Catheter Ablation Of Paroxysmal Atrial Fibrillation Research Articles

Head-Up Tilt.

Autonomic dysfunction has been associated with paroxysmal atrial fibrillation (PAF). The head-up tilt test (HUTT) is an important diagnostic tool for autonomic dysfunction. The aim of this study was to examine atrial fibrillation recurrence after RFCA by performing HUTT. A total of 488 consecutive patients with PAF who underwent RFCA were prospectively enrolled. HUTT was positive in 154 (31.6%) patients after a mean follow-up of 22.7 ± 3.5 months, and 163 (33.4%) had a recurrence. HUTT positive was significantly higher in PAF patients with recurrence compared to those without (68 (41.7%) versus 86 (26.5%), P < 0.001). Multivariate Cox regression analysis revealed that HUTT positive (HR: 1.96; 95% CI: 1.49-2.48, P < 0.001), left atrial diameter (HR: 1.77; 95%CI: 1.15-2.11, P = 0.004), AF duration (HR: 1.27; 95%CI: 0.98-1.83, P = 0.014), and sleep apnea (HR: 1.02; 95%CI: 0.81-1.53, P = 0.032) were independent predictors of clinical recurrence after RFCA. The success rate of ablation was 70.4% in patients in the HUTT negative group compared with 58.4% in patients in the HUTT positive group (log-rank P = 0.006). Patients with a positive headup tilt test were at an increased risk of AF recurrence after catheter ablation. Our results suggest that HUTT was a significant predictor for AF recurrence after catheter ablation for PAF.

Update on atrial fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia encountered in clinical practices with significant morbidity, mortality and socioeconomic burden. Its prevalence and incidence are on the rise due to an increase in population age. AF has complex electrophysiological mechanisms, etiology and natural history and thus management is a challenge. More than 80% of cases in AF are related to an underlying structural heart disease. Stroke and congestive heart failure remain the most significant complications of AF. Depending on the patient’s symptoms, duration and type of AF, structural heart disease and non-cardiac comorbidities, several management options are currently available. Asymptomatic AF carries similar risks as symptomatic AF. Rate control approach in majority of cases especially elderly patients is reasonable. Novel anticoagulation agents have shifted the paradigm in stroke prevention and management in patients with AF. Catheter ablation of paroxysmal AF in patients with no to minimal structural heart disease who have failed at least one antiarrhythmic agent appears reasonable.

Predictors of recurrence after a repeat ablation procedure for paroxysmal atrial fibrillation: role of left atrial enlargement

This study sought to explore the predictors of recurrence in patients with paroxysmal atrial fibrillation (AF) undergoing repeat catheter ablation, especially the impact of left atrial (LA) remodelling after the original procedure on the outcome of repeat procedure. Ninety-five patients undergoing repeat ablation were enrolled in this study. Repeat procedure endpoints were pulmonary vein isolation, linear block when linear ablation is performed, and non-inducibility of atrial tachyarrhythmia by burst pacing. Patients with LA enlargement between the pre-original procedure and pre-repeat procedure were categorized as Group 1 (35 patients), while individuals with no change or decrease of LA diameter were categorized as Group 2 (60 patients). The mean duration from the original procedure to the repeat procedure was 12 months (1-40 months). After 29.6 ± 20.5 (3-73) months follow-up from the repeat procedure, 33 patients experienced recurrence (34.7%). The recurrence rate was significantly higher in Group 1 than in Group 2 (51.4 VS. 25.0%, P = 0.017). In univariate analysis, LA remodelling was the only predictor of recurrence. In multivariate analysis, after adjustment for age and LA diameter, Group 1 had a greater risk of recurrence after the repeat procedure (hazard ratio = 2.22, 95% confidence interval: 1.02-4.81, P = 0.043). Left atrial enlargement after undergoing the original catheter ablation of paroxysmal AF was an independent risk factor of recurrence after repeat ablation.

