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IntroductionThe assessment of the ventricular myocardial substrate critically depends on the size of mapping electrodes, their orientation with respect to wavefront propagation, and interelectrode distance. We conducted a dual-center study to evaluate the impact of microelectrode mapping in patients undergoing catheter ablation (CA) of ventricular tachycardia (VT). MethodsWe included 21 consecutive patients (median age, 68 [12], 95% male) with structural heart disease undergoing CA for electrical storm (n = 14) or recurrent VT (n = 7) using the QDOT Micro catheter and a multipolar catheter (PentaRay, n = 9). The associations of peak-to-peak maximum standard bipolar (BVc) and minibipolar (PentaRay, BVp) with microbipolar (BV mu Max) voltages were respectively tested in sinus rhythm with mixed effect models. Furthermore, we compared the features of standard bipolar (BE) and microbipolar (mu BE) electrograms in sinus rhythm at sites of termination with radiofrequency energy. ResultsBV(mu Max) was moderately associated with both BVc (beta = .85, p < .01) and BVp (beta = .56, p < .01). BV mu Max was 0.98 (95% CI: 0.93-1.04, p < .01) mV larger than corresponding BVc, and 0.27 (95% CI: 0.16-0.37, p < .01) mV larger than matching BVp in sinus rhythm, with higher percentage differences in low voltage regions, leading to smaller endocardial dense scar (2.3 [2.7] vs. 12.1 [17] cm(2), p < .01) and border zone (3.2 [7.4] vs. 4.8 [20.1] cm(2), p = .03) regions in microbipolar maps compared to standard bipolar maps. Late potentials areas were nonsignificantly greater in microelectrode maps, compared to standard electrode maps. At sites of VT termination (n = 14), mu BE were of higher amplitude (0.9 [0.8] vs. 0.4 [0.2] mV, p < .01), longer duration (117 [66] vs. 74 [38] ms, p < .01), and with greater number of peaks (4 [2] vs. 2 [1], p < .01) in sinus rhythm compared to BE. Conclusionmicroelectrode mapping is more sensitive than standard bipolar mapping in the identification of viable myocytes in SR, and may facilitate recognition of targets for CA.

Introduction Sacubitril/valsartan (ARNI) has demonstrated a significant benefit compared to angiotensin inhibitor (enalapril) in decreasing both morbidity and mortality in patients with heart failure with reduced ejection fraction (HFrEF). While. recent studies demonstrated that in HFrEF patients, ARNI decreased ventricular arrhythmias no data is available with regards to the supraventricular arrhythmic burden in HFrEF patients with an implantable cardioverter defibrillator (ICD) or cardiac resynchronisation therapy-defibrillator (CRT-D) and remote monitoring. The aim of out study was to assess if ARNI therapy was able to significantly reduce supraventricular arrhythmias. More specifically the primary endpoint was the incidence of AT/AF episodes, as detected by the device. Secondary endpoints included the total burden of AT/AF, the mean number of premature ventricular contractions (PVC) per hour and the percentage of biventricular pacing per day (in patients with CRT-D). Methods We conducted a multicentre, observational, prospective registry : the SAVE THE RHYTHM (SAacubitril Valsartan rEal-world registry evaluating THE arRHYTHMia burden in HFrEF patients with implantable cardioverter defibrillator). We enrolled all patients with HFrEF, ICD or CRT-D actively followed through remote monitoring and starting treatment with sacubitril/valsartan. All patients were followed-up for at least one year. Results At the end of enrollment, 265 patients from 5 centres had at least one sacubitril/valsartan prescription (88% males, age 68±10 years). The annual incidence of AT/AF episodes decreased from 16.6% before sacubitril/valsartan to 12.8%, 6.7% and 0.7% according to the maximum tolerated dose (24/26 mg, 49/51 mg and 97/103 mg, respectively; p=0.026). After treatment with sacubitril/valsartan, patients with at least one episode of AT/AF decreased from 32.6% to 26.5% (24/26 mg), 24.3% (49/51 mg) and 6.9% (97/103 mg); p=.041. A significant decrease in the number of PVC (-28 per hour) and in the rate of appropriate shock (-0.8% per year) were seen in patients with a previous diagnosis of paroxysmal or persistent AF. Patients with permanent AF (n=7) experienced no benefits from sacubitril/valsartan therapy in terms of arrhythmic burden reduction. Patients with a CRT device (41%) experienced a significant increase in biventricular pacing time (+3% per day). Discussion Therapy with sacubitril/valsartan could decrease arrhythmic burden in patients with non-permanent AF and HFrEF and reduce subclinical supraventricular arrhythmias in patients with no history of AF.

