[Clinical usefulness of stored electrograms in implantable defibrillators]

The storage of intracavitary electrograms by the automatic implantable defibrillators is one of the latest advantages. The objective of this study was to determine the clinical utility and limitations of electrograms stored by the new generation of defibrillators.

We have implanted at our institution 43 generators with the facility of storing electrograms; 8 Ventak P2, 17 PRxII, and 1 PRxIII from CPI, 14 Jewel, from Medtronic and 3 Guardian ATP 4215, from Telectronics. All were implanted with an endocavitary system lead, an only one patient needed a subcutaneous patch. Mean age was 57 +/- 16 years, 36 were males and 7 women. The mean left ventricular ejection fraction was 44 +/- 23%. The mean follow up was 6 +/- 8 months (limits 1-20 months).

We registered and analyzed a total of 268 episodes in 20 patients. Fourteen (82%) received what was considered appropriate therapy. Three patients (from 17 with any treatment delivered by the defibrillator) presented an inappropriate therapy. The parameters, "onset" and "stability", were differentiated in each arrhythmia, the "onset" is useful to differentiate sinus tachycardia, but not atrial fibrillation, from ventricular tachycardia. Programming a stability value between 30-40 mseg eliminates 88% of inappropriate therapies due to atrial fibrillation. In all patients, the identification of the event, facilitated by the stored electrograms, allowed us to resolve the problem.

The programmable features "onset" and "stability" allowed us to eliminate a significant number of inappropriate therapies. The stored electrograms facilitate the identification of the events, leading to treatment by the generator, and were very useful in guiding the clinical management of the patient.