Pulmonary vein isolation (PVI) with cryoballoon to treat symptomatic atrial fibrillation (AF) is well established. The most frequent complication during cryoballoon-based PVI is phrenic nerve injury. Data on PNI with Arctic Front has been described previously. However, data for the balloon system Polar X is scarce. The purpose of this retrospective study was to compare the incidence and characteristics of PNI between the two cryoballoon systems. The study enrolled patients, who underwent cryoballoon-based PVI between January 2024 and October 2024 in our center. Continuous PN pacing was performed during energy delivery at the right sided pulmonary veins using a multipolar catheter positioned in the vena cava superior. The safety endpoint PNI was diagnosed, if a decrease or loss of diaphragmatic movement either through palpation or fluoroscopic imaging and/or a reduction in compound motor action potential amplitude was observed. The delivery of refrigerant was stopped by using the double-stop technique. A total of 654 consecutive patients were enrolled. There were 452 patients in the Arctic Front group and 202 patients in the Polar X group. The safety endpoint occurred in 22 patients (4,9%) in the Arctic Front group, while 18 patients (8,9%) in the Polar X group (p<0,05). The mean temperature measured at the time of PNI was -50,6 ± 5,9 °C in the Arctic Front group and -52,3 ± 9,0°C in Polar X group (p =0,5). There was no significant difference in temperature between patients with or without PNI within both groups (-52,3± 6,0°C in Arctic Front group without PNI and -55,7± 6,8°C in Polar X group, respectively). Time to PNI was 142,6 ± 73,1 sec in Arctic Front group and 146,1 ± 55,7 sec in Polar X group (p=0,5). The ablation time was significantly shorter compared to the patients without PNI in both systems. In our study we found significantly more phrenic nerve palsies in the Polar X group, which is consistent with previous findings in smaller patient populations. Balloon temperature and ablation time were not found to be critical factors for PNI. The potential mechanism may be related to the compliant design of the Polar X system, which results in the positioning of the balloon more distally. The next generation, called PolarX Fit, features pressure-controlled sizing (28 to 31 mm). It is conceivable that the larger size may reduce the risk of PNI, but this hypothesis still needs to be evaluated.

Aims Digital health is becoming increasingly powerful and available but is frequently not effectively integrated into daily practice. A hybrid programme was developed to provide holistic diagnostic and therapeutic patient care in atrial fibrillation. Methods and results Patients (n = 68) were recruited at the electrophysiology centre following successful interventional restoration of sinus rhythm. The 12-month programme consists of the key modalities: (i) self-recording of one-lead electrocardiograms (ECGs), (ii) short-term remote ECG diagnosis and medical advice by video consultation, and (iii) App-based education on lifestyle and risk factor optimization with video consultation. Patients recorded 29 092 ECGs, averaging 1.42 ECGs/day. Recurrent arrhythmia was found and confirmed in 39 patients. In all cases, arrhythmia was first diagnosed based on wearable ECG over the platform, rather than by standard in-office ECG/Holter. No false positive occurred. Patients with recurred arrhythmia were treated by pulmonary vein isolation (n = 17), electric cardioversion (n = 17), antiarrhythmic medication (n = 5), or other interventional procedures (n = 1). Most patients (n = 30) scheduled a video consultation over the App as the first medical touchpoint after arrhythmia occurrence. In 21 patients with arterial hypertension, systolic blood pressure was reduced by 8.0 +/- 8.6 mmHg (mean +/- SD), P < 0.01. In 25 patients with obesity (body mass index >= 30), body weight was reduced by 3.6 +/- 5.5 kg (mean +/- SD), P < 0.01. Conclusion This real-world analysis indicates that the hybrid holistic programme is applicable in daily practice and is actively followed by patients and improves diagnostic and therapeutic outcomes. These promising data need to be confirmed in a controlled randomized study.

