Ventriculoatrial conduction metrics for classification of ventricular tachycardia with 1 : 1 retrograde conduction in dual-chamber sensing implantable cardioverter defibrillators

The introduction of dual-chamber sensing in implantable cardioverter defibr illators (ICDs) has greatly reduced the incidence of false detection due to supraventricular tachycardias. The remaining arrhythmias which serve to co nfound classification are supraventricular tachycardias (SVTs) with 1:1 ant erograde conduction and ventricular tachycardias (VT) with 1:1 retrograde c onduction. An algorithm has been designed and tested (28 patients) which em ploys ventriculoatrial (VA) conduction measurements to separate 1:1 VTs fro m 1:1 SVTs. A study was conducted to assess realistic VA interval boundarie s for classification of arrhythmias with 1:1 retrograde atrial conduction. Intracardiac atrial and ventricular recordings of 7 passages of VT with ret rograde conduction 12 passages of atrioventricular nodal reentrant tachycar dia (AVNRT), 3 passages of atrial tachycardia (AT), 8 passages of sinus tac hycardia (ST), and 2 passages of orthodromic reentrant tachycardia (ORT) we re analyzed. Automated real-time atrial and ventricular waveform recognitio n was performed on each passage and VA intervals were measured. Separation of VT with retrograde conduction from other 1:1 supraventricular tachycardi as was effected by imposing discrete VA interval boundaries. VA boundaries of 80 ms to 234 ms classified 1:1 VT with 100% sensitivity (SENS) and 80% s pecificity (SPEC). Ln addition, the lower boundary completely classified AV NRT with 100% SENS and 100% SPEC, and all passages of ST were contained abo ve the upper boundary. These findings could be of importance in algorithms for next-generation implantable cardioverter defibrillators which include t wo-chamber (atrial and ventricular) sensing and two-chamber inter val measu rements.