Key result
Inappropriate ICD shocks occur in ~25% of repaired Tetralogy of Fallot patients, linked to lower VT detection rates.
Why the study?
Patients with repaired Tetralogy of Fallot often undergo ICD implantation at younger ages and face an increased risk of sudden cardiac death and inappropriate shocks.
Cohort (n=44)
No
Inappropriate ICD shocks occur in one quarter of patients with repaired Tetralogy of Fallot, underscoring the critical importance of judicious VT therapy cutoff programming to minimize unnecessary therapies.
May warrant higher VT detection thresholds to limit inappropriate shocks in repaired Tetralogy of Fallot with ICD; leaves open optimal programming in prospective studies.
BACKGROUND: Patients with Tetralogy of Fallot (TOF) are at increased risk for sudden cardiac death, often undergo implantable cardioverter defibrillator (ICD) implantation at younger ages, and are at greater risk of experiencing inappropriate shocks. We investigated occurrences of ICD shocks in TOF patients to identify prevalence, characteristics associated with inappropriate shocks, and therapeutic interventions after inappropriate shocks. METHODS: Records of patients with repaired TOF and ICD implantation who were followed at Columbia University Irving Medical Center between 1/1/2000 and 5/1/2019 were analyzed. RESULTS: 44 patients with repaired TOF and ICD implantation were reviewed. Mean age at implantation was 39 ± 13 years. Eight (18%) patients received both appropriate and inappropriate shocks, 6 (14%) received only appropriate shocks, and 3 (7%) received only inappropriate shocks. Three patients received inappropriate shocks for sinus tachycardia, 7 for atrial arrhythmias, and 1 for noise artifact. Inappropriately shocked patients had lower beat per minute (bpm) cutoff values for ICD therapy (mean = 162 ± 24 bpm vs. 182 ± 16 bpm, p = 0.007). After inappropriate shocks, 1 patient underwent lead replacement, 1 had the VT cutoff increased, and 6 were treated with medications. CONCLUSIONS: One quarter of TOF patients with ICDs experienced inappropriate shock therapy, the timing of which was most often clustered within the first two years after implant or years later. Lower shock therapy zones were associated with increased risk for inappropriate shocks, and the majority of inappropriate shocks resulted from atrial arrhythmias with rapid ventricular response. Treatments for inappropriate shocks included increasing VT therapy bpm and rhythm and/or rate control medications.
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Goldenthal et al. (2020) conducted a cohort in Repaired Tetralogy of Fallot with ICD (n=44). Implantable cardioverter-defibrillator (ICD) was evaluated on Prevalence of inappropriate ICD shock therapy. In patients with repaired Tetralogy of Fallot and an ICD, 25% experienced inappropriate shocks, which were associated with lower programmed VT detection rates (162 vs 182 bpm, p=0.007).
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