Abstract Background The current ESC guidelines on atrial fibrillation recommend the assessment of disease burden and the rigorous management of cardiovascular risk factors. A digital patient care program (Digital Health Program Atrial Fibrillation) was offered to patients following pulmonary vein isolation or cardioversion in cooperation with a major German statutory health insurer and a leading cardiology clinic. The 12 month program consists of the following functions: (1) self-recording of 1-channel-ECGs by patients with the possibility to receive short-term assessment by a teledoctor; (2) Patient education on health literacy, management of risk factors and lifestyle optimization via an App; (3) Monitoring of blood pressure and body weight; (4) Medication management via the App; und (5) videoconsultations on demand. When needed, medication was optimized by the teledoctors, or patients were referred to their family practice or cardiologists. Results an interim analysis of 72 patients that have participated in the first 6 months of the program showed: 1.) Over 20,000 ECGs were written, or a mean of approx. 1.5 ECGs/patient/day. Based on the teledoctor assessment of the ECGs and the videoconsultation over the platform recurring atrial fibrillation could be detected early and with high reliability, and patients could be advised. 2.) Figure A.: In patients with known, but insufficiently controlled arterial blood pressure at baseline (systolic blood pressure > 130 mmHg), blood pressure was reduced by 7.2 ±7.8 mmHg (mean ± std); n = 20. 3.) Figure B.: In obese patients at baseline (BMI ≥ 30) the body weight was reduced by 3.03 ±4.71 KG (mean ± std); n = 26. Summary: The combination self-recorded ECGs with high adherence, the feedback by the App and the possibility to book a short-term teledoctor appointment made it possible to perform quick and reliable assessment and give concrete recommendations to the patient. Furthermore, the accompanying education program led to reduced blood pressure and body weight. This systematic analysis of a real world digital patient care program indicates that the program is feasible and effective. These results need to be confirmed in a controlled study.Figure 1

Abstract Background Pulsed field ablation (PFA) is a relatively new technology for isolation of pulmonary veins in patients with atrial fibrillation (AF). Data addressing reasons for recurrent atrial fibrillation despite primarily successful pulmonary vein isolation (PVI) using PFA are scarce, due to an up to date limited number of patients treated this way. Objective The aim of this study was to analyze electrophysiological characteristics of reconduction and / or left atrial substrate of patients referred to our center for Re-Do procedures for recurrent AF after an initial PVI using PFA. Methods 90 patients (mean age 66±9 years, 69 male (77%)) had been treated in our center from November 2021 to July 2023 with PVI using PFA. 9 (10%) of these patients were referred for Re-Do procedures. These were performed by radiofrequency ablation (RFA) using Carto system including high density mapping and high power / short duration (HPSD) ablation. We analyzed location of PV reconnection and low voltage areas (LVA) in the left atria. Results 7 out of 9 patients (77%) presented with reconnections of pulmonary veins. In one patient a single vein showed reconduction (RSPV), in 5 patients 2 veins were conducting (1x LSPV, 3x LIPV, 1 left sided common os (LCo), 1x RSPV, 3x RIPV). None of the patients showed 3 or 4 reconnected veins. Areas of reconduction in each vein were: LSPV 1x ridge, 1x posterior; LIPV 1x posterior, 1x anterior and posterior; LCo 1x posterior, RSPV 1x anterior, 2x carina, 1x anterior and posterior; RIPV 1x complete, 2x carina. In 7 patients a fibrotic atrial cardiomyopathy (FACM) was diagnosed via high density mapping of LVA’s. In 2 of these patients all 4 pulmonary veins were chronically isolated after the initial PVI. All patients except one (very small anterior LVA) with FACM ≥1 were treated with additional linear or encircling lesions according to the individual extent of the fibrotic areas. 2 patients had no LVA’s detectable. In one of those 2 patients 2 veins had reconnected. The other patient had chronically isolated veins (no proof of dormant conduction with adenosine) and no detectable non-PV-triggers under isoprenaline. Conclusion In the population of patients undergoing PVI using PFA in our center, only 10% had clinically relevant recurrences leading to the necessity of a Re-Do procedure. Most patients (77%) in this setting had reconnections of pulmonary veins. There is a tendency of posterior reconnections of the left pulmonary veins and reconnections of the carina of the right pulmonary veins, but the number of patients is too small to clearly define predilection sites that have to be paid attention to when using PFA. Additionally, left atrial substrate is an important problem in patients with recurrent AF despite primarily successful PVI and has to be considered and thoroughly addressed in Re-Do procedures.Reconnection of LSPV and anterior LVAAblation of RSPV and LSPV (posterior)

