Aims Low-voltage areas (LVAs) found during left atrial (LA) electroanatomical mapping are increasingly targeted by radiofrequency catheter ablation (RFCA) on top of pulmonary vein isolation to improve arrhythmia-free survival in patients with atrial fibrillation (AF). However, pre-procedural prediction of LVAs remains challenging. The purpose of the present study was to describe the association between parameters of LA function and dimensions, respectively, derived from pre-procedural cardiovascular magnetic resonance (CMR) imaging, and the presence of LVAs on LA voltage mapping. Methods and results Patients who underwent first-time RFCA for paroxysmal or persistent AF and who were in stable sinus rhythm during pre-procedural CMR imaging were included in this study. Cardiovascular magnetic resonance-derived parameters of LA function and dimensions were calculated. Low-voltage areas were defined as areas with bipolar voltage amplitudes of <= 0.5 mV on electroanatomical mapping. In total, 259 consecutive patients were included in this analysis. Low-voltage areas were found in 25 of 259 patients (9.7%). Compared with those without LVAs, patients with LVAs were significantly older, were more likely to be female, had a higher CHA(2)DS(2)-VASc score, had larger LA volumes, and had a lower LA total emptying fraction (TEF). In multivariate analysis, only LA TEF [odds ratio (OR) 0.885, 95% confidence interval (CI) 0.846-0.926, P < 0.001] and the CHA(2)DS(2)-VASc score (OR 1.507, 95% CI 1.115-2.038, P = 0.008) remained independently associated with the presence of LVAs. Conclusion Left atrial TEF and the CHA(2)DS(2)-VASc score were independently associated with the presence of LVAs found during LA electroanatomical mapping. These findings may help to improve pre-procedural prediction of pro-arrhythmogenic LVAs and to improve peri-procedural patient management. [GRAPHICS] .

Abstract Funding Acknowledgements Type of funding sources: None. Background Preprocedural contrast-enhanced cardiovascular magnetic resonance (CMR) or computed tomography (CT) imaging of the left atrium (LA) and pulmonary veins (PVs) is usually employed to facilitate catheter mapping and ablation of atrial fibrillation (AF). Incidental findings (IFs) are common on cardiac imaging prior to AF catheter ablation (AFCA). However, previous studies were of small size and have mainly focused on radiological extracardiac IFs detected on preprocedural CT scan. Purpose To assess the prevalence of major cardiac and extracardiac IFs on routine preprocedural CMR in a large cohort of consecutive patients scheduled for first-time AFCA, and to report its impact on clinical decision-making and management. Methods All consecutive patients who underwent routine preprocedural CMR prior to first-time AFCA between April 2015 and March 2019 were considered for analysis. Main exclusion criteria were referral for repeat AFCA; prior cardiac CT or CMR imaging; and general contraindication to CMR or AFCA. All CMR examinations consisted of survey images with full thoracic coverage, cardiac cine and late-gadolinium enhancement imaging, and three-dimensional contrast-enhanced CMR angiography of the LA/PVs. An IF was defined as major when any newly detected finding either resulted in cancellation of the AFCA procedure or intentional deviation from the standard AFCA protocol. In patients with accessory or anomalous PVs the ablation strategy was individually tailored aiming at isolation of all PVs. Results Two thousand consecutive patients (62±10 years; 59% male) with paroxysmal (48%) or persistent (52%) AF were included. Among the entire study cohort 172 patients (8.6%) had a total of 184 cardiac (75%) and extracardiac (25%) major IFs (Fig. A+B). Preprocedural detection of a major IF resulted in cancellation of the scheduled AFCA procedure in 88 patients (4.4%). Forty-two patients (2.1%) have thereupon never been ablated, 46 patients (2.3%) underwent postponed AFCA after a median time from CMR imaging of 83 (32-213) days. The remaining 84 patients with major IF (4.2%) underwent an individualized approach to AFCA (Fig. A). The most common major IFs were accessory or anomalous PVs in 76 (3.8%), extracardiac abnormalities suspicious of malignancy in 29 (1.5%), and positive stress perfusion imaging in 19 (1.0% overall; 7.2% of 261 tested) patients. In 19 patients (1.0%) preprocedural CMR detected a previously unknown intracardiac thrombus or structural cardiac disease. Conclusion Unexpected major IFs on routine preprocedural CMR affected clinical decision-making and therapeutic management in 8.6% of patients scheduled for first-time AFCA at our institution. Whether preprocedural CMR imaging may improve safety and outcome of AFCA needs to be addressed in future research.

