Atrial fibrillation fundamentals: from physiopathology to transcatheter ablation.

Atrial fibrillation (AF) is a common and harmful arrhythmia. Its complex pathogenesis can be outlined using Coumel's Triangle, that considers at the base of AF three different factors: substrate, trigger, and catalyst factor. The triangle can serve as a guide to understand the mechanism of action of the different possible treatments. Anti-arrhythmic drug therapies have a modest efficacy and no proven benefit on prognosis. Interventional therapy is more effective, especially if employed in the first stages of the disease, and can reduce mortality in selected populations. Ablative schemes must be different depending on the type of AF (paroxysmal, persistent) and the presence or absence of atrial dilation.

Minimal fluoroscopy approach for right-sided supraventricular tachycardia ablation with a novel ablation technology: Insights from the multicenter CHARISMA clinical registry.

BACKGROUND: No data exist on the ability of the novel Rhythmia 3-D mapping system to minimize fluoroscopy exposure during transcatheter ablation of arrhythmias. We report data on the feasibility and safety of a minimal fluoroscopic approach using this system in supraventricular tachycardia (SVT) procedures. METHODS: Consecutive patients were enrolled in the CHARISMA registry at 12 centers. All right-sided procedures performed with the Rhythmia mapping system were analyzed. The acquired electroanatomic information was used to reconstruct 3-D cardiac geometry; fluoroscopic confirmation was used whenever deemed necessary. RESULTS: Three hundred twenty-five patients (mean age = 56 ± 17 years, 57% male) were included: 152 atrioventricular nodal reentrant tachycardia, 116 atrial flutter, 41 and 16 right-sided accessory pathway and atrial tachycardia, respectively. Overall, 27 481 s of fluoroscopy were used (84.6 ± 224 s per procedure, equivalent effective dose = 1.1 ± 3.7 mSv per patient). One hundred ninety-two procedures (59.1%) were completed without the use of fluoroscopy (zero fluoroscopy, ZF). In multivariate analysis, the presence of a fellow in training (OR = 0.15, 95% CI: 0.05-0.46; p = .0008), radiofrequency application (0.99, 0.99-1.00; p = .0002), and mapping times (0.99, 0.99-1.00; p = .042) were all inversely associated with ZF approach. Acute procedural success was achieved in 97.8% of the cases (98.4 vs. 97% in the ZF vs. non-ZF group; p = .4503). During a mean of 290.7 ± 169.6 days follow-up, no major adverse events were reported, and recurrence of the primary arrhythmia was 2.5% (2.1 vs. 3% in the ZF vs. non-ZF group; p = .7206). CONCLUSIONS: The Rhythmia mapping system permits transcatheter ablation of right-sided SVT with minimal fluoroscopy exposure. Even more, in most cases, the system enables a ZF approach, without affecting safety and efficacy.

Safety, efficacy, and reproducibility of cavotricuspid isthmus ablation guided by the ablation index: acute results of the FLAI study.

AIMS: Ablation index (AI) is a marker of lesion quality during catheter ablation that incorporates contact force, time, and power in a weighted formula. This index was originally developed for pulmonary vein isolation as well as other left atrial procedures. The aim of our study is to evaluate the feasibility and efficacy of the AI for the ablation of the cavotricuspid isthmus (CTI) in patients presenting with typical atrial flutter (AFL). METHODS AND RESULTS: This prospective multicentre non-randomized study enrolled 412 consecutive patients with typical AFL undergoing AI-guided cavotricuspid isthmus ablation. The procedure was performed targeting an AI of 500 and an inter-lesion distance measurement of ≤6 mm. The primary endpoints were CTI 'first-pass' block and persistent block after a 20-min waiting time. Secondary endpoints included procedural and radiofrequency duration and fluoroscopic time. A total of 412 consecutive patients were enrolled in 31 centres (mean age 64.9 ± 9.8; 72.1% males and 27.7% with structural heart disease). The CTI bidirectional 'first-pass' block was reached in 355 patients (88.3%), whereas CTI block at the end of the waiting time was achieved in 405 patients (98.3%). Mean procedural, radiofrequency, and fluoroscopic time were 56.5 ± 28.1, 7.8 ± 4.8, and 1.9 ± 4.8 min, respectively. There were no major procedural complications. There was no significant inter-operator variability in the ability to achieve any of the primary endpoints. CONCLUSION: AI-guided ablation with an inter-lesion distance ≤6 mm represents an effective, safe, and highly reproducible strategy to achieve bidirectional block in the treatment of typical AFL.