Which is the best catheter to perform atrial fibrillation ablation? A comparison between standard ThermoCool, SmartTouch, and Surround Flow catheters

Catheter ablation (CA) is an established therapy for atrial fibrillation (AF). The SmartTouch catheter (STc) provides information about catheter tip to tissue contact force (CF). The Surround Flow catheter (SFc) provides a uniform cooling of the tip during ablation. We sought to analyze the impact of STc and SFc on CA of paroxysmal AF in terms of feasibility and acute efficacy. Sixty-three patients (mean age 57.6 ± 9.8 years, 53 males) with paroxysmal AF underwent pulmonary veins (PVs) antral isolation, by using standard ThermoCool catheter (TCc) in 21, STc in 21, and SFc in 21. Total procedural, fluoroscopy, and radiofrequency (RF) delivery times; percentage of persistently deconnected PVs after 30 min; and percentage of isolated PVs at the end of the procedure were measured. The use of both STc and SFc obtained a reduction of fluoroscopy time (TCc 34 ± 18 min, STc 20 ± 10 min, p < 0.001; SFc 21 ± 13 min, p = 0.02 vs TCc) and RF time (TCc 41 ± 13 min, STc 30 ± 14 min, p = 0.013; SFc 30 ± 9 min, p < 0.01 vs TCc). The use of STc resulted in a reduction of procedural time (TCc 181 ± 53 min, STc 140 ± 53 min, p < 0.001; SFc 170 ± 51 min, p = NS vs TCc). The percentage of isolated PVs was comparable between groups (TCc 96 % vs STc 98 % vs SFc 96 %; p = NS). The percentage of deconnected PVs at 30 min was lower in TCc (89 %) than in STc (95 %) and in SFc (95 %) group (p < 0.05). Both STc and SFc allowed a simplification of CA of paroxysmal AF. In addition, they reduced early PVs reconnection. Sixty-three patients with paroxysmal AF underwent ablation by standard ThermoCool, SmartTouch, or Surround Flow catheter. Both the SmartTouch and the Surround Flow significantly reduced radiofrequency and fluoroscopy times, as well as pulmonary veins reconnection rate at 30 min. Moreover, the SmartTouch reduced overall duration of the procedure.

Efficacy of catheter ablation for atrial fibrillation in patients with a permanent pacemaker for atrioventricular block.

Catheter ablation has been established to be an effective therapy for drug-refractory paroxysmal AF and is recommended as the treatment of choice for many patients, including those with a permanent pacemaker (PM). However, the clinical efficacy of catheter ablation of paroxysmal AF in patients with a permanent PM for atrioventricular block (AVB) is not clear. Twenty-nine patients with a permanent PM for AVB (AVB + PM group), and 145 age- and gender-matched control patients (on a 1:5 basis) without AVB and without a permanent PM (no-AVB + no-PM group), were included in this study. Atrial fibrillation (AF) recurrence was defined as the occurrence of confirmed atrial tachyarrhythmia lasting more than 30 seconds beyond 3 months after catheter ablation in the absence of any antiarrhythmic treatment. During a mean follow-up period of 14.2 ± 8.6 months (range, 3-30 months), 54 patients (31.0%) developed recurrence of AF. The recurrence rate was higher in the AVB + PM group than in the no-AVB + no-PM group (48.3% versus 27.6%, P = 0.005). Cox regression analysis with adjustment for age, valvular heart disease, AVB and a PM together, left atrial (LA) diameter and PV isolation identified LA diameter (hazard ratio 1.054, 95% confidence interval 1.001-1.110, P = 0.047) and AVB and a PM together (hazard ratio 2.095, 95% confidence interval 1.109-3.960, P = 0.023) as two independent predictors of recurrence of AF. Patients with a permanent PM for AVB were at an increased risk of recurrence of AF after catheter ablation.

Outcome of pulmonary vein isolation ablation for paroxysmal atrial fibrillation: predictive role of left atrial mechanical dyssynchrony by speckle tracking echocardiography