Introduction: Preprocedural cardiovascular magnetic resonance (CMR) or computed tomography (CT) imaging of the left atrium/pulmonary veins is usually employed to guide catheter ablation of atrial fibrillation (AFCA). Incidental findings (IFs) are common on cardiac imaging prior to AFCA. However, previous studies have mainly focused on extracardiac IFs detected on CT scan. We aimed to assess the prevalence of relevant cardiac and extracardiac IFs on routine preprocedural CMR in a large patient cohort scheduled for first-time AFCA and report its impact on clinical decision-making and management. Methods and results: We included 2000 consecutive patients (62 +/- 10 years; 59% male) who underwent CMR prior to first-time AFCA between April 2015 and March 2019. Among these patients 172 (8.6%) had a total of 184 major IFs. Detection of major IFs resulted in cancellation of the scheduled AFCA procedure in 88 patients (4.4%). Forty-two patients (2.1%) have never been ablated, 46 (2.3%) underwent postponed AFCA after a median time of 83 (32-213) days. The remaining 84 patients (4.2%) underwent an individualized approach to AFCA. The most common major IFs were accessory or anomalous PVs in 76 (3.8%), extracardiac abnormalities suspicious of malignancy in 29 (1.5%), and positive stress perfusion imaging in 19 (7.2% of 261 tested) patients. In 19 patients (1.0%) preprocedural CMR provided the diagnosis of a previously unknown structural cardiac disease. Conclusions: Unexpected relevant findings on routine preprocedural CMR affected clinical decision-making and management in 8.6% of patients scheduled for first-time AFCA. However, whether preprocedural CMR imaging may improve overall clinical outcome needs to be addressed in future research.

Introduction Atrial fibrillation (AF) has been recognised as the most prevalent sustained arrhythmia. Recently, a growing body of evidence has suggested that AF might be involved in the progression of cognitive impairment (CIM), potentially extending into types of dementia. Accordingly, the purpose of the present study was to summarise the findings of investigations examining association between AF and cognitive function as well as highlighting the possible causes of discrepancy between the findings and reviewing the probable mechanisms of CIM in patients affected with AF. Methods A systematic search in the literature was conducted in the databases of PubMed, Scopus, Cochrane Library, and Google Scholar with no language restrictions, using specified search terms to identify studies published between 1 January 1990 and 1 April 2018. Then, study designs, participant information, diagnostic approaches used for cognitive assessments, and incidence/prevalence rates of CIM and/or dementia were assessed. Results Out of the initial 2,364 articles retrieved, a total number of 40 studies were selected for data collection. Most studies had suggested a significant relationship between AF and CIM. In this regard, cerebral hypo-perfusion, altered cerebral blood flow, cerebral micro-bleeds, micro-emboli, vascular inflammation, cerebral small vessel diseases, vascular inflammation, and genetic factors were considered as the possible mechanisms of CIM in patients suffering from AF. It seemed that differences in study settings and designs, variations of diagnostic tools for CIM and AF, as well as underlying conditions such as age groups, concurrent chronic diseases, and therapeutic interventions for AF might be amongst probable factors justifying the diversity of findings across the selected articles. Conclusion Although evidence is much more directed towards an association between AF and CIM, the role of AF in CIM needs to be confirmed in-depth via longer prospective and cohort studies at larger scales using accurate neuropsychological and cognitive function assessments. Moreover, the mechanisms involved in the relationship between AF and Alzheimer's disease (AD) require further studies. To conclude, the effect of different therapeutic strategies of AF on CIM should be investigated in more clinical trials.