Left Atrial Function After Radiofrequency Catheter Ablation of Atrial Fibrillation--Can Pre-Ablation Function Predict Contractile Improvement During Follow-up?

BACKGROUND: Data are lacking on the effect of radiofrequency catheter ablation (RFCA) on atrial function. The aim of this study was to determine a cut-off of pre-ablation left atrial (LA) function in order to predict atrial functional recovery after RFCA. METHODS AND RESULTS: A total of 64 atrial fibrillation (AF) patients who underwent RFCA were enrolled (age, 59.05±12.09 years; 36% persistent AF; LA volume 37.8±13.6 ml/m(2)). LA emptying fraction (LAEF), LA active fraction (LAAEF), LA passive emptying fraction (LAPEF) and LA expansion index (LAEI) were evaluated in sinus rhythm before and 48 h, 15 days, 1, 2, 3 and 9 months after ablation. LA function improvement was defined as any positive increase in LAEF compared with baseline. On univariate and multivariate analysis only baseline atrial function proved to be an independent predictor of LA function improvement after ablation (P=0.002; OR=0.001; 95% CI: 0.000-0.099). On receiver operating characteristic analysis (AUC=0.70), cut-off for baseline LAEF was 40%. At 9 months, patients with LAEF <40% had significant improvement in atrial performance (LAEF, P=0.01; LAAEF, P=0.036; LAEI, P=0.004); a significant negative correlation between baseline LAEF and LA function improvement was observed (r=-0.62; 95% CI: -0.83 to -0.26; P(r=0)<0.002). CONCLUSIONS: Baseline LAEF is an independent predictor of LA function recovery after RFCA. The beneficial effect of AF ablation is most evident in patients with LAEF<40%.

Pulmonary vein isolation with a new multipolar irrigated radiofrequency ablation catheter (nMARQ™): feasibility, acute and short-term efficacy, safety, and impact on postablation silent cerebral ischemia.

BACKGROUND: Simultaneous multipolar ablation catheters have been proposed to simplify pulmonary vein isolation (PVI) in paroxysmal atrial fibrillation (AF). Recently, a new multipolar irrigated radiofrequency (RF) ablation catheter (nMARQ™, Biosense Webster Inc., Diamond Bar, CA, USA) combining both 3-dimensional electroanatomic mapping and multipolar open-irrigated ablation capability has been developed. Aim of our study was to assess feasibility, acute and short-term success and safety of PVI by the use of this new technology with particular regard to the incidence of postablation silent cerebral ischemia (SCI). METHODS AND RESULTS: Twenty-five patients (76% males; age 57 ± 13 years) with paroxysmal AF underwent PVI using the nMARQ™ catheter. PVI, confirmed by Lasso catheter mapping, was achieved in 100 out of 102 pulmonary veins (98%) identified, and final PVI was obtained in 24 out of 25 (96%) patients. The overall concordance between Lasso and nMARQ™ signals in demonstrating PVI was 78%. No major procedural complications occurred and no patient suffered SCI, on the basis of cerebral magnetic resonance imaging performed before and after the procedure. Following a 6-month follow-up, 17/25 (68%) patients remained free from AF without antiarrhythmic drugs. CONCLUSIONS: In our preliminary experience, PVI with nMARQ™ catheter appears to be feasible and safe, without incidence of SCI. Long-term clinical efficacy has to be evaluated in further studies.

Use of oral gadobenate dimeglumine to visualise the oesophagus during magnetic resonance angiography in patients with atrial fibrillation prior to catheter ablation.

BACKGROUND: Atrio-oesophageal fistula was first reported as a fatal complication of surgical endocardial and percutaneous endocardial radiofrequency ablation for atrial fibrillation, with an incidence after catheter ablation between 0.03% and 0.5%. Magnetic resonance angiography (MRA) was usually performed to obtain pre-procedural 3D images, used to merging into an electro-anatomical map, guiding step-by-step ablation strategy of AF. Our aim was to find an easy, safe and cost-effective way to enhance the oesophagus during MRA. METHODS: In 105 consecutive patients, a right-left phase encoding, free breathing, 3D T1 MRA sequence was performed in the axial plane, >24 hours before catheter ablation, using an intravenous injection of gadobenate dimeglumine contrast medium. The oesophagus was enhanced using an oral gel solution of 0.7 mL gadobenate dimeglumine contrast medium mixed with approximately 40 mg thickened water gel, which was swallowed by the patients on the scanning table, immediately before the MRA sequence acquisition. RESULTS: The visualisation of the oesophagus was obtained in 104/105 patients and images were successfully merged, as left atrium and pulmonary veins, into an electro-anatomical map, during percutaneous endocardial radiofrequency ablation. All patients tolerated the study protocol and no immediate or late complication was observed with the oral contrast agent administration. The free-breathing MRA sequence used in our protocol took 7 seconds longer than MRA breath-hold conventional sequence. CONCLUSION: Oesophagus visualization with oral gadobenate dimeglumine is feasible for integration of oesophagus anatomy images into the electro-anatomical map during AF ablation, without undesirable side effects and without significantly increasing cost or examination time.

