title: Effects of glucose-induced insulin secretion on ST segment elevation in the Brugada syndrome.
abstract: BACKGROUND
  ST segment elevation in patients with Brugada syndrome is known to fluctuate occasionally, influenced by multiple factors. Insulin has been shown to affect QT dispersion in healthy volunteers, as well as result in abnormality of ventricular repolarization in patients with congenital long QT syndrome.
  
  
  RESULTS
  To assess a possible role of insulin in ST segment elevation in patients with Brugada syndrome, an oral glucose tolerance test (OGTT) was administered to 20 patients with Brugada syndrome and 20 normal patients without ST-T changes as a control group. Plasma glucose and potassium levels, immunoreactive insulin concentration (IRI), and ST segment elevation and ST-T wave changes on 12-lead ECG during OGTT were analyzed. Augmentation (>1 mm) of ST elevation or morphologic changes in ST-T waves were observed frequently in response to increased IRI during OGTT [15/20 cases (75%)] in patients with Brugada syndrome but in none of the patients in the control group [0/20 cases (0%), P < 0.01]. The changes returned to baseline 180 minutes after the glucose load in 9 of 15 patients. Patients who showed coved-type ST elevation before the glucose load exhibited positive ECG changes more frequently than patients with saddleback-type elevation or transiently normalized ST segment [8/8 cases (100%) vs 7/12 (58%), P < 0.05]. There was no significant difference between the two groups in terms of glucose, IRI, and potassium levels during OGTT.
  
  
  CONCLUSIONS
  The findings suggest that glucose-induced insulin secretion is one of the contributing factors to fluctuation of ST segment elevation in patients with Brugada syndrome.
authors.affiliation: Department of Cardiology, Yokohama Minami Kyosai Hospital, Kanagawa, Yokohama, Japan. nisizaki@yhb.att.ne.jp
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Nishizaki
authors.forename: Harumizu
authors.initials: H
authors.lastname: Sakurada
authors.forename: Takashi
authors.initials: T
authors.lastname: Ashikaga
authors.forename: Noriyoshi
authors.initials: N
authors.lastname: Yamawake
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Fujii
authors.forename: Masataka
authors.initials: M
authors.lastname: Arita
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Isobe
authors.forename: Masayasu
authors.initials: M
authors.lastname: Hiraoka
mesh_terms: D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000378:metabolism; D002037:Bundle-Branch Block / Q000097:blood / Q000503:physiopathology*; D004562:Electrocardiography; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood* / Q000378:metabolism / Q000502:physiology; D000078790:Insulin Secretion; D008297:Male; D008875:Middle Aged; D013577:Syndrome; D014693:Ventricular Fibrillation
chemical_list: D001786:Blood Glucose; D007328:Insulin