Although few clinical variables have been associated with recurrence of atrial fibrillation (AF) after pulmonary vein isolation (PVI) the role of left atrial (LA) mechanical function in the outcome of catheter ablation of AF is not adequately defined. The aim of our study was to determine whether LA mechanical dyssynchrony as evaluated by speckle tracking echocardiography can predict outcome of PVI ablation procedure in patients with paroxysmal AF. Twenty-five patients (age 58 ± 11 years, [mean ± standard deviation], 17 males) with paroxysmal AF who met specific enrollment criteria pertaining to clinical presentation and follow-up, assessment of LA mechanical dyssynchrony, and strategy of catheter ablation procedure were enrolled. For LA mechanical dyssynchrony assessment, the time to peak longitudinal strain (TPk) in opposing walls in the midportion of the LA walls at peak atrial contraction in standard two- and four-chamber echocardiographic views by vector velocity imaging (VVI) was measured. Outcome of PVI procedure, whether no recurrence (NR) or AF recurrence (AFR) after 3 months of post-procedural blanking period, was evaluated based on AF-related symptoms and documentation of AF by electrocardiogram, continuous 24-h Holter, and intermittent event monitor recordings. During a follow-up period of 20.3 ± 8.6 months, 18 out of 25 (72 %) patients had no recurrence (NR group), and 7 out of 25 (28 %) patients had recurrence of AF (AFR group). Significant gender difference was observed in terms of outcome such that all AFR patients were men and no woman had recurrence of AF. Between the NR and AFR groups, neither the left atrial diameter, 4.0 ± 0.3 and 4.2 ± 0.2 cm, respectively (p = 0.2), nor the left atrial volume indexes, 45 ± 15 and 48 ± 20 ml/m(2), respectively (p = 0.56), were statistically significantly different. For LA mechanical function, compared to the patients in NR group who had maximum opposing wall TPk delay of 39.9 ± 12.0 ms, those in the AFR group demonstrated significantly more LA mechanical dyssynchrony with maximum opposing wall TPk delay of 64.4 ± 17.0 ms prior to ablation (p = 0.007). Using receiver operative characteristic analyses of the data that had an area under the curve of 0.865, we identified a maximum opposing wall delay cutoff value of 51 ms which predicted AF recurrence with sensitivity and specificity values of 89 and 72 %, respectively (p = 0.005). Speckle tracking strain analysis echocardiography can evaluate the LA mechanical dyssynchrony quantitatively. The severity of LA mechanical dyssynchrony by VVI can predict the outcome of PVI catheter ablation for paroxysmal AF.

The impact of haemodialysis on the outcomes of catheter ablation in patients with paroxysmal atrial fibrillation

The outcomes of catheter ablation (CA) in patients with paroxysmal atrial fibrillation (PAF) who are undergoing haemodialysis (HD) have not been fully elucidated. This study aimed to determine the impact of HD on CA outcome in these patients. We examined 1364 consecutive PAF patients (mean age, 61 ± 10 years) who underwent CA, including 32 (2.3%) patients undergoing HD. The patients undergoing HD had a significantly lower body mass index (P < 0.0001), higher CHADS2 score (P = 0.006), and higher prevalence of structural heart disease (P < 0.0001), hypertension (P = 0.002), and congestive heart failure (P = 0.02). Echocardiography indicated a larger left atrial diameter (P < 0.0001) and left ventricular diameter (P = 0.0002) in the HD patients. Haemodialysis was a significant predictor of AF recurrence (hazard ratio 2.56; 95% confidence interval 1.56-4.03; P = 0.0004) in the overall population. Sinus rhythm maintenance rates in the HD patients at 1, 3, and 5 years were 42.3, 37.6, and 19.7%, respectively, after the first procedure, and 64.7, 54.9, and 47.1%, respectively, after the final procedure (median, 2; range, 1-2 procedures); these rates were significantly lower than those in the non-HD patients (P < 0.0001). The 5-year survival rate was 78.1% in the HD patients. Haemodialysis was significantly associated with AF recurrence after CA for PAF. However, an ∼50% success rate for sinus rhythm maintenance without antiarrhythmic drug therapy in HD patients suggested that CA could be an option for the treatment of AF.