Long-term efficacy and safety of two different rhythm control strategies in elderly patients with symptomatic persistent atrial fibrillation.

BACKGROUND: We prospectively compared the efficacy, safety, and quality of life (QoL) impact of catheter ablation versus antiarrhythmic drugs (AAD) in elderly patients with persistent atrial fibrillation (AF). METHODS AND RESULTS: Four hundred and twelve consecutive patients, aged ≥ 70 years, underwent ablation (Group A, 153 patients) or AAD (Group B, 259 patients). Study endpoints: treatment failure (any AF/AT lasting >30 seconds) and treatment-related adverse events (acute when ≤1 month of procedure and long term when >1 month). At a follow-up of 60 ± 17 months, 43% and 46% patients in Group B versus 58% and 76% in Group A were in sinus rhythm (SR), respectively, after one (P = 0.003) and 2 procedures (P < 0.001). Fifteen acute adverse events occurred (6.7% in Group A vs 1% in Group B, P < 0.001), mainly periprocedural cerebral thromboembolism (3.3% in Group A vs 0.7% in Group B, P = 0.058). Previous TIA/stroke resulted the only independent predictor of periprocedural cerebrovascular accidents (OR 1.2, 95%IC 1.1-1.3). At follow-up, 74 long-term adverse events occurred (7.7% in Group A vs 23.9% in Group B, P < 0.001) with Group B patients more often experiencing AAD-related adverse events (12.7% vs 2.6%, P < 0.001). Group A and absence of AF/AT recurrences significantly improved QoL scores (P < 0.001). CONCLUSIONS: In elderly persistent AF patients, catheter ablation is more effective in maintaining SR and in improving QoL than AAD but is affected by a higher risk of embolic complications, particularly in patients with previous TIA/stroke. Over time, Group A patients more likely discontinued AAD with a reduction of long-term adverse events.

Long-term results of transcatheter atrial fibrillation ablation in patients with impaired left ventricular systolic function.

INTRODUCTION: Long-term outcome of AF ablation in patients with impaired LVEF is unknown. The aim of this study is to evaluate sinus rhythm (SR) maintenance, clinical status, and echocardiographic parameters over a long-term period following atrial fibrillation (AF) transcatheter ablation in patients with left ventricular ejection fraction (LVEF) <50%. METHODS AND RESULTS: A total of 196 patients (87.2% males, age 60.5 ± 10.2 years) with LVEF <50% underwent radiofrequency transcatheter ablation for paroxysmal (22.4%) or persistent (77.6%) AF. Patients were followed up for 46.2 (16.4-63.5) months regarding AF recurrences, functional class, and echocardiographic parameters. All patients underwent pulmonary vein isolation, while 167 (85.2%) required additional atrial lesions. Eleven (5.6%) patients suffered procedural complications. During follow-up, 58 (29.6%) patients required repeated ablations. At the follow-up end, 15 (7.7%) patients died, while 74 (37.8%) documented at least one episode of AF, atrial flutter, or atrial ectopic tachycardia. Eighty-three (47.2%) patients maintained antiarrhythmic drugs. During follow-up, NYHA class improved by at least one class more frequently among patients maintaining SR compared to those experiencing relapses (70.6% vs 47.9%, P = 0.003). LVEF showed a broader relative increase in patients maintaining SR (32.7% vs 21.4%; P = 0.047) and mitral regurgitation grading significantly decreased (P <0.001) only within these patients. At multivariable analysis SR maintenance emerged as an independent predictor (odds ratio 4.26, 95% CI 1.69-10.74, P = 0.002) of long-term clinical improvement (reduction in NYHA class ≥ 1 and relative increase in LVEF ≥ 10%). CONCLUSIONS: Although not substantially worse than in patients with preserved LVEF, AF ablation in patients with impaired LVEF is affected by high long-term recurrence rate. Among these patients SR maintenance is associated with greater clinical improvement.

