Efficacy and safety of dextrose-insulin in unmasking non-diagnostic Brugada ECG patterns.

BACKGROUND Typical diagnostic, coved-type 1, Brugada ECG patterns fluctuate spontaneously over time with a high proportion of non-diagnostic ECG patterns. Insulin modulates ion transport mechanisms and causes hyperpolarization of the resting potential. We report our experience with unmasking J-ST changes in response to a dextrose-insulin test. METHODS Nine patients, mean age 40.5±19.4years (range: 15-65years), presented initially with a non-diagnostic ECG pattern, which was suggestive of Brugada syndrome (group I). They were compared with 10 patients with normal ECG patterns (group II). Participants received an infusion of 50g of 50% dextrose, followed by 10IU of intravenous regular insulin. Positive changes were defined by conversion to a diagnostic ECG pattern. RESULTS The dextrose-insulin test was positive in six of seven (85.7%) patients (kappa 0.79, p=0.02) that was confirmed with a pharmacologic test (kappa 1, p=0.003). One had an inconclusive test, and two with a negative test had an early repolarization ECG pattern. All subjects in group II had a negative test (p<0.01). The maximum changes of the J-ST segment were observed 41.3±31.4minutes (range 3-90minutes) after dextrose-insulin infusion. One patient had monomorphic ventricular bigeminy without spontaneous or induced ventricular fibrillation. CONCLUSION Changes in J-ST segment in the Brugada syndrome are influenced by glucose-insulin, and this report reproduces and supports the efficacy and safety of this metabolic test in the differential diagnosis of patients with non-diagnostic ECG patterns.