Inappropriate therapy from atrial fibrillation and sinus tachycardia in automated implantable cardioverter defibrillators

Background Inappropriate therapy from supraventricular tachyarrhythmias (at rial fibrillation [AF] and sinus tachycardia [ST]) in patients with implant ed cardioverter defibrillators is a major challenge. We tested the performa nce of stability algorithms from 3 manufacturers for episodes of inappropri ate therapy delivered because of AF and an onset algorithm for all episodes of inappropriate therapy caused by ST. Methods Therapy was classified as caused by ventricular tachycardia (VT), S T, or AF from review of stored intracardiac electrograms, history, clinical information, and R-R data before study inception. By using 30 to 60 R-R in tervals before therapy, sensitivity and specificity for a family of stabili ty values and percentage of onset values were calculated for each manufactu rer and receiver operating characteristic curves generated. Results of the 217 patients monitored, 62 (29%) received inappropriate ther apy, and 40 had complete R-R information available. Of the 40 patients, 21 patients received therapy for AF, 19 for ST, and 1 patient for noise; 15 (3 8%) also received appropriate therapy for VT. We analyzed 83 episodes of VT from 18 patients, 94 episodes of AF from 21 patients, and 56 episodes of S T from 19 patients. Specificity, in the clinically relevant sensitivity ran ge of greater than or equal to 95%, was comparable across manufacturers at about 40%. An onset value of 80% was associated with 91% sensitivity and 95 % specificity for the specific algorithm tested. Conclusions Inappropriate therapy is a common problem in implantable cardia c defibrillators. The performance of the stability algorithms used to diffe rentiate AF from VT was less than ideal, though comparable across manufactu rers. The onset algorithm accurately differentiates ST From VT.