Three-year follow-up of patients with right bundle branch block and ST segment elevation in the right precordial leads: Japanese Registry of Brugada Syndrome. Idiopathic Ventricular Fibrillation Investigators. (57/664)

OBJECTIVES: We sought to determine the prevalence of right bundle branch block (RBBB) and ST segment elevation in the working Japanese population, as well as the event rate during a three-year prospective follow-up period. BACKGROUND: A poor prognosis of RBBB and ST segment elevation has been reported in Europe and South America, even in asymptomatic patients; however, a large population of asymptomatic patients with sporadic RBBB and ST segment elevation has not been studied. METHODS: Ten thousand 12-lead electrocardiograms (ECGs) were obtained during annual check-ups of working adults in the Tokyo area. This three-year prospective follow-up study consisted of 105 patients, including 20 with ventricular fibrillation, 18 with syncope and 67 who were asymptomatic. They were registered from 46 institutions in Japan. RESULTS: The prevalence of ECG abnormalities in working adults was 0.16%. A coved-type ST segment elevation was related to a history of cardiac events, and 18% of registered patients had PR prolongation and 9.5% had left-axis deviation. The cumulative cardiac event-free rate was 67.6% in the symptomatic group and 93.4% in the asymptomatic group (p = 0.0004) after three years. CONCLUSIONS: The recurrence rate of cardiac events in symptomatic patients was similar to that reported previously, but it was very low in sporadic asymptomatic patients. The ECG findings may help us to select patients for further examination and more accurate evaluation of their prognoses.  (+info)

Arrhythmias in patients with Brugada-type electrocardiographic findings. (58/664)

Brugada syndrome is characterized by marked ST-segment elevation in the right precordial leads (Bru-ECG) and is associated with a high risk for sudden death. However, it is unclear whether the arrhythmogenesis is caused by the mechanisms responsible for Bru-ECG. The present study investigated the risk of arrhythmias in patients with Bru-ECG by retrospectively analyzing 30 patients (28 men; mean age, 51+/-14 years) with Bru-ECG. Aborted sudden cardiac death (ventricular fibrillation or syncope) occurred in 9 patients (30%); paroxysmal atrial fibrillation was present in 9 (30%) patients in addition to malignant ventricular arrhythmias, and some type of arrhythmic event (aborted sudden cardiac death or paroxysmal atrial fibrillation) occurred in 15 patients (50%). Of all the arrhythmic events, 93% occurred at night or early in the morning, and 92% had pronounced ST-segment elevation. These results suggest that Bru-ECG may be associated not only with an increased risk of ventricular tachyarrhythmias but also with an increased risk of paroxysmal atrial fibrillation, and that the arrhythmogenesis may be related to the pronounced ST-segment elevation.  (+info)

Novel mechanism for Brugada syndrome: defective surface localization of an SCN5A mutant (R1432G). (59/664)

The SCN5A gene encodes the alpha subunit of the human heart sodium channel (hH1), which plays a critical role in cardiac excitability. Mutations of SCN5A underlie Brugada syndrome, an inherited disorder that leads to ventricular fibrillation and sudden death. This study describes changes in cellular localization and functional expression of hH1 in a naturally occurring SCN5A mutation (R1432G) reported for Brugada syndrome. Using patch-clamp experiments, we show that there is an abolition of functional hH1 expression in R1432G mutants expressed in human tsA201 cells but not in Xenopus oocytes. In tsA201 cells, a conservative positively charged mutant, R1432K, produced sodium currents with normal gating properties, whereas other mutations at this site abolished functional sodium channel expression. Immunofluorescent staining and confocal microscopy showed that the wild-type alpha subunit expressed in tsA201 cells was localized to the cell surface, whereas the R1432G mutant was colocalized with calnexin within the endoplasmic reticulum. The beta(1) subunit was also localized to the cell surface in the presence of the alpha subunit; however, in its absence, the beta(1) subunit was restricted to a perinuclear localization. These results demonstrate that the disruption of SCN5A cell-surface localization is one mechanism that can account for the loss of functional sodium channels in Brugada syndrome. The full text of this article is available at http://www.circresaha.org.  (+info)