Atrial fibrillation (AF) is associated with changes in left atrial (LA) anatomy, function and substrate [ [1] Nedios S. Koutalas E. Kosiuk J. Sommer P. Arya A. Richter S. et al. Impact of asymmetrical dilatation of the left atrium on the long-term success after catheter ablation of atrial fibrillation. Int. J. Cardiol. 2015; 184: 315-317 Abstract Full Text Full Text PDF PubMed Scopus (16) Google Scholar , [2] von Bary C. Dornia C. Eissnert C. Nedios S. Roser M. Hamer O.W. et al. Predictive value of left atrial volume measured by non-invasive cardiac imaging in the treatment of paroxysmal atrial fibrillation. J. Interv. Card. Electrophysiol. 2012; 34: 181-188 Crossref PubMed Scopus (31) Google Scholar ]. LA volumes are related to the success of AF catheter ablation, but the relation to other functional and structural parameters are less well understood. Additionally, ablation for AF could also cause LA functional impairment. Therefore, assessing these changes with cardiac magnetic resonance imaging (CMRi) could help us predict outcomes and improve patient selection. Analyses like these are important additions to the literature investigating the role of pre-procedural imaging. Left atrial functional and structural changes associated with ablation of atrial fibrillation - Cardiac magnetic resonance studyInternational Journal of CardiologyVol. 305PreviewLeft atrial (LA) volumes are related to success of atrial fibrillation (AF) ablation, but the relation to other functional and structural parameters is less well understood. Our goal was to detect potential functional and structural predictors of arrhythmia recurrence after ablation using cardiac magnetic resonance imaging (CMRi) and to non-invasively assess the relation between LA functional and structural remodeling pre- and post-ablation. Full-Text PDF

Aims To determine the clinical utility of a combined single-session cardiovascular magnetic resonance (CMR) imaging protocol integrating adenosine stress perfusion and three-dimensional pulmonary vein angiography for stratification of atrial fibrillation (AF) patients referred for pulmonary vein isolation (PVI) and complaining about chest pain syndromes. Methods and results The preprocedural CMR examination (adenosine stress perfusion, late gadolinium enhancement, and three-dimensional pulmonary vein angiography) was performed in 357 consecutive AF patients with chest pain syndromes referred for PVI. Stress perfusion results were used for stratification: ischaemia positive patients underwent invasive coronary angiography, ischaemia negative patients underwent PVI, and follow-up/outcome data were collected (combined primary endpoint of cardiac death/non-fatal myocardial infarction). The integrated CMR protocol had a high success rate (356/357, 99.7%), a short total examination duration (<30 min in all patients), and delivered high-quality three-dimensional pulmonary vein angiography in all patients undergoing PVI (324/324, 100%). Variants of pulmonary vein anatomy were identified in 33% of all patients (117/357). Stress positivity (28/356, 8%) had a high positive predictive value for identification of obstructive coronary artery disease (86%), while stress negativity carried a low short-term event rate following PVI (cumulative 1-year event-free survival rate, 99.6%). Conclusion Combined single-session CMR as a routine diagnostic workup for AF patients with chest pain syndromes prior to PVI proved to represent a time-efficient and effective stratification tool.

