Idiopathic ventricular fibrillation: the ongoing quest for diagnostic refinement

Area of Science:

• Cardiology
• Genetics
• Molecular Autopsy

Background:

• Historically, sudden cardiac arrest (SCA) survivors with ventricular fibrillation (VF) and normal heart structure were diagnosed with idiopathic ventricular fibrillation (IVF).
• The definition of IVF has evolved with the identification of genetic heart diseases (GHDs) and channelopathies as causes of unexplained sudden cardiac death (SCD).
• Molecular autopsy has revealed that cardiac channelopathies underlie up to 35% of unexplained SCD in young individuals.

Purpose of the Study:

• To review the changing definition and diagnostic approaches for unexplained SCA survivors.
• To discuss the epidemiology and controversies surrounding the role of genetic background in these patients.
• To highlight the underdiagnosis of GHDs among SCA survivors.

Main Methods:

• Review of literature on the evolution of IVF definition and diagnostic strategies.
• Discussion of molecular autopsy findings in unexplained SCD.
• Analysis of underdiagnosis factors including underuse of pharmacological challenges and ECG misinterpretations.

Main Results:

• Genetic heart diseases are increasingly recognized as the cause of previously labeled idiopathic ventricular fibrillation.
• Despite improved awareness, GHDs are still underdiagnosed in SCA survivors.
• Underdiagnosis stems from underutilization of provocative tests, misinterpretation of ECG abnormalities, and measurement errors.

Conclusions:

• The concept of idiopathic ventricular fibrillation has been largely replaced by the identification of specific genetic channelopathies.
• Extensive diagnostic evaluation is crucial for unexplained SCA survivors.
• Addressing diagnostic challenges is essential to improve the recognition and management of GHDs in this population.