Implanted defibrillators in trouble: initial device misclassification leads to correct diagnosis—a case series

Supraventricular tachycardia, mistakenly diagnosed as ventricular tachycardia, may lead to inappropriate ICD therapy. Inappropriate ICD therapy associates with increased morbidity and mortality. A reduction of inappropriate therapy is therefore desired.

We present three different cases that beautifully illustrate the diagnostic possibilities of stored electrograms. Initial differential diagnoses in all three patients included ventricular tachycardia, focal atrial tachycardia, atrio-ventricular re-entry tachycardia, and atrio-ventricular nodal re-entry tachycardia. The first case was diagnosed as atrio-ventricular nodal re-entry tachycardia. In the second case, atrio-ventricular re-entry tachycardia was revealed. Ectopic atrial tachycardia was the reason for inappropriate therapy in the third patient.

Thorough analysis of stored electrograms yielded correct diagnosis in all cases, which subsequently was confirmed by electrophysiological study.