Idiopathic ventricular fibrillation (IVF) is a diagnosis given when a person has survived ventricular fibrillation and subsequent thorough investigation (including ECG, echocardiogram, cardiac MRI, coronary angiography, electrophysiology study, provocation testing, and genetic testing) has failed to identify any structural, electrical, or inherited cause. It is a diagnosis of exclusion, meaning it is only made after all other explanations have been ruled out.
How common is it
Idiopathic VF accounts for approximately 5 to 10% of cardiac arrest cases in younger patients where no clear cause can be identified. In some series it is the most common single diagnosis after out-of-hospital cardiac arrest in young adults once coronary artery disease is excluded.
The importance of thorough investigation
Many conditions that were once labelled idiopathic VF are now recognised as specific entities with advancing technology. For example, what was previously called idiopathic VF is now sometimes identified as a very early or concealed form of ARVC, a channelopathy with atypical features, or a condition driven by ectopic beats originating from specific sites such as the Purkinje fibres. A specialist inherited cardiac condition clinic should review every case.
Management
Because no correctable cause is identified, the management of idiopathic VF focuses on preventing recurrence. An ICD is recommended for all survivors of idiopathic VF to provide protection if VF recurs. Quinidine has been used to reduce VF burden in some patients. Close follow-up and repeat investigation over time are important, as a cause may become apparent as the patient’s condition evolves.
Uncertainty and its impact
Receiving a diagnosis of "we cannot find a cause" can be psychologically difficult. Survivors of idiopathic VF may find the uncertainty particularly challenging, and psychological support should form part of their care.
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