Idiopathic ventricular fibrillation: The search for substrates

Sudden cardiac arrest (SCA) is a devastating event that in unwitnessed cases almost always leads to death. This has a large impact on patients and their families and despite major achievements over the years, SCA still causes many lives annually. When all known causes of an arrest are excluded after completing an extensive diagnostic work-up, a patient is diagnosed with idiopathic ventricular fibrillation (VF). This diagnosis is currently defined as “a cardiac arrest survivor, preferably with documentation of VF, in which all structural, channelopathic, metabolic and toxicological conditions are excluded’’. These patients are left uncertain about their cause and prognosis. This thesis aimed to identify previously unknown or unrecognized substrates that may underlie VF in these patients. Using various approaches, ranging from genetic testing to multiple imaging modalities and by using the Dutch Idiopathic VF Registry, potential substrates were investigated. This led to a focus on three different substrates: patients with genetic predispositions, patients with undetected or unrecognized structural substrates, and patients with electrical substrates.