Matching Ablation Endpoints to Long-Term Outcome: The Prospective Multicenter Italian Ventricular Tachycardia Ablation Registry.

BACKGROUND: Multicenter ventricular tachycardia (VT) ablation studies have shown poorer outcomes compared with single-center experiences. This difference could be related to heterogeneous mapping and ablation strategies. OBJECTIVES: This study evaluated a homogenous simplified catheter ablation strategy for different substrates and compared the results with those of a single referral center. METHODS: This was a multicenter prospective VT ablation registry of patients with the following 4 causes of VT: previous myocardial infarction; previous myocarditis; arrhythmogenic right ventricular dysplasia; or idiopathic dilated cardiomyopathy. The procedural protocol included precise mapping and ablation steps with the combined endpoint of late potential (LP) abolition and noninducibility of VT. The long-term primary efficacy endpoint was freedom from VT. RESULTS: A total of 309 patients were enrolled. LPs were present in 70% of patients and were abolished in 83%. At the end of the procedure 74% of LPs were noninducible. The primary combined endpoint of LP abolition and noninducibility was achieved in 64% of patients with LPs at baseline. Freedom from VT at 12 months was observed in 67% of patients. In the overall study group, VT inducibility was the only predictor of freedom from VT (P = 0.013). In patients with LPs, the VT recurrence rate was lower both for patients with complete LP abolition (P = 0.040) and for patients meeting the composite endpoint (P = 0.035). CONCLUSIONS: A standardized VT mapping and ablation technique reproduced the procedural outcomes of a single referral center in a multicenter prospective study. LP abolition and noninducibility were effective in reducing VT recurrences in patients with 4 causes of cardiomyopathy. (Ventricular Tachycardia Ablation Registry; NCT03649022).

Bladder Chemoprophylaxis Following Ureterorenoscopy in Patients with Upper Tract Urothelial Carcinoma.

Kidney-sparing procedures for upper tract urothelial carcinoma (UTUC) have evolved from imperative to elective indications for management of low-risk disease. Ureterorenoscopy is the most common procedure for the diagnosis, treatment, and surveillance of UTUC. A notable consideration following ureterorenoscopy is the higher risk of downstream bladder seeding. Here we review the importance of and scientific evidence for chemoprophylaxis after ureterorenoscopy. PATIENT SUMMARY: For patients with low-risk cancer of the upper urinary tract, a procedure called ureterorenoscopy (URS) involving insertion of a thin telescope through the ureter and into the kidney is increasingly used for biopsy. URS increases the risk of cancer seeding in the bladder. We review evidence on the benefit of prophylactic bladder chemotherapy after URS.

Supracrestal tissue esthetic management (STEM) technique and current approaches in restorative and surgical treatment of deep margins.

Carious lesions with deep margins represent a challenge in daily clinical practice. The following key points are discussed in this article: how to manage a deep margin from a restorative point of view; when and how to perform a surgical procedure; and when it is favorable to carry out definitive restoration work after surgery. The restorative materials and adhesive procedures available today allow minimally invasive techniques to be used on dental tissue with a high preservation of tooth structure. These materials and techniques help to avoid adverse periodontal tissue reactions. Depending on the clinical situation, three treatment options are available when dealing with a subgingival margin. If the depth of the cavity margin is at a maximum distance of 1.5 mm below the gingival margin, isolation with rubber dam allows the performance of interproximal margin relocation, thereby facilitating optimal restoration and periodontal tissue integration. If the margin is located deeper than 1.5 mm below the gingival margin, surgery is necessary before any restorative work can take place. When the margin is within 2 mm above the bone crest, a supracrestal tissue esthetic management (STEM) procedure is undertaken, which means that no ostectomy is required and only osteoplasty is necessary to reshape the preexisting supracrestal attachment, thereby allowing the restorative work to proceed. When the margin is less than 2 mm above the bone crest, crown lengthening with minimal ostectomy and subsequent osteoplasty becomes necessary.

Successful Percutaneous Retrieval of an Embolized Left Atrial Appendage Occluder.

A 75-year-old man with a previous mitral valve repair experienced embolization of a left atrial appendage occlusion device in the left atrium. The device was successfully retrieved using a double snaring technique, without the need for open surgery. This is an unusual report of left atrial appendage occluder retrieval, confirming the feasibility of the technique and the high flexibility of the device. (Level of Difficulty: Advanced.).