BackgroundElectrographic flow (EGF) mapping enables full spatiotemporal reconstruction of organized wavefront propagation to identify extrapulmonary vein sources of atrial fibrillation (AF).ObjectivesFLOW-AF (A Randomized Controlled Study to Evaluate the Reliability of the Ablacon Electrographic FLOW [EGF] Algorithm Technology [Ablamap Software] to Identify AF Sources and Guide Ablation Therapy in Patients With Persistent Atrial Fibrillation) was multicenter, randomized controlled study of EGF mapping to: 1) stratify a nonparoxysmal AF population undergoing redo ablation; 2) guide ablation of these extrapulmonary vein AF sources; and 3) improve AF recurrence outcomes.MethodsFLOW-AF enrolled persistent atrial fibrillation (PerAF)/long-standing PerAF patients undergoing redo ablation at 4 centers. One-minute EGF maps were recorded from standardized biatrial basket positions. Patients with source activity ≥26.5% were randomized 1:1 to PVI + EGF-guided ablation vs PVI only; patients without sources ≥26.5% threshold were not randomized. Follow-up and electrocardiographic monitoring occurred at 3, 6, and 12 months.ResultsWe enrolled 85 patients (age 65.6 ± 9.3 years, 37% female, 24% long-standing PerAF). Thirty-four (40%) patients had no sources greater than threshold; at least 1 source greater than threshold was present in 46 (60%) (EGF-guided ablation, n = 22; control group, n = 26). Patients with sources were older (68.2 vs 62.6 years; P = 0.005) with higher CHA2DS2-VASc scores (2.8 vs 1.9; P = 0.001). The freedom from safety events was 97.2%, and 95% of EGF-identified sources were successfully ablated. In randomized patients, AF-free survival at 12 months was 68% for EGF-guided ablation vs 17% for the control group (P = 0.042); freedom from AF/atrial tachycardia/atrial flutter at 12 months was 51% vs 14% (P = 0.103), respectively.ConclusionsIn nonparoxysmal AF patients undergoing redo ablation, EGF mapping identified AF sources in 60% of patients, and could be successfully ablated in 95%. Compared with PVI alone, PVI + source ablation improved AF-free survival by 51% on an absolute basis. (FLOW-AF: A Study to Evaluate the Ablacon Electrographic FLOW EGF Technology [A Randomized Controlled Study to Evaluate the Reliability of the Ablacon Electrographic FLOW (EGF) Algorithm Technology (Ablamap Software) to Identify AF Sources and Guide Ablation Therapy in Patients With Persistent Atrial Fibrillation]; NCT04473963)

BACKGROUND Electrographic flow (EGF) mapping enables the dy-namic detection of functional or active atrial fibrillation (AF) sour-ces outside the pulmonary veins (PVs), and the presence or absence of these sources offers a novel framework for classifying and treat-ing persistent AF patients based on the underlying pathophysiology of their AF disease.OBJECTIVE The primary objective of the FLOW-AF trial is to eval-uate the reliability of the EGF algorithm technology (Ablamap soft-ware) to identify AF sources and guide ablation therapy in patients with persistent AF.METHODS The FLOW-AF trial (NCT04473963) is a prospective, multicenter, randomized clinical study in which patients with persistent or long-standing persistent AF who have failed prior PV isolation (PVI) undergo EGF mapping after confirmation of intact PVI. In total, 85 patients will be enrolled and stratified based on the presence or absence of EGF-identified sources. Patients with an EGF-identified source above the predetermined activity threshold of 26.5% will be randomized in a 1:1 fashion to PVI only vs PVI 1 ablation of EGF-identified extra-PV sources of AF.RESULTS The primary safety endpoint is freedom from serious adverse events related to the procedure through 7 days following the randomization procedure; and the primary effectiveness endpoint is the successful elimination of significant sources of exci-tation with the target parameter the activity of the leading source. CONCLUSIONS The FLOW-AF trial is a randomized study designed to evaluate the ability of the EGF mapping algorithm to identify pa-tients with active extra-PV AF sources.