Impact of the origin of sinus node artery on recurrence after pulmonary vein isolation in patients with paroxysmal atrial fibrillation

Background Major atrial coronary arteries, including the sinus node artery (SNA), were commonly found in the areas involved in atrial fibrillation (AF) ablation and could cause difficulties in achieving linear block at the left atrial (LA) roof. The SNA is a major atrial coronary artery of the atrial coronary circulation. This study aimed to determine impact of the origin of SNA on recurrence of AF after pulmonary vein isolation (PVI) in patients with paroxysmal AF. Methods Seventy-eight patients underwent coronary angiography for suspected coronary heart disease, followed by catheter ablation for paroxysmal AF. According to the origin of SNA from angiographic findings, they were divided into right SNA group (SNA originating from the right coronary artery) and left SNA group (SNA originating from the left circumflex artery). Guided by an electroanatomic mapping system, circumferential pulmonary vein ablation (CPVA) was performed in both groups and PVI was the procedural endpoint. All patients were followed up at 1, 3, 6, 9 and 12 months post-ablation. Recurrence was defined as any episode of atrial tachyarrhythmias (ATAs), including AF, atrial flutter or atrial tachycardia, that lasted longer than 30 seconds after a blanking period of 3 months. Results The SNA originated from the right coronary artery in 34 patients (43.6%) and the left circumflex artery in 44 patients (56.4%). Freedom from AF and antiarrhythmic drugs (AADs) at 1 year was 67.9 % (53/78) for all patients. After 1 year follow-up, 79.4% (27/34) in right SNA group and 59.1% (26/44) in left SNA group (P=0.042) were in sinus rhythm. On multivariate analysis, left atrium size (HR=1.451, 95%CI: 1.240-1.697, P &lt;0.001) and a left SNA (HR=6.22, 95%CI: 2.01-19.25, P=0.002) were the independent predictors of AF recurrence. Conclusions The left SNA is more frequent in the patients with paroxysmal AF. After one year follow-up, the presence of a left SNA was identified as an independent predictor of AF recurrence after CPVA in paroxysmal AF.

Questionable levels of evidence in new atrial fibrillation guidelines? Reply

We read with interest the 2012 focused update of the ESC Guidelines for the management of atrial fibrillation (AF), and more specifically the recommendations formulated for catheter ablation (CA).1 A class I-level of evidence (LoE) A recommendation is attributed to CA for paroxysmal AF in symptomatic drug-refractory patients. In randomized controlled trials (RCTs), AF recurs off-antiarrhythmic drug (AAD) in one-third of patients, 1 year after a single CA.2,3 We have documented that AF recurs in up to 50% after 2 years, which is in line with other observational studies.4,5 The procedure has a …

Differences in catheter ablation of paroxysmal atrial fibrillation between males and females

Catheter ablation (CA) has become a standard treatment for patients with atrial fibrillation (AF). However, gender-related differences associated with CA of paroxysmal AF (PAF) remain unclear. We compared 1124 consecutive patients (mean age, 61 ± 10 years; male, n=864) with PAF scheduled for CA between the genders. Females were significantly older (p<0.0001), and had a lower body-mass-index (p=0.02), smaller left atrial dimension (LAD; p=0.04), larger LAD indexed by the body-surface-area (LADI; p<0.0001) and better left ventricular ejection fraction (p<0.0001) at baseline. Ischemic heart disease (p=0.007) was more frequent in males, whereas hypertrophic cardiomyopathy (p=0.007) and mitral stenosis (p=0.001) were more frequent in females. More additional procedures were performed to eliminate non-pulmonary vein foci in females than males (p<0.05), but those locations were similar between the genders. The incidence of procedure-related complications was similar between genders (p=0.73). Sinus rhythm was similarly maintained between females and males after the first CA (56.4% vs. 59.3% at 5 years, p=0.24), but was significantly lower in females after the last CA (76.5% vs. 81.3% at 5 years, p=0.007). More females did refuse multiple CA procedures (especially a second one) than males (37.8% in females vs. 27.4% in males, p=0.02). The age (HR, 0.98/y, p=0.01), duration of AF (HR, 1.04/y, p=0.0001), number of failed anti-arrhythmic-drugs (HR, 1.10, p=0.03) and LADI (HR, 1.89 per 10mm/m(2), p=0.001) were significantly associated with AF-recurrence in males, but not in females. Specific differences and similarities between the genders were observed in PAF patients undergoing CA.

