Arrhythmias in Adults with Repaired Tetralogy of Fallot

Abstract & Commentary

By John P. DiMarco, MD, PhD

Source: Khairy P. Arrhythmia burden in adults with surgically repaired tetralogy of fallot. Circulation. 2010;122:868-875.

In this paper, Khairy and colleagues from the Alliance for Adult Research in Congenital Cardiology (AARCC) conducted a multi-center, cross-sectional study on the prevalence of arrhythmias in adult patients who had previously undergone surgical repair of either tetralogy of Fallot or pulmonary atresia with ventricular septal defect. The patients were collected by the 11 U.S. and Canadian centers that participate in the AARCC and followed in a single database. Data analyzed included demographic variables, comorbidities, anatomical features, surgical history, antiarrhythmic catheter interventions, medical therapy, and clinical arrhythmias. Arrhythmia-specific data included current rhythm, most recent QRS duration, history of sustained arrhythmias, and history of arrhythmia interventions, including electrophysiologic studies, catheter ablation procedures, and pacemaker or implantable cardioverter-defibrillator (ICD) insertions. Data from 556 patients are included in this report. The mean age at the time of data collection was 36.8 + 12 years. The patients had undergone a mean of 2.5 + 1.5 cardiac surgeries with prior palliative shunts in 47%, pulmonary transannular patches in 80%, RV-to-pulmonary-artery conduits in 11%, and pulmonic valve replacement in 43%. The median age at corrective surgery was 5.0 years. The average left ventricular ejection fraction at last follow-up was 58 + 9%. LV diastolic dysfunction was present in 25%, and 16% had moderate or greater systolic right ventricular dysfunction. Pulmonic and tricuspid regurgitation of at least moderate severity was present in 47.6% and 15.3% of the group, respectively. Sustained atrial arrhythmias had been noted in 89 patients, sustained ventricular arrhythmias in 81 patients, and no arrhythmias in 408 patients.

A history of at least one clinically sustained arrhythmia, implantation of a pacemaker or ICD, or a catheter-ablation procedure was noted in 43% of the patients. Pacemakers were placed for bradycardia indications in 7.9% of the patients. ICDs were implanted in 10.4% of the patients, with 27 patients receiving them for primary prevention of sudden death and 19 patients receiving them after a sustained episode of ventricular tachycardia or ventricular fibrillation. Twelve of 27 patients who received an ICD for primary prevention later experienced one or more episodes of clinical ventricular arrhythmia that was treated by their ICD. Clinical, sustained ventricular tachycardia was documented in 79 patients (14.2%). In the multivariate analysis, the number of prior cardiac surgeries, the QRS duration, and the presence of left diastolic dysfunction were significant predictors of ventricular arrhythmias.

Atrial tachyarrhythmias were noted in 20.1% of the study group. Intra-atrial reentrant tachycardia was seen in 11.5%, atrial fibrillation in 7.4%, and other arrhythmias in 6.7%. Intra-atrial reentrant tachycardia was associated with the increased number of prior cardiac surgeries and the presence of either hypertension or right atrial enlargement. Atrial fibrillation was associated with age, prior cardiac surgery, left atrial enlargement, and decreased ejection fraction.

The authors conclude that the arrhythmia burden in adults with surgical repair tetralogy of Fallot is high, with a high prevalence of sustained atrial and ventricular arrhythmias and bradycardia. Both atrial and ventricular arrhythmias increase with age. Atrial fibrillation and ventricular arrhythmias were more common in patients with left ventricular dysfunction. The identification of diastolic dysfunction as a risk factor for ventricular arrhythmias is a new observation.

Commentary

This study provides important data on the prevalence and natural history of atrial and ventricular arrhythmias after surgical correction of tetralogy of Fallot. The high prevalence of atrial and ventricular arrhythmias and bradycardia in these patients clearly indicates the need for careful long-term follow-up. It is difficult from these data to know if improved surgical techniques used in the last two decades will lower the incidence of late post-operative arrhythmias. The authors clearly document that the prevalence of arrhythmias seems to increase markedly 30-40 years after surgery. Therefore, the highest prevalence is seen in those who were operated on more than 25-30 years ago. Hopefully, the more recent tendencies for earlier complete repair will lower the future prevalence of arrhythmias in these patients.