PurposeThe application of a novel platform for nonfluoroscopic catheter sensor tracking within pre-recorded x-ray loops in the context of catheter ablation of atrial fibrillation (AF) demonstrated significant potential for reduction of fluoroscopy. We sought to provide the first prospective randomized comparison of fluoroscopy needs, procedure times, and complications in AF catheter ablation with or without additional use of nonfluoroscopic catheter visualization (NFCV).MethodsPatients with AF were randomized into two groups before scheduled radiofrequency ablation: (1) using established mapping systems and fluoroscopy as needed (CONV group) or (2) with additional NFCV (NFCV group). All procedures were performed in the same lab using the same ablation catheter tip technology and the same mapping and ablation strategies. Primary endpoints were radiation time and dose. Secondary endpoints were procedural parameters, complications, and long-term success.ResultsA total of 80 patients (48 male patients, mean age 60years, 46 patients with paroxysmal AF) were randomized into the two groups. Clinical parameters between both groups were similar. NFCV use reduced mean fluoroscopy time (1.9 vs. 13.2min, p<0.001) and mean dose (510 vs. 1549Gycm(2), p<0.001) significantly. Procedural parameters were similar in the two groups. One conservatively treated groin complication occurred (1.3%).ConclusionsRadiation exposure can be significantly reduced by using the novel NFCV technology in addition to standard AF ablation technologies without negative effects on procedure durations, success rates, or complication rates. With the use of the technology, abandonment of lead protection for EP staff is possible following transseptal puncture.

Die Kardioversion von Vorhofflimmern bzw. Vorhofflattern ist ein klinischer Sonderfall, da das Risiko eines ischämischen Schlaganfalls bzw. thromboembolischer Ereignisse dabei erhöht ist. In diesem Beitrag werden – basierend auf der aktuellen Empfehlungslage – wesentliche Aspekte der Antikoagulation im Rahmen der Kardioversion praxisrelevant beleuchtet.

Atrial fibrillation (AF) is the most common human arrhythmia. Interventional treatment with catheter ablation is an established technique that is increasingly applied and has become one of the main treatment modalities in patients with AF. Ablation results in significant improvement of symptoms and the quality of life. There is as yet no clear evidence of any impact of the procedure on hard clinical endpoints, except in patients with heart failure, who seem to benefit significantly from ablation. The cornerstone of the procedure is the achievement of pulmonary vein isolation. Radiofrequency energy is the main applied energy source, but cryoballoon ablation has emerged as a safe and effective alternative to radiofrequency ablation. Additional ablation strategies and novel technical features have been proposed but without unequivocal proof of clinical benefit. The most promising of these seems to be substrate mapping of the left atrium with substrate modification in areas with low voltage as an adjunct to pulmonary vein isolation. Complication rates remain considerable despite accumulated experience and can be partly reduced by application of preventive measures.

Aims:This study aimed to assess the impact of supraventricular tachycardia (SVT) on long-term results of radiofrequency catheter ablation therapy of ventricular tachycardia (VT) in a large cohort of patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C).Methods and results:Supraventricular tachycardia occurrence has been studied in patients from our ARVD/C registry (70 patients, 48 male, age 53.2 ± 14.0, 45 patients (64.3%) with previous VT ablation). SVT were diagnosed in 26 of 70 patients (37.1%). Atrial fibrillation (AF) was the most frequent atrial arrhythmia, diagnosed in 17 patients (24.3%). In univariate analysis advanced age, clinical symptoms of heart failure, enlarged right atrium, diagnosis of significant tricuspid regurgitation (TR), and inappropriate implantable cardioverters-defibrillators therapy were associated with SVT. In binary logistic regression analysis only heart failure: hazard ratio (HR) 10.89, 95% confidence interval (95% CI) 1.08-109.96 (P = 0.043) and significant TR: HR 4.79, 95% CI 1.35-16.33 (P = 0.015) remained associated with SVT. In patients with previous VT ablation Cox multiple regression survival analysis revealed older age (≥53 years): HR 4.63, 95% CI 1.51-14.24 (P = 0.008) and SVT: HR 3.01, 95% CI 1.15-7.89 (P = 0.025) as predictors for VT recurrence during the follow-up.Conclusion:SVT and older age are associated with the recurrence of VT after catheter ablation in patients with ARVD/C.