Pulmonary vein isolation to treat paroxysmal atrial fibrillation: conventional versus multi-electrode radiofrequency ablation

For patients with symptomatic atrial fibrillation (AF), a curvilinear multi-electrode ablation (MEA) catheter has been reported to be successful to achieve pulmonary vein (PV) isolation. However, this approach has not been compared prospectively with conventional PV isolation (CPVI) using a standard circular mapping catheter and 3D electro-anatomic mapping. In this prospective non-randomized study, we compared the efficacy of these two techniques. Of 185 consecutive patients, age 54.6 ± 10.1 years, with symptomatic paroxysmal AF (PAF), 96 patients underwent PV isolation by CPVI and 89 patients underwent MEA to isolate the PVs. CPVI was performed by encircling the left- and right-sided PVs. During MEA, the PV ablation catheter (Medtronic, USA) was used to isolate PVs with duty-cycled radiofrequency energy. The mean procedure time was 171.73 ± 52.87 min for CPVI and 133.25 ± 37.99 min for MEA, respectively (P < 0.001). The mean fluoroscopy time was 31.07 ± 14.97 for CPVI and 30.07 ± 11.45 min for MEA (P = 0.651). At 12 months, 80% of patients who underwent CPVI and 82% of patients who underwent MEA were free of symptomatic PAF off antiarrhythmic drug therapy (P = 0.989). Among the variables of age, gender, duration and frequency of PAF, left ventricular ejection fraction, left atrial size, structural heart disease, and the ablation technique, only an increased left atrial size was an independent predictor of recurrent PAF. Left atrial flutter occurred after CPVI in two patients and after MEA ablation in three patients. In patients undergoing catheter ablation for PAF, MEA and CPVI proved equally efficacious.

ORAL PRESENTATION

ORAL PRESENTATION

Associations among the CHADS2 score, atrial substrate properties, and outcome of catheter ablation in patients with paroxysmal atrial fibrillation

The CHADS₂ score (congestive heart failure, hypertension, age >75 years, diabetes, and previous stroke/transient ischemic attack) is used for the risk stratification of strokes in patients with atrial fibrillation (AF). This study aimed to investigate the associations between the CHADS₂ score, atrial substrate, and outcome of catheter ablation in patients with paroxysmal AF. A total of 247 paroxysmal AF patients who received catheter ablation were enrolled. The patients were divided into 3 groups according to their CHADS₂ score (group 1: score 0, group 2: score 1 to 2, and group 3: score 3 to 6). The bi-atrial substrate properties and outcome of catheter ablation were analyzed. The CHADS₂ scores in these 3 groups were 0 (group 1), 1.24 ± 0.48 (group 2), and 3.60 ± 0.83 (group 3), respectively. The left atrial voltage became lower (group 1 vs. 2 vs. 3 = 2.08 ± 0.73 mV vs. 1.80 ± 0.81 mV vs. 1.06 ± 0.69 mV) and the activation time longer (group 1 vs. 2 vs. 3 = 93.4 ± 17.7 ms vs. 101.9 ± 21.2 ms vs. 112.2 ± 21.7 ms), whereas the CHADS₂ score increased. During a follow-up of 17.3 ± 7.0 months, 23.1% of the study population suffered from recurrences. The recurrence rates of these 3 groups were 13.0% (group 1), 27.6% (group 2), and 45.9% (group 3), respectively. The groups of different CHADS₂ scores remained as the independent predictor of recurrence in the multivariate analysis. A high CHADS₂ score was associated with different left atrial substrate properties and a poor outcome after catheter ablation of paroxysmal AF.

Associations Between Renal Function, Atrial Substrate Properties and Outcome of Catheter Ablation in Patients With Paroxysmal Atrial Fibrillation

Renal dysfunction was reported to be associated with a higher recurrence rate after electric cardioversion of atrial fibrillation (AF). The aim of this study was to investigate the associations between renal function, atrial substrate properties and outcome of catheter ablation in paroxysmal AF patients. A total of 232 paroxysmal AF patients that underwent catheter ablation were enrolled in the study. The estimated glomerular filtration rate (GFR) was calculated using the Cockcroft-Gaut equation normalized by the body surface area, and the patients were divided into 3 groups according to their GFR (group 1: ≥ 90 ml·min⁻¹·1.73 m⁻², group 2: 60-90 ml·min⁻¹·1.73 m⁻² and group 3: < 60 ml·min⁻¹·1.73 m⁻²). The left atrial (LA) voltage became lower and the activation time longer when the GFR decreased from group 1 to group 3. During a follow up of 25.4 ± 13.3 months, 15.9% of the study population suffered from AF recurrences. The recurrence rates of those 3 groups were 6.9%, 14.5% and 38.9%, respectively. The LA dimension, LA voltage and groups of renal function were identified to be the independent predictors of an AF recurrence in the multivariate analysis. A decreased GFR was associated with an abnormal LA substrate and high recurrence rate of catheter ablation in patients with paroxysmal AF.