Abstract Background Various randomized multicenter studies have shown that percutaneous left atrial appendage closure (LAAC) is not inferior in stroke prevention compared to vitamin K antagonists (VKA) and can be performed safely and effectively. Aims The prospective multicenter ORIGINAL registry in the Free State of Saxony (saxOnian RegIstry analyzinG and followINg left atrial Appendage cLosure) investigated the efficiency and safety of LAAC with Watchman or Amulet device in a real word setting. A special focus was put on the influence of LAAC frequency on periprocedural efficiency and safety. Methods and results The total of 482 consecutive patients (Abbott Amulet N = 93 and Boston Scientific Watchman N = 389) were included in the periinterventional analyses. After 6 weeks, 353 patients completed the first follow-up including transoesophageal echocardiography (TEE) (73.2%). Successful LAAC could be performed in more than 94%. The complication rate does not significantly differ between device types (p = 0.92) according to Fischer test and comprised 2.2% in the Amulet and 2.3% in the Watchman group. The kind of device and the frequency of LAAC per study center had no influence on the success and complication rates. Device related thrombus could be revealed more frequently in the Watchman group (4.5%) than in the Amulet group (1.4%) but this difference is still not significant in Fisher test (p = 0.14). Same conclusion can be made about residual leakage 1.1% versus 0% [not significant in Fisher test (p = 0.26)]. Dual antiplatelet therapy followed the intervention in 64% and 22% of patients were discharged under a combination of an anticoagulant (VKA/DOAC/Heparin) and one antiplatelet agent. Conclusions The ORIGINAL registry supports the thesis from large, randomized trials that LAAC can be performed with a very high procedural success rate in the everyday clinical routine irrespective of the used LAA device (Watchman or Amulet). The postprocedural antithrombotic strategy differs widely among the participating centers. Trial registration Name of the registry: "saxOnian RegIstry analyzinG and followINg left atrial Appendage cLosure", Trial registration number: DRKS00023803; Date of registration: 15/12/2020 'Retrospectively registered'; URL of trial registry record: https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00023803 .

Electrographic flow (EGF) mapping is a novel method of visualizing near real-time cardiac action potential flow to detect distinct AF mechanisms characterized by EGF parameters including source activity, active fractionation (FRC) and stable circuits (SC).

AIMSPulmonary vein isolation (PVI) for atrial fibrillation (AF) has become increasingly safe and effective with the evolution of single-tip ablation catheters aided by contact force sensing (ST-CF) and single-shot devices such as the second-generation pulmonary vein ablation catheter (PVAC) Gold multi-electrode array. The multicentre randomized GOLD FORCE trial was conducted to evaluate non-inferiority of safety and efficacy of PVAC Gold PVI compared to ST-CF ablation for paroxysmal AF.METHODS AND RESULTSThe primary efficacy endpoint documented AF recurrence ≥30 s was assessed by time-to-first-event analysis after a 90-day blanking period using repeated 7-day Holters. Secondary endpoints include acute success and procedural characteristics. Safety endpoints included procedural complications, stroke/transient ischaemic attack (TIA), tamponade, bleeding, and access site complications. Two hundred and eight patients underwent randomization and PVI (103 assigned to PVAC Gold, 105 to ST-CF). Acute success rates were 95% and 97% for PVAC Gold and ST-CF, respectively. At 12 months, AF recurrence was observed in 46.6% of the PVAC Gold group and in 26.2% of the ST-CF group [absolute efficacy difference 20.4% (95% confidence interval, CI 7.5-33.2%), hazard ratio 2.05 (95% CI 1.28-3.29), P = 0.003]. PVAC Gold had significantly shorter procedure and ablation times. Complication rates were 5.7% and 4.9% for PVAC Gold and ST-CF, respectively (P = 0.782).CONCLUSIONIn this multicentre randomized clinical trial, ablation with ST-CF and PVAC Gold ablation catheters non-inferiority for efficacy was not met. AF recurrence was significantly more frequent in the PVAC Gold group compared to single-tip contact force group. Both groups had similarly low rates of adverse events. PVAC Gold ablation had significantly shorter procedure and ablation times.

