5205Electrocardiographic predictors of appropriate implantable cardioverter defibrillator therapies in patients with tetralogy of Fallot

Abstract

Abstract Background The electrocardiogram (ECG) is widely available and may contribute to a better risk stratification for sudden cardiac death in patients with tetralogy of Fallot. QRS duration has been consistently associated with outcomes, with a lack of specificity for sudden mortality and a relatively low predictive value. New markers such as QRS fragmentation and vectocardiographic parameters have been recently suggested. Purpose To identify ECG predictors of appropriate therapies in patients with tetralogy of Fallot and implantable cardioverter defibrillator (ICD). Methods The DAI-T4F study is a large ongoing national French registry including all patients with tetralogy of Fallot and ICD (NCT03837574). Information have been collected prospectively since 2010 with annual update. Baseline patient characteristics and clinical events during the follow-up were analyzed with central adjudication. Cox proportional hazard models were used to identify factors associated with appropriate ICD therapies. Results A total of 134 patients (median age 41.7 years, 70.7% males) were enrolled. During a median (IQR) follow-up of 6.1 (2.7–10.2) years, 59 (44.0%) patients received at least one appropriate ICD therapy, giving annual incidence of 5.5% and 7.1% in primary and secondary prevention, respectively (p=0.058). Overall, QRSd ≥180ms (p=0.073), QRS fragmentation (p=0.052), and QRS vector magnitude (vm, p=0.327) were not significantly associated with appropriate ICD therapies, whereas QRS fragmentation in right leads (HR=1.7, 95% CI: 1.1–2.9, p=0.039) and the association of QRSd ≥180ms and overall QRS fragmentation (HR=1.9, 95% CI: 1.1–3.4, p=0.036) were associated with an increased risk of appropriates ICD therapies. In patients with ICD for primary prevention (47 patients, 35.1%), 53.8% had QRS fragmentation, 48.6% had decreased QRS vm, and 41.0% had QRSd ≥180ms. In this group, while non-sustained ventricular tachycardia (NSVT) considered isolated was not associated with ventricular events during follow-up (p=0.069), respective combinations with QRSd ≥180 ms (HR=7.2, 95% CI: 1.6–32.7, p=0.011), QRS fragmentation (HR=3.8, 95% CI: 1.2–12.4, p=0.025), or decreased QRS vm (HR=3.6, 95% CI: 1.1–12.1, p=0.042) were all associated with a higher incidence of appropriate ICD therapies. Positive predictive value and negative predictive value were 0.33 and 0.85, 0.58 and 0.74, and 0.36 and 0.84 in patients with NSVT and QRS ≥180ms, NSVT and QRS fragmentation, and NSVT and decreased QRS vm, respectively. Conclusions Our findings highlight that cumulative risk score derived from ECG may contribute to improve risk stratification in patients with tetralogy of Fallot, in particular QRS fragmentation and QRS vm in association with QRS duration and other traditional risk factors.