Relação entre Gordura Epicárdica e Fibrilação Atrial Não Pode Ser Totalmente Explicada pela Fibrose Atrial Esquerda / The Relationship between Epicardial Fat and Atrial Fibrillation Cannot Be Fully Explained by Left Atrial Fibrosis

Resumo Fundamento O tecido adiposo epicárdico (TAE) tem sido associado à fibrilação atrial (FA), mas seus mecanismos fisiopatológicos permanecem obscuros. Objetivos Medir a correlação entre TAE e fibrose do átrio esquerdo (AE), e avaliar sua capacidade de prever recidiva após o isolamento da veia pulmonar (IVP). Métodos Pacientes com FA inscritos para um primeiro procedimento de IVP foram submetidos à tomografia computadorizada (TC) cardíaca e ressonância magnética cardíaca (RMC) em menos de 48 horas. Quantificou-se o TAECE em imagens de TC realçadas com contraste no nível do tronco da coronária esquerda. Quantificou-se a fibrose do AE em RMC tridimensional com realce tardio isotrópico de 1,5 mm. Após o isolamento da veia pulmonar (IVP), os pacientes foram submetidos a seguimento para checar a recidiva da FA. A significância estatística foi definida com p<0,05. Resultados A maioria dos 68 pacientes (46 homens, idade 61±12 anos) tinha FA paroxística (71%, n=48). Os pacientes apresentavam volume TAECE mediano de 2,4 cm3/m2 (intervalo interquartil [IIQ] 1,6-3,2 cm3/m2) e um volume médio de fibrose do AE de 8,9 g (IIQ 5-15 g). A correlação entre TAECE e fibrose do AE foi estatisticamente significativa, mas fraca (coeficiente de correlação de postos de Spearman = 0,40, p=0,001). Durante um seguimento médio de 22 meses (IIQ 12-31), 31 pacientes (46%) tiveram recidiva da FA. A análise multivariada produziu dois preditores independentes de recidiva da FA: TAECE (FC 2,05, IC de 95% 1,51-2,79, p<0,001) e FA não paroxística (FC 2,36, IC de 95% 1,08-5,16, p=0,031). Conclusão A correlação fraca entre TAE e AE sugere que a fibrose do AE não é o principal mecanismo que liga o TAE e a FA. O TAE mostrou-se mais fortemente associado à recidiva da FA do que à fibrose do AE, corroborando a existência de outros mediadores mais importantes do TAE e da FA.

Abstract Background Epicardial adipose tissue (EAT) has been associated with atrial fibrillation (AF), but its pathophysiological mechanisms remain unclear. Objectives To measure the correlation between EAT and left atrium (LA) fibrosis, and to assess their ability to predict relapse after pulmonary vein isolation (PVI). Methods Patients with AF enrolled for a first PVI procedure underwent both cardiac computerized tomography (CT) and cardiac magnetic resonance (CMR) imaging within less than 48 hours. EATLMwas quantified on contrast-enhanced CT images at the level of the left main. LA fibrosis was quantified on isotropic 1.5 mm 3D delayed enhancement CMR. After pulmonary vein isolation (PVI), patients were followed up for AF relapse. Statistical significance was set at p<0.05. Results Most of the 68 patients (46 men, age 61±12 years) had paroxysmal AF (71%, n=48). Patients had a median EATLMvolume of 2.4 cm3/m2(interquartile range [IQR] 1.6-3.2 cm3/m2), and a median amount of LA fibrosis of 8.9 g (IQR 5-15 g). The correlation between EATLMand LA fibrosis was statistically significant but weak (Spearman's R=0.40, p=0.001). During a median follow-up of 22 months (IQR 12-31), 31 patients (46%) had AF relapse. Multivariate analysis yielded two independent predictors of AF relapse: EATLM(HR 2.05, 95% CI 1.51-2.79, p<0.001), and non-paroxysmal AF (HR 2.36, 95% CI 1.08-5.16, p=0.031). Conclusion The weak correlation between EAT and LA suggests that LA fibrosis is not the main mechanism linking EAT and AF. EAT was more strongly associated with AF relapse than LA fibrosis, supporting the existence of other more important mediators of EAT and AF.

