A systematic approach to the evaluation of survivors of SCA should identify potentially correctable or reversible causes, underlying structural heart disease and the less common inherited arrhythmia syndromes. An explanation for SCA can be identified in the majority of survivors from routine diagnostic investigations (including coronary angiography and cardiac imaging), as SCA occurs most commonly in the context of structural heart disease.

The remaining patients with unexplained cardiac arrest based on initial diagnostic evaluation should undergo further systematic and progressive clinical testing, including cardiac imaging and provocative pharmacological testing. A cause can be identified in more than half of the patients with apparently unexplained cardiac arrest with this strategy of systematic diagnostic testing. The minority of patients without an identifiable cause despite this strategy of rigorous testing are diagnosed with idiopathic ventricular fibrillation.