Failure to detect life‐threatening arrhythmias in ICDs using single‐chamber detection criteria

Abstract

Background There are anecdotal reports of sudden death despite a functional implantable cardioverter defibrillator (ICD). We sought to describe scenarios leading to fatal or near‐fatal outcome due to inappropriately inhibited ICD therapy in devices programmed with single‐chamber detection criteria. Methods Programmed settings, episode lists, and intracardiac electrograms from 24 patients with a life‐threatening event (n = 12) or fatal outcome (n = 12) related to failed ventricular arrhythmia detection were used to clarify the underlying scenario. Results Fifty episodes of failed ventricular arrhythmia detection were identified and categorized into six scenarios: (1) spontaneous ventricular tachycardia (VT) or ventricular fibrillation (VF) with a rate below the detection limits, (2) misclassification of polymorphic VT (PVT) or VF as supraventricular tachycardia (SVT), (3) misclassification of VT/VF as cluster of nonsustained VT episodes, (4) misclassification of monomorphic VT (MVT) as SVT, (5) inappropriate shock abortion, and (6) false termination detection. These scenarios occurred respectively 6, 9, 3, 9, 8, and 15 times. In 9/9 (100%) patients with PVT/VF classified as SVT, rate stability was active for rates ranging from 222 to 250 beats/min. MVT detected as SVT was due to the sudden onset criterion in 7/9 (78%) patients and twice a consequence of the rate stability criterion active for rates ranging from 200 to 250 beats/min. Conclusion We describe six scenarios leading to failure of ventricular arrhythmia detection in a single‐chamber detection setting withholding life‐saving therapy. These scenarios are more likely to occur with high‐rate programming and long detection times, especially if combined with rate stability and sudden onset.

Novel ventricular tachyarrhythmia detection enhancement detects undertreated life-threatening arrhythmias

“…However, multiple reports have revealed that generic compliance with guideline-directed ICD programming recommendations, with or without undersensing, may lead to delayed, or in some instances even withholding, delivery of the HV therapy. 13 , 14 , 15 , 23 Moreover, postmortem studies suggest that mortality in ICD-implanted patients can be due to undertreated ventricular tachyarrhythmias. 13 , 18 , 24 , 25 It is well recognized that undersensing of ventricular signals (R waves) during VF in ICDs is a known limitation of the therapy.…”

“…Analysis of these episodes suggests that inadequate discriminator programming resulted in incorrect rhythm diagnosis. Stroobandt and colleagues 14 demonstrated that SVT discriminators are crucial in reducing inappropriate therapy, with far-field morphology discriminator particularly effective. Programming of available discriminators, regardless of device manufacturer, is recommended by expert guidelines and is key to reducing inappropriate HV therapy delivery.…”

“… 11 , 12 Following these changes in recommended programming, several reports suggested that using generic programming of longer detection times and faster detection rates—with or without device undersensing—may lead to delayed or undelivered therapy for PVT or VF, regardless of device manufacturer. 13 , 14 , 15 …”

A case of withheld defibrillator treatment for 9 minutes of ventricular tachycardia

“…Polymorphic VT and ventricular fibrillation (VF) with unstable, sensed R-R intervals as well as VT of a single morphology and unstable R-R intervals have also been implicated in withholding of appropriate ICD therapy. 5 SVT discriminators function in an ICD to differentiate supraventricular tachyarrhythmias from VT / ventricular fibrillation in order to avoid inappropriate therapy. In Medtronic devices, these complement the basic tachycardia detection algorithm within the VT zone: consecutive R-R intervals shorter than the programmed VT detection cycle length are counted until that number reaches the programmed number of intervals to detect (NID), at which point VT is detected.…”

Real-world use of a novel ventricular tachyarrhythmia detection algorithm: A case report

“… 4 , 5 These changes in recommended programming can lead to delayed or undelivered therapy for polymorphic ventricular tachycardia and ventricular fibrillation (VF). 6 , 7 …”