Idiopathic Ventricular Fibrillation (IVF)
Details
Idiopathic ventricular fibrillation is a diagnosis of exclusion, made after a patient survives sudden cardiac arrest with documented VF and all other identifiable causes (structural disease, other channelopathies, metabolic causes) have been ruled out. It is a major cause of SCD in young patients without structural or electrical heart disease.
Key Facts
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IVF occurs due to Purkinje fiber-derived short-coupled premature ventricular complexes (PVCs) that fall on the T wave — the R-on-T phenomenon — initiating VF. (sources/channelopathies-jaha-2025)
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Associated genes: CALM1, RYR2-encoded cardiac Ca²⁺ channel, IRX-encoded Iroquois homeobox transcription factors, DPP6 promoter haplotype on chromosome 7. The DPP6 haplotype level is >20× higher in IVF patients vs. healthy controls — potentially useful as a diagnostic biomarker. (sources/channelopathies-jaha-2025)
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Diagnosis: Requires systematic exclusion of other causes. Workup includes: 12-lead ECG + Holter monitoring (rule out J-wave syndromes/QT syndromes); IV epinephrine test; procainamide challenge test; electrophysiological testing; myocardial biopsy. Cardiac MRI, exercise treadmill test, and sodium channel blockers are highest-performing components. Genetic testing advised for all unexplained SCD survivors; cardiomyopathy-related genetic variants should also be investigated. (sources/channelopathies-jaha-2025)
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No strict diagnostic workup exists; guideline recommendations are general. Variants of uncertain significance are more common than pathogenic/likely pathogenic variants in IVF genetic testing. (sources/channelopathies-jaha-2025)
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Management (acute): ICD or pharmacotherapy with isoproterenol, verapamil, or quinidine for electrical storm or recurrent ICD discharges. (sources/channelopathies-jaha-2025)
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Management (chronic): Quinidine to suppress recurrent ICD discharges/electrical storms. Percutaneous catheter ablation for recurrent IVF with similar PVC morphology unresponsive to pharmacotherapy. (sources/channelopathies-jaha-2025)
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Ongoing trials: quinidine/verapamil pilot study (NCT05593757); electrophysiological properties of conduction system in apparent IVF (NCT03963271). (sources/channelopathies-jaha-2025)
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ESC 2022 guideline recommendations:
- IVF diagnosed in SCA survivor, preferably with documented VF, after exclusion of structural, channelopathic, metabolic, or toxicological aetiology: Class I (Level B). (sources/VA-SCD-ESC-2022)
- ICD implantation: Class I (Level B). (sources/VA-SCD-ESC-2022)
- Isoproterenol infusion, verapamil, or quinidine for acute electrical storm or recurrent ICD discharges: Class IIa. (sources/VA-SCD-ESC-2022)
- Quinidine for chronic therapy to suppress electrical storm or recurrent ICD discharges: Class IIa. (sources/VA-SCD-ESC-2022)
- Clinical testing (history, ECG, exercise test, echo) of first-degree family members: Class IIb. (sources/VA-SCD-ESC-2022)
- Genetic testing of channelopathy and cardiomyopathy genes in IVF patients: Class IIb. (sources/VA-SCD-ESC-2022)
Contradictions / Open Questions
- Diagnosis of exclusion — no standardized exclusion protocol: IVF requires systematic exclusion of all other causes, but no single validated exclusion protocol exists; the workup described (ECG, Holter, MRI, IV epinephrine, procainamide challenge, EPS, biopsy) is not universally applied or standardized across institutions. This means the IVF label is heterogeneously applied — some diagnosed cases may harbor undetected ERS, BrS, or occult structural disease, particularly if CMR or provocative testing was omitted. (sources/channelopathies-jaha-2025)
- Genetic testing — VUS predominant over P/LP: Variants of uncertain significance are more common than pathogenic or likely pathogenic variants in IVF genetic testing, and genetic testing carries only a Class IIb recommendation. The diagnostic yield is low and the management impact of VUS findings is nil. This creates a clinical scenario where genetic testing is frequently performed but rarely actionable, generating patient anxiety without clear therapeutic direction. (sources/channelopathies-jaha-2025, sources/VA-SCD-ESC-2022)
- DPP6 haplotype as biomarker — not in clinical use: The DPP6 haplotype is elevated >20× in IVF patients vs. healthy controls and is described as a potential diagnostic biomarker. However, it is not in clinical use, has not been validated in a prospective independent cohort, and is not included in guideline-recommended workup. The gap between research finding and clinical implementation is unresolved. (sources/channelopathies-jaha-2025)
Connections
- Related to concepts/Sudden-Cardiac-Death
- Related to concepts/Ion-Channel-Mutations
- Related to entities/Early-Repolarization-Syndrome
- Related to entities/Brugada-Syndrome
- Related to entities/Long-QT-Syndrome
- Related to concepts/Electrical-Storm