Long-term efficacy and impact on quality of life of atrial fibrillation catheter ablation in competitive athletes.

BACKGROUND: Limited data are available on the efficacy of catheter ablation (CA) for sport-associated atrial fibrillation (AF), in particular at long term follow-up. Moreover, the impact of AF CA on Quality of Life (QoL) in this population remains unknown. We aimed to determine AF CA efficacy in athletes, to assess the impact on athletes' QoL (with SF36 score) and on training capabilities in a long-term follow-up (FU). METHODS: A total of 1215 AF patients' candidates to CA between January 2007 and December 2012, were retrospectively screened. Athletes were defined as patients performing ≥5 h/week of vigorous sports, achieving a total of ≥1500 h lifetime sport activity, for at least one year before AF first symptomatic episode. RESULTS: Out of 1215 AF patients, 133 were considered competitive athletes and underwent CA. Overall, 43% of our cohort showed typical or atypical atrial flutter, which required a more extensive ablation procedure. Before AF, athletes used to practice for a mean of 8.5±2.7 h/week, while after the first AF episode the mean practice duration decreased to 2.8±2.5 h/week. At 10-year follow-up, 83% of athletes did not present any recurrent event, and training capabilities increased up to 5.6±3.6 h/week after the procedure. Moreover, intense physical activity before AF CA was related to long-term AF recurrence rates (P=0.05). QoL scores significantly improved in each single domain (P<0.05). CONCLUSIONS: AF CA represents an effective procedure to maintain sinus rhythm in athletes, with a significant improvement in QoL.

A case report of long-term successful stereotactic arrhythmia radioablation in a cardiac contractility modulation device carrier with giant left atrium, including a detailed dosimetric analysis.

Introduction: Catheter ablation (CA) is the current standard of care for patients suffering drug-refractory monomorphic ventricular tachycardias (MMVTs). Yet, despite significant technological improvements, recurrences remain common, leading to increased morbidity and mortality. Stereotactic arrhythmia radioablation (STAR) is increasingly being adopted to overcome the limitations of conventional CA, but its safety and efficacy are still under evaluation. Case presentation: We hereby present the case of a 73-year-old patient implanted with a mitral valve prosthesis, a cardiac resynchronization therapy-defibrillator, and a cardiac contractility modulation device, who was successfully treated with STAR for recurrent drug and CA-resistant MMVT in the setting of advanced heart failure and a giant left atrium. We report a 2-year follow-up and a detailed dosimetric analysis. Conclusion: Our case report supports the early as well as the long-term efficacy of 25 Gy single-session STAR. Despite the concomitant severe heart failure, with an overall heart minus planned target volume mean dosage below 5 Gy, no major detrimental cardiac side effects were detected. To the best of our knowledge, our dosimetric analysis is the most accurate reported so far in the setting of STAR, particularly for what concerns cardiac substructures and coronary arteries. A shared dosimetric planning among centers performing STAR will be crucial in the next future to fully disclose its safety profile.

Ablation Index Predicts Successful Ablation of Focal Atrial Tachycardia: Results of a Multicenter Study.

A radiofrequency energy lesion transmurality marker incorporating power, contact force, and time (Ablation Index, AI) was shown to be associated with outcomes of catheter ablation (CA) of multiple arrhythmias, but was never systematically assessed in the CA of focal atrial tachycardias (AT). We aimed to evaluate the role of AI as a predictor of outcomes in focal AT CA, and therefore, retrospectively included 45 consecutive patients undergoing CA for focal AT in four referral electrophysiology laboratories. Clinical and procedural information were collected. For each patient, maximum and mean (by averaging maximum AI values for each radiofrequency ablation lesion) AI were measured. The primary outcome was focal AT-free survival, and was systematically assessed with periodical Holter monitors or cardiac implantable electronic devices. CA was acutely effective in each case; however, 20% (n = 9) of the study population experienced a focal AT recurrence over a median follow-up of 288 days. Both maximum and mean AI values were significantly higher among patients without AT recurrences (maximum AI = 568 ± 91, mean AI = 426 ± 105) than in patients with AT relapses (maximum AI = 447 ± 142, mean AI = 352 ± 76, p = 0.036, and p = 0.028, respectively). The optimal cutoffs associated with freedom from recurrences were 461 for maximum AI (sensitivity, 0.89; specificity, 0.56) and 301 for mean AI (sensitivity, 0.97; specificity, 0.44). In a time-to-event analysis, maximum AI was significantly associated with survival free from AT recurrence (p = 0.001), whereas mean AI was not (p = 0.08). In summary, maximum AI is the best procedural parameter associated with the outcomes of CA for focal AT, and may help standardize the procedural approach.

