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Inappropriate ICD Shocks — EECC MCQ

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ModerateArrhythmia & ElectrophysiologyInappropriate ICD ShocksEECC

A 68-year-old man with a single-chamber ICD receives a shock while gardening. Device interrogation shows the shock was delivered for sinus tachycardia at 165 bpm that was incorrectly classified as VT. He was exercising vigorously at the time. What type of ICD therapy is this?

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Correct answer: B — Inappropriate ICD shock due to supraventricular tachycardia misclassified as VT

Inappropriate ICD shocks (delivery of shock therapy for rhythms other than VT/VF) occur in approximately 10-20% of ICD patients. The most common cause is supraventricular tachycardia (particularly AF, sinus tachycardia during exercise, or atrial flutter) that exceeds the programmed VT detection rate. Programming strategies to reduce inappropriate shocks include: higher detection rates, longer detection intervals, SVT discriminators (morphology, onset criteria, stability), and high-rate-only programming. The MADIT-RIT and ADVANCE III trials showed that these programming changes significantly reduce inappropriate shocks and mortality. Dual-chamber ICDs provide additional discrimination using atrial sensing.

Reference: ESC (2022): Guidelines on VA and SCD Prevention; MADIT-RIT Trial