Improvement of the programming of the sustained rate duration in patients with an implantable cardioverter-defibrillator and known atrial fibrillation

The discrimination of supraventricular versus ventricular tachycardias by a n implantable cardioverter-defibrillator (ICD) is still a remaining clinica l problem. The false positive detection of supraventricular as ventricular tachycardias causes inadequate electrical therapies of the ICD. To improve the increase of specificity criterias like "Onset" or "Stability" are offer ed. If these criterias during tachycardia are not fulfilled, the "sustained rate duration" (SRD) is offered as a security criterion. The SRD reasons t he delivery of the therapy during tachycardia after a programmable time. Aim of the study was to evaluate, if SRD in patients with known arrhythmia absoluta (AA) in atrial fibrillation and programmed "Onset"/"Stability" inc reases the sensitivity without loss of specificity in the treatment of hemo dynamically tolerated ventricular tachycardias and which programming should be chosen. Our patient collective included 274 patients (pts) with new implanted ICD o f the third generation. In 39 (14 %) pts AA was known in the medical histor y. From these 39 (100 %) pts, is (46 %) pts had known tachyarrhythmic episo des (group I) in the area of the ventricular tachycardia-zone greater than or equal to 160 beats per minute, whereas in 21 (54 %) pts a tachyarrhythmi a absoluta (TAA) was unknown (group II). During follow-up of 12 +/- 8 (2-26 ) months, 151 tachycardias occurred and could be classified as supraventric ular tachycardias by stored electrograms. In 9/18 pts of group I, a TAA occurred during follow-up. The initial progra mmed SRD during first TAA was 62 +/- 39 (35-90) s and was prolonged to 135 +/- 64 (90-180) s. After this prolongation, no inadequate therapy was deliv ered. In group II, 19/21 (90 %) were inadequately treated during TAA. The initial SRD-programming was 45 +/- 28 (0-90)s and was prolonged to 201 +/- 150 (60 -480) s during follow-up. After prolongation of the SRD, no more inadequate therapies due to AA were delivered. In pts with new implanted ICD and known TAA, which is hemodynamically toler ated, the SRD should be programmed beside all other available detection par ameters for improving the increase of specificity at least 135 s to avoid i nadequate therapies of the ICD. In pts with unknown TAA, SRD should be prol onged to 135 s at least the second tachyarrhythmic episode, which is hemody namically well tolerated.