Catheter ablation especially in persistent atrial fibrillation has limited success. Strategies beyond pulmonary veins isolation failed to demonstrate improvement of long-term rhythm maintenance. The vein of Marshall (VOM) is a promising therapeutic target as it fit perfectly with “Coumel’s triangle”: triggers in form of focal activities or stable reentries priming atrial fibrillation comes typically from tissue surrounding the VOM, it colocalize with mitral line especially in the epicardial part difficult to approach by endocardial ablations, it contains autonomic parasympathetic and sympathetic innervation implicated in arrhythmogenesis. Epicardial chemical ablation by ethanol delivery directly inside the vein of Marshall represents an attractive therapeutic approach eliminating arrhythmic triggers and autonomic modulators and, as it colocalize with the trajectory of the mitral isthmus, completing the integrity of that linear lesion. Based on advantages provided from VOM alcoholization, this technique has been progressively introduced in addiction to standard ablation strategies in atrial fibrillation treatment. This chapter aims to describe the electrophysiological characteristics of vein of Marshall, the technical aspects of ethanol delivery and the evidences from the literature supporting the emerging role of VOM alcoholization in atrial fibrillation treatment.

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.

Cardiac amyloidosis may result in an aggressive form of heart failure (HF). Cardiac contractility modulation (CCM) has been shown to be a concrete therapeutic option in patients with symptomatic HF, but there is no evidence of its application in patients with cardiac amyloidosis. We present the case of TTR amyloidosis, where CCM therapy proved to be effective. The patient had a history of multiple HF hospitalizations due to an established diagnosis of wild type TTR-Amyloidosis with significant cardiac involvement. Since he was highly symptomatic, except during continuous dobutamine and diuretic infusion, it was opted to pursue CCM therapy device implantation. At follow up, a significant improvement in clinical status was reported with an increase of EF, functional status (6 min walk test improved from zero meters at baseline, to 270 m at 1 month and to 460 m at 12 months), and a reduction in pulmonary pressures. One year after device implantation, no other HF hospital admission was needed. CCM therapy may be effective in this difficult clinical setting. The AMY-CCM Registry, which has just begun, will evaluate the efficacy of CCM in patients with HF and diagnosed TTR amyloidosis to bring new evidence on its potential impact as a therapeutic option.

Funding Acknowledgements Type of funding sources: None. Background Sacubitril/valsartan (S/V) has demonstrated a significant benefit in decreasing mortality and morbidity in patients with heart failure with reduced ejection fraction (HFrEF) when compared to angiotensin inhibition. Recent studies demonstrated that the benefits of S/V encompass a positive cardiac remodeling, leading to a reduction of ventricular arrhythmias. The effect of S/V on the supraventricular arrhythmic burden is still unknown. Purpose To evaluate the effect of sacubitril/valsartan on the supraventricular arrhythmic burden in HFrEF patients with an implantable cardioverter defibrillator (ICD) or cardiac resynchronisation therapy-defibrillator (CRT-D) and remote monitoring. Methods The SAVE THE RHYTHM is a multicentre, observational, prospective registry is enrolling all patients with HFrEF, ICD or CRT-D actively followed through remote monitoring and starting treatment with sacubitril/valsartan. All patients are followed-up at least one year after sacubitril/valsartan start. The primary endpoint is the number of sustained atrial tachycardia or AF (AT/AF). Secondary endpoints include incidence of AT/AF in the total population, total burden of AT/AF (defined as the percentage of time in AT/AF per day), mean number of premature ventricular contractions (PVC) per hour and percentage of biventricular pacing per day (in patients with CRT-D). All primary and secondary endpoints are collected through remote monitoring. Results At the time of the second ad interim analysis, 188 patients (85.2% male, age 68 ± 10 years) were consecutively enrolled. In patients without permanent AF, treatment with S/V was associated with a reduced incidence of AT/AF episodes, which changed from 32.6% (before treatment start) to 24.3%, 20.5% and 6.9% according to the sacubitril/valsartan dose (24/26 mg, 49/51 mg and 97/103 mg respectively; p= 0.041). A significant decrease in the median annual number of AT/AF episodes was also seen in these patients (16/year before treatment; 12/year at 24/26 mg; 6/year at 49/51 mg and 1/year at 97/103 mg; p = 0.046). No significant differences were reported in terms of PVC or biventricular pacing (all p = NS). Patients with permanent AF experienced no benefits from sacubitril/valsartan therapy in terms of arrhythmic burden reduction. No new diagnosis of clinical AF was made after starting treatment with sacubitrl/valsartan in all patients. Conclusions Preliminary data suggest that therapy with S/V could reduce the episodes of AT/AF in patients with HFrEF and remote monitoring, and the benefit seems related to the maximum tolerated dose of S/V. No positive effect has been noted in patients with permanent AF.

