Enhanced Detection Criteria in Implantable Defibrillators

Abstract

Programming sudden onset and stability detection criteria with a sustained rate duration safety net for triggering tachycardia therapy results in appropriate device management in most patients with supraventricular and slow (< 210 beats/min) ventricular tachycardias.

2015 HRS/EHRA/APHRS/SOLAECE expert consensus statement on optimal implantable cardioverter-defibrillator programming and testing

“…It withholds therapy if acceleration across the sinus-VT rate boundary is gradual. Because onset discriminators classify the rhythm only once, and thus cannot correct misclassifications, they are now used infrequently and only with an override feature and/or other discriminators [112][113][114][115]. Chamber of onset is a related, interval-based, dual-chamber discriminator that classifies a 1:1 tachycardia as SVT if the atrial rhythm accelerates at the device-defined onset.…”

“…Because interval variability in conducted AF decreases at faster rates, stability becomes unreliable in discriminating VT from conducted AF at ventricular rates greater than 170 bpm [112,115]. Interval stability can also fail if drugs (e.g., amiodarone) cause monomorphic VT to become irregular or induce polymorphic VT to slow into the SVT-VT discrimination zone [114,117].…”

“…The risk of the misclassification of either VT or VF as SVT by the discrimination algorithms can either prevent VT detection or delay the time to therapy (underdetection), as documented in clinically significant situations [112,113,115,125]. When modern algorithms are programmed to recommended parameters, clinically significant underdetection is rare.…”

“…The premise is that the ventricular rate during transient sinus tachycardia or AF will decrease to below the VT rate boundary before the override duration is exceeded. In one study, an override duration of 3 minutes delivered inappropriate therapy to 10% of SVTs [112]. Because SVT is much more common than VT, programming an override duration of less than 5-10 minutes results primarily or solely in inappropriate SVT therapy [122].…”

New Ways to Avoid Unnecessary and Inappropriate Shocks

“…These two algorithms have been traditionally underused due to concern of misclassification of a true VT as a nonshockable rhythm by the device, thereby continuously withholding a necessary therapy. However, several publications have demonstrated that programming sudden onset and stability detection criteria with a sustained rate duration safety net for triggering tachycardia www.intechopen.com therapy results in appropriate device management in most patients with supraventricular and slow ventricular tachycardias (Brugada et al, 1998). Recent data from the MADIT II trial (Daubert et al, 2008) showed that the stability detection algorithm was programmed less frequently in patients receiving inappropriate shocks (17% v s .…”