DEFIBRILATION-GUIDED RADIOFREQUENCY ABLATION OF ATRIAL FIBRILLATION SECONDART TO AN ATRIAL FOCUS

<正> ObJective:We aim to identify a focal source of atrial fibrillnion(AF) by unmasking spontaneouscarly re-initiation AF after transvenous atrial defibrillation(TADF) and descride a method of usingrepeated TADF to map the earlicst focus of spontaneous AF re-initlation,followed by focalradiofrequency(RF)ablation,Baekgromod:AF may develop secondary to a rapidly dischargingatrial focus such the remainder of the atrium cannot follow synchonously,although the incidenceof this occuming in patients with AF is uncertain.Mapping and RF ablation of this focus may becurative but is limited if the patient is in AF.Consistent spontaneous early ne-initiation of AF byatrial ectopic beats have been observed following defibrillation,which we hypothesized mighthave a focal mechanism.Methods:We performed electmphysiology study and TADF onconsecuutive patients with ECG documented,drug refractory AF without structural heart disease.TADF was perforrmed using a 3/3ms biphasic wave form delivered using catheter based electrodesin the right atrium and the coronary sinus.We observed reproducible early re-initiation of AF(within 2 minutes)by art atrial focus thai showed a consistent atrial activation pattern and couplingcycle length to preceding sinus beat after repeated defibrillation which also facilitated mapping ofthe earliest site of the focus.Temperature guided RF ablation was then perfonned at this siteaiming at suppression of early AF re-initiation,Clinical and ambulatory ECG recording were madeto assess recumence,Resultn:44 lone AF patrients(40 men and 4 women)with a mean age of58±13 years underwent TADF.There were 32 persistent and 12 paroxysmal AF.Nine patients(20%;paroxysmal AF:5 persistent AF:4)had early re-initiation of AF immediately afterdefibrilation Their mead age was significantly younger than that without a putative focal re-initimtion(40±10 versus 62±9 years,p<0.001).The earliest atrial activation was mapped at the rightsuperior(n=4)and left superior(n=3)pulmonary vein orifices in the seven patients who underwentRF ablation with an average activation time of 86±38 ms ahead of the high right atrial electrogram.A left atrial focus was suggested by advabcement of all coronary sinus alrial recordings at firstthchycardia beat,compared to the right atrial activation sequence.The foci showed fragmentedatrial electrograms,a ptogressively shcrtened cycle length in the first eycles and conducthionblock to the rest of the atrium until AF was re-initiated.RF catheter ablation of the focus resultedin suppression of spontaneous AF re-initriation despite pace-inducibility Of AF,an improvclinical outcome was observed over s follow-up of 8±4 months.Concluslon:A novel method ofdefibrillation-guided mapping can help to unmask,map and eblate a potential atrial focus leadingto AF.beth for patients with paroxysmal and persistent AF.A rapidly discharging atrial focus isthe cause of AF recurrence after restoration of sinus rhythm in 20% of patients with lone AF whoare in general younger,and these patients may benefit from the identification of a potential curablecause of AF.