Catheter ablation of atrial fibrillation in patients with hypertrophic cardiomyopathy: a European observational multicentre study.

AIMS: Atrial fibrillation (AF) is common in hypertrophic cardiomyopathy (HCM). Data on the efficacy of catheter ablation of AF in HCM patients are sparse. METHODS AND RESULTS: Observational multicentre study in 137 HCM patients (mean age 55.0 ± 13.4, 29.1% female; 225 ablation procedures). We investigated (i) the efficacy of catheter ablation for AF beyond the initial 12 months; (ii) the available risk scores, stratification schemes and genotype as potential predictors of arrhythmia relapse, and (iii) the impact of cryoballoon vs. radiofrequency in procedural outcomes. Mean follow-up was 43.8 ± 37.0 months. Recurrences after the initial 12-month period post-ablation were frequent, and 24 months after the index procedure, nearly all patients with persistent AF had relapsed, and only 40% of those with paroxysmal AF remained free from arrhythmia recurrence. The APPLE score demonstrated a modest discriminative capacity for AF relapse post-ablation (c-statistic 0.63, 95% CI 0.52-0.75; P = 0.022), while the risk stratification schemes for sudden death did not. On multivariable analysis, left atrium diameter and LV apical aneurysm were independent predictors of recurrence. Fifty-eight patients were genotyped; arrhythmia-free survival was similar among subjects with different gene mutations. Rate of procedural complications was high (9.3%), although reducing over time. Outcome for cryoballoon and radiofrequency ablation was comparable. CONCLUSION: Very late AF relapses post-ablation is common in HCM patients, especially in those with persistent AF. Left atrium size, LV apical aneurysm, and the APPLE score might contribute to identify subjects at higher risk of arrhythmia recurrence. First-time cryoballoon is comparable with radiofrequency ablation.

Analysis of a 10-year period of lead removal in a referral centre.

OBJECTIVES: Our goal was to analyse all lead extraction procedures (transvenous or open surgery) performed in our centre and the short- and long-term follow-up data from these patients. METHODS: All lead extractions performed from 2008 to 2017 were retrospectively reviewed for patient characteristics and indications for device implantation; indications for lead extraction; techniques used; peri- and postprocedural complications and short- and long-term follow-up data. RESULTS: A total of 159 patients (282 leads) were included [age 70 (62-78) years; 72% men]. The median follow-up time was 57 (25-90) months. Patients with lead explants were excluded. The most common indication for lead removal was infection (77%). A surgical approach was necessary in 14 patients (9%) owing to unsuccessful transvenous removal (n = 3), large vegetation in the lead (n = 4), concomitant valvular endocarditis (n = 2), other indications for open surgery (n = 4) and complicated transvenous removal (n = 1). Removal was tried for 282 leads. Of those, 256 were completely removed. Clinical success was achieved in 155 individual patients (98%). Complications occurred in 6 patients: 3 persistent infections, 1 stroke and 2 blood vessel ruptures. The procedure-related mortality rate was 2% (n = 3). CONCLUSIONS: Lead removal was associated with a high success rate and low all-cause complication and mortality rates. Emergency surgery because of acute complications was rare, and open-heart surgery was most frequently elective and not associated with a worse outcome.

Atrioventricular node reentrant tachycardia: Remote magnetic navigation ablation versus manual ablation - impact on operator fluoroscopy time.