Brugada syndrome (BrS) is a disorder characterized by cardiac conduction system dysfunctions, which increases the risk of sudden cardiac death, without heart structural alterations. The diagnosis is based on the ECG tracing analysis: BrS patients have common anomalies. The typical ECG pattern, however, can remain latent and patients can be asymptomatic: the first symptom often coincides with death. Recently, a new mutation associated with BrS has been identified and characterized by HEK 293 cells. This study aims to analyse, through numerical simulation of the O ‘Hara-Rudy (ORd) model, the mutation effects on the ventricular action potential (AP). Under normal conditions, the simulation results do not show significant alterations in the mutant AP. For this reason, we hypothesized that the pathological BrS phenotype could be triggered by other factors.

Background Cavotricuspid isthmus (CTI) radiofrequency (RF) catheter ablation is the standard treatment for patients suffering from CTI‐dependent atrial flutter (AFL). The aim of this study was to compare the use in clinical practice of 8‐mm gold‐tip catheter (8mmRFC) and open‐irrigated gold‐tip catheter (irrRFC) for RF typical AFL ablation. Methods Patients with typical AFL were treated with 8mmRFC or irrRFC catheters according to investigator preferences. The primary endpoint was the cumulative radiofrequency time (CRFT). Fluoroscopy time, acute and 6‐month success rates were secondary endpoints. Results After excluding 3 patients with left AFL, 157 of the enrolled patients (median age 71.8 [interquartile range, 64.1‐76.2], 76% men, 91% in NYHA class ≤II, 65% with no structural heart disease) were analyzed: 74 (47%) subjects were treated with the 8mmRFC and 83 (53%) with the irrRFC. The median CRFT was 3 [2‐6] minutes in the 8mmRFC group and 5 [3‐7] minutes in the irrRFC group (P = .183). There were no significant differences in ablation success rates, intraprocedural CTI reconnections, audible steam pops, and procedural times. In the 8mmRFC group, a significantly lower fluoroscopy time was observed as compared to the irrRFC group (8 [5‐12] vs 15 [10‐20] minutes, P

Background The traditional technique for subcutaneous implantable cardioverter defibrillator (S-ICD) implantation, which involves three incisions and a subcutaneous pocket, is associated with possible complications, including inappropriate interventions. The aim of this prospective multicenter study was to evaluate the efficacy and safety of an alternative intermuscular two-incision technique for S-ICD implantation. Methods The study population included 36 consecutive patients (75% male, mean age 44 ± 12 years [range 20–69]) who underwent S-ICD implantation using the intermuscular two-incision technique. This technique avoids the superior parasternal incision for the lead placement and consists of creating an intermuscular pocket between the anterior surface of the serratus anterior and the posterior surface of the latissimus dorsi muscles instead of a subcutaneous pocket. Results All patients were successfully implanted in the absence of any procedure-related complications with a successful 65-J standard polarity defibrillation threshold testing, except in one, who received a second successful shock after pocket revision. During a mean follow-up of 10 months (range 3–30), no complications requiring surgical revision were observed. At device interrogation, stable sensing without interferences was observed in all patients. Two patients (5.5%) experienced appropriate and successful shock on ventricular fibrillation and in four patients (11%), a total of seven nonsustained self-terminated ventricular tachycardias were correctly detected. No inappropriate interventions were observed. Conclusions Our experience suggests that the two-incision intermuscular technique is a safe and efficacious alternative to the current technique for S-ICD implantation that may help reducing complications including inappropriate interventions and offer a better cosmetic outcome, especially in thin individuals.

