FEASIBILITY OF ATRIAL-FIBRILLATION DETECTION AND USE OF A PRECEDING SYNCHRONIZATION INTERVAL AS A CRITERION FOR SHOCK DELIVERY IN HUMANS WITH ATRIAL-FIBRILLATION

Objectives. This study assessed the feasibility of detecting atrial fi brillation (AF) and delivery of appropriately timed R ware shocks usin g an implantable strial defibrillator. Background. For atrial defibril lation therapy to be feasible in an implantable form, AF must be detec ted in a specific fashion, and tile risk of ventricular proarrhythmia should be minimized, Methods. Eleven patients with AF underwent testin g with an implantable atrial defibrillator (METRIX 3000 Automatic Atri al Defibrillator, InControl, Inc,). Wideband electrograms (EGMs) were recorded from the right ventricular (RV) bipolar catheter and from the multipolar catheters located In the right atrium (RA) and coronary si nus (CS). Atrial fibrillation detection was performed using two serial algorithms - quiet interval analysis and baseline crossing analysis - that detect atrial activity on the RA-CS channel, Ventricular sensing using a minimal preceding synchronization interval of 500 ms as a cri terion for synchronous shock delivery was performed from filtered RV a nd RV-CS EGMs. Results. The AF detection algorithms were applied to 53 AF data segments and 18 normal sinus rhythm data segments, Atrial fib rillation was detected appropriately in 49 instances, and the specific ity for detecting AF and normal sinus rhythm was 100%, Synchronization criterion efficacy tvas assessed by delivering shock markers and shoc ks, Of the 2,025 R waves processed, 557 (27,5%) were marked as suitabl e for shock delivery, in addition, 69 therapeutic and 11 test shocks w ere delivered during AF, All shock markers and shocks were delivered s ynchronously with the R wave, and the synchronization criterion aas ne ver violated, Conclusions. Atrial fibrillation can be detected in a sp ecific fashion using the RA-CS lead configuration and serial detection algorithms for atrial sensing, The delivery of properly timed shocks is feasible and should minimize the risk of ventricular proarrhythmia.