INTRODUCTION AND AIMS: Remote magnetic navigation systems have demonstrated benefits in the ablation of difficult substrates. Their role in the ablation of atrioventricular nodal reentrant tachycardia (AVNRT), however, has only been studied in small patient series. The aim of this study was to compare the results of AVNRT ablation using magnetic navigation, in a center where every procedure is performed with this system, with manual ablation. METHODS: We selected 139 consecutive patients undergoing AVNRT ablation with magnetic navigation by a single operator between January 2009 and June 2016 and compared them to a group of 101 consecutive patients undergoing manual ablation in the same period by the same operator in another hospital. The methodology was the same in both groups. Success rates, complications, procedure time, radiofrequency time, total and operator fluoroscopy time, and recurrence rates were compared. RESULTS: There were no differences in success and complication rates. Procedure and total fluoroscopy times were not significantly different, but operator fluoroscopy time was significantly shorter with the magnetic navigation system (2.4±1.5 min vs. 7.2±4 min; p<0.001). The recurrence rate was higher in the manual group, although without statistical significance. CONCLUSIONS: The ablation of AVNRT with magnetic navigation is feasible using the same methodology as for manual ablation. Success and complication rates were similar. Operator fluoroscopy time was significantly less with the magnetic navigation system.

Cardiac computed tomography previous to atrial fibrillation ablation - effects of technological improvements and protocol optimization. / Tomografia computorizada cardíaca prévia a ablação de fibrilhação auricular ­ efeitos da evolução tecnológica e otimização de protocolos.

BACKGROUND: Cardiac computed tomography (CT) can provide a precise tridimentional anatomic map and exclude intra-cardiac thrombus. We aimed to access the impact of CT protocol optimization and technological evolution on the contrast and radiation dose as well as on image quality previous to atrial fibrillation (AF) ablation. METHODS: From a prospective registry of consecutive patients who underwent cardiac CT in a single center, we selected 270 patients in whom the CT was done for evaluation prior to AF ablation and they were distributed in 3 groups: Group1: the first 150 patients included; Group2: the last 60 patients performed with the same CT scanner; Group3: the first 60 exams performed with the new CT scanner. Quality of the protocol was access based on radiation dose, contrast volume used, the use of a second (delayed) acquisition, and on quantitative image quality analisis (signal to noise and contrast to noise ratios; density homogeneity racio between LA and LAA). RESULTS: We found a significant radiation dose as well as contrast dose reduction between the first and last subgroups (G1: 5,6mSv and 100ml; G2: 1,3mSv and 90ml; G3: 0,6mSv and 65ml). Even though group 3 had less radiation and contrast used it still had better quantitative image quality (signal/noise of 13,5; contrast/noise 14,8; density homogeneity racio of 0,92). CONCLUSION: Protocol optimization and technology both contributed to significant lower radiation dose and contrast volume used on cardiac CTs prior to AF ablation, without compromising image quality.

Impact of prophylactic cavotricuspid isthmus ablation in atrial fibrillation recurrence after a first pulmonary vein isolation procedure.

INTRODUCTION: PVI is a well-established therapy for patients with drug refractory atrial fibrillation (AF). However, it remains unclear whether prophylactic cavotricuspid isthmus (CTI) ablation at the time of PVI improves long-term freedom from AF. OBJECTIVE: To compare the outcomes of patients who underwent PVI alone vs. PVI + prophylactic CTI ablation. METHODS: Propensity score (PS) matching analysis based on a registry dataset of 1931 consecutive patients who underwent a first AF catheter ablation. After excluding those with documented/inducible atrial flutter (n = 233), 1698 individuals were available for matching. Following adjustment for age, gender, body mass index (BMI), hypertension, smoking, diabetes, LA volume, type of AF, and type of navigation (magnetic vs. manual), PS matched 411 patients who underwent PVI + CTI ablation with 411 receiving PVI alone. RESULTS: PS analysis yielded a study population of 822 matched patients (58 ±â€¯11 years, 69% males, 64% with paroxysmal AF). Over a median 2 years follow-up period there were 278 AF recurrences (34%). Survival free of AF (Log rank p = .965) and annual relapse rates were similar in the two groups - 10.9%/year vs 10.1%/year (PVI vs PVI + CTI, respectively, p = .97). CTI ablation remained unassociated with AF-free survival (HR 1.09, 95%CI: 0.84-1.41, p = .54) after Cox regression adjustment for age, sex, type of AF, LA volume, hypertension, diabetes, BMI and center. Female gender, current smoking, indexed LA volume and non-paroxysmal AF were identified as independent predictors of relapse after matching. CONCLUSIONS: Prophylactic CTI ablation at the time of a first PVI does not seem to improve long-term freedom from AF.