Background: Brugada syndrome (BrS) is a cardiac disorder characterized by conduction abnormalities that can lead to sudden death; syncope and cardiac arrest are clinical manifestations which are often associated with an enhancement of the vagal activity. Mutations in the SCN5A gene (Na v 1.5 channel) are the most common cause of the inherited forms of BrS. Objective: To characterize the functional behavior of mutant Na v 1.5 channels expressing a novel heterozygous mutation (S805L) recently identified in an Italian family affected by the BrS. Methods: HEK cells were used as experimental model to express both the wild-type (WT) and the mutated S805L channels (alone, Homo or in combination, Hetero) and the accessory β-subunit (SCN1B). Patch-clamp and western blot experiments were carried out to assess the dysfunctional role of the mutation. Results: When compared to the WT current, the S508L mutation significantly (P&It0.05) decreases the peak current density by about 65% for the Homo condition (WT: -120.2±10.2, n=28); Homo: -40.3±4.2, n=16) and by 35% for the Hetero condition (Hetero: -78.2±8.3, n=27). Densitometric analysis carried out on western blot data further support the conclusion that S805L channels are less abundant in the plasma membrane. We also observed that the S805L mutation positively shifts the V½ values of the voltage dependence of the inactivation of both Homo and Hetero currents (V½: WT -85.5±0.2 mV, n=55; Homo -80.9±0.3 mV, n=22; Hetero -81.9±0.2 mV, n=25; P&It0.05); a positive shift of the V½ of the activation was also observed but only in the Homo condition (V½: WT -33.0±0.4 mV, n=28; Homo -30.0±0.5, n=16, P&It0.05). The kinetics of recovery from inactivation and the amplitude of the late sodium current were also evaluated but they were unaffected by the mutation. Conclusion: When expressed in the Hetero condition, the S805L mutation causes a reduction in the channel expression, however, the positive shift of the inactivation curve suggests an increase in Na channel availability. We thus believe that the precise quantitative balance between these two phenomena and their relation with vagal activity may underlie the clinical manifestation of the disease.

The traditional technique for subcutaneous implantable cardioverter defibrillator (S-ICD) implantation, which involves three incisions and a subcutaneous pocket, is associated with possible complications, including inappropriate interventions. The aim of this prospective multicenter study was to evaluate the efficacy and safety of an alternative intermuscular two-incision technique for S-ICD implantation.The study population included 36 consecutive patients (75% male, mean age 44 ± 12 years [range 20-69]) who underwent S-ICD implantation using the intermuscular two-incision technique. This technique avoids the superior parasternal incision for the lead placement and consists of creating an intermuscular pocket between the anterior surface of the serratus anterior and the posterior surface of the latissimus dorsi muscles instead of a subcutaneous pocket.All patients were successfully implanted in the absence of any procedure-related complications with a successful 65-J standard polarity defibrillation threshold testing, except in one, who received a second successful shock after pocket revision. During a mean follow-up of 10 months (range 3-30), no complications requiring surgical revision were observed. At device interrogation, stable sensing without interferences was observed in all patients. Two patients (5.5%) experienced appropriate and successful shock on ventricular fibrillation and in four patients (11%), a total of seven nonsustained self-terminated ventricular tachycardias were correctly detected. No inappropriate interventions were observed.Our experience suggests that the two-incision intermuscular technique is a safe and efficacious alternative to the current technique for S-ICD implantation that may help reducing complications including inappropriate interventions and offer a better cosmetic outcome, especially in thin individuals.

Background— Remote magnetic navigation–guided ablation with 3-dimensional (3D)-image integration could provide maximum benefit in patients with complex anatomy. We reviewed supraventricular tachycardia (SVT) ablation in adult patients with congenital heart disease to assess the contribution of these technologies. Methods and Results— One hundred fifty-four SVT ablation procedures (228 SVTs) using a 3D-electroanatomic mapping system in 116 adult patients with congenital heart disease (mean age, 41; 76 male) were classified into 3 groups: Group A, manual mapping/ablation (n=60 procedures); Group B, remote magnetic navigation–guided mapping/ablation with normal femoral vein access (49); and Group C, remote magnetic navigation–guided mapping/ablation with difficult access (45). Group A included simple anomalies with less SVTs. Group B comprised predominantly Fontan patients with more SVTs. Group C included more complex defects, such as intra-atrial baffle or interrupted inferior venous access, in which retrograde aortic and superior venous accesses were used exclusively with more frequent use of image integration (97.8%; P P =0.370). In group C, fluoroscopy time was the shortest (median, 4.2 min; P P P =0.787) during a mean 20-months follow-up period. Conclusions— The combination of remote magnetic navigation, 3D-image integration, and electroanatomic mapping system facilitated safe and feasible ablation with very low fluoroscopy exposure even in patients with complex anomalies.

