Yoshihisa Enjoji

Assessment of Noninvasive Markers in Identifying Patients at Risk in the Brugada Syndrome: Insight Into Risk Stratification

OBJECTIVES The aim of this study was to compare the use of various noninvasive markers for detecting risk of life-threatening arrhythmic events in patients with Brugada syndrome. BACKGROUND The role of conduction disturbance in arrhythmogenesis of the syndrome is controversial, whereas it is well established that repolarization abnormalities are responsible for arrhythmias. The value of noninvasive markers reflecting conduction or repolarization abnormalities in identifying patients at risk for significant arrhythmias has not been shown. METHODS We assessed late potentials (LP) using signal-averaged electrocardiography (ECG), microvolt T-wave alternans (TWA), and corrected QT-interval dispersion (QTD) in 44 consecutive patients who had ECGs showing a pattern of right bundle branch block and ST-segment elevation in leads V1 to V3 but structurally normal hearts. The patients were compared with 30 normal individuals. RESULTS Eleven patients were excluded from data analysis because of an absence of ECG manifestations of Brugada syndrome at the time of the tests. A history of life-threatening events defined as syncope and aborted sudden death was present in 19 of 33 patients (58%); in 15 of the 19 patients, stimulation induced ventricular fibrillation or polymorphic ventricular tachycardia. The LP were present in 24 of 33 patients (73%); TWA were present in 5 of 31 patients (16%); and a QTD >50 ms was present in 9 of 33 patients (27%). The incidence of LP in Brugada patients was significantly (p < 0.0001) higher than in the controls, whereas incidences of TWA and QTD were not significantly different. Multivariate logistic regression analysis revealed that the presence of LP had the most significant correlation to the occurrence of life-threatening events (p = 0.006). CONCLUSIONS Late potentials are a noninvasive risk stratifier in patients with Brugada syndrome. These results may support the idea that conduction disturbance per se is arrhythmogenic.

Combined assessment of T-wave alternans and late potentials used to predict arrhythmic events after myocardial infarction ☆: A prospective study

OBJECTIVES The aim of the present study was to determine whether the combination of two markers that reflect depolarization and repolarization abnormalities can predict future arrhythmic events after acute myocardial infarction (MI). BACKGROUND Although various noninvasive markers have been used to predict arrhythmic events after MI, the positive predictive value of the markers remains low. METHODS We prospectively assessed T-wave alternans (TWA) and late potentials (LP) by signal-averaged electrocardiogram (ECG) and ejection fraction (EF) in 102 patients with successful determination results after acute MI. The TWA was analyzed using the power-spectral method during supine bicycle exercise testing. No antiarrhythmic drugs were used during the follow-up period. The study end point was the documentation of ventricular arrhythmias. RESULTS The TWA was present in 50 patients (49%), LP present in 21 patients (21%), and an EF <40% in 28 patients (27%). During a follow-up period of 13 +/- 6 months, symptomatic, sustained ventricular tachycardia or ventricular fibrillation occurred in 15 patients (15%). The event rates were significantly higher in patients with TWA, LP, or an abnormal EF. The sensitivity and the negative predictive value of TWA in predicting arrhythmic events were very high (93% and 98%, respectively), whereas its positive predictive value (28%) was lower than those for LP and EF. The highest positive predictive value (50%) was obtained when TWA and LP were combined. CONCLUSIONS The combined assessment of TWA and LP was associated with a high positive predictive value for an arrhythmic event after acute MI. Therefore, it could be a useful index to identify patients at high risk of arrhythmic events.

Relationship Between ST-Segment Morphology and Conduction Disturbances Detected by Signal-Averaged Electrocardiography in Brugada Syndrome

Background: Although arrhythmogenesis of Brugada syndrome is still unknown, it has been reported to be associated with conduction disturbances. Two ST‐segment morphologies (coved and saddle‐back patterns) have been described in this syndrome. No study has sought to determine which morphology has stronger conduction disturbances, thereby associating with life‐threatening events.

Catheter ablation of fatal ventricular tachyarrhythmias storm in acute coronary syndrome--role of Purkinje fiber network.