Localized right ventricular morphological abnormalities detected by electron-beam computed tomography represent arrhythmogenic substrates in patients with the Brugada syndrome. (60/664)

AIMS: This study was designed to determine, using electron-beam CT, whether there are morphological abnormalities in patients with the Brugada syndrome and to elucidate the relationship between those abnormalities and arrhythmogenesis. METHODS AND RESULTS: Twenty-six consecutive patients with the Brugada syndrome and 23 age- and gender-matched control subjects (controls) were evaluated for morphological abnormalities using electron beam CT. Electron beam CT demonstrated morphological abnormalities of the right ventricle in 21 (81%) of 26 patients, but in only two (9%) of 23 controls. The sites of morphological abnormalities were the right ventricular outflow tract area in 17 patients and the inferior wall of the right ventricle in four patients. Of the seven patients with monoform premature ventricular contractions recorded only in the acute phase, four of the five patients with premature ventricular contractions from the right ventricular outflow tract area had morphological abnormalities in the right ventricular outflow tract area, and the other two patients with premature ventricular contractions from the inferior wall of the right ventricle had morphological abnormalities in the inferior wall of the right ventricle. CONCLUSION: The sites of morphological abnormalities detected by electron beam CT in patients with the Brugada syndrome were related to the origins of premature ventricular contractions recorded only in the acute phase, which may trigger ventricular fibrillation. These morphological abnormalities may be related to arrhythmogenic substrates in patients with the Brugada syndrome.  (+info)

Inflammatory left ventricular microaneurysms as a cause of apparently idiopathic ventricular tachyarrhythmias. (61/664)

BACKGROUND: We sought to investigate the arrhythmogenic role, incidence, treatment, and prognosis of inflammatory left ventricular (LV) microaneurysms in patients with apparently idiopathic ventricular tachyarrhythmias. Methods and Results-- We studied 156 consecutive patients (71 men, 85 women; mean age, 44.1+/-11.8 years) with severe ventricular arrhythmias and normal 2D echo cardiac parameters by coronary and ventricular angiography, biventricular endomyocardial biopsy, and electrophysiological study. Polymerase chain reaction was used to detect genomic sequences of enterovirus, adenovirus, Epstein Barr virus, cytomegalovirus, herpes simplex viruses, influenza A and B viruses, and hepatitis C virus in frozen endomyocardial samples. Of these patients, 15 (9.6%) showed angiographic evidence of single or multiple LV microaneurysms. All 15 patients had recurrent episodes of ventricular tachycardia with right bundle-branch block morphology, and the arrhythmias originated within or close to the aneurysms in those patients (n=6) undergoing ventricular mapping. A lymphocytic myocarditis was observed in LV biopsies of all patients and in the right ventricles of 3 patients. Polymerase chain reaction analysis was performed in 12 and viral genomes were found in 5 (42%): hepatitis C virus in 2, enterovirus in 2, and influenza virus A in 1. The patients were treated with antiarrhythmics, and cardiac function was preserved for the next 47+/-39.5 months of follow-up. No major clinical event was registered, and arrhythmias were successfully treated by antiarrhythmics. CONCLUSIONS: Inflammatory LV microaneurysms, often of viral origin, are a consistent cause of apparently idiopathic ventricular arrhythmias. Their prognosis so far has been benign, and aggressive therapeutic strategies have been unnecessary.  (+info)

Prevalence of asymptomatic ST segment elevation in right precordial leads with right bundle branch block (Brugada-type ST shift) among the general Japanese population. (62/664)