Development and validation of a risk score for predicting atrial fibrillation recurrence after a first catheter ablation procedure - ATLAS score.

Aims: Several predictors of relapse after catheter ablation of atrial fibrillation (AF) have been established, but assessing each patient's individual risk remains challenging. Our aim was to develop and validate a score to estimate the risk of AF recurrence after the first radiofrequency pulmonary vein isolation (PVI) procedure. Methods and results: Independent predictors of AF relapse were identified retrospectively in a two-centre registry of 1934 patients who underwent a first PVI procedure. Using the Cox regression hazard ratios of designated variables, a risk score was developed in a random sample of 50% of the patients (development cohort) and validated in the remaining (validation cohort) half. The accuracy and discriminative power of the predictive model were assessed in both subgroups. During a follow-up of 4.2 ± 2.7 years, 522 patients (27%) relapsed. Five independent predictors of AF recurrence were identified and included in the score: age >60 years (1 point), female sex (4 points), non-paroxysmal AF (2 points), current smoking (7 points) and indexed left atrial volume (1 point for each 10 mL/m2). The score showed good discriminative power (censored c-statistic of 0.75 in both cohorts). In the development group, AF relapse rates were 8, 11, and 17%/year for low (<6 points), intermediate (6-10 points), and high-risk patients (>10 points), respectively (P < 0.001). In the validation group, AF recurrence rates were 8, 11, and 18%/year, respectively (P < 0.001). Conclusion: A simple risk score to estimate the rate of AF recurrence after ablation was developed and validated. An external assessment of its usefulness as a patient selection tool seems warranted.

Adenosine-guided pulmonary vein isolation versus conventional pulmonary vein isolation in patients undergoing atrial fibrillation ablation: An updated meta-analysis.

BACKGROUND: Recurrent atrial fibrillation episodes following pulmonary vein isolation (PVI) are frequently due to reconnection of PVs. Adenosine can unmask dormant conduction, leading to additional ablation to improve AF-free survival. We performed a meta-analysis of the literature to assess the role of adenosine testing in patients undergoing atrial fibrillation (AF) ablation. METHODS: PubMed, EMBASE, and Cochrane databases were searched through until December 2015 for studies reporting on the role of adenosine guided-PVI versus conventional PVI in AF ablation. RESULTS: Eleven studies including 4099 patients undergoing AF ablation were identified to assess the impact of adenosine testing. Mean age of the population was 61±3years: 25% female, 70% with paroxysmal AF. Follow up period of 12.5±5.1months. A significant benefit was observed in the studies published before 2013 (OR=1.75; 95%CI 1.32-2.33, p<0.001, I2=11%), retrospective (OR=2.05; 95%CI 1.47-2.86, p<0.001, I2=0%) and single-centre studies (OR=1.58; 95%CI 1.19-2.10, p=0.002, I2=30%). However, analysis of studies published since 2013 (OR=1.41; 95% CI 0.87-2.29, p=0.17, I2=75%) does not support any benefit from an adenosine-guided strategy. Similar findings were observed by pooling prospective case-control (OR=1.39; 95%CI 0.93-2.07, p=0.11, I2=75%), and prospective randomized controlled studies (OR=1.62; 95%CI 0.81-3.24, p=0.17, I2=86%). Part of the observed high heterogeneity can be explained by parameters such as dormant PVs percentage, use of new technology, improvement of center/operator experience, patients' characteristics including gender, age, and AF type. CONCLUSIONS: Pooling of contemporary data from high quality prospective case-control & prospective randomized controlled studies fails to show the benefit of adenosine-guided strategy to improve AF ablation outcomes.

Safety and Long-Term Outcomes of Catheter Ablation of Atrial Fibrillation Using Magnetic Navigation versus Manual Conventional Ablation: A Propensity-Score Analysis.