Aims Efforts to reduce radiation exposure during catheter ablation procedures have included the use of various technological measures. Significant results have been achieved to the point where near lead-free procedures in routine clinical practice has become a realistic goal. The integration of MediGuide technology [non-fluoroscopic catheter visualization technology (NFCV)] and three-dimensional electroanatomical mapping is one of the methods developed in response to radiation reduction initiatives. We aimed to evaluate the impact of this NFCV technology on atrial fibrillation (AF) catheter ablation in terms of reduction in procedural and radiation time as well as safety aspects. Methods and results Between March 2012 and March 2017, a total of 1000 patients underwent AF ablation using NFCV. Patient and procedural data and complications within the first 3 months were entered into a prospective registry and analysed. We assessed procedure time, fluoroscopy time, and dose and complications. In a cohort of 1000 patients (62.9 ± 11 years; 72% men; left ventricular ejection fraction 57%; and left atrial diameter 43.2 mm), the median procedure time was 120 min, median fluoroscopy time was 0.90 min, and the median fluoroscopy dose of was 345.1 cGy · cm2. Stratification of the first (Group 1) and the last 250 (Group 2) cases showed significant improvement in the median procedure time (140-110 min) and reduction in the median fluoroscopy time (6-0.5 min) and the median dose (2263-151.9 cGy · cm2). The overall complication rate was 2.0%. Conclusion The use of NFCV technology enables safe, consistent, and 'near lead-free' performance of AF ablation in routine clinical practice.

BACKGROUND:Ventricular arrhythmias (VAs) are common in patients after left ventricular assist device (LVAD) implantation. OBJECTIVE:The purpose of this study was to determine the predictors of VAs and their impact on mortality in LVAD patients. METHODS:A total of 98 consecutive patients with an implantable cardioverter-defibrillator (ICD) (86 [88%] male, mean age 57 ± 10 years), 57 [58%] with nonischemic dilated cardiomyopathy) who had received an LVAD between May 2011 and December 2013 at our institution were included in the study. RESULTS:Mean left ventricular ejection fraction and left ventricular end-diastolic diameter were 20% ± 8% and 73 ± 11 mm, respectively. Seventy-three patients (75%) had atrial fibrillation (AF). During the 12 months before LVAD implantation, 38 patients (39%) had experienced ≥1 episode of VAs (11.5 ± 20) requiring ICD therapies. The number of patients with VAs was comparable among all types of ICDs (P = .48). During the 12-month follow-up after LVAD implantation, 48 patients (49%) experienced ≥1 episode of VAs (30 ± 98) with appropriate ICD therapies. The prevalence of VAs was significantly higher among patients with pre-LVAD VAs compared to those without VAs during the year before LVAD implantation (66% vs 38%; P = .008). In a binary multiple logistic regression analysis, pre-LVAD VAs (hazard ratio 5.36, 95% confidence interval 2.0-14.3; P = .001) and AF (hazard ratio 3.1, 95% confidence interval 1.1-11.9; P = .024) predicted post-LVAD VAs. CONCLUSION:Pre-LVAD VAs and AF predict the occurrence of VAs after LVAD implantation. According to the latest data on the negative impact of post-LVAD VAs on all-cause mortality, further studies should clarify the reasonability of maintaining sinus rhythm in patients with AF and/or prophylactic catheter ablation of ventricular tachycardias before LVAD implantation.

This study aimed to analyze the influence of scar distribution between the endocardium and the epicardium in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C).

