Armin Luik

Cryoablation Versus Radiofrequency Energy for the Ablation of Atrioventricular Nodal Reentrant Tachycardia (the CYRANO Study) Results From a Large Multicenter Prospective Randomized Trial

Background— Cryoablation has emerged as an alternative to radiofrequency catheter ablation (RFCA) for the treatment of atrioventricular (AV) nodal reentrant tachycardia (AVNRT). The purpose of this prospective randomized study was to test whether cryoablation is as effective as RFCA during both short-term and long-term follow-up with a lower risk of permanent AV block. Methods and Results— A total of 509 patients underwent slow pathway cryoablation (n=251) or RFCA (n=258). The primary end point was immediate ablation failure, permanent AV block, and AVNRT recurrence during a 6-month follow-up. Secondary end points included procedural parameters, device functionality, and pain perception. Significantly more patients in the cryoablation group than the RFCA group reached the primary end point (12.6% versus 6.3%; P=0.018). Whereas immediate ablation success (96.8% versus 98.4%) and occurrence of permanent AV block (0% versus 0.4%) did not differ, AVNRT recurrence was significantly more frequent in the cryoablation group (9.4% versus 4.4%; P=0.029). In the cryoablation group, procedure duration was longer (138±54 versus 123±48 minutes; P=0.0012) and more device problems occurred (13 versus 2 patients; P=0.033). Pain perception was lower in the cryoablation group (P<0.001). Conclusions— Cryoablation for AVNRT is as effective as RFCA over the short term but is associated with a higher recurrence rate at the 6-month follow-up. The risk of permanent AV