How to avoid inappropriate therapy

With wider indications for implantable cardioverter defibrillator therapy, more patients at lower risk for ventricular tachyarrhythmia receive this treatment. To maintain the ratio of benefit versus side-effects at an acceptable level, the risk of inappropriate implantable cardioverter defibrillator therapy has to be minimized.

Implantable cardioverter defibrillators require the activation of enhanced detection criteria. These can avoid inappropriate therapy of sinus tachycardia (gradual onset) and atrial fibrillation (irregular rate) while other regular supraventricular tachycardias may be misclassified even with combinations of criteria (QRS morphology, abrupt onset, regular rate). Carefully programmed, dual-chamber implantable cardioverter defibrillators provide better ventricular tachyarrhythmia/supraventricular tachycardias discrimination. Key issues are long tachycardia detection (18 cycles or more), deactivation or restrictive programming of safety therapy despite supraventricular tachycardia classification, and restriction of shock therapy to high tachycardia rates (>or=250 bpm). Further developments are necessary to reduce the incidence of inappropriate therapy due to lead failure that is more frequent in physically active patients.

With optimized programming, the rate of inappropriate ventricular tachyarrhythmia detection is significantly reduced. Particularly the prevention of inappropriate shocks has important implication for the quality of life and acceptance of implantable cardioverter defibrillator treatment.