Simon Kircher

Tailored Atrial Substrate Modification Based On Low-Voltage Areas in Catheter Ablation of Atrial Fibrillation

Background—Reduced electrogram amplitude has been shown to correlate with diseased myocardium. We describe a novel individualized approach for catheter ablation of atrial fibrillation (AF) based on low-voltage areas (LVAs) in the left atrium (LA). We sought to assess (1) the incidence of LVAs in patients undergoing AF catheter ablation, (2) the distribution of LVAs within the LA, and (3) the effect of an individualized ablation strategy on long-term rhythm outcomes. Methods and Results—In 178 patients with paroxysmal or persistent AF, LA voltage maps were created during sinus rhythm after circumferential pulmonary vein isolation. Subsequent substrate modification was confined to the presence of LVA (<0.5 mV) and inducible regular atrial tachycardias. LVAs were identified in 35% and 10% of patients with persistent and paroxysmal AF, respectively. The LA roof and the anterior, septal, and posterior wall LA were most often affected. The 12-month atrial tachycardias/AF-free survival was 62% for patients without LVAs and 70% for patients with LVAs and tailored substrate modification (P=0.3). Success rate in a comparison group of 26 LVA patients without further substrate modification was 27%. Conclusions—LVAs can be found at preferred sites in 10% of patients with paroxysmal AF and in 35% of patients with persistent AF. This is the first clinical report describing a consistent voltage-based approach for substrate modification in addition to circumferential pulmonary vein isolation irrespective of AF type. Application of this limited individualized approach may have the potential to compensate for the impaired 12-month outcome of patients with endocardial structural defects.

Steerable Versus Nonsteerable Sheath Technology in Atrial Fibrillation Ablation A Prospective, Randomized Study

Background— Steerable sheath technology is designed to facilitate catheter access, stability, and tissue contact in target sites of atrial fibrillation (AF) catheter ablation. We hypothesized that rhythm control after interventional AF treatment is more successful using a steerable as compared with a nonsteerable sheath access. Methods and Results— One hundred thirty patients with paroxysmal or persistent drug-refractory AF undergoing their first ablation procedure were prospectively included in a randomized fashion in 2 centers. Ablation was performed by 10 operators with different levels of clinical experience. Treatment outcome was measured with serial 7-day Holter ECGs and additional symptom-based arrhythmia documentation. Single procedure success (freedom from AF and/or atrial macroreentrant tachycardia) was significantly higher in patients ablated with a steerable sheath (78% versus 55% after 3 months, P=0.005; 76% versus 53% after 6 months, P=0.008). Rate of pulmonary vein isolation, procedure duration, and radiofrequency application time did not differ significantly, whereas fluoroscopy time was lower in the steerable sheath group (33±14 minutes versus 45±17 minutes, P<0.001). Complication rates showed no significant difference (3.2% versus 5%, P=0.608). On multivariable analysis, steerable sheath usage remained the only powerful predictor for rhythm outcome after 6 months of follow-up (hazard ratio, 2.837 [1.197 to 6.723]). Conclusions— AF catheter ablation using a manually controlled, steerable sheath for catheter navigation resulted in a significantly higher clinical success rate, with comparable complication rates and with a reduction in periprocedural fluoroscopy time. Clinical Trial Registration— URL: http://clinicaltrials.gov. Unique identifier: NCT00469638.

Novel oral anticoagulants in a real-world cohort of patients undergoing catheter ablation of atrial fibrillation

AIMS Experiences with novel oral anticoagulants (NOACs) early after atrial fibrillation (AF) catheter ablation are limited and show controversial results. We aimed to assess the longer-term safety, efficacy, and acceptance of NOACs in a large real-world cohort of patients presenting for AF catheter ablation. METHODS AND RESULTS From July 2010 until June 2012, 259 patients undergoing AF catheter ablation were prospectively included. Novel oral anticoagulants were given for at least 3 months post-ablation. Clinical outcome (stroke, thromboembolic events, major bleeding), adverse effects, and drug adherence were assessed at discharge and follow-up. On admission patients were presented with a variety of anticoagulants including 54 patients (21%) already on NOACs prior ablation. After ablation 38% of patients received dabigatran 110 mg, 56% 150 mg, and 6% received rivaroxaban 20 mg. There were four periprocedural thromboembolic and major bleeding complications (1.5%), all in patients without NOACs prior ablation (two on warfarin and two on heparin). During long-term follow-up [311 (199; 418) days] no stroke, systemic embolism, or major haemorrhage could be observed. Uneventful electrical cardioversions and reablation procedures were performed in 27 and 12 patients on dabigatran, respectively. Novel oral anticoagulants were prematurely stopped or switched to another anticoagulant due to side effects or at the preference of the treating general practitioner in 9 and 10 patients, respectively. CONCLUSION In this prospective observational study, anticoagulation with NOACs following AF catheter ablation was safe and effective at long-term follow-up. Fast onset of action makes NOACs especially attractive in patients without effective anticoagulation on admission and in patients following periprocedural complications.