Background: Although indexed left atrial volume (iLAV) is the most accurate measure of left atrial size, it has not been evaluated prospectively as predictor of recurrence of atrial fibrillation (AFib) after successful cardioversion (CV). Methods: We prospectively selected 76 patients (mean age 66.1 ± 13.6 years, 65.8% men) with AFib who underwent successful CV. Baseline clinical and echocardiographic characteristics were obtained before CV. LAV was measured using Simpson's method and indexed to body surface area. All patients were scheduled for follow-up visit at 1, 6, 12 months, and then annually. A 24-hour Holter ECG was performed within 6 months and each time the patients reported symptoms suggestive of arrhythmia. Results: The 52 patients (68.4%) with AFib recurrence had larger iLAV (35.5 ± 8.9 mL/m2 vs 27.0 ± 6.7 mL/m2, P < 0.001). Anteroposterior LA diameter was not associated with AFib relapse (OR 1.08, 95% CI: 0.96–1.21, P = 0.09). Each unit increase in iLAV was associated with a 1.15-fold increased risk of recurrence (OR 1.15, 95% CI: 1.06–1.25, P < 0.001). In a multivariable model, iLAV remained the only independent predictor of relapse (adjusted OR 1.14, 95% CI: 1.02–1.28, P = 0.02). The area under ROC curves, generated to compare LA diameter, and iLAV as predictors of AFib recurrence were 0.56 (SE 0.07) versus 0.78 (SE 0.05), respectively (P = 0.003). Conclusion: This is the first prospective study to show that larger iLAV, as a more accurate measure of LA remodeling than anteroposterior diameter, is strongly and independently associated with a higher risk of AFib recurrence after CV. (Echocardiography 2012;29:276-284)

Luigi Padeletti1, Giosuè Mascioli2, Alessandro Paoletti Perini1, Gino Grifoni1, Laura Perrotta1, Procolo Marchese3, Luca Bontempi3, Antonio Curnis31Istituto di Clinica Medica e Cardiologia, Università degli Studi di Firenze, Italia; 2Elettrofisiologia, Istituto Humanitas Gavazzeni, Bergamo, Italia; 3Elettrofisiologia, Spedali Civili, Brescia, ItaliaAbstract: Population aging and broader indications for the implant of cardiac implantable electronic devices (CIEDs) are the main reasons for the continuous increase in the use of pacemakers (PMs), implantable cardioverter-defibrillators (ICDs) and devices for cardiac resynchronization therapy (CRT-P, CRT-D). The growing burden of comorbidities in CIED patients, the greater complexity of the devices, and the increased duration of procedures have led to an augmented risk of infections, which is out of proportion to the increase in implantation rate. CIED infections are an ominous condition, which often implies the necessity of hospitalization and carries an augmented risk of in-hospital death. Their clinical presentation may be either at pocket or at endocardial level, but they can also manifest themselves with lone bacteremia. The management of these infections requires the complete removal of the device and subsequent, specific, antibiotic therapy. CIED failures are monitored by competent public authorities, that require physicians to alert them to any failures, and that suggest the opportune strategies for their management. Although the replacement of all potentially affected devices is often suggested, common practice indicates the replacement of only a minority of devices, as close follow-up of the patients involved may be a safer strategy. Implantation of a PM or an ICD may cause problems in the patients' psychosocial adaptation and quality of life, and may contribute to the development of affective disorders. Clinicians are usually unaware of the psychosocial impact of implanted PMs and ICDs. The main difference between PM and ICD patients is the latter's dramatic experience of receiving a shock. Technological improvements and new clinical evidences may help reduce the total burden of shocks. A specific supporting team, providing psychosocial help, may contribute to improving patient quality of life.Keywords: pacemaker, cardiac cardioverter-defibrillator, cardiac implantable electronic devices, infection, recall, quality of life&nbsp

