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Ventricular Arrhythmia Risk Stratification in Patients With Tetralogy of Fallot at the Time of Pulmonary Valve Replacement | Journal Scan
Study Questions:
What is the optimal approach to managing the risk of future ventricular arrhythmias in tetralogy of Fallot (TOF) patients undergoing pulmonary valve replacement (PVR)?
Methods:
This was a retrospective cohort study of previously repaired TOF patients undergoing PVR. The primary outcome was sustained ventricular tachycardia (VT), cardiac arrest, appropriate implantable cardioverter-defibrillator (ICD) therapy, or sudden cardiac death (SCD) during follow-up.
Results:
The study included 205 patients, with a median follow-up of 6.7 years and complete in 98%. The primary outcome occurred in 19 patients with 95% freedom from event at 5 years, 90% at 10 years, and 79% at 15 years. Univariate risk factors for developing the primary outcome were history of VT (hazard ratio [HR], 4.7; 95% confidence interval [CI], 1.6-13.4), history of ICD implantation (HR, 4.1; 95% CI, 1.3-12.8), longer (+10 ms) QRS duration (HR, 1.2; 95% CI, 1-1.3), QRS ≥180 ms (HR, 2.89; 95% CI, 1.1-7.5), left ventricular ejection fraction (LVEF) <50% (HR, 3.62; 95% CI, 1.4-9.4), and older age (+5 years) (HR, 1.26, 95% CI, 1.1-1.5). Kaplan-Meier survival analysis (log-rank) showed lower freedom from event with history of VT, LVEF <50%, and QRS ≥180 ms. Twenty-two patients had undergone surgical cryoablation for VT or prophylaxis at the time of PVR. Of these, 1/22 reached the primary outcome versus 18/186 nonablated patients. Patients undergoing ablation were more likely to be older, have an ICD, and have inducible VT at electrophysiology (EP) study. Kaplan-Meier survival analysis showed no difference between ablated and nonablated patients reaching the primary outcome.
Conclusions:
Repaired TOF patients undergoing PVR are at risk for future ventricular arrhythmias if they have a history of VT, QRS ≥180 ms, or LVEF <50%. The authors advocate for EP study in this high-risk group around the time of PVR, and suggest that surgical cryoablation may be beneficial.
Perspective:
This study identifies several risk factors for the development of VT, cardiac arrest, appropriate ICD therapy, or SCD in repaired TOF patients; some of which have been identified in previous studies (Khairy P, et al., Circulation 2008;1:250-7). The somewhat speculative conclusions that EP study is indicated at the time of PVR and that cryoablation is beneficial are not clearly supported by the data. Inducible VT at EP study was not analyzed as a risk for the outcome. The outcome of those undergoing surgical cryoablation was not different than those not undergoing ablation. Although the two groups differed at baseline, the differences did not match those risks identified by Kaplan-Meier survival analysis. While the study does add to our current knowledge, it does not solve the challenging question of how to address risk in repaired TOF.
Keywords: Arrhythmias, Cardiac, Cryosurgery, Death, Sudden, Cardiac, Defibrillators, Electrophysiology, Heart Arrest, Pulmonary Valve, Risk Factors, Stroke Volume, Survival Analysis, Tachycardia, Tetralogy of Fallot
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