Long-term clinical experience with the EGM width detection criterion for differentiation of supraventricular and ventricular tachycardia in patients with implantable cardioverter defibrillators

Inappropriate therapy by ICDs due to SVTs is an important problem. A third generation ICD with a new detection criterion ("EGM width criterion") for d ifferentiation of SVTs and VTs by measuring the width of the intracardiac E GM was studied in 47 patients. A wide EGM was defined as the longest measur ed EGM plus 4-12 ms (programmed as EGM width threshold). EGM width detectio n function was programmed to the "Passive" mode so that no therapy was with held. During a follow-up of 29.9 +/- 8.3 (12-45) months, 489 spontaneous ep isodes were analyzed. SVTs occurred in ten patients with 305 episodes; 301 were correctly classified by use of the new detection criterion. In four pa tients four episodes were incorrectly detected as wide QRS tachycardias. Th us specificity for SVT was 98.7% (on a per episode basis) and 60% on a per patient basis. Of 184 VTs in 23 patients, 118 episodes were correctly class ified (19 patients), however, in 4 patients 66 VTs were falsely detected as SVTS, 62 (94%) of which occurred in I patient with complete left BBB and c ontinuously increasing QRS width in 12-lead surface ECGs. Overall sensitivi ty (on a per episode basis) for VT detection was 64.1% and 96.7% in patient s with stable width of the QRS complex in a 12-lead surface. ECG. These dat a show that this criterion is not superior to data on rate dependent detect ion criteria and furthermore not applicable in patients with complete BBB.