Aims We analysed the type and mechanism of supraventricular arrhythmias encountered in a series of symptomatic adults with atrial isomerism undergoing catheter ablation procedures. Methods and results The study population included consecutive adults with atrial isomerism who had previously undergone surgical repair or palliation of the associated anomalies. Patients underwent electrophysiological study for symptomatic arrhythmia in our institution between 2010 and 2012 using magnetic navigation in conjunction with CARTO RMT and three-dimensional (3D) image integration. Eight patients (five females) with a median age of 33 years [interquartile range (IQR) 24–39] were studied. Access to the cardiac chambers of interest was obtained retrogradely via the aorta using remotely navigated magnetic catheters in six patients. Radiofrequency ablation successfully targeted twin atrioventricular (AV) nodal reentrant tachycardia in two patients, atrial fibrillation (AF) in three, focal atrial tachycardia (AT) mainly originating in the left-sided atrium in four patients, and macro-reentrant AT dependent on a right-sided inferior isthmus in three patients. The median fluoroscopy time was 3.0 min (IQR 2–11). After a median follow-up of 10 months (IQR 6–21), five of the ablated patients are free from arrhythmia; two patients experienced episodes of self-terminated AF and AT, respectively, within one month post-ablation; the remaining patient had only non-sustained AT during the electrophysiological study and was managed medically. Conclusion Various supraventricular tachycardia mechanisms are possible in adults with heterotaxy syndrome, all potentially amenable to radiofrequency ablation. The use of remote magnetic navigation along with 3D mapping facilitated the procedures and resulted in a short radiation time.

Aims Atrial fibrillation (AFib) induces remodelling of the left atrium (LA). Indexed LA volume (iLAV) as more accurate measure of LA size has not been evaluated as predictor of recurrence of AFib after cardioversion. Methods and results We identified 411 adults (mean age 64.1 ± 11.4 years, 34.5% women) who underwent successful cardioversion and with no history of other atrial arrhythmia, stroke, congenital heart disease, valvular dysfunction, surgery, thyroid dysfunction, acute or chronic inflammatory disease, and pacemaker. All echocardiographic data were retrieved from the laboratory database. iLAV was measured off-line using Simpson's method. Clinical characteristics and recurrence of clinical AFib were determined by review of medical records. Patients with scheduled follow-up of at least 6 months were included. About 250 patients (60.8%) developed AFib recurrence after a median (25th–75th percentile) follow-up of 345.0 (210.0–540.0) days. Patients with AFib recurrence had significantly greater iLAV than patients without AFib recurrence (39.7 ± 8.4 vs. 31.4 ± 4.6, P < 0.001). Each mL/m2 increase in iLAV was associated with a 30% increased risk of AFib recurrence [odds ratio (OR) 1.30, confidence interval (CI) 1.23–1.38, P < 0.001]. In a multivariable model, each mL/m2 increase in iLAV was independently associated with a 21% increase in the risk of AFib recurrence (OR 1.21, CI 1.11–1.30, P < 0.001). The areas under receiver operating characteristic curves, generated to compare LA diameter and iLAV as predictors of AFib recurrence, were 0.59 ± 0.3 and 0.85 ± 0.2, respectively ( P < 0.001). Conclusion The present study is the first to show that larger iLAV before cardioversion, as a more accurate measure of LA remodelling than LA diameter, is strongly and independently associated with higher risks of AFib recurrence.

Purpose Although rare, children and young adults can suffer from significant cardiac arrhythmia, especially in the context of congenital malformations and after cardiac surgery. Methods A total of 62 patients (32 female, median age 20 years) underwent an invasive electrophysiology study between 2008–2011: half had normal cardiac anatomy, whereas the remaining patients had various types of congenital heart disease. All patients were treated using either conventional techniques (CVN) or remote magnetic navigation (RMN). Results Patients treated with the RMN system differed substantially from patients in the CVN group with respect to presence of congenital heart disease (67 % vs. 37 %), previous cardiac surgery (59 % vs. 20 %) or failed previous conventional ablation (22 % vs. 9 %), respectively. Although these more complex arrhythmias resulted in longer median procedure duration (180 vs. 130 min, p = 0.034), the median overall fluoroscopy exposure in the RMN group was significantly lower (4.1 vs. 5.2 min, p = 0.020). Clinical outcome was comparable in both groups without complications caused by the ablation. Conclusions Catheter ablation using remote magnetic navigation is safe and feasible in children and young adults and is especially valuable in patients with abnormal cardiac morphologies. RMN resulted in significantly lower radiation exposure compared with the conventional technique.