INTRODUCTION: Whether or not the potential advantages of using a magnetic navigation system (MNS) translate into improved outcomes in patients undergoing atrial fibrillation (AF) ablation is a question that remains unanswered. METHODS AND RESULTS: In this observational registry study, we used propensity-score matching to compare the outcomes of patients with symptomatic drug-refractory AF who underwent catheter ablation using MNS with the outcomes of those who underwent catheter ablation using conventional manual navigation. Among 1,035 eligible patients, 287 patients in each group had similar propensity scores and were included in the analysis. The primary efficacy outcome was the rate of AF relapse after a 3-month blanking period. At a mean follow-up of 2.6 ± 1.5 years, AF ablation with MNS was associated with a similar risk of AF relapse as compared with manual navigation (18.4% per year and 22.3% per year, respectively; hazard ratio 0.81, 95% CI 0.63-1.05; P = 0.108). Major complications occurred in two patients (0.7%) using MNS, and in six patients (2.1%) undergoing manually navigated ablation (P = 0.286). Fluoroscopy times were 21 ± 10 minutes in the manual navigation group, and 12 ± 9 minutes in the MNS group (P < 0.001), whereas total procedure times were 152 ± 52 minutes and 213 ± 58 minutes, respectively (P < 0.001). CONCLUSIONS: In this propensity-score matched comparison, magnetic navigation and conventional manual AF ablations seem to have similar relapse rates and a similar risk of complications. AF ablations with magnetic navigation take longer to perform but expose patients to significantly shorter fluoroscopy times.

Natural history of Brugada syndrome in a patient with congenital heart disease.

Risk stratification of sudden death in patients with Brugada syndrome (BrS) is a controversial issue, and there is currently no consensus on the best method. Examination of data from the natural history of the disease is of fundamental importance and may help to identify relatives at risk. At the same time, study of the genetic mutations responsible for the disease may also contribute to risk stratification of the syndrome, enabling identification of asymptomatic relatives carrying mutations. This paper presents the case of a young man, aged 26, monitored as a pediatric cardiology outpatient from birth for a simple structural heart defect not requiring surgery. Analysis of the evolution of the patient's electrocardiogram revealed the appearance, at the age of 20, of a pattern compatible with type I BrS. Following an episode of syncope and induction of polymorphic ventricular tachycardia in the electrophysiological study, a cardioverter-defibrillator was implanted. One year later, a single shock terminated an episode of ventricular fibrillation. A molecular study of the SCN5A gene identified a rare mutation, c.3622G>T (p.Glu1208X), recently described and associated with more severe phenotypes in patients with BrS, as in the case presented.

Subcutaneous implantable cardioverter-defibrillator: Initial experience.

BACKGROUND: Implantable cardioverter-defibrillators (ICDs) are important tools in the prevention of sudden death, but implantation requires transvenous access, which is associated with complications. Subcutaneous implantable cardioverter-defibrillators (S-ICDs) may prevent some of these complications. AIM: To evaluate the therapeutics and complications associated with S-ICD systems. METHODS: S-ICD implantation was planned in 23 patients, for whom the indications were vascular access problems, increased risk of infection or young patients with long predicted follow-up. The population consisted of four patients with ischemic heart disease, three of them on hemodialysis (two with subclavian vein thrombosis), five with left ventricular noncompaction, four with Brugada syndrome, three with arrhythmogenic right ventricular cardiomyopathy, one with transposition of the great vessels, two with dilated cardiomyopathy and four with hypertrophic cardiomyopathy. RESULTS: S-ICDs were implanted in 21 patients, two having failed to fulfil the initial screening criteria. Mean implantation time was 77 minutes, with no complications. Defibrillation tests were performed, and in one patient the generator had to be repositioned to obtain an acceptable threshold. In a mean follow-up of 14 months, 10 patients had S-ICD shocks, which were appropriate in half of them; one developed infection, one needed early replacement due to loss of telemetry and one patient died of noncardiac cause. CONCLUSIONS: S-ICD implantation can be performed by cardiologists with a high success rate. Initial experience appears favorable, but further studies are needed with longer follow-up times to assess the safety and efficacy of this strategy compared to conventional devices.