Associations between the atrial electromechanical interval, atrial remodelling and outcome of catheter ablation in paroxysmal atrial fibrillation

ObjectiveThe atrial electromechanical (PA–PDI) interval was reported to be a useful predictor of new-onset atrial fibrillation (AF) and the occurrence of AF after coronary artery bypass surgery. The aim of...

Robotic Navigation in Catheter Ablation for Paroxysmal Atrial Fibrillation: Midterm Efficacy and Predictors of Postablation Arrhythmia Recurrences

Remote navigation systems represent a novel strategy for catheter ablation of atrial fibrillation (AF). The goal of this study is to describe a single-center experience with the electromechanical robotic system (Sensei, Hansen Medical) in treatment of patients with paroxysmal AF. Out of 200 patients who underwent robotically guided ablation for AF between 2007 and 2009 at our institute, 100 patients (29 women, age 56.5 ± 10 years) had paroxysmal AF refractory to antiarrhythmic drugs. Electroanatomic mapping using NavX system (St. Jude Medical) provided anatomical shell for subsequent circumferential ablation with robotic catheter (Artisan) loaded with a 3.5-mm, open-irrigation, cooled-tip ablation catheter. A mean of 69 radiofrequency current applications (duration 2082 ± 812 seconds) were delivered to achieve circumferential electrical isolation of pulmonary venous antra. Total procedural time reached 222 ± 54 minutes. The mean fluoroscopic time was 11.9 ± 7.8 minutes. There were no major procedure-related complications. After a median follow-up of 15 months (range 3-28 months), 63% of the patients were free from any atrial arrhythmias ≥ 30 seconds after the single procedure. Success rate increased to 86% after 1.2 procedures. Multivariate analysis revealed that only predictor of recurrent AF/AT was shorter overall procedural time (207 ± 36 vs 236 ± 64 minutes in patients with and without recurrences, respectively, P = 0.0068). This study demonstrates feasibility and safety of robotic navigation in catheter ablation for paroxysmal AF. Midterm follow-up documents success rate comparable to other technologies and potential for improvement in more extensive ablation along the ridges with thicker myocardium.

Relationship between renal function and the risk of recurrent atrial fibrillation following catheter ablation

BackgroundAlthough several clinical variables are associated with the recurrence of atrial fibrillation (AF) following catheter ablation, the influence of renal function remains to be determined.ObjectiveTo evaluate the association of renal...

New guidelines for the management of atrial fibrillation: what’s new?

