Predictors of successful complex catheter ablation for persistent atrial fibrillation despite failure of targeted procedural arrhythmia termination.

INTRODUCTION: Procedural atrial fibrillation (AF) termination is considered as a predictor of long-term success after catheter ablation for persistent AF (persAF). However, some patients remain free of arrhythmia recurrences despite failure to achieve AF termination. The objective of this study was to assess long-term outcome and prognostic factors in patients undergoing complex ablation without procedural AF termination. METHODS AND RESULTS: This study comprised 419 patients (63.8 ± 10.2 years, 63.4% male) undergoing complex ablation for persAF. Patients without procedural AF termination (n = 137, 64.2 ± 9.7 years, 63.5% male) were categorized into patients who remained in sinus rhythm (SR) in long-term outcome (SR-group) and patients with recurrence of AF or atrial tachycardia (AT) (AR-group). During a follow-up (FU) of 19.6 ± 14.6 months, the SR-group consisted of 65 (47.5%) and the AR-group of 69 (50.4%) patients. Three patients (2.2%) were lost to FU. Left atrial appendage (LAA) flow velocity and left atrium volume index (LAVI) could be identified as predictors for long-term success. LAA flow velocity and baseline AF cycle length (AFCL) were significantly associated with the type of arrhythmia recurrence (AF vs AT), ie, higher values of both are predictive for AT rather than AF recurrences. Patients with a LAVI < 34.4 mL/m² and significant AFCL increase during the ablation procedure had rather AT than AF recurrences. CONCLUSION: Patients with an arrhythmia-free outcome despite failure of procedural AF termination during complex ablation for persAF are characterized by specific morphological and functional properties that are easy to obtain.

Correlation between atrial fibrillation driver locations and complex fractionated atrial electrograms in patients with persistent atrial fibrillation.

INTRODUCTION: The aim of this study was to evaluate a spatial correlation between active atrial fibrillation (AF) drivers measured by electrocardiographic imaging and complex fractionated atrial electrograms (CFAEs) in patients with persistent AF. METHODS: Sixteen patients with persistent AF were included. A biatrial geometry relative to an array of 252-body-surface-electrodes was obtained from a noncontrast computed tomography scan. The reconstructed unipolar AF electrograms were signal-processed (ECVUE™, CardioInsight Technologies Inc., Cleveland, OH, USA) to identify AF drivers. Before driver ablation, a biatrial mapping using the NavX system (St. Jude Medical, St. Paul, MN, USA) was performed to identify CFAEs. CFAE and driver regions were then quantified and compared. RESULTS: AF was terminated by driver ablation in 11/16 (70%) patients. The mean number of ablated driver regions was 4 ± 1 per patient. The most frequent driver locations were the inferior left atrium and coronary sinus, the right pulmonary veins, and the right atrium. In 49/63 (78%) of the driver locations, more than 75% of the driver site showed CFAEs. The mean ablated driver area was 58 ± 24 cm2 (19 ± 11% of total surface area). The mean CFAE area was 178 ± 59 cm2 (49 ± 16%). The percentage of non-ablated CFAE area was 76 ± 13% of total CFAEs. In 9/11 patients with AF termination, the termination site showed CFAEs. CONCLUSIONS: There is a significant overlap between AF driver regions identified by the ECVUE™ system and CFAE areas identified by the NavX system. AF driver regions are smaller and mostly embedded in larger CFAE areas. Selective ablation of drivers in CFAE areas seems sufficient to terminate persistent AF in the majority of patients.

Systematic ajmaline challenge in patients with long QT 3 syndrome caused by the most common mutation: a multicentre study.

AIMS: Overlap syndromes of long QT 3 syndrome (LQT3) and the Brugada syndrome (BrS) have been reported. Identification of patients with an overlapping phenotype is crucial before initiation of Class I antiarrhythmic drugs for LQT3. Aim of the present study was to elucidate the yield of ajmaline challenge in unmasking the Brugada phenotype in patients with LQT3 caused by the most common mutation, SCN5A-E1784K. METHODS AND RESULTS: Consecutive families in tertiary referral centres diagnosed with LQT3 caused by SCN5A-E1784K were included in the study. Besides routine clinical work-up, ajmaline challenge was performed after informed consent. A total of 23 subjects (11 female, mean age 27 ± 14 years) from 4 unrelated families with a family history of sudden cardiac death and familial diagnosis of the SCN5A-E1784K mutation underwent ajmaline challenge and genetic testing. Sixteen subjects (9 female) were found to be heterozygous carriers of SCN5A-E1784K. Ajmaline challenge was positive in 12 out of the 16 (75%) mutation carriers, but negative in all non-carriers. Following ajmaline, a significant shortening of the rate-corrected JT (JTc) interval was observed in mutation carriers. The baseline JTc interval was significantly longer in mutation carriers with a positive ajmaline challenge compared with those with a negative one. CONCLUSION: Overlap of LQT3 and BrS in patients carrying the most common mutation is high. Therefore, ajmaline challenge represents an important step to rule out potential BrS overlap in these patients before starting sodium channel blockers for the beneficial effect of QT shortening in LQT3.