Ablation of recurrent atrial fibrillation (AF) is common. Studies indicate that AF recurrence is primarily due to pulmonary vein (PV) re-conduction. This retrospective analysis characterized and evaluated recurrent AF patients using focal impulse and rotor mapping (FIRM) plus PV re-isolation, with follow up at 3, 6, 12, and 24 months after the repeat ablation. Patients (consecutive, n = 100) underwent FIRM-guided ablation followed by conventional PV re-isolation for recurrent AF treatment. All FIRM patients had failed one or more conventional ablation procedures (1.4 ± 0.08) for paroxysmal (14%), persistent (15%), and long-standing persistent (71%) AF. Stable rotors were identified in 97/100 patients: 60% in the right atrium (RA) and 82% in left atrium (LA) (mean 1.5 ± 0.8 and 2.1 ± 1.2 per patient, respectively). No correlation was noted between the previous number of ablations, AF duration, or LA diameter to the number of rotors (R2 = 0.0039, R2 = 0.0017, and R2 = 0.006, respectively). In this limited observation, only 22% of identified rotors were associated with proximity to low voltage areas. The 12- and 24-month arrhythmia free rate was 93% (13/14) and 92% (12/13) for paroxysmal AF, 60% (9/15) and 47% (7/15) for persistent AF, and 70% (48/69) and 64% (43/67) for long-standing persistent AF, respectively, after a single FIRM procedure and re-isolation of the veins. The data show a benefit for FIRM-guided ablation in recurrent AF at 12 months. No correlation was found between rotors and tissue characterization, AF duration, or previous number of ablations, suggesting that rotors may play an independent role in maintaining recurrent AF after prior failed ablation.

Abstract Background Oral anticoagulation for prophylaxis of central and peripheral embolisation is limited in its use in patients with atrial fibrillation (AF) and bleeding events. As an alternative to anticoagulation, the interventional closure of the left atrial appendage (LAAO) is available. A common clinical dilemma is the treatment of patients with potential peri-device leakage following LAA occlusion. The specific definition of the severity of the leak and the long-term clinical implications have not yet been sufficiently investigated. Methods The multi-centre ORIGINAL registry was initiated 2014. The aim of this registry is to analyze the safety and efficacy of the procedure in patients with a high risk of bleeding in everyday clinical practice and to evaluate hemorrhagic and thromboemb. events in the long term follow-up. Patients with an indication for LAA occl. were included in the registry after informed consent. The impl., follow-up and anticoagulation regimens are performed according to the standard of the participating centers. 521 patients with AF underwent an implantation of an LAA closure device between Jul. 2014 and Nov. 2018. A mean follow-up of 463 days could be reached in 386 patients. Results The periprocedural complication rate was 3.8% of which 5 patients experienced pericardial effusion (successful treatment with pericardial puncture or surgical), 2 patients had periprocedural stroke and 1 patient suffered from air embolism. In 27 patients a peri-device flow due to incomplete occlusion was detected by TEE (5.4% of the implantations). The size ranged between 1 and 8 mm (mean 2.28 mm (SD=2.11)). The eccentricity index (EI) of the LAA in these patients was 1.22 (SD 0.17), and thus the LAA rather oval, while those LAA without leakage tend to be more circular (EI 1.08 with SD=0.17). 2 of the patients with leakage (7.4%) experienced stroke or peripheral embolism, respectively. The annual risk for stroke/TIA/peripheral embolism of these patients was 5.84%, the annual risk of the patients without leakage was 2.04%. Patients with a leakage >6 mm were treated with rivaroxaban in full therapeutic dosage. One patient underwent an additional procedure. Conclusion The evaluation and management of para-device leakage after an interventional LAA occlusion represents a challenge. Currently, limited data are available on the optimal strategy. Those data indicate that residual peri-device flow into the LAA after percutaneous closure with the Watchman device represents no cause for alarm. However, our data suggest, that patients with peridevice leak might be at a higher risk of thromboembolic events. Furthermore, it could be shown, that these patients had rather oval ostium of the LAA, while those LAA without leakage tend to be more circular. This implicates the importance of advanced imaging methods, such as 3D-TEE, which are capable to precisely determine the size of the LAA and the degree of its circularity. Acknowledgement/Funding None

