Mortality Risk Increases With Clustered Ventricular Arrhythmias in Patients With Implantable...

Area of Science:

• Cardiology
• Electrophysiology
• Medical Statistics

Background:

• Electrical storm, defined as ≥3 ventricular arrhythmia (VA) episodes in 24 hours, is linked to adverse outcomes.
• The prognostic impact of arrhythmia clusters outside this definition remains less understood.

Purpose of the Study:

• To investigate the adverse prognosis associated with ventricular arrhythmia clusters beyond the traditional electrical storm definition.
• To analyze the impact of varying cluster lengths and event counts on patient outcomes.

Main Methods:

• Analysis of 14,515 implantable cardioverter-defibrillator-detected events from the Resynchronization in Ambulatory Heart Failure trial.
• Clustering defined as ≥2 VA events within 3 months; prognostic importance evaluated by varying cluster parameters.
• Comparison of mortality rates between patients with clustered, unclustered, or no arrhythmias.

Main Results:

• Patients with clustered VA (≥2 events/3 months) faced a significantly higher mortality risk (HR: 2.68) compared to those with no arrhythmia.
• Even the least dense cluster (2 VA events/3 months) showed increased mortality risk (HR: 2.85).
• Mortality risk increased with higher VA burden and shorter cluster length, with implantable cardioverter-defibrillator shocks associated with higher risk than antitachycardia pacing.

Conclusions:

• Clustered ventricular arrhythmias, even as few as 2 events within 3 months, are significantly associated with adverse prognosis.
• The prognostic risk increases with greater cluster density (more events in shorter periods).
• Findings suggest refining arrhythmia monitoring and management strategies for patients with clustered VA events.