Cardiac arrhythmias in patients with Danon disease.

AIMS: Different cardiac arrhythmias have been suggested to be associated with Danon disease, e.g. Wolff-Parkinson-White syndrome. However, a systematic electrophysiological investigation of patients with Danon disease is lacking thus far. METHODS AND RESULTS: Seven patients with Danon disease (4 males, 35.8 ± 10.8 years; 3 females, 51.3 ± 19.9 years) from 3 different families were studied. In all patients, the presence of Danon disease was confirmed by western blot of biopsy material or genetic testing. The patients were characterized by 12-lead electrocardiogram (ECG), Holter ECG, echocardiography, and serial implantable cardioverter defibrillator (ICD) interrogations (in ICD recipients). All male patients underwent electrophysiological investigation (EP study). Asymptomatic ventricular tachyarrhythmias were documented in six of the seven patients. Moreover, 5 of the 7 patients suffered from atrial fibrillation (AF), with 1 of them experiencing thromboembolic stroke at the age of 30 years. In male patients, the initial QRS complex was characterized by a slurring upstroke and shortened PQ interval mimicking ventricular pre-excitation. One male patient showed initial QRS complex slurring with prolonged PR interval. However, the presence of an accessory pathway was excluded by an EP study in all patients. In female patients, initial QRS complex slurring was significantly less distinct. In four patients, ICD implantation was performed for primary prevention of sudden cardiac death. However, sustained ventricular arrhythmias were not documented in any of the patients. CONCLUSIONS: The present study indicates that the distinct surface ECG pattern in Danon disease is not associated with ventricular pre-excitation. Atrial fibrillation is frequently observed in these patients and may be associated with thromboembolic events in the young, while sustained ventricular arrhythmias occur less frequently than previously reported.

Multicentre evaluation of non-invasive biatrial mapping for persistent atrial fibrillation ablation: the AFACART study.

AIMS: Non-invasive electrocardiogram (ECG) mapping allows the activation of the entire atrial epicardium to be recorded simultaneously, potentially identifying mechanisms critical for atrial fibrillation (AF) persistence. We sought to evaluate the utility of ECG mapping as a practical tool prior to ablation of persistent AF (PsAF) in centres with no practical experience of the system. METHODS AND RESULTS: A total of 118 patients with continuous AF duration <1 year were prospectively studied at 8 European centres. Patients were on a median of 1 antiarrhythmic drug (AAD) that had failed to restore sinus rhythm. Electrocardiogram mapping (ECVUE™, CardioInsight, USA) was performed prior to ablation to map AF drivers (local re-entrant circuits or focal breakthroughs). Ablation targeted drivers depicted by the system, followed by pulmonary vein (PV) isolation, and finally left atrial linear ablation if AF persisted. The primary endpoint was AF termination. Totally, 4.9 ± 1.0 driver sites were mapped per patient with a cumulative mapping time of 16 ± 2 s. Of these, 53% of drivers were located in the left atrium, 27% in the right atrium, and 20% in the anterior interatrial groove. Driver-only ablation resulted in AF termination in 75 of the 118 patients (64%) with a mean radiofrequency (RF) duration of 46 ± 28 min. Acute termination rates were not significantly different amongst all 8 centres (P = 0.672). Ten additional patients terminated with PV isolation and lines resulting in a total AF termination rate of 72%. Total RF duration was 75 ± 27 min. At 1-year follow-up, 78% of the patients were off AADs and 77% of the patients were free from AF recurrence. Of the patients with no AF recurrence, 49% experienced at least one episode of atrial tachycardia (AT) which required either continued AAD therapy, cardioversion, or repeat ablation. CONCLUSION: Non-invasive mapping identifies biatrial drivers that are critical in PsAF. This is validated by successful AF termination in the majority of patients treated in centres with no experience of the system. Ablation targeting these drivers results in favourable AF-free survival at 1 year, albeit with a significant rate of AT recurrence requiring further management.