At the ESC Congress 2010 in Stockholm, four new practice guidelines were introduced concerning 1) grown-up congenital heart disease, 2) myocardial revascularisation, 3) use of cardiac resynchronisation therapy (CRT) and devices in patients with heart failure, and 4) atrial fibrillation (AF). In this Editor’s page a short summary is given of the new guidelines on AF. The Task Force on AF was chaired by Professor John Camm (London, UK) and included 24 European experts in arrhythmias. There are a number of important modifications compared with the previous 2006 AF guidelines. First, based on the presentation and duration of the arrhythmia, five types of AF can clinically be distinguished: 1) first diagnosed, 2) paroxysmal, 3) persistent, 4) long-standing, and 5) permanent AF. Second, the new 2010 AF guidelines clearly state that initial clinical evaluation should include 1) a determination of the European Heart Rhythm Association (EHRA) score of AF-related symptoms, 2) an estimation of stroke-bleeding risk, and 3) a check for conditions that predispose to AF and for further complications. Third, regarding antithrombotic treatment, in patients with a CHADS2 score of 0–1, it has been recommended to use the CHA2DS2-VASc score. CHADS2 stands for Cardiac Failure, Hypertension, Age, Diabetes, and Stroke (doubled). VASc stands for Vascular disease, Age 65-74 years, and Sex category. The CHADS2 stroke risk stratification scheme allows the assessment of risk, particularly suited to assist primary care physicians. Unless contraindicated, chronic oral anticoagulation therapy (OAC) is recommended in patients with a CHADS2 score of ≥2. The international normalised ratio (INR) should be in the range of 2.0 to 3.0, unless contraindicated. For a more detailed stroke risk assessment, the CHA2DS2-VASc score is recommended. Fourth, the new AF guidelines emphasise the importance of bleeding risk assessment before starting anticoagulation. In this case the HAS-BLED bleeding risk score is recommended (Hypertension, Abnormal renal and liver function, Stroke, Bleeding, Labile INRs, Elderly >5 years, Drugs or alcohol). A score of ≥3 is considered indicative of ‘high-risk’ patients who require caution and regular review after starting antithrombotic therapy. Fifth, the guidelines extensively address the choice of antiarrhythmic therapy for recurrent AF. Recommendations are made on the basis of selecting safer medication instead of more effective, but less safe therapy. The results of current clinical trials with dronedarone now allow, for the first time, recommendation of dronedarone in patients with AF. In patients with adrenergic AF and no or minimal structural heart disease, dronedarone is recommended if β-blocking agents (including sotalol) are not effective. In patients with left ventricular hypertrophy, coronary artery disease, and stable New York Heart Association (NYHA) class I/II, dronedarone is the antiarrhythmic drug of choice. However, dronedarone should not be used in AF patients with NYHA class III/IV or in unstable patients with NYHA class II. In these patients, β-blocking agents are recommended as first-line therapy. Lastly, the new Guidelines recommend that catheter ablation for paroxysmal AF should be considered in symptomatic patients who have previously failed a trial of antiarrhythmic medication (Class IIa, level of evidence A). At present, there is insufficient evidence that successful AF ablation will result in reduced mortality. Surgical ablation of AF should be considered in patients with symptomatic AF undergoing cardiac surgery. To conclude, the new 2010 AF practice guidelines are a true step forward and their clinical implementation will have major impact in appropriately treating patients with AF (see also the article of I.C. van Gelder et al. on page 522–3).

Möglichkeiten und Grenzen der interventionellen Therapie von Vorhofflimmern

Recently, significant progress has been made treating atrial fibrillation (AF) with catheter ablation emerging as an increasingly important technique. Electrical disconnection of the pulmonary veins (PV) is a widely accepted endpoint for interventional treatment of paroxysmal AF (PAF). According to the current guidelines, catheter ablation can be considered as a therapeutic option in patients who failed antiarrhythmic drug treatment for PAF. The procedural endpoint for PVI is achievement of permanent electrical isolation of the PVs, which in the vast majority of patients harbor triggered electrical activity inducing and maintaining PAF. The success rate of this approach in patients with PAF ranges between 60 and 80% after a single procedure and augments to > 80 % in patients undergoing a repeat procedure to abolish recovered PV connection. However, it is now evident that persistent or long-standing persistent AF may not be successfully treated by PVI alone since the majority of patients have AF maintaining substrate beyond the PV. From a pathophysiological perspective this is explained by structural and electrical remodeling of the atrial myocardium in patients with persistent AF. Therefore, it is today widely accepted that additional substrate modification is required to effectively address persistent AF using catheter ablation. It has been shown that a combined approach of PV isolation, ablation of fractionated atrial electrograms and application of lines to treat atrial macro-reentrant tachycardias ("stepwise approach") aiming for restoration of sinus rhythm is a favorable strategy to treat persistent AF. However, significant expertise is needed to accomplish all steps within these complex procedures. Therefore, catheter ablation for persistent AF cannot yet be considered "clinically established" and should only be performed in high volume centers. Additional data is needed to verify the beneficial effect of this strategy and determine "predictors" identifying patients profiting most from these ablation strategies. In patients with PAF, catheter ablation has emerged as an established therapy also in comparison to antiarrythmic drug treatment. Recent studies have shown that catheter ablation for PAF is superior to antiarrhythmic drug treatment with regard to mid-term suppression of any atrial arrhythmia. Overall, catheter ablation for AF has still to be considered as a symptomatic treatment since evidence for beneficial effects with regard to more robust clinical endpoints such as death, rehospitalization and ischemic cerebral events are not yet available.