Percutaneous endocardial occlusion of incompletely surgically ligated left atrial appendage.

INTRODUCTION: Surgical ligation of the left atrial appendage is considered standard of care in patients who undergo mitral valve surgery or as an adjunct to a surgical Maze procedure for treatment of atrial fibrillation (AF). However, several studies have demonstrated that this can result in incompletely surgically ligated left atrial appendage (ISLL) in a significant number of patients. It is believed that ISLL may in turn promote thrombus formation and lead to clinically relevant thromboembolic events. A novel approach for percutaneous endocardial occlusion of ISLL is described. METHODS AND RESULTS: Seven patients with AF and ISLL following prior open-chest, surgical suture ligation in the absence of rheumatic heart disease, underwent percutaneous endocardial ISLL occlusion using an Amplatzer Septal Occluder device guided by fluoroscopy and transesophageal echocardiography through a novel approach. Three patients were diagnosed in the setting of acute embolic stroke, 2 at the time of cardiac arrhythmia ablation and 2 by elective precardioversion transesophageal echocardiography. All patients were treated with oral anticoagulation therapy. Acute and long-term ISLL occlusion was successfully achieved in 6 patients, in whom oral anticoagulation was eventually discontinued without any embolic events during 10 ± 2 months of follow-up. CONCLUSION: Percutaneous endocardial occlusion of ISLL is feasible using an Amplatzer Septal Occluder device. Additional studies are required to evaluate the long-term safety and efficacy of this therapeutic treatment strategy in patients with ISLL.

Resting heart rate is a powerful predictor of arrhythmic events in patients with dilated cardiomyopathy and implantable cardioverter-defibrillator.

UNLABELLED: Patients with dilated cardiomyopathy and implantable cardioverter-defibrillator (ICD) are a high-risk group for arrhythmias. They regularly undergo cardiopulmonary exercise testing (CPET) to assess cardiac reserve and to guide clinical decisions or therapeutic adjustments. Data from previous studies demonstrate that prognosis in patients with heart failure (HF) worsens with the presence of appropriate shocks. OBJECTIVE: The purpose of this study was to evaluate the value of CPET parameters to predict shocks and other arrhythmic events in HF patients with ICD, in order to identify a high-risk group for arrhythmias. METHODS: This was a prospective single-center registry of 61 consecutive patients (mean age 55 +/- 15 years, 18% female), with dilated cardiomyopathy (ischemic etiology in 57%) and ICD, who underwent symptom-limited maximal CPET six months or less before device implantation. Minimum follow-up was 180 days. The primary endpoint was appropriate shock and the composite endpoint was appropriate shock and/or ventricular fibrillation (VF) and/or sustained ventricular tachycardia (VT), which were then correlated with hemodynamic variables (heart rate and blood pressure) and CPET parameters. RESULTS: During a mean follow-up of 27 months, eight patients died (13%), two of them from arrhythmic cause (3.3%), and 16 (26%) patients received at least one appropriate ICD shock, eight (13%) due to VF. Sustained VT was recorded in 23 patients (38%) and nonsustained VT in 42 patients (69%). CPET showed that the group with the primary end point had lower peak VO2, anaerobic threshold and chronotropic reserve. On multivariate analysis, resting heart rate was the only independent predictor of appropriate shock (HR 1.06; 95% CI 1.01-1.10; p = 0.025). Univariate analysis identified peak VO2, anaerobic threshold, VE/VCO2 slope, resting heart rate and heart rate decrease during the first minute of recovery, and systolic blood pressure during exercise as predictive of the composite endpoint (shock/VF/sustained VT). Multivariate analysis identified resting heart rate and peak VO2 as independent predictors, with HR 1.04; 95% CI 1.00-1.09 (p = 0.050) and HR 0.88; 95% CI 0.78-0.98 (p = 0.026), respectively. The best cut-off for resting heart rate to predict the composite and primary endpoints was > 76 bpm (area under the ROC curve: 0.67; 95% CI 0.53-0.78 and 0.65; 95% CI 0.51-0.76, respectively). CONCLUSION: Resting heart rate and peak VO2 were identified in multivariate analysis as good predictors of arrhythmic events and resting heart rate was the only independent predictor of appropriate shock in HF patients with ICD. Both advanced stage heart failure and sympathetic overdrive may be associated with the development of malignant arrhythmias.

