Polymorphic ventricular tachycardia-part I: structural heart disease and acquired causes

Area of Science:

• Cardiology
• Electrophysiology
• Genetics

Background:

• Polymorphic ventricular tachycardia (PMVT) is a rare ventricular tachyarrhythmia with a distinctive, evolving QRS morphology.
• While often associated with structural heart disease, PMVT is increasingly recognized as a cause of sudden cardiac death in individuals without apparent myocardial substrate.
• The underlying mechanisms involve abnormal repolarization, cellular heterogeneities, and principles of triggering and reentry.

Purpose of the Study:

• To elucidate the mechanisms of polymorphic ventricular tachycardia (PMVT).
• To highlight the role of channelopathies in PMVT and sudden cardiac death.
• To underscore the diagnostic challenges posed by subtle electrocardiographic changes and the impact of pharmaceuticals on ion channel function.

Main Methods:

• Review of existing literature on PMVT.
• Analysis of mechanistic pathways including repolarization abnormalities and reentry.
• Discussion of channelopathies and their clinical implications.

Main Results:

• PMVT is mechanistically distinct from ventricular fibrillation.
• Abnormal repolarization and cellular heterogeneities are central to PMVT.
• Channelopathies represent a significant, often subtle, risk factor for PMVT and sudden cardiac death.

Conclusions:

• PMVT pathogenesis involves abnormal repolarization and reentry, particularly in the absence of structural heart disease.
• Channelopathies, often presenting with minimal ECG changes, are critical contributors to sudden cardiac death.
• The risk of PMVT and sudden cardiac death is amplified by the widespread use of ion channel-affecting drugs.