Catheter ablation has become the most common therapy in patients with atrial fibrillation (AF). However, despite significant advances in technology and operators’ experience, ablation outcomes remain suboptimal, especially in patients with persistent AF. Focal impulse and rotor modulation (FIRM) represents a new technology for mapping and ablation of patient-specific AF sources. This approach is based on the concept of localized sources, which can be understood as organized rotational waves or focal impulses driving disorganized AF. Several studies, mainly single-center case series, have shown an incremental benefit in long-term outcome when adding FIRM-guided ablation to conventional pulmonary vein isolation (PVI). Therefore, the results of ongoing multicenter randomized trials are needed to support this data.

BACKGROUND:There is a lack of procedural and follow-up data on pulmonary vein isolation (PVI) with the second-generation pulmonary vein ablation catheter® (PVAC Gold) in patients with atrial fibrillation (AF). This study provides data on PVI procedures and 1-year follow-up results with PVAC Gold in patients with AF treated in clinical practice.METHODS AND RESULTS:Three hundred and eighty four patients with documented symptomatic paroxysmal (n=198) or persistent (n=186) AF were included in a non-randomized prospectively designed database. Patients were enrolled consecutively at 2 high-volume centers. Procedural as well as 1year follow-up data were systematically analyzed. Average procedure times±standard deviations were 94±23min and 97±23min, respectively, in patients with paroxysmal and persistent AF. Average fluoroscopy times were 14.7±5.4min and 15.2±5.6min and total application times 18.1±5.0min and 18.8±5.2min, respectively, in the 2 patient cohorts. At 12months, 70.7% (70/99) and 61.9% (70/113) of patients with paroxysmal and persistent AF, respectively, were free from AF. Four early complications occurred. In the group with persistent AF, 1 posterior cerebral infarction occurred 2days after the procedure during initiation of anticoagulation. There was no phrenic nerve palsy or esophageal injury associated with the procedures. No thromboembolic events were recorded during follow-up.CONCLUSIONS:In patients with paroxysmal or persistent AF, second generation multi-electrode-phased radiofrequency ablation delivers favorable mid-term PVI success rates with few procedure-related or follow-up complications.

FIRM Ablation Outcomes for Recurrent Nonparoxysmal AFIntroductionA patient‐tailored ablation approach focused on the elimination of both pulmonary vein triggers as well as substrate drivers may result in favorable outcomes in recurrent persistent AF patients.ObjectiveWe evaluated the long‐term outcomes of rotor ablation combined with conventional pulmonary vein isolation (PVI) in patients with recurrent nonparoxysmal AF.MethodsFifty‐eight consecutive patients underwent FIRM‐guided rotor ablation followed by conventional PVI for the treatment of recurrent nonparoxysmal AF. A software algorithm was used to display rotational activity at rotor sites by creating propagation maps from unipolar electrograms recorded using a 64‐electrode basket catheter. These rotor sites were targeted for ablation, followed by conventional PVI.ResultsAll patients had nonparoxysmal AF (83% longstanding persistent) and a previously failed conventional ablation procedure. Stable rotors were identified in all patients (mean of 3.0 ± 1.6 per patient), with 55.2% having right atrial rotors and 96.6% left atrial rotors, respectively. Complications occurred in 5.2% of patients, none related to the FIRM procedure. The median follow‐up was 12 months. At 6 and 12 months of follow‐up, 73.2% and 76.9% of patients remained free from AF/AT, respectively. Excluding 2 patients who underwent a successful redo ablation procedure/electrical cardioversion, at 12 months of follow‐up, 69.2% were free from any AF/AT and 73.1% were free from AF after a single FIRM‐guided ablation procedure.ConclusionA high degree of success was observed in this cohort of primarily longstanding persistent AF patients treated for recurrent AF with FIRM‐guided rotor ablation. Prospective randomized controlled trials are needed.

