Enhanced detection criteria in implantable defibrillators

Area of Science:

• Cardiology
• Biomedical Engineering
• Electrophysiology

Background:

• Third-generation implantable defibrillators (ICDs) feature enhanced detection criteria to prevent inappropriate shocks for fast supraventricular arrhythmias.
• This study prospectively evaluated these advanced criteria in ICD patients with electrogram storage capabilities.

Purpose of the Study:

• To assess the efficacy of enhanced detection criteria in ICDs for managing supraventricular and ventricular tachycardias.
• To analyze the performance of sudden onset and stability algorithms in differentiating arrhythmias.

Main Methods:

• Prospective analysis of 82 consecutive patients with Guidant-CPI ICDs.
• Systematic programming of sudden onset >9% and stability <40 msec in therapy zone 1, with a sustained rate duration security mechanism.
• Analysis of all detected tachycardia episodes, including supraventricular and ventricular tachycardias.

Main Results:

• Sudden onset criteria effectively detected sinus tachycardias (65/67 episodes); stability criteria were useful for atrial fibrillation (31/32 episodes).
• Initial ventricular tachycardia (VT) detection sensitivity was 90% (451/497 episodes).
• Adding a sustained rate duration criterion improved VT sensitivity to 100% but decreased specificity for supraventricular arrhythmias from 96% to 83%.

Conclusions:

• Sudden onset and stability criteria, with a sustained rate duration safety net, enable appropriate ICD therapy for most supraventricular and slow ventricular tachycardias (<210 bpm).
• The combination of sudden onset >9% and stability <40 msec demonstrated the best overall specificity and sensitivity for arrhythmia detection.