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Performance of the 2015 International Task Force Consensus Statement Risk Stratification Algorithm for Implantable
Gabriela M Orgeron1, Anneline Te Riele1, Crystal Tichnell1
1From the Department of Medicine, Division of Cardiology (G.M.O., C.T., W.W., B.M., A.B., D.P.J., H.T., H.C., C.A.J.) and Department of Radiology (I.R.K., S.L.Z.), Johns Hopkins Hospital, Baltimore, MD; and Department of Heart and Lungs, Division of Cardiology, University Medical Center Utrecht, and Netherlands Heart Institute (A.t.R.).
Insights
The 2015 algorithm for implantable cardioverter-defibrillator placement in arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVC/HCM) needs refinement. It underestimated VT/VF risk and failed to differentiate risk between Class I and IIa indications.
Area of Science:
- Cardiology
- Electrophysiology
- Genetics
Background:
- Ventricular arrhythmias are a significant complication of arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVC/HCM).
- A 2015 International Task Force Consensus Statement introduced a risk stratification algorithm for implantable cardioverter-defibrillator (ICD) placement in ARVC/HCM patients.
Purpose of the Study:
- To evaluate the performance of the 2015 ARVC/HCM risk stratification algorithm.
- To assess its accuracy in predicting ventricular arrhythmias (VT/VF) and ventricular fibrillation/flutter (VF).
Main Methods:
- 365 ARVC/HCM patients were classified using the algorithm's indications (Class I, IIa, IIb, III).
- Primary outcome was survival free from sustained VT/VF; secondary outcome was incidence of VF/flutter (cycle length <240 ms).
- Follow-up duration was a median of 4.2 years.
Main Results:
- The algorithm underestimated VT/VF incidence compared to expected rates.
- It failed to differentiate VF/flutter risk between Class I and IIa indications (P=0.97).
- VT/VF risk differentiation was also limited for primary prevention in Class I vs. IIa patients (P=0.22).
Conclusions:
- The algorithm shows overall risk differentiation but lacks precision for specific patient groups.
- Refinements are needed, particularly for distinguishing risk between Class I and IIa indications.
- Incorporating Holter monitor results may improve risk stratification accuracy.
Background:
Ventricular arrhythmias are a feared complication of arrhythmogenic right ventricular dysplasia/cardiomyopathy. In 2015, an International Task Force Consensus Statement proposed a risk stratification algorithm for implantable cardioverter-defibrillator placement in arrhythmogenic right ventricular dysplasia/cardiomyopathy.
Methods And Results:
To evaluate performance of the algorithm, 365 arrhythmogenic right ventricular dysplasia/cardiomyopathy patients were classified as having a Class I, IIa, IIb, or III indication per the algorithm at baseline. Survival free from sustained ventricular arrhythmia (VT/VF) in follow-up was the primary outcome. Incidence of ventricular fibrillation/flutter cycle length <240 ms was also assessed. Two hundred twenty-four (61%) patients had a Class I implantable cardioverter-defibrillator indication; 80 (22%), Class IIa; 54 (15%), Class IIb; and 7 (2%), Class III. During a median 4.2 (interquartile range, 1.7-8.4)-year follow-up, 190 (52%) patients had VT/VF and 60 (16%) had ventricular fibrillation/flutter. Although the algorithm appropriately differentiated risk of VT/VF, incidence of VT/VF was underestimated (observed versus expected: 29.6 [95% confidence interval, 25.2-34.0] versus >10%/year Class I; 15.5 [confidence interval 11.1-21.6] versus 1% to 10%/year Class IIa). In addition, the algorithm did not differentiate survival free from ventricular fibrillation/flutter between Class I and IIa patients (P=0.97) or for VT/VF in Class I and IIa primary prevention patients (P=0.22). Adding Holter results (<1000 premature ventricular contractions/24 hours) to International Task Force Consensus classification differentiated risks.
Conclusions:
While the algorithm differentiates arrhythmic risk well overall, it did not distinguish ventricular fibrillation/flutter risks of patients with Class I and IIa implantable cardioverter-defibrillator indications. Limited differentiation was seen for primary prevention cases. As these are vital uncertainties in clinical decision-making, refinements to the algorithm are suggested prior to implementation.
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