Is verapamil a double-edged sword in rate control of paroxysmal atrial fibrillation?

Over the last decade, remarkable progress has been made in the field of atrial fibrillation (AF) pathophysiology and management. There is no doubt that radiofrequency catheter ablation therapy improves the quality of life and left ventricular function in patients with symptomatic AF by improving the maintenance of sinus rhythm. 1 A new antiarrhythmic agent, dronedarone, was recently shown to reduce the composite outcome of cardiovascular hospitalization and death in patients with AF. 2 Moreover, novel approaches such as the dominant frequency (DF) analysis of atrial electrograms have offered clinicians a better insight into the pathogenesis of AF. 3 Despite these advancements, longterm maintenance of sinus rhythm is challenging, and persistent or permanent AF still develops in many patients. In these cases, control of the ventricular rate has an essential role in alleviating the symptoms and preventing the development of tachycardia-induced cardiomyopathy. Spectral analysis of atrial recordings increasingly has been used to detect areas with high atrial activation rate during AF. The main benefit of frequency domain analysis is that it can be applied to the complex electrograms of AF more easily than time domain measurements. 3 Experimental and clinical studies indicate that the DF sites within the pulmonary veins (PV) have an important role in the initiation and maintenance of paroxysmal AF. 4,5 Furthermore, it has been postulated that DF mapping can be used to guide rapid identification of extrapulmonary sites that drive AF. 6 In this issue, Kushiyama et al 7 report the results of a study that evaluated the effects of verapamil on regional distribution of DFs in the PVs and atria in 43 patients undergoing catheter ablation of paroxysmal AF. They found that the highest DF was localized in the PVs and showed that there was a substantial PV-to-atria DF gradient at baseline. These findings are in agreement with previous studies indicating that the PVs are the main drivers of paroxysmal AF. 4,5 It is well established that beta-blockers, calcium channel antagonists, and digitalis slow ventricular rate, but much fewer data are available on their effect on atrial arrhythmogenesis. Verapamil is a nondihydropyridine calcium channel antagonist with potent negative chronodropic and dromodropic effects. Due to its use-dependent dromodropic action, verapamil is highly effective in controlling rapid ventricular rate in AF, but has less effect on atrioventricular (AV) nodal conduction at a normal rate. Kushiyama et al 7 showed that verapamil caused variable changes in the PV excitation. The maximum PV DF increased in 65% of the patients and decreased in the remaining 35%. In contrast, verapamil consistently increased the DFs in all of the atrial recording sites. As a result of these tissue-specific effects, verapamil eliminated the PV-to-atria DF gradient. According to the investigators, this is attributable to regional heterogeneities of action potential morphology and ionic currents responsible for the repolarization (e.g., I CaL ) in the PV myocardial muscle sleeves and atria rather than to a reflex increase in sympathetic tone in response to a reduction in blood pressure. Prior studies indicate that the extrapulmonary DF areas and the absence of the PV-to-atria frequency gradient can be used to identify additional ablation targets. For example, Lin et al 6 have shown that the DF shifts to the right atrium when AF is initiated in the superior vena cava. Sanders et al 5 reported that termination of permanent AF requires ablation of extrapulmonary high-frequency sites in addition to PV isolation. Hence, it is tempting to speculate that ablation of the verapamil-induced atrial high-frequency areas may improve the long-term efficacy of catheter ablation of paroxysmal AF. The results of Kushiyama et al 7 are also important with regard to rate control of AF because they raise the possibility that verapamil may provoke paroxysmal AF by creating new high-frequency sources in the atria. In keeping with this, verapamil facilitated the induction of sustained AF. That is, in all of the 6 patients with no inducible AF at baseline, sustained AF was easily induced after verapamil by burst pacing from the coronary sinus. These findings are consistent with experimental data indicating that verapamil promotes maintenance of AF by shortening the atrial refractory period and AF cycle length and enhancing reentrant activity in the atria. 8 In lieu of these data, the usefulness of verapamil for ventricular rate control in patients with paroxysmal AF may be limited by its profibrillatory effect in