Device Therapy for Rate Control: Pacing, Resynchronisation and AV Node Ablation.

Atrioventricular node ablation (AVNA) is generally reserved for patients whose atrial fibrillation (AF) is refractory all other therapeutic options, since the recipients will often become pacemaker dependent. In such patients, this approach may prove particularly useful, especially if a tachycardia-induced cardiomyopathy is suspected. Historically, an "ablate and pace" approach has involved AVNA and right ventricular pacing, with or without an atrial lead. There is also an evolving role for atrioventricular node ablation in patients with AF who require cardiac resynchronisation therapy for treatment of systolic heart failure. A mortality benefit over pharmacotherapy has been demonstrated in observational studies and this concept is being further investigated in multi-centre randomised control trials.

Primary Persistent Atrial Fibrillation: A Distinct Arrhythmia Subentity of an Ablation Population.

INTRODUCTION: Persistent atrial fibrillation (persAF) can occur either as a sustained arrhythmia that has progressed from initially paroxysmal AF or as primary persAF without a history of any spontaneously terminated episode. There is a paucity of data differentiating between the 2 different persAF entities. Thus, we prospectively evaluated baseline characteristics, electrophysiological features, and ablation outcome in these 2 patient cohorts. METHODS AND RESULTS: A total number of 154 consecutive persAF patients (63 ± 10 years, f = 42, longstanding persAF = 60) were characterized in terms of having primary persAF (P-persAF group) or persAF that secondarily progressed from paroxysmal AF (S-persAF group). All patients underwent de novo catheter ablation using the stepwise approach. PersAF entities were characterized by detailed patient history, sequential Holter monitoring, and reports of documented modes of AF conversion, respectively. The P-persAF group had a higher number of young patients (<50 years), a shorter AF history, and a higher number of congestive heart failure. The HATCH score did not differ between the groups. Procedural AF termination rate was significantly higher in S-persAF than in P-persAF patients (n = 55 [81%] vs. n = 58 [68%], P = 0.043). At 1-year follow-up, the arrhythmia-free survival after a single procedure was significantly lower in patients with P-persAF (26% vs. 43%, P = 0.016). Categorization to P-persAF was the strongest independent predictor of arrhythmia recurrence. CONCLUSIONS: P-persAF seems to be a specific arrhythmia entity that is associated with a lower AF-termination rate and a worse outcome after catheter ablation as compared to S-persAF.

The Incidence of Audible Steam Pops Is Increased and Unpredictable With the ThermoCool® Surround Flow Catheter During Left Atrial Catheter Ablation: A Prospective Observational Study.

INTRODUCTION: Open irrigated radiofrequency (RF) ablation catheters with a porous tip (56 holes, TC-SF) permit delivering RF energy in a temperature-controlled mode without temperature rise. This prospective observational study investigated the association of different catheter parameters on the occurrence of audible steam pops during left atrial (LA) ablation. METHODS AND RESULTS: A total of 226 patients underwent TC-SF catheter ablation for atrial fibrillation. RF power delivery, impedance and catheter tip temperature were continually recorded throughout the ablation. Pulmonary vein isolation was performed with a maximum of 27 W and LA electrogram-guided or linear ablation with a maximum of 30 W. A total of 59 audible steam pops occurred, 2 of them resulting in pericardial tamponade. In the initial 89 patients, with an irrigation flow rate of 10 mL/min, 18 steam pops with one tamponade occurred in 12 (14%) patients. Subsequently, the irrigation flow rate was increased to 20 mL/min in the following 137 patients, resulting in the occurrence of 41 steam pops including one case of tamponade in a total of 30 (22%) patients. The maximal power was significantly higher in RF applications associated with a pop than those that did not. In only 12 (20%) steam pops, a significant impedance change occurred immediately before pop occurrence (4 [7%] impedance rise >10 ohm, 8 [13%] impedance drop >15 ohm). CONCLUSIONS: The TC-SF catheter does not provide sufficient feedback from the ablated tissue to prevent steam popping.

Reduction of ICD shock burden by eliminating back-up pacing induced ventricular tachyarrhythmias.

