Distinct U wave changes in patients with catecholaminergic polymorphic ventricular tachycardia (CPVT)

Area of Science:

• Cardiology
• Genetics
• Electrophysiology

Background:

• Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a genetic disorder linked to fatal arrhythmias and sudden cardiac death.
• Understanding the electrocardiogram (ECG) characteristics of CPVT is crucial for diagnosis and management.

Observation:

• This study investigated U-wave alterations in seven patients from six families diagnosed with CPVT.
• Patients experienced bidirectional tachycardia and polymorphic ventricular tachycardia (VT) induced by exercise or isoproterenol.
• A novel mutation in the ryanodine receptor 2 (RyR2) gene was identified in two families.

Findings:

• U-wave alternans were observed in two patients, particularly in leads V3-V5, during ventricular pacing and post-exercise recovery.
• One patient exhibited a U-wave inversion that normalized after sinus arrest, accompanied by T-wave changes.
• These specific U-wave phenomena were not observed in other subjects undergoing similar provocative testing.

Implications:

• U-wave alterations may represent a significant, previously unrecognized ECG marker for CPVT.
• Further research is needed to elucidate the genesis and clinical significance of these U-wave changes in CPVT.
• Identifying novel genetic mutations (RyR2) and associated ECG findings advances the understanding of CPVT pathophysiology.