Color-coded three-dimensional entrainment mapping for analysis and treatment of atrial macroreentrant tachycardia

BACKGROUND Mapping and ablation of atrial macroreentrant tachycardia focus on activation mapping with identification of the area of slow conduction. OBJECTIVE The purpose of this study was to evaluate a new concept for analysis and treatment of macroreentrant tachycardia based on color-coded three-dimensional (3D) entrainment mapping and subsequent placement of strategic lesion lines. METHODS Twenty-six patients presented with macroreentrant tachycardia (cycle length 329 +/- 70 ms). Using nonfluoroscopic systems (CARTO 12, NavX 14), sequential mapping of the target atrium was performed. On each mapping point, the 3D location was paired with color-coded entrainment information so that the reentrant circuit could be directly visualized. RESULTS Procedural duration, fluoroscopy time, and radiofrequency time measured 181 +/- 58, 37 +/- 19, and 31 +/- 17 minutes, respectively. Thirty-nine macroreentrant tachycardias were ablated: perimitral 9, around pulmonary vein ostium 6, through left atrial roof 5, around left atrial appendage 3, right atrial cavotricuspid isthmus dependent 6, around right atrial scar 2, around superior vena cava 1, within the septum 5, and within the coronary sinus 2. Tachycardia termination and noninducibility of any macroreentrant tachycardia was the procedural end-point. In case of left atrial macroreentrant tachycardia, pulmonary vein isolation was completed. Follow-up with serial 7-day Holter covered 302 +/- 82 days. Two (8%) patients experienced recurrences of a pretreated macroreentrant tachycardia. CONCLUSION In patients with macroreentrant tachycardia, color-coded 3D entrainment mapping is feasible to accurately determine and visualize the 3D location of the reentrant circuit and to plan a strategic ablation line concept. That approach, not targeting the area of slow conduction of the circuit, resulted in excellent procedural success (100%), with long-term freedom from any tachycardia recurrences in 88% of patients.

Computed tomography model-based treatment of atrial fibrillation and atrial macro-re-entrant tachycardia

Aims Accurate orientation within true three-dimensional (3D) anatomies is essential for the successful radiofrequency (RF) catheter ablation of atrial fibrillation (AF) and atrial macro-re-entrant tachycardia (MRT). In this prospective study, ablation of AF and MRT was performed exclusively using a pre-acquired and integrated computed tomography (CT) image for anatomical 3D orientation without electro-anatomic reconstruction of the left atrium (LA). Methods and results Fifty-four consecutive patients suffering from AF (n = 36) and/or MRT (n = 18) underwent RF catheter ablation. A 3D CT image was registered into the NavX-Ensite system without reconstruction of the atrial chamber anatomy. The quality of CT alignment was assessed and validated according to fluoroscopy information, electrogram characteristics, and tactile feedback at 31 pre-defined LA control points. The ablation of AF as well as mapping and ablation of MRT was performed within the 3D CT anatomy. In all patients, mapping and ablation could be performed without the reconstruction of the respective atrial chamber anatomy. The overall CT alignment was highly accurate with true surface contact in 90% (84%; 100%) of the control points. Complete isolation of all pulmonary vein (PV) funnels was achieved in 35 of 36 patients (97%) with AF. In patients with persistent AF (n = 11), additional isolation of the posterior LA (box lesion) and the placement of a mitral isthmus line were performed. The MRT mechanisms were as follows: around a PV ostium (n = 6), perimitral (n = 4), through LA roof (n = 5), septal (n = 2), and around left atrial appendage (n = 1). After a follow-up of 122 ± 33 days, 22/25 (88%) patients with paroxysmal AF, 8/11 (73%) with persistent AF, and 16/18 (89%) with MRT remained free from arrhythmia recurrences. Conclusion For patients with AF and MRT, our study shows the feasibility of successful placement of complex linear ablation line concepts guided by an integrated 3D image anatomy alone rather than catheter-based virtual chamber surface reconstructions.