INTRODUCTION: Implantable cardioverter defibrillators (ICD) may have the capacity to provoke or worsen ventricular tachyarrhythmias (VT). It has been reported that ICD shocks by itself can increase mortality. This study aimed to determine the role of back-up pacing-induced VT (PIT) in the overall ICD shock burden by avoiding pause-related ventricular back-up pacing. METHODS AND RESULTS: A population of 550 single-chamber ICD patients was studied. Of them, 17 (3%, 69 ± 16 years, 14 male) patients had documented episodes of PIT. A total of 431 VT episodes were documented including 89 (21%) due to PIT. In 3 patients, VT events were exclusively PITs. After ≥2 documented PITs, the pacing output for VVI pacing was set to a subthreshold level resulting in noncapturable ventricular back-up pacing. All other device parameters remained unchanged to prove a potential proarrhythmic effect of pause related back-up pacing. During a follow-up of 99 ± 39 months after reducing the pacing output to a subthreshold level, no further episodes of PIT were observed (P < 0.001). Moreover, with the prevention of PITs, the ICD shock burden decreased significantly (pre: 150 vs. post: 18, P < 0.001). However, a single event of pause-induced VT occurred due to missing back-up pacing. CONCLUSIONS: PIT is a frequent mechanism of VTs in ICD patients resulting in a substantially increased shock burden. Elimination of pause-related back-up pacing by subthreshold pacing output effectively abolishes PIT and thus significantly reduces ICD shock burden.

Impact of structural heart disease on the acute complication rate in atrial fibrillation ablation: results from the German Ablation Registry.

INTRODUCTION: Catheter ablation (CA) has emerged as a widespread therapeutic option in the treatment of atrial fibrillation (AF). Currently, no safety data with regard to the impact of the underlying structural heart diseases (SHD) are available. We sought to assess the risk for acute and long-term complications during CA of AF in relation to underlying SHD. METHODS AND RESULTS: We included 6,211 patients in a prospective registry undergoing CA of AF in 41 nationwide centers. All patients were divided into 4 groups according to the underlying heart disease: No SHD (69.4%), hypertensive heart disease (HHD) (12.0%), coronary artery disease (CAD) (15.1%), and cardiomyopathy (CM) (3.6%). In univariate analysis, patients with HHD had an overall complication rate of 7.28%, whereas patients without an SHD had a significantly lower rate of 6.01% (P < 0.01). Multivariate analysis revealed that HHD (adjusted odds ratio [OR]: 1.97 [95% confidence interval (CI): 1.02-3.83], P = 0.0442) and age (years; OR: 1.04 [95% CI: 1.01-1.07], P = 0.0155) were independent predictors of severe, nonfatal complications and death. Other SHD including CAD (OR: 1.48 (0.73-3.00), P = 0.2797) and CM (OR: 2.37 [0.70-7.99], P = 0.1630) failed to reach statistical significance. Male sex was protective (OR: 0.47 [95% CI: 0.27-0.81], P = 0.0062). CONCLUSION: In general, CA of AF has a low number of severe complications. In our prospective registry HHD emerged as an independent predictor of severe, nonfatal complications during AF ablation but other SHD including CAD and CM did not. The influence of HHD on the complication rate should be considered in patient selection.

Cardiovascular magnetic resonance demonstrates reversible atrial dysfunction after catheter ablation of persistent atrial fibrillation.

INTRODUCTION: There is a paucity of data on atrial injury following ablation of persistent atrial fibrillation (AF). This study aimed at assessing reversibility of atrial dysfunction after successful persistent AF ablation using cardiovascular magnetic resonance (CMR). METHODS AND RESULTS: CMR was performed during sinus rhythm (SR) in 20 consecutive patients with persistent AF at baseline (BL) within 24 hours after ablation and after 6-month follow-up (FU). Catheter ablation included atrial substrate modification using the stepwise approach following pulmonary vein isolation (PVI) in order to attempt termination of persistent AF. Active left (LA) and right atrial (RA) function were quantified by calculating the active emptying fraction (AEF) from transvalvular flow profiles using velocity encoded (VENC) CMR. LA appendage (LAA) function was quantified by measurements of peak a-wave velocities from flow profiles perpendicular to the LAA orifice. Peri-atrial edema was assessed using black-blood T2 -weighted CMR. A significant improvement was found in LA-AEF from 18 (12-26)% at BL to 25 (22-35)% at FU (P = 0.0001). Furthermore, RA-AEF significantly increased from 31 (19-35)% at BL to 40 (35-51)% at FU (P < 0.0001). A significant improvement was also found for LAA a-wave velocities from 45 (31-65) cm/s at BL to 62 (49-75) cm/s at FU (P < 0.01). The area of peri-atrial edema on T2 -weighted CMR decreased from 1393 (1098-1797) mm(2) at BL to 24 (1-92) mm(2) at FU (P < 0.0001). CONCLUSION: CMR demonstrates reversibility of LA, LAA, and RA dysfunction associated with resorption of peri-atrial edema in patients with SR after persistent AF ablation.