[Circumferential pulmonary vein isolation with the cryoballoon technique]. / Isolamento circunferencial das veias pulmonares com a técnica do criobalão.

We present a clinical case on cryoballoon ablation of paroxysmal atrial fibrillation. This is a report of the first case performed at our center using this new technology.

Atrial tachycardia ablation in a patient with double outlet right ventricle corrected by surgery.

The development of surgical and percutaneous techniques for treatment or palliation of congenital heart disease has prolonged survival in these patients and has increased late complications, particularly arrhythmias. Such arrhythmias are more frequently refractory to medical therapy, requiring percutaneous ablation. We present the clinical case of a 14-year-old child with complex congenital heart disease (double outlet right ventricle) who underwent two corrective surgeries (Rastelli operation and subsequent replacement of the homograft in the conduit connecting the right ventricle to the pulmonary artery; ventricular septal defect closure and tricuspid valve repair). After the second surgery the patient presented with wide complex syncopal tachycardia, refractory to medical therapy. Electrophysiologic study (EPS) identified an isthmus-dependent atrial flutter that was successfully treated by radiofrequency (RF) ablation (a linear block was created along the cavo-tricuspid isthmus). Three months later a new episode of tachycardia occurred, but without syncope. The second EPS revealed an atrial tachycardia originating from the lateral wall of the right atrium, which was treated by ablation with focal application of RF energy. Four months after the last EPS the child remains free of arrhythmic symptoms, under no anti-arrhythmic therapy.

Ablation of atrial fibrillation in mitral valve disease patients: five year follow-up after percutaneous pulmonary vein isolation and mitral balloon valvuloplasty.

BACKGROUND: The association between atrial fibrillation (AF) and mitral valve disease is frequent. Isolation of the pulmonary veins by radiofrequency energy applications performed intraoperatively has been proposed for patients with AF in whom mitral valve surgery has been indicated. Balloon mitral valvuloplasty is currently the preferred procedure for patients with mitral stenosis and a favorable valve anatomy. AIM: To evaluate the short- and long-term results of percutaneous pulmonary vein isolation for the treatment of AF in patients with mitral stenosis undergoing balloon mitral valvuloplasty. METHODS: Five patients (four male and one female, age 43 +/- 4 years) underwent balloon mitral valvuloplasty concomitant with pulmonary vein isolation between August 1996 and February 1997. These patients had permanent AF, diagnosed 31 +/- 12 months previously; their mitral valve area was 1.0 +/- 0.25 cm2 and their left atria measured 54 +/- 5 mm. Balloon mitral valvuloplasty was performed via a transseptal approach, and then four ablation lines were created in the left atrial posterior wall to encircle all four pulmonary veins. Radiofrequency applications lasted 45 seconds each, and aimed at a maximum preset temperature of 65 degrees C. Electrical cardioversion was performed at the end of the procedure. RESULTS: Mitral valve area increased 1.0 +/- 0.3 cm2 after valvuloplasty. The number of radiofrequency applications per patient was 37 +/- 3, and the average duration of the entire treatment was 131 +/- 28 minutes. Fluoroscopy time averaged 32 +/- 12 minutes. All patients were discharged in sinus rhythm, and mitral flow Doppler evaluation at one month showed a biphasic pattern in all cases, with the A wave measuring 70 +/- 15 cm/sec. Three patients maintained sinus rhythm at five-year follow-up. Of these patients, one had developed a left atrial flutter at four-year follow-up and underwent ablation. The remaining two patients presented AF at five year follow-up. CONCLUSIONS: Percutaneous isolation of the pulmonary veins concomitant with balloon mitral valvuloplasty had suppressed AF in 60% of patients by five-year follow-up.

