Optimal combination of discriminators for differentiating ventricular from supraventricular tachycardia by dual-chamber defibrillators

Introduction: Dual-chamber implantable cardioverter defibrillators (ICDs) use discriminators to differentiate between supraventricular tachycardias (SVTs) and ventricular tachycardias (VT), the accuracy of which may depend on the type and method used. ICDs can combine rate branching of tachyarrhythmias according to their A:V relationship with two SVT-VT discriminators in each rate branch, using ANY (either) or ALL (both) logic. Our goal was to determine the optimal discriminator combination. Methods: Stored electrogram data from 596 spontaneous tachyarrhythmias from 203 patients with Photon DR ICDs were analyzed. Arrhythmias are first classified by the relationship of atrial and ventricular rates (rate branches V < A, V = A, and V > A) followed by additional discriminators: morphology and/or sudden onset if V = A; morphology and/or interval stability if V < A. Data were analyzed for all combinations of ANY and ALL logic. Results: Sensitivity and specificity were calculated for all spontaneous episodes in each analysis. V = A branch: ALL logic produced unacceptably low sensitivity, whereas morphology provided only similar sensitivity but better specificity than ANY logic. A > V branch: ANY logic provided adequate sensitivity. The combination of morphology only in V = A with interval stability or morphology (ANY logic) in V < A, provided the optimal result with sensitivity, specificity, positive, and negative predictive values of 99%, 79%, 87%, and 98%, respectively. Conclusion: SVT-VT combined discriminators strongly influence dual-chamber SVT-VT discrimination performance. In our study, optimal programming is morphology only in the V = A branch and morphology or interval stability (ANY) in the V < A branch. ALL logic should be used with caution due to loss of sensitivity.