Aims This randomized single-centre study sought to compare the efficacy and safety of pulmonary vein isolation (PVI) plus voltage-guided ablation vs. PVI with or without linear ablation depending on the type of atrial fibrillation (AF). Methods and results Overall, 124 ablation-naive patients with paroxysmal or persistent AF were randomized to PVI with (persistent AF) or without (paroxysmal AF) additional linear ablation (control group) vs. PVI plus ablation of low-voltage areas (LVAs) irrespective of AF type. Bipolar voltage mapping was performed during stable sinus rhythm. An LVA consisted of  ≥ 3 adjacent mapping points that each had a peak-to-peak amplitude ≤0.5 mV. After a mean follow-up of 12 ± 3 months, significantly more patients in the LVA ablation group were free from atrial arrhythmia recurrence >30 s off antiarrhythmic drugs (AADs) after a single procedure (primary endpoint) compared with control group patients [40/59 (68%) vs. 25/59 (42%), log-rank P = 0.003]. Arrhythmia-free survival on or off AADs was found in 33/59 control group patients (56%) and in 41/59 LVA ablation group patients (70%) (adjusted log-rank P = 0.10). During the 7 day Holter monitoring period at 12 months, significantly more patients in the LVA ablation group were free from arrhythmia recurrence on or off AADs [45/50 (90%) vs. 33/46 (72%), P = 0.04]. No between-group differences were observed regarding procedure duration, fluoroscopy time, and major complications. Conclusion In this single-centre study, individually tailored substrate modification guided by voltage mapping was associated with a significantly higher arrhythmia-free survival rate compared with a conventional approach applying linear ablation according to AF type.

Remote ischemic preconditioning (RIPC) has been studied in models of different cardiovascular entities. Recently, a beneficial effect of RIPC on incidence of atrial fibrillation (AF) in postsurgical patients has been suggested. However, the potential impact of RIPC on electrophysiological- and thrombogenesis-related parameters in the setting of paroxysmal nonvalvular AF has not been investigated. The aim of the study is to answer the following questions: (1) Does RIPC have impact on inducibility of AF in patients with known paroxysmal AF? If yes, what are the direct electrophysiological mechanisms of this phenomenon, and could RIPC be implemented to reduce AF burden? (2) Does RIPC have the potential to minimize thrombogenic effects of simulated episodes of AF? If so, what are inhibited components of thrombogenesis and can this be used to reduce thromboembolic risk related to paroxysmal AF? The presented study is a 2-arm, randomized, placebo-controlled, double-blinded, single-center trial in a cohort of 146 patients with paroxysmal AF referred for AF ablation in sinus rhythm. The study will collect electrophysiological data such as variability of P-wave morphology, atrial refractory period, conduction times, and inducibility/sustainability of AF. Furthermore, AF-induced prothrombotic processes will be analyzed by quantification of platelet aggregates, analysis of platelet function, and measurement of thrombogenesis-related plasma markers. Moreover, the study will provide a unique bio-database for further analysis of molecular and genetic mechanisms responsible for observed results.

Rotor Elimination as Endpoint for AF AblationsBackgroundThere remains a lack of consensus regarding the ideal ablation strategy for atrial fibrillation (AF), particularly in patients with persistent or longstanding persistent AF. Given increasing evidence from clinical imaging studies that rotors sustain AF, rotor elimination may be a desirable procedural endpoint. However, there is no description to date of the clinical outcomes using rotor elimination during ablation as the procedural endpoint. Moreover, a series of studies question whether procedural AF termination is a desirable endpoint for ablation after many forms of AF ablation.Methods and ResultsWe report a single‐center experience of rotor elimination during AF ablation using Focal Impulse and Rotor Mapping (FIRM), describing 20 consecutive patients with case descriptions of 3 patients with recurrent longstanding persistent AF after prior ablation. In all cases, endocardial mapping using a 64‐electrode basket catheter was performed to identify rotors, which were eliminated using radiofrequency catheter ablation. After it was verified that all identified rotors were eliminated, standard ablation consisting of PV isolation was performed. Notably, persistent AF terminated in only 1/20 (5%) patients. However, after a follow‐up of 6 months, single‐procedure freedom from AF was 80% (16/20 patients) with only 1 patient on antiarrhythmic drugs. All three patients in the highlighted series are AF free despite the lack of acute procedural AF termination.ConclusionsPatients with persistent AF including those with unsuccessful prior ablation can be treated successfully by rotor targeted ablation, using the elimination of all rotors rather than acute AF termination as the procedural endpoint.