Ventricular fibrillation (VF) or ventricular tachycardia (VT) storm is a life-threatening arrhythmia. Antiarrhythmic drugs (AADs) are not necessarily effective to rescue life from such conditions. Catheter ablation (CA) targeting triggering premature ventricular contractions (PVCs) of VF or VT that originates from Purkinje fiber network (PFN) is reported to be effective, especially in idiopathic patients. However, in condition of acute coronary syndrome (ACS), the efficacy of CA is not well understood. To clarify the usefulness of CA as an alternative way to AADs, we performed CA in four patients with VF or VT storm. The Purkinje potential was seen just before the myocardial ventricular wave during sinus rhythm that became more prominent and double components during the initiating PVC at the targeted area. Following CA, spontaneous episodes of VF or VT were no longer observed. CA is an efficacious way to bail out PFN-related VF or VT storm even in ACS.

Nifekalant and disopyramide in a patient with short QT syndrome: evaluation of pharmacological effects and electrophysiological properties.

We assessed several pharmacological effects on electrocardiogram parameters and effective refractory period (ERP) in a patient with a short QT syndrome (SQTS). Pharmacological challenge tests revealed that disopyramide and selective Ikr blocker, nifekalant normalized QT interval, and ERP of the atrial and ventricular myocardium. This study suggested that disopyramide and nifekalant should be feasible for the drug treatment of the SQTS. Moreover, QT interval was paradoxically prolonged at higher heart rates induced with isoproterenol infusion or an exercise test, although the mechanism of this QT prolongation remains to be investigated.

Predicting the recurrence of ventricular tachyarrhythmias from T-wave alternans assessed on antiarrhythmic pharmacotherapy : A prospective study in patients with dilated cardiomyopathy

Background: Microvolt T‐wave alternans (TWA) has been proposed as a useful index to identify patients at risk of ventricular tachyarrhythmias. Recent studies have demonstrated that antiarrhythmic drugs, such as amiodarone and procainamide, decrease the prevalence of TWA. In this study, we tested whether TWA in patients on antiarrhythmic pharmacotherapy significantly predicts the recurrence of ventricular tachyarrhythmias in patients with dilated cardiomyopathy.

Catheter Ablation for an Incessant Form of Antiarrhythmic Drug-Resistant Ventricular Fibrillation After Acute Coronary Syndrome

A 77‐year‐old man was admitted with an acute coronary syndrome (ACS), severe heart failure (HF), and repeated ventricular fibrillation (VF) episodes. A single premature ventricular complex (PVC) induced ventricular tachycardia (VT), which degenerated to VF reproducibly. This PVC was eliminated by catheter ablation at the left ventricular posteroseptal region where double Purkinje potentials preceding the ventricular wave had been recorded. The electrical storm disappeared, and programmable stimulation failed to induce any tachyarrhythmias after the ablation. A Purkinje fiber network‐related PVC served as a trigger and as a substrate for VT and VF in a case of ACS with HF.

Hypothermia with extracorporeal membrane oxygenation for sudden cardiac death and submersion

A case of successful recovery from cardiopulmonary arrest and submersion is reported. The victim collapsed due Fig. 1 (Left panel) Twelve-lead ECG on admission. (Right panel) Cor descending (LAD) and circumflex (LCX) arteries were occluded. No revascularized by aspiration of thrombus and direct stenting. 0735-6757/

Focal ablation for atrial fibrillation originating from the inferior vena cava and the posterior left atrium

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Ventricular Late Potential in Patients with Apparently Normal Electrocardiogram; Predictor of Brugada Syndrome

We identified a case of paroxysmal atrial fibrillation (AF) originating from inferior vena cava (IVC) and the low-posterior left atrium (LA). Both foci, the IVC and the low-posterior LA, simultaneously served not only as trigger but also as driver for maintenance of AF. During AF, the IVC and the low-posterior LA continuously demonstrated the rapid and fractionated potentials that exit into both atria with conduction block. Focal ablation for ectopic beats within the IVC and the low-posterior LA completely eliminated the storm of AF.