Comparison of posterior indirect adhesive restorations (PIAR) with different preparation designs according to the adhesthetics classification. Part 1: Effects on the fracture resistance.

AIM: To investigate whether: 1) in the adhesive era, a full-crown restoration in a molar tooth is more resistant compared with an overlay-type restoration; b) a posterior indirect adhesive restoration (PIAR) is similar to a sound tooth from a mechanical point of view. MATERIALS AND METHODS: Seventy extracted molars were divided into five groups (1. Butt Joint; 2. Full Bevel; 3. Shoulder; 4. Full Crown; 5. Sound Tooth (control); N = 14) and prepared with four different PIAR overlay design types (according to an adhesthetics classification). Seven expert dentists performed all the preparation and cementation phases with codified protocols. A CAD/CAM workflow was used to realize the 56 monolithic lithium disilicate restorations. The samples were tested with thermomechanical aging (margin quality data will be given in Part 2 of this article series), and the resistance to fracture was then tested and analyzed. RESULTS AND CONCLUSIONS: In terms of fracture resistance in a situation of overload and within the limitations of the present study, it is possible to conclude that the Full Bevel group showed higher fracture strength than all the other groups. All PIAR restorations performed equally or better than the natural control tooth in the Sound Tooth group. The Full Crown group did not perform better than partial overlay PIAR. The fracture types were limited to the crown in 50% or more of the samples; the rest involved the cervical part of the root. The preparation design that involved the root the least was the Full Crown group (14%).

Comparison of posterior indirect adhesive restorations (PIAR) with different preparations designs according to the adhesthetics classification.

AIM: To investigate whether different restoration designs, overlay types, and full crowns in posterior teeth have similarly acceptable marginal sealing and quality. MATERIALS AND METHODS: For Part 1 of the present study (investigation of fracture resistance), 70 extracted molars were divided into five groups (N = 14), prepared with four different posterior indirect adhesive restoration (PIAR) overlay design types, according to the adhesthetics classification. The groups were: 1. Butt Joint; 2. Full Bevel; 3. Shoulder; 4. Full Crown; 5. Sound Tooth. For Part 2 of the study (present article; marginal quality), there was no group 5, and only 56 of the 70 extracted molars were used. Seven expert dentists performed all the preparation and cementation phases with codified protocols. A CAD/CAM workflow was used to realize the 56 monolithic lithium disilicate restorations. The samples were tested with thermomechanical loading (TML) and the marginal quality evaluated. The data relating to fracture resistance are presented in Part 1 of this study (Int J Esthet Dent 2021;16:2-17). RESULTS AND CONCLUSIONS: In terms of marginal quality after TML, within the limitations of the present study, in molar teeth (without endodontic treatments) restored with different monolithic ceramic lithium disilicate PIAR designs, it is possible to present the following conclusions.

Zero-fluoroscopy atrial fibrillation ablation in the presence of a patent foramen ovale: a multicentre experience.

INTRODUCTION: Atrial fibrillation ablation has historically been guided by fluoroscopy, with the related enhanced risk deriving from radiation. Fluoroscopy exposure may be confined to guide the transseptal puncture. Small sample size study presented a new methodology to perform a totally fluoroless atrial fibrillation ablation in the case of a patent foramen ovale (PFO). We evaluated this methodology in a large sample size of patients and a multicentre experience. METHODS AND RESULTS: Two hundred and fifty paroxysmal atrial fibrillation patients referred for first atrial fibrillation ablation with a CARTO3 electroanatomic mapping system were enrolled. In 58 out of 250 patients, a PFO allowed crossing of the interatrial septum, and a completely fluoroless ablation was performed applying the new method (Group A). In the remaining patients, a standard transseptal puncture was performed (Group B). Pulmonary vein isolation was achieved in all patients with comparable procedural and clinical outcomes at short- and long-term follow-up. CONCLUSION: The presence of a PFO may allow a completely fluoroless well tolerated and effective atrial fibrillation ablation. Probing the fossa ovalis looking for the PFO during the procedure is desirable, as it is not time-consuming and can potentially be done in every patient undergoing atrial fibrillation ablation.