[Stored intracardiac electrograms: accuracy of arrhythmia classification in patients with cardioverter/defibrillator...

A cardioverter/defibrillator that is capable of storing endocardial electrograms before and after electrical device therapy was implanted in 29 patients presenting drug refractory ventricular arrhythmias. During a follow-up period of 7.5 +/- 4.6 months 15/29 patients (51%) experienced a total number of 112 pulse generator discharges. In 104 arrhythmia episodes the stored electrogram was analyzed. Morphological criterias of the stored electrogram as detectable P-waves and changes in the QRS-morphology during tachycardia compared to sinus rhythm served for classification of the documented arrhythmia. The analysis of the stored electrogram established a definitive diagnosis of the arrhythmia and allows to distinguish supraventricular arrhythmias from ventricular arrhythmias in every episode. 72/104 (69.2%) of the discharges were classified as appropriate, 32/104 (30.8%) of the device discharges were not appropriate and caused by atrial fibrillation and flutter, sinustachycardia and AV-nodal reentrant tachycardia. In two patients device discharges caused by a sensing malfunction ot the pulse generator was detected by the analysis of the stored electrogram. The new diagnostic feature of stored electrogram shows a high accuracy of rhythm classification and represents a major advance in the treatment with cardioverter/defibrillators.