Focal impulse and Rotor Modulation (FIRM) has been introduced recently as a new approach for ablation of atrial fibrillation (AF).We report a case of FIRM-guided rotor ablation, performed in combination with (re)-pulmonary vein isolation in a patient with recurrent persistent AF and two previous failed conventional ablation procedures.Four rotors could be detected and successfully ablated in this patient, one in the right atrium and three in the left atrium.Notably, the patient experienced a short-term recurrence of AF with spontaneous conversion back to sinus rhythm 11 weeks after the procedure.However, now the patient has been in stable sinus rhythm for 19 months.This case highlights the need to effectively address the specific AF mechanisms, especially in patients with recurrent persistent atrial fibrillation.FIRM-guided rotor ablation seems to be a beneficial option for these patients.

Purpose: Despite significant progress in catheter techniques suboptimal ablation outcomes are observed for patients with atrial fibrillation (AF). This effect is potentially related to the standard approaches of most ablation techniques which mainly focus on anatomic rather than patient specific functional targets. Recently, two new ablation concepts have been introduced which are aimed on patient specific targets. First, stable electrical rotors and focal sources have been demonstrated to sustain AF. Therefore, the ablation of rotors has been associated in first studies with an improved clinical outcome in comparison to conventional ablation. Second, there is increasing evidence that atrial fibrosis can not only be considered as predictor for the ablation outcome but also as a primary disease driving AF. Along this line, atrial fibrosis could be a target for tailored ablation. The aim of this study is to investigate the correlation between rotor acticity and left atrial fibrosis in patients with AF. Methods: Patients that underwent redo procedure for AF using Focal Impulse and Rotor Mapping (FIRM) were analyzed for number and location of rotors and for degree and location of left atrial fibrosis. Left atrial (LA) voltage maps were generated during sinus rhythm after rotor and pulmonary vein isolation. Low voltage was defined as a signal amplitude < 0,5 mV. Fibrosis was categorized as stage 1 (<10% of the LA wall), 2 (≥10%- < 20%), 3 (≥20%- < 30%), and 4 (≥30%). Results: 42 patients (mean age 62 ± 9 years, 31 male) with recurrent AF (37 persistent, 5 paroxysmal) were included. There were 21 patients in stage 1 (50%), 7 in stage 2 (17%), 9 in stage 3 (21%) and 5 in stage 4 (12%). In patients with stage 1 we observed a mean number of RA rotors of 0.6 ± 0,7 (0–2) and LA rotors of 1.4 ± 0.9 (0–4), with stage 2 0.3 ± 0.5 (0–1) and 1.9 ± 0.7 (1–3), with stage 3 1.1 ± 1.1 (0–3) and 2.3 ± 1.0 (1–4) and with stage 4 0.6 ± 0.5 (0–1) and 3.0 ± 1.2 (2–5), respectively. We found significant more LA rotors (2.3 ± 1.0; 1–5) in patients with verification of LA fibrosis (stage 2–4) than in patients without relevant LA fibrosis (p = 0.04). A total of 29 out of 80 LA rotors (36%) in all patients were located in a spacial vicinity of a low voltage area. As expected, the number was higher in patients with LA fibrosis (59%), also depending on the degree of fibrosis (stage 2: 38%, stage 3: 57%, stage 4: 80%). Conclusions: Rotor activity has been identified in patients with and without LA fibrosis. However, more LA rotors have been observed in patients with LA fibrosis. Depending on the degree of fibrosis an increasing number of rotors have been found in spacial vicinity of LA fibrosis areas.