Automated three-dimensional activation versus conventional mapping for catheter ablation of atrial tachycardia - A prospective randomized trial.

Background: The automated NavX Ensite Precision latency-map (LM) algorithm aims to identify atrial tachycardia (AT) mechanisms. However, data on a direct comparison of this algorithm with conventional mapping are scarce. Methods: Patients scheduled for AT ablation were randomized to mapping with the LM- algorithm (LM group) or to conventional mapping (conventional only group: ConvO), using entrainment and local activation mapping techniques. Several outcomes were exploratively analyzed. Primary endpoint was intraprocedural AT Termination. If AT termination with only automated 3D-Mapping failed, additional conventional methods were applied (conversion). Results: A total of 63 patients (mean 67 years, 34 % female) were enrolled. In the LM group (n = 31), the correct AT mechanism was identified in 14 patients (45 %) using the algorithm alone compared to 30 patients (94 %) with conventional methods. Time to termination of the first AT was not different between groups (LM group 34 ± 20 vs. ConvO 43.1 ± 28.3 min; p = 0.2). However, when AT termination did not occur with LM algorithm, time to termination prolonged significantly (65 ± 35 min; p = 0.01). After applying conventional methods (conversion), procedural termination rates did not differ between LM group (90 %) vs. ConvO (94 %) (p = 0.3). During a follow-up time of 20 ± 9 months, no differences were observed in clinical outcomes. Conclusion: In this small prospective, randomized study, the use of the LM algorithm alone may lead to AT termination, but less accurate than conventional methods.

A rare case of right heart failure with the necessity for veno-arterial extracorporeal membrane oxygenation following pulmonary vein stenosis after radiofrequency ablation for atrial fibrillation.

Pulmonary vein stenosis (PVS) after radiofrequency energy-mediated percutaneous pulmonary vein isolation as a treatment option for atrial fibrillation is a serious complication and the prevalence in historical reports varies between 0% and 42%. Symptoms of PVS are nonspecific and can include general symptoms such as dyspnea, cough, recurrent pneumonia, and chest pain. Pathophysiologically it increases the postcapillary pressure in the pulmonary circuit and may result in pulmonary hypertension (PH). Misdiagnosis and delayed treatment are common. We here report a case of a 59-year-old female with a history of pulmonary vein ablation followed by progressive dyspnea (New York Heart Association IV), right heart failure, CPR, and the need for extracorporeal membrane oxygenation (ECMO). Further treatment strategy includes pulmonary vein dilatation and stenting of both the left superior pulmonary vein and left inferior pulmonary vein, as well as balloon dilatation of RIPV under temporary ECMO support. Symptomatic, severe PVS is a rare complication after catheter ablation of atrial fibrillation. PVS can result in life-threatening complications such as PH with acute right heart failure. Early diagnosis is crucial but challenging. Mechanical cardiopulmonary support by veno-arterial ECMO for bridging to angioplasty could be a lifesaving option.

Intravenous administration of magnesium and potassium solution lowers energy levels and increases success rates electrically cardioverting atrial fibrillation.

BACKGROUND: External biphasic electrical cardioversion (CV) is a standard treatment option for patients suffering from acute symptoms of atrial fibrillation (AF). Nevertheless, CV is not always successful, and thus strategies to increase the success rate are desirable. OBJECTIVE: The purpose of this study was to evaluate the effect of intravenously administered K/Mg solution on the biphasic CV energy threshold and success rate to restore sinus rhythm (SR) in patients with AF. METHODS: The study consisted of 170 patients with persistent AF. The patients were randomly assigned to undergo biphasic CV either with (n = 84) or without (n = 86) pretreatment with K/Mg solution. An energy step-up protocol of 75, 100, and 150 W (J) was used. RESULTS: Biphasic CV of AF was effective in 81 (96.4%) patients in the pretreatment and 74 (86.0%) patients in the control group (P = 0.005). The effective energy level required to achieve SR was significantly lower in the pretreated group (140.8 ± 26.9 J vs 182.5 ± 52.2 J, P = 0.02). No K/Mg-solution-associated side effects such as hypotension or bradycardia were observed. CONCLUSION: Administration of K/Mg solution positively influences the success rate of CV in patients with persistent AF. Furthermore, significantly less energy is required to successfully restore SR and therefore K/Mg pretreatment may facilitate SR restoration in patients undergoing CV for AF.