Takashi Hirono

Relationship between dominant prolongation of the filtered QRS duration in the right precordial leads and clinical characteristics in Brugada syndrome.

Background: Electrical abnormalities in the RVOT may be involved in Brugada syndrome.

Variable Electrocardiographic Effects of Short‐Term Quinidine Sulfate Administration in Brugada Syndrome

Quinidine, a class I antiarrhythmic agent with blocking property of transient outward current, is a possible candidate for the suppression of ventricular fibrillation in patients with Brugada syndrome; although there is a concern that its ability to these effects may be proarrhythmic. Therefore, we evaluated the effect of quinidine sulfate on ST‐segment elevation in Brugada syndrome. In 8 patients with Brugada syndrome, the magnitude of ST‐elevation at the J‐point (STJ), and the ST‐segment configuration in leads V1–V3, were compared before and on day 2 after the initiation of quinidine administration. In 3 patients, quinidine attenuated STJ by ≥0.1 mV. Of these 3 patients, ST‐segment elevation was normalized in 2 patients, while the ST‐segment configuration was unchanged in another. In another 3 patients, quinidine augmented STJ by ≥0.1 mV without any change of ST‐segment configuration, and the augmentation was returned to baseline after the discontinuation of quinidine. Quinidine exhibited no effect on the ST‐segment in the remaining 2 patients. The favorable effects of quinidine on the ST‐segment tended to be more pronounced in patients with prominent ST‐elevation at baseline. In 1 patient, quinidine was effective in eliminating both ST‐segment elevation and repetitive tachyarrhythmia episodes. In conclusion, the effects of quinidine on ST‐segment elevation were variable. Quinidine may potentially augment the ST‐segment elevation in some patients with Brugada syndrome.

Electrophysiologic study guided therapy with sotalol for life-threatening ventricular tachyarrhythmias

The aim of this study was to investigate the long‐term efficacy and safety of electrophysiologic study (EPS)‐guided sotalol administration combined with implantable cardioverter defibrillators (ICD) for ventricular tachyarrhythmias (VTA). This study enrolled 92 patients with both structural heart disease and sustained VTA. Sotalol was administered to 57 patients, and its efficacy was assessed by EPS. Long‐term treatment was continued in combination with ICD in 31 patients (57%) whose VTA was no longer inducible (responder group) and in 16 patients whose VTA remained inducible (nonresponder group). The long‐term outcomes were compared among the responder group, the nonresponder group, and 35 ICD recipients untreated with antiarrhythmic drugs (ICD‐only group). During a mean follow‐up of 44 ± 33 months, the recurrence of VTA was not significantly different between all patients treated with sotalol (30%) and patients in the ICD‐only group (46%). However, the recurrence of VTA was significantly lower in the responder (13%) than in the nonresponder (63%) or the ICD‐only groups (46%). There was no significant difference in VTA recurrence between the nonresponder and the ICD‐only groups. One patient each in the responder and the ICD‐only groups died suddenly, and all‐cause mortality was similar in the three groups. The incidence of inappropriate ICD discharges was less in the sotalol than in the ICD‐only groups. No patient had to discontinue long‐term sotalol treatment because of the adverse effects. In conclusion, sotalol reduced VTA recurrence in the responding patients and inappropriate ICD discharge. EPS may predict the efficacy of sotalol for VTA recurrence.

Effects of intravenous magnesium in a prolonged QT interval model of polymorphic ventricular tachycardia focus on transmural ventricular repolarization.

Background: This study was performed to clarify the antiarrhythmic effects of magnesium sulfate (Mg++) in a prolonged QT interval canine model of polymorphic ventricular tachyarrhythmia (VTA).

Heart Rate Variability Is a Useful Parameter for Evaluation of Anticholinergic Effect Associated with Inducibility of Atrial Fibrillation

Background: Disopyramide is thought to have an advantageous effect for atrial fibrillation (AF) associated with vagal activity because of its anticholinergic effect.

Postprandial Variations in ST‐Segment in a Patient with Brugada Syndrome and Partial Gastrectomy

A 74‐year‐old man with a history of partial gastrectomy presented with an electrocardiogram consistent with Brugada syndrome and marked meal related fluctuations in the ST segment. ST‐segment elevation was prominently attenuated at 30 minutes and increased at 120 minutes after meals. Analysis of heart rate variability revealed a relationship between postprandial heightened parasympathetic activity and increase in Brugada‐type ECG abnormality. A rapid postprandial increase in blood glucose may initially stimulate sympathetic nervous activity and secondarily increase parasympathetic tone. Food intake can be associated with fluctuations in ST‐segment elevation in patients with the Brugada syndrome.