Catheter ablation of atrial fibrillation supported by novel nonfluoroscopic 4D navigation technology

BACKGROUND The MediGuide technology (MGT) represents a novel sensor-based electromagnetic 4-dimensional (4D) navigation system allowing real-time catheter tracking in the environment of prerecorded X-ray loops. OBJECTIVE To report on our clinical experience in atrial fibrillation (AF) ablation with recently available MGT-enabled ablation catheters. METHODS The MGT was used in addition to a conventional 3D mapping system in 80 patients with AF (age 61 ± 10 years; 47 men; 40 with persistent AF), who underwent circumferential pulmonary vein isolation and voltage mapping with and without substrate modification. Short native right anterior oblique/left anterior oblique loops were used as background movies for the nonfluoroscopic placement of sensor-equipped diagnostic catheters into the coronary sinus and the right ventricle. After single transseptal puncture, selective angiograms of the pulmonary veins were used as background movies for near nonfluoroscopic left atrial reconstruction. Computed tomography registration as well as mapping/ablation was performed by using the new open-irrigated MGT-enabled ablation catheter. RESULTS MGT application was not associated with a change in established workflow. Large parts of the procedure (mean entire duration 167 ± 47 minutes) could be done without additional fluoroscopy, whereas median residual fluoroscopy duration of 4.6 (interquartile range: 2.9, 7.1) minutes was mainly used for the acquisition of background loops, transseptal puncture, occasional verification of transseptal sheath position, and manipulation of the circular mapping catheter. Three (4%) minor complications occurred. CONCLUSIONS The MGT integrates easily into the workflow of standard AF ablation and allows for high-quality nonfluoroscopic 4D catheter tracking. This results in low radiation exposure for patients and staff without complicating the workflow of the procedure.

Impact of Metabolic Syndrome on Left Atrial Electroanatomical Remodeling and Outcomes After Radiofrequency Ablation of Nonvalvular Atrial Fibrillation

Background—Recent studies reported worse outcomes after atrial fibrillation (AF) ablation in patients with metabolic syndrome (MetS). However, mechanisms of AF recurrence in MetS remain unclear. Method and Results—We performed pulmonary vein isolation and voltage mapping in 236 patients with AF (age 61±9.6 years; persistent AF 64%; MetS 54%). Left atrial (LA) low voltage areas were semiquantitatively estimated and presented as low voltage index. MetS was defined according to National Cholesterol Education Program Adult Treatment Panel III. Follow-up for AF recurrence ⩽12 months was performed. LA low voltage areas were observed in 46% of patients with MetS versus 8.2% patients without MetS ; P<0.0001. MetS was an independent predictor of LA low voltage areas: odds ratio, 11.64; 95% confidence interval, 4.381–30.903; P<0.0001. Observed AF recurrence at 12 months was 42.7% in MetS versus 36.1% in the non-MetS group (P=0.303). The presence of LA low voltage areas was a predictor of 12-month AF recurrence: odds ratio, 2.99; 95% confidence interval, 1.36–6.56; P=0.006. Probability of 12-month AF recurrence increased with 84.5% for every unit of low voltage Index. Conclusions—MetS was not associated with worse outcomes after radiofrequency catheter ablation of AF, but LA low voltage areas were more frequently observed in patients with MetS. The presence and extent of LA low voltage areas may influence the long-term outcomes after catheter ablation.

Prospective, multicenter validation of a clinical risk score for left atrial arrhythmogenic substrate based on voltage analysis: DR-FLASH score

BACKGROUND Left atrial (LA) low-voltage areas (LVAs) are frequently observed in patients with atrial fibrillation (AF) and may predict AF recurrence after catheter ablation. OBJECTIVE The aim of this study was to develop and validate a clinical tool to identify LVAs that are associated with AF recurrence after pulmonary vein isolation (PVI). METHODS In a cohort of 238 patients, voltage maps were created during LA procedures. LVAs were defined as areas with electrogram amplitudes <0.5 mV. On the basis of regression analysis, predictors of LA substrate were identified. These parameters were used to establish a dedicated risk score (DR-FLASH score, based on diabetes mellitus, renal dysfunction, persistent form of AF, LA diameter >45 mm, age >65 years, female sex, and hypertension). This risk score was then prospectively validated in a multicenter cohort of 180 patients. The association of the score with long-term recurrence of atrial arrhythmias after circumferential PVI was tested in a retrospective cohort of 484 patients. RESULTS The DR-FLASH score effectively identified LVA substrate (C statistic = 0.801, P < .001). In the prospective multicenter validation cohort, the predictive value of the DR-FLASH score was confirmed (C statistic = 0.767, P < .001). The probability for the presence of LA substrate increased by a factor of 2.2 (95% confidence interval [CI] 1.6-2.9, P < .001) with each point scored. Furthermore, the risk of AF recurrence after PVI increased by a factor of 1.3 (95% CI 1.1-1.5, P < .001) with every additional point and was almost 2 times higher in patients with a DR-FLASH score >3 (odds ratio 1.7, 95% CI 1.1-2.8, P = .026). CONCLUSION The DR-FLASH score may be useful to identify patients who may require extensive substrate modification instead of PVI alone.

