Implantable Cardioverter-Defibrillators in Tetralogy of Fallot

Abstract

Background-Tetralogy of Fallot is the most common form of congenital heart disease in implantable cardioverterdefibrillator (ICD) recipients, yet little is known about the value of ICDs in this patient population. Methods and Results-We conducted a multicenter cohort study in high-risk patients with Tetralogy of Fallot to determine actuarial rates of ICD discharges, identify risk factors, and characterize ICD-related complications. A total of 121 patients (median age 33.3 years; 59.5% male) were enrolled from 11 sites and followed up for a median of 3.7 years. ICDs were implanted for primary prevention in 68 patients (56.2%) and for secondary prevention in 53 (43.8%), defined by clinical sustained ventricular tachyarrhythmia or resuscitated sudden death. Overall, 37 patients (30.6%) received at least 1 appropriate and effective ICD discharge, with a median ventricular tachyarrhythmia rate of 213 bpm. Annual actuarial rates of appropriate ICD shocks were 7.7% and 9.8% in primary and secondary prevention, respectively (Pϭ0.11). A higher left ventricular end-diastolic pressure (hazard ratio 1.3 per mm Hg, Pϭ0.004) and nonsustained ventricular tachycardia (hazard ratio 3.7, Pϭ0.023) independently predicted appropriate ICD shocks in primary prevention. Inappropriate shocks occurred in 5.8% of patients yearly. Additionally, 36 patients (29.8%) experienced complications, of which 6 (5.0%) were acute, 25 (20.7%) were late lead-related, and 7 (5.8%) were late generator-related complications. Nine patients died during follow-up, which corresponds to an actuarial annual mortality rate of 2.2%, which did not differ between the primary and secondary prevention groups. Conclusions-Patients with tetralogy of Fallot and ICDs for primary and secondary prevention experience high rates of appropriate and effective shocks; however, inappropriate shocks and late lead-related complications are common.

Inappropriate ICD Shocks in Pediatric and Congenital Heart Disease Patients

“…In larger adult studies, the rate of IS has been reported to range from 10% to 15%. 16,25,27 However, most studies of ICD use in pediatric and CHD patients have found rates of IS to be between 20% and 30% in these patient populations, 10,11,13,14,[34][35][36][37][38][39][40] with some studies observing IS in up to 40% to 50% of patients and, in some instances, with inappropriate shocks being more frequent than appropriate shocks. 12,19,41,42 This is likely a result of a more active lifestyle, faster rates of sinus tachycardia, longer duration of implantation, smaller patient size, and a higher rate of device and lead complications relative to adult patients.…”

“…Khairy et al reported data from tetralogy of Fallot and transposition of the great arteries patient populations, demonstrating detection rates in patients receiving an appropriate shock of 213 bpm and 222 bpm, respectively. 34,81 Additionally, in a population of ICD patients with Brugada syndrome, the mean detected tachycardia rate in appropriate shocks was 335 bpm, with the suggestion that a single VF zone at 222 bpm would reduce IS by 70%, although it could potentially lead to the missing of appropriate shocks in 1.7% of patients. 82 The frequency of use of ATP and its effectiveness in this population is not well known, although some authors have found the success rate to be low, and have advocated against its routine use.…”

ICD Implantations in the Pediatric and Young Adult Population

“…During follow-up the number of appropriate shocks was considerable (30% of patients). This was, however, at the cost of a 5.8% yearly incidence of inappropriate shocks, and the occurrence of complications in 36 patients, mostly (70%) lead-related (Khairy et al, 2008). In Fallot patients with unstable ventricular tachycardia, their rhythm abnormalities may in some patients be treated by catheter ablation (Kriebel et al, 2007).…”

Implantable cardioverter–defibrillator therapy in congenital heart disease

“…Hence, these patients are the most studied group and the most common recipients of ICDs in the adult congenital heart disease population. Older age at repair, long QRS duration (>180 ms), history of a prior palliative shunt, inducible sustained VT at electrophysiological study, prior ventriculotomy, documented nonsustained VT, and left ventricular dysfunction (confirmed by an elevated left ventricular end-diastolic pressure [>12 mmHg]) all appear to contribute to the risk of SCD and appropriate ICD discharge [14][15][16]. Unfortunately, these criteria retain a fairly low specificity when confronted with each patient, who requires a highly individualized risk assessment based on their complex background.…”