Right bundle branch block: Prevalence, incidence, and cardiovascular morbidity and mortality in the general population

Background: Right bundle branch block (RBBB) is among the most common electrocardiographic abnormalities. Objectives: To establish the prevalence and incidence of RBBB in the general population without cardiovascular events (CVE) and whether RBBB increases cardiovascular morbidity and mortality compared with patients with a normal electrocardiogram (ECG). Methods: A historical study of two cohorts including 2981 patients from 29 primary health centres without baseline CVE. Cox (for CVE) and logistic (for cardiovascular factors) regression was used to assess their association with RBBB. Results: Of the patients (58% women; mean age 65.9), 92.2% had a normal ECG, 4.6% incomplete RBBB (iRBBB) and 3.2% complete RBBB (cRBBB). Mean follow-up was five years. Factors associated with appearance of cRBBB were male sex (HR = 3.8; 95%CI: 2.4-6.1) and age (HR = 1.05 per year; 95%CI: 1.03-1.08). In a univariate analysis, cRBBB was associated with an increase in all-cause mortality but only bifascicular block (BFB) was significant after adjusting for confounders. cRBBB tended to increase CVE but the results were not statistically significant. Presence of iRBBB was not associated with adverse outcomes. Patients with iRBBB who progressed to cRBBB showed a higher incidence of heart failure and chronic kidney disease. Conclusion: In this general population cohort with no CV disease, 8% had RBBB, with a higher prevalence among men and elderly patients. Although all-cause mortality and CVE tended to increase in the presence of cRBBB, only BFB showed a statistically significant association with cRBBB. Patients with iRBBB who progressed to cRBBB had a higher incidence of CVE. We detected no effect of iRBBB on morbidity and mortality.

Diagnosis of right bundle branch block: a concordance study

BACKGROUND

Right bundle branch block is one of the most common electrocardiographic abnormalities. Most cases of right bundle branch block are detected in asymptomatic patients in primary care, so a correct interpretation of electrocardiograms (ECGs) at this level is necessary. The objective of this research is to determine the degree of concordance in the diagnosis of incomplete and complete right bundle branch block between four primary care researchers and a cardiologist.

METHODS

The research design is a retrospective cohort study of patients over 18 years of ages of patients over 18 years of ages who underwent an ECG for any reason and were diagnosed with right bundle branch block by their physician. The physicians participating, 4 primary care researchers and a cardiologist were specialized in interpreting electrocardiographic records. The diagnosis of incomplete and complete right bundle branch block was recorded and other secondary variables were analysed. In case of diagnostic discordance between the researchers, the ECGs were reviewed by an expert cardiologist, who interpreted them, established the diagnosis and analysed the possible causes for the discrepancy.

RESULTS

We studied 160 patients diagnosed with right bundle branch block by their general practise. The patients had a mean age of 64.8 years and 54% of them were men. The concordance in the diagnosis of incomplete right bundle branch block showed a Fleiss' kappa index (k) of 0.71 among the five researchers and of 0.85 among only the primary care researchers. The k for complete right bundle branch block was 0.93 among the five researchers and 0.96 among only the primary care researchers.

CONCLUSION

The interobserver agreement in the diagnosis of right bundle branch block performed by physicians specialized in ECG interpretation (primary care physicians and a cardiologist) was very good. The variability was greater for the diagnosis of incomplete right bundle branch block.

[Treatment of cardiac arrhythmia with radiofrequency in pediatrics]

OBJECTIVE

The use of radiofrequency ablation of cardiac arrhythmias in pediatrics requires demonstration that the technique is effective and devoid of significant complications. In this study we present our experience in the ablation of cardiac arrhythmias in children and adolescents.

PATIENTS AND METHODS

Between January 1992 and January 1997 we performed a total of 1,543 radiofrequency ablation procedures. Of these, 130 were performed in 117 patients younger than 18 years of age (58 were younger than 14 years old). Indication for ablation was the presence of drug refractory recurrent paroxysmal supraventricular tachycardia in 112 patients and permanent ventricular preexcitation in 5 asymptomatic patients. Final diagnosis in the 112 symptomatic patients was: 4 atrial tachycardias, 21 atrio-ventricular nodal reentrant tachycardias, 53 Wolff-Parkinson-White (WPW) syndromes, 33 orthodromic tachycardias using a concealed accessory pathway and 1 idiopathic left ventricular tachycardia.

RESULTS

The initial ablation procedure was effective in 109/117 patients (93%) with a total duration of 90 +/- 31 minutes, using 16 +/- 11 minutes of radioscopy and a median of 4 radiofrequency applications. During follow-up, recurrence occurred in 9 patients (8%). In 7 of them and in 6 of those with an unsuccessful initial procedure, a second effective procedure was performed in 11/13 patients. Finally, radiofrequency ablation was effective in 111/117 patients (95%). We observed a single complication in a 15 year old girl who presented a thrombosis of the right femoral artery requiring balloon recanalization. Comparison of these results with those in the adult population showed no difference in terms of effectiveness, recurrences or complications.

CONCLUSIONS

Radiofrequency ablation of cardiac arrhythmias in pediatric and young patients can be safely and effectively done. Results are similar to those obtained in adults suggesting that indications for ablation can also be similar.

[Transient atrioventricular conduction 1:1 in a patient with common atrial flutter following the administration of adenosine triphosphate]

A patient with atrial flutter and 2:1 atrioventricular conduction and acceleration to 1:1 conduction after administration of a single i.v. dose of 10 mg adenosin triphosphate (ATP) is presented. Despite the fact that ATP is a very useful drug for the treatment of paroxysmal supraventricular tachycardia. Its use as a diagnostic tool in atrial flutter must be carefully considered and the possibility of transient acceleration of AV conduction must be taken into account.

[Sustained monomorphic ventricular tachycardia in myotonic dystrophy]

Myotonic dystrophy is an hereditary multisystemic disease, characterized by slowly progressive myotonic atrophy of skeletic muscles. The heart is frequently affected with occurrence of arrhythmias and His-Purkinje system dysfunction and, less frequently, myocardial dysfunction. The surface ECG is the most sensible indicator of heart disease, and the most common electrophysiological finding is the prolongation of the H-V interval. Patients usually have few cardiovascular symptoms, but when present, the most frequent are: syncope, arrhythmias, atrioventricular block, congestive heart failure and sudden death. We present two patients with sustained monomorphic ventricular tachycardia as initial presentation of cardiac disease.

Acute and transient ST segment elevation during bacterial shock in seven patients without apparent heart disease

Acute elevation of the ST segment in several ECG leads was observed in seven patients with bacterial shock during the course of therapy. Six patients had bacterial pneumonia, one had acute cholecystitis, and none had a previous history of heart disease. At the onset of the ST elevation, all patients were receiving dopamine infusion, which in four of them was inadvertently increased shortly before the ECG changes, the ST elevation was not associated with chest pain, pericardial friction rub, or acute changes in the heart rate, or arterial blood pressure. In four patients the maximum ST elevation was greater than or equal to 5 mm. In each instance the ST segment returned to the isoelectric line within 24 hours, and subsequent development of Q waves or changes in the QRS was not observed. Although the existence of an acute pericarditis or an acute myocarditis as possible causes of the ST elevation cannot be fully ruled out, the sudden onset, prominent magnitude, and brief duration of the ST elevation are perhaps more indicative of an acute ischemic event, possibly related to a transient coronary vasoconstriction induced by the dopamine infusion.