patients with type 1 Brugada electrocardiogram (ECG) and an episode of syncope are diagnosed as symptomatic Brugada syndrome; however, all episodes of syncope may not be due to ventricular tachyarrhythmia.


RESULTS
Forty-six patients with type 1 Brugada ECG (all males, 51 +/- 13 years, 29 spontaneous, 17 Ic-drug induced), 20 healthy control subjects (all males, 35 +/- 11 years), and 15 patients with suspected neurally mediated syncope (NMS; 9 males, 54 +/- 22 years) underwent the head-up tilt (HUT) test. During the HUT test, 12-lead ECGs were recorded in all patients, and the heart rate variability was investigated in some patients. Sixteen (35%) of 46 patients with Brugada ECG, 2 (10%) of 20 control subjects, and 10 (67%) of 15 patients with suspected NMS showed positive responses to the HUT test. Although no significant differences were observed in HUT-positive rate among Brugada patients with documented VT (7/14; 50%), syncope (5/19; 26%) and asymptomatic patients (4/13; 31%), the HUT-positive rate was significantly higher in patients with documented VT (50%) and those with VT or no symptoms (11/27, 41%) compared to that in control subjects (10%) (P < 0.05). Augmentation of ST-segment amplitude (> or =0.05 mV) in leads V1-V3 was observed in 11 (69%) of 16 HUT-positive patients with Brugada ECG during vasovagal responses, and was associated with augmentation of parasympathetic tone following sympathetic withdrawal.


CONCLUSIONS
Thirty-five percent of patients with Brugada ECG showed vasovagal responses during the HUT test, suggesting that some Brugada patients have impaired balance of autonomic nervous system, which may relate to their syncopal episodes.
Division of Cardiology, Department of Internal Medicine, National Cardiovascular Center, Suita, Japan.
Miki
M
Yokokawa
Hideo
H
Okamura
Takashi
T
Noda
Kazuhiro
K
Satomi
Kazuhiro
K
Suyama
Takashi
T
Kurita
Naohiko
N
Aihara
Shiro
S
Kamakura
Wataru
W
Shimizu
D000328:Adult; D000368:Aged; D001342:Autonomic Nervous System Diseases / Q000139:chemically induced* / Q000175:diagnosis*; D053840:Brugada Syndrome / Q000175:diagnosis* / Q000188:drug therapy*; D004562:Electrocardiography / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D026941:Sodium Channel Blockers / Q000009:adverse effects* / Q000627:therapeutic use; D013575:Syncope / Q000139:chemically induced*; D016896:Treatment Outcome
D026941:Sodium Channel Blockers