This chapter summarizes clinically relevant aspects of currently applied follow-up strategies after atrial fibrillation (AF) ablation and their implications for ablation success. A more objective rhythm assessment, however, based on regularly scheduled or even continuous electrocardiogram (ECG) monitoring may be advantageous in both clinical care and clinical research trials for several reasons. First, a follow-up strategy solely based on symptom reporting is considerably limited by the high incidence of asymptomatic arrhythmia recurrences after ablation and a poor symptom-arrhythmia correlation, respectively. Then, valid rhythm surveillance is a prerequisite for the comparison of different rhythm control interventions in both clinical practice and research trials. In clinical practice, follow-up is usually based on intermittent or noncontinuous rhythm monitoring technologies including scheduled and symptom-triggered standard ECGs, Holter ECGrecordings, external loop recorders, and event recorders. The accuracy of detecting arrhythmia recurrences depends chiefly upon the intensity and duration of follow-up.

A technological platform (MediGuide) has been recently introduced for non-fluoroscopic catheter tracking. In several studies, we have demonstrated that the application of this non-fluoroscopic catheter visualization system (NFCV) reduces fluoroscopy time and dose by 90-95% in a variety of electrophysiology (EP) procedures. This can be of relevance not only to the patients, but also to the nurses and physicians working in the EP lab. Furthermore, in a subset of indications such as supraventricular tachycardias, NFCV enables a fully non-fluoroscopic procedure and allows the lab staff to work without wearing lead aprons. With this protocol, we demonstrate that even complex procedures such as ablations of atrial fibrillation, that are typically associated with fluoroscopy times of >30 min in conventional settings, can safely be performed with a reduction of >90% in fluoroscopy exposure by the additional use of NFCV.

Introduction: Pulmonary vein (PV) isolation forms the cornerstone of any ablation procedure for atrial fibrillation (AF). There is, however, no uniform strategy how to detect and target left atrial (LA) arrhythmogenic substrate outside the PV antra. Fibrosis that corresponds well to LA low-voltage areas (LVAs) seems to play a key role in AF arrhythmogenesis and might therefore be a suitable target for additional substrate modification (SM). Objective: The purpose of this prospective randomized study was to compare a novel technique for SM based on ablation of potentially arrhythmogenic LA LVAs with a standard approach consisting of empiric LA linear ablation. Methods: Patients (pts) with symptomatic paroxysmal or persistent AF were randomized to standard (group 1) or personalized (group 2) SM. Circumferential PV isolation was the primary step in both groups. In group 1, pre-defined linear lesions were applied at the LA roof and bottom, respectively, and at the mitral isthmus only in pts with persistent AF. In group 2, targets for SM (i.e. LVAs) were identified by detailed bipolar voltage mapping (BVM) during sinus rhythm irrespective of AF type. Peak-to-peak electrogram amplitudes were defined as “normal” (> 0.5 mV), as “low voltages” (0.2 to 0.5 mV), or as “scar” (< 0.2 mV). LVAs were targeted by tissue homogenization and / or strategic linear lesions. The primary endpoint was freedom from any atrial arrhythmia (i.e. AF, atrial flutter, or atrial tachycardia) > 30 seconds off antiarrhythmic drugs on serial 7-d-Holter ECG recordings after a follow-up period of 12 months. Results: In total, 124 ablation-naïve pts (mean age 63 ± 9 years, 62 % male, 49 % with persistent AF) were enrolled in this study. LVAs were present in 18 % of pts with paroxysmal and in 41 % of pts with persistent AF (p<0.05). At the end of the follow-up period, 25 out of 59 pts (42 %) in the conventional group were free from arrhythmia recurrence as compared to 40 out of 59 pts (68 %) in the BVM-guided group (unadjusted log rank p = 0.003). Conclusion: Personalized SM guided by endocardial BVM is associated with a higher success rate compared to a conventional approach applying empirical SM based on AF phenotype.