Successful treatment of ventricular fibrillation storm triggered by short-long-short sequence; time to avoid managed...

Area of Science:

• Cardiology
• Electrophysiology
• Medical Devices

Background:

• Sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM) is primarily due to ventricular tachyarrhythmias.
• Implantable cardioverter defibrillator (ICD) therapy is a key treatment for preventing SCD in high-risk patients.
• Managed Ventricular Pacing (MVP) mode is designed to minimize ventricular pacing, but its interaction with arrhythmia prevention algorithms requires careful consideration.

Observation:

• A 28-year-old male with HCM and an ICD (programmed in MVP mode) experienced recurrent ventricular fibrillation (VF) and ICD shocks despite antiarrhythmic drugs.
• Analysis of stored electrograms revealed that VF was consistently initiated by short-long-short sequences.
• The Ventricular Rate Stabilization (VRS) algorithm, when activated within the MVP mode, failed to prevent these recurrent VF episodes.

Findings:

• Deactivating the MVP mode and reprogramming the ICD to DDD mode with the VRS algorithm enabled resulted in complete arrhythmia suppression.
• This reprogramming successfully prevented further episodes of VF and avoided ICD shocks.
• The study highlights that the VRS algorithm's effectiveness in preventing short-long-short sequence-induced ventricular arrhythmias is compromised when the ICD is in AAI mode during MVP.

Implications:

• Physicians managing HCM patients with ICDs must be aware of the limitations of the VRS algorithm within the MVP mode.
• Reprogramming ICDs to a different pacing mode (e.g., DDD) may be necessary to effectively utilize the VRS algorithm for preventing specific ventricular arrhythmias.
• Optimizing ICD programming based on individual patient arrhythmia patterns, particularly short-long-short sequences, is crucial for effective SCD prevention in HCM.