Epicardial electroanatomical mapping for intraoperative evaluation of bilateral pulmonary vein isolation.

UNLABELLED: Eight patients (pts; 2 female, 58 +/- 12 yrs) with paroxysmal atrial fibrillation (AF) (duration 39 +/- 20 months) underwent AF surgery, with concomitant myocardial revascularization in 2 pts and myomectomy in 1 (HOCM). AF was idiopathic in the remaining 5 pts. AF surgery consisted of bilateral isolation of the pulmonary veins (PV) using radiofrequency (RF) energy applied epicardially by a heptapolar catheter (Thermaline) in 5 pts and by a new system (Atricure) in 3 pts. For the former, each set of 7 simultaneous applications aimed at a maximum duration of 2 + 2 min., preset temperature 80 degrees C and output 150 watts. With the new system, bipolar applications were carried out; energy delivery was controlled by impedance monitoring and applications were ended after abrupt, sustained elevation of impedance. Epicardial bipolar voltage mapping (CARTO) was performed before and after each RF procedure. Using the navigator catheter, points were recorded at the insertion of each PV and at the non-isolated left atrial posterior wall. The amplitude of the local electrograms (LE) was measured before and after RF applications. If the LE amplitude inside the isolated zone was not 0.1 mV and not reduced by > 80%, a second application was performed. A maximum of 2 epicardial applications were carried out in each pt and if the final result was unsatisfactory, further endocardial applications were performed. RESULTS: Baseline LE amplitudes were > 1 mV in all cases. Successful isolation of right PVs was achieved in 7 pts, after one set of applications in 5 and a second set in 2. Left PV isolation required 2 sets of epicardial applications in all pts, being successful in only 2; 4 pts (one with associated myomectomy and 3 with idiopathic AF) received endocardial applications. Overall, bilateral PV isolation was achieved in 5 pts. CONCLUSIONS: CARTO bipolar voltage mapping is a fast, simple means for evaluation of epicardial PV isolation.

Epicardial radiofrequency applications: in vitro and in vivo studies on human atrial myocardium.

OBJECTIVES: To obtain a better understanding of tissue damage induced in human atria by epicardial radiofrequency ablation and its correlation with intra-tissue temperatures measured sub-epicardially and sub-endocardially. METHODS: Radiofrequency (RF) currents were delivered to human atrial tissues using experimental set-ups to simulate surgical RF epicardial ablation at 80, 85 and 90 degrees C. Sub-endocardial and sub-epicardial temperatures were measured with thermocouples during the ablations. Twelve samples from in vitro epicardial ablations were histologically assessed. Localized RF epicardial ablations at same temperatures were performed on 38 mitral patients with concomitant atrial fibrillation (AF) before full cardiopulmonary bypass and samples histologically assessed. All patients had endocardial RF ablation at 70 degrees C to treat AF. RESULTS: In vitro Sub-endocardial temperatures were lower than 50 degrees C except on thin atria (approximately 2-3 mm) in ablations at 80 and 85 degrees C and on thicker atria (approximately 5 mm) in ablations at 90 degrees C. Lesions measured 0.85-1.98 mm, all showed epicardial and myocardial damage but none were transmural. Mitral patients: Lesions measured 0.38-3.25 mm and 13/25 induced at 70 degrees C, 2/8 at 80 degrees C, 1/4 at 85 degrees C and 0/1 at 90 degrees C were confined to the epicardium leaving the myocardium undamaged. The remaining had damage of the epicardium and of variable portions of the myocardium, and three were transmural. CONCLUSIONS: The application temperature and the intra-tissue temperature are not the sole factors that determine lesion depth. The thickness and the composition of the epicardium and of the myocardium are major determinants in the formation of the lesion.