Quantitative analysis of isolation area and rhythm outcome in patients with paroxysmal atrial fibrillation after circumferential pulmonary vein antrum isolation using the pace-and-ablate technique.

Background— We sought to determine the relationship between the size of the left atrial isolated surface area (ISA) after pulmonary vein antrum isolation for paroxysmal atrial fibrillation (AF) and rhythm outcome during a 12-month follow-up. Methods and Results— One hundred one consecutive patients with paroxysmal AF (mean age, 59±11 years; median [range] AF history, 36 [24–96] months; mean left atrial size, 42±6 mm) were enrolled. The ISA was defined as the ratio of the total isolated antral surface area excluding the pulmonary veins to the sum of the total isolated antral surface area and the left atrial posterior wall surface area, while considering the individual characteristics of antral anatomy. All surface areas were assessed using the NavX system. Patients were divided into 4 groups according to ISA (group I: <50%; group II: 50 to <60%; group III: 60 to <70%; group IV: ≥70%). The average ISA for all patients was 59.2±11.6%. Subgroup analysis showed that ISA was 42.8±4.2% in group I (n=23), 54.2±3.0% in group II (n=23), 64.3±3.0% in group III (n=33), and 73.9±3.6% in group IV (n=22). After a 12-month follow-up period, 70% of patients in group I, 78% in group II, 97% in group III, and 100% in group IV were free from AF and atrial macroreentrant tachycardia. There was a significant difference between groups I and III, I and IV, II and III, and II and IV but not groups I and II and groups III and IV (log-rank test P=0.024, 0.016, 0.037, 0.044, 0.584, and 0.500, respectively). Receiver operating characteristic curve analysis yielded an optimal cutoff value of 55% for ISA. Conclusions— After 12 months, a larger ISA was associated with a significantly lower AF and macroreentrant tachycardia recurrence rate. ISA≥55% may thus serve as a predictor for long-term success after pulmonary vein antrum isolation.

Use of electrical coupling information in AF catheter ablation: A prospective randomized pilot study

BACKGROUND Catheter contact is important for radiofrequency (RF) ablation. Local electrical catheter-to-tissue coupling has been described as a tool to objectively measure contact. OBJECTIVE We hypothesized that pulmonary vein isolation (PVI) ablation using electrical coupling information (ECI) would yield higher rates of PVI than an approach without ECI. METHODS Forty patients with atrial fibrillation were prospectively included. In each patient, 1 pair of pulmonary veins (PVs) was randomly chosen to be encircled with ECI available while the other pair was encircled without use of ECI. RESULTS The rate of PVI was significantly higher in PVs encircled with ECI available (58% vs 30%; P = .024). PV encircling with coupling resulted in slightly longer procedure (26.5 [interquartile range {IQR} 22-32.5] vs 23.5 [IQR 19-26.5] minutes; P = .019), fluoroscopy (9.0 [IQR 6-12] vs 6.9 [IQR 4-8.6] minutes; P = .011), and RF (20.0 [IQR 16.5-23.5] vs 17.3 [IQR 15.1-20.6] minutes; P = .015) times. For nonisolated PVs, the coupling group had significantly fewer gaps (3.0 [IQR 1.8-7] vs 6.0 [IQR 4-11]; P = 0.021) and gap mapping/closure needed shorter procedure (9.0 [IQR 4-16] vs 13.0 [IQR 11-21] minutes; P = .04), fluoroscopy (3.9 [IQR 2-7.1] vs 6.0 [IQR 4.6-7.9] minutes; P = .038), and RF (1.9 [IQR 0.9-5] vs 5.2 [IQR 3.3-8.6] minutes; P = .016) times. CONCLUSIONS The use of ECI improved lesion deployment measured as higher rates of PVI after anatomical encircling. For nonisolated PVs, fewer gaps and faster gap closure were found using ECI.