Tachycardias in children originating in the right ventricular outflow tract: lack of clinical features predicting the presence and severity of the histopathological substrate

Myocardial Biopsy In "Idiopathic» Atrial Fibrillation And Other Arrhythmias: Nosological Diagnosis, Clinical And Morphological Parallels, And Treatment

BACKGROUND

The nosological nature of "idiopathic" arrhythmias and the effect of etiotropic and pathogenetic treatment are often unknown.

METHODS AND RESULTS

19 patients (42.6±11.3 years, 9 women) with atrial fibrillation (n = 16), supraventricular (n = 10) and ventricular (n = 4) premature beats, supraventricular (n = 2) and ventricular tachycardia (n = 1), left bundle branch block (n= 2), AV block (n = 2) without structural heart changes. Viruses were identified (polymerase chain reaction, PCR) along with measurement of anti-heart antibodies (AHA) and endomyocardial biopsy (EMB). EMB allowed to establish diagnosis in all patients: infectious-immune myocarditis (n = 11, parvovirus-positive in 1),parvovirus-positive endomyocarditis (n = 1),systemic (n = 2) and myocardial (n = 1) vasculitis,Fabry's disease (n = 1), arrhythmogenic right ventricular dysplasia (n = 1),unspecified genetic cardiomyopathy (n = 2, herpes virus 6 one positive). Level of AHA had the greatest significance for myocarditis diagnostics. All patients with myocarditis/vasculitis had background therapy: acyclovir (n = 10), IV immunoglobulin (n = 2), meloxicam (n = 12), hydroxychloroquine (n = 15), steroids (n = 14, 31.1±12.5 mg/day), azathioprine 150 mg/day (n = 2). Median follow-up was 4 years. Treatment significantly reduced the rate of arrhythmias (8 [5;8] to 3 [1.25;7.75] points); disappearance of bundle branch block was noted.

CONCLUSION

EMB allowed to diagnose immune-mediated inflammatory diseases in 78.9% patients with 'idiopathic' arrhythmias and genetic diseases in 21.1%. Background therapy of myocarditis improved the antiarrhythmic efficiency, and allowed the best premed for interventional treatment.

Prediction of ventricular arrhythmias using cardiovascular magnetic resonance

Ventricular tachycardia (VT) is the commonest cause of sudden cardiac death (SCD) in developed countries. Coronary artery disease (CAD) is the most frequent cause of VT in individuals over the age of 30, while hypertrophic cardiomyopathy (HCM), myocarditis and congenital heart disease in those below 30 years of age. Cardiac magnetic resonance (CMR), a non-invasive, non-radiating technique, can reliably detect the changes in ventricular volumes and the ejection fraction that can be predictive of VT/SCD. Furthermore, the capability of CMR to perform tissue characterization and detect oedema, fat and fibrotic substrate, using late gadolinium enhanced images (LGE), can predict VT/SCD in both ischaemic and non-ischaemic cardiomyopathy. The extent of LGE in HCM is correlated with risk factors of SCD and the likelihood of inducible VT. In idiopathic-dilated cardiomyopathy, the presence of midwall fibrosis, assessed by CMR, also predicts SCD/VT. Additionally, in arrhythmogenic right ventricle (RV) dysplasia/cardiomyopathy, CMR has an excellent correlation with histopathology and predicted inducible VT on programmed electrical stimulation, suggesting a possible role in evaluation and diagnosis of these patients. A direct correlation between LGE and VT prediction has been identified only in chronic Chagas' heart disease, but not in viral myocarditis. In CAD, infarct size is the strongest predictor of VT inducibility. The peri-infarct zone may also play a role; however, further studies are needed for definite conclusions. Left ventricle, RV, right ventricular outflow tract (RVOT) function, pulmonary regurgitation and LGE around the infundibular patch and RV anterior wall play an important role in the VT prediction in repaired Tetralogy of Fallot. Finally, in treated transposition of great arteries, the extent of LGE in the systemic RV correlates with age, ventricular dysfunction, electrophysiological parameters and adverse clinical events, suggesting prognostic importance.

Right ventricular outflow tract tachycardia in children

OBJECTIVE

To assess the clinical spectrum of right ventricular outflow tract tachycardia and its management in children.

STUDY DESIGN

Five centers identified patients for retrospective review. Patients (age <18 years) demonstrating ventricular tachycardia with an inferior axis and left bundle branch block were included. Patients with structural heart disease, myocarditis, cardiomyopathy, or long QT syndrome were excluded. Demographics, clinical presentation, investigations, and treatment were analyzed. Holter data were used to quantify ectopy.

RESULTS

Patients (n = 48) were referred for evaluation of incidental findings (39/48), near syncope or syncope (7/48), or other (2/48). Investigations included magnetic resonance imaging (51%), endomyocardial biopsy (25%), and angiography (23%). Medical treatment was initiated in 26 of the 48 patients. The most common indications for treatment were frequent ectopy and symptoms. Medical treatment (P <.007) and observation alone (P <.02) were both associated with a reduction in ectopy. Symptoms persisted in 3 of 13 patients who were treated medically and in all untreated patients. At follow-up, there were no deaths and no difference in ectopy (P <.46) between patients who were treated medically and patients who were observed. Ablation was attempted in 6 of the 48 patients (successful in 4/6).

CONCLUSION

The clinical spectrum and management of right ventricular outflow tract tachycardia in children are diverse. Both medical therapy and observation alone were associated with a reduction in ectopy.