Abstract 14941: External Validation of a Risk Score to Predict Appropriate Implantable Cardioverter Defibrillator Therapy for Primary Prevention in Tetralogy of Fallot
Background Previously, a risk score by Khairy and colleagues was developed to predict appropriate implantable cardioverter defibrillator (ICD) therapy for primary prevention of sudden cardiac death (SCD) in tetralogy of Fallot (TOF). The aim of this study was to asses the validity and applicability of this risk score.
Methods Patients included in a retrospective international multicentre cohort were stratified according to the risk score system (0-12 points); low risk (0 to 2 points), intermediate risk (3 to 5 points) and high risk (≥6 points). Freedom from appropriate ICD shocks was compared between these groups. Risk factors were prior shunt (2 points), inducible sustained ventricular tachycardia (VT, 2 points), QRS≥180 ms (1 point), ventriculotomy incision (2 points), nonsustained VT (2 points), left ventricular end-diastolic pressure≥12mmHg (LVEDP, 3 points). Moderate to severe systemic ventricular dysfunction was used because LVEDP values lacked in our cohort.
Results Thirty-six patients with TOF had an ICD implant for primary prevention (72% male, mean age 37±12). During a median follow-up of 5.5 years, seven patients (19%) received appropriate shocks. The 8-year survival curve to first appropriate shock was 90%, 70% and 75% for low, intermediate and high risk patients, respectively (Figure 1). The discriminative ability of the score was poor (area under the receiver operating curve 0.65). Survival curves were consistent in the low risk versus intermediate/high risk with those reported in the development and internal validation of the risk score. However, the event rate in intermediate and high risk group was considerably lower than reported in the original cohort of the risk score.
Conclusion These findings suggest that the risk score is capable in identifying low versus intermediate/high risk patients. The event rates of arrhythmias in adults with TOF and ICD for primary prevention are possibly overestimated.
- © 2011 by American Heart Association, Inc.