OBJECTIVE: To examine the modality and morbidity of asymptomatic ST segment elevation in leads V1 to V3 with right bundle branch block (Brugada-type ST shift). METHODS: 8612 Japanese subjects (5987 men and 2625 women, mean age 49.2 years) who underwent a health check up in 1997 were investigated. Those with Brugada-type ST shift underwent the following further examinations over a two year period after the initial check up: ECG, echocardiogram, 24 hour Holter monitoring, treadmill exercise testing, signal averaged ECG, and slow kinetic sodium channel blocker loading test (cibenzoline, 1.4 mg/kg). RESULTS: Asymptomatic Brugada-type ST shift was found in 12 of 8612 (0.14%) subjects. Eleven of these 12 subjects were followed up. Follow up ECG exhibited persistent Brugada-type ST shift in seven of 11 (63.6%) subjects. ST shift was transformed from a saddle back to a coved type in three subjects. None of the subjects had morphological abnormalities or abnormal tachyarrhythmias. Positive late potentials were found in seven of 11 (63.6%) subjects. Augmentation of ST shift was shown by both submaximal exercise and drug administration in one of the 11 subjects (9.1%). CONCLUSIONS: Asymptomatic subjects with Brugada-type ST shift were not unusual, at a rate of 0.14% in the general Japanese population. Almost all of the subjects had some abnormalities in non-invasive secondary examinations. Additional and prospective studies are needed to confirm the clinical significance and the prognosis of asymptomatic Brugada-type ST shift.  (+info)

Value of non-invasive and invasive studies in patients with bundle branch block, syncope and history of myocardial infarction. (63/664)

The prognosis of patients with bundle branch block (BBB) and myocardial infarction (MI) is poor, particularly for patients suffering from syncope. The purpose of this study was to investigate the diagnostic value of some techniques for the evaluation of the mechanism of syncope in patients with MI and BBB and their prognosis. METHODS: We prospectively obtained the results of clinical history, 24 h Holter monitoring, left ventricular ejection fraction (LVEF), signal-averaged ECG (SAECG) and programmed ventricular stimulation in 130 patients with syncope, MI and BBB. 81 of them had right (R)BBB and 49-left (L)BBB. RESULTS: Ventricular tachycardia (VT) was identified as the main cause of syncope in patients with MI and BBB: 68% of them had inducible VT. The sensitivity (se) and specificity (sp) of non sustained VT on Holter monitoring for the detection of VT were respectively 42.5 and 47% in patients with RBBB, 62 and 36% in those with LBBB; se and sp of LVEF <40% were 67.5% and 65% in patients with RBBB, 85 and 9% in those with LBBB; se and sp of the combination of 2 of the 3 SAECG criteria, QRS duration > 155 ms, LAS duration >30 ms and RMS 40 < 17 microV were respectively 50 and 57% in patients with RBBB; se and sp of the combination of 2 of the 3 criteria QRS duration >165 ms, LAS duration >40 ms and RMS 40 <17 microV were 73 and 55.5%) in patients with LBBB. During the follow-up (4.7 years +/- 2.5), 12 patients died suddenly and 12 patients died from heart failure. Univariate and multivariate analysis revealed than only the induction of VT was a significant predictor of sudden death. A long QRS duration (> 165 ms) and induction of VT were independent predictors of total cardiac mortality. CONCLUSION: Among noninvasive studies, only the determination of filtered QRS duration was a significant predictor of cardiac mortality in the case of a prolongation (> 165 ms). Sudden death was only predicted by the induction of sustained VT. Because of the high incidence of inducible sustained VT, the low value of Holter monitoring and decreased LVEF for the prediction of ventricular arrhythmias and the poor prognosis of patients with inducible VT and low LVEF, systematic programmed ventricular stimulation is indicated in patients with MI, syncope and BBB, whatever the non-invasive studies results.  (+info)

Atrioventricular conduction in patients with clinical indications for transvenous cardiac pacing. (64/664)

Eighty patients with clinical indications for cardiac pacing had atrioventricular conduction analysed by His bundle study. The indications for cardiac pacing included high grade atrioventricular block, sick sinus node syndrome without tachycardia, bradycardia-tachycardia syndrome, unstable bilateral bundle-branch block, and uncontrolled ventricular irritability. Complete heart block, Wenckeback block (Mobitz I), and 2:1 block were noted proximal and distal to the His bundle. Mobitz II block only occurred distal to the His bundle. Of special interest were the high incidence of distal conduction abnormalities by His bundle analysis (40/80, 50%), the re-establishment of normal atrioventricular conduction in acutely ill patients with recent evidence of heart block, and the high incidence of intraventricular conduction disturbances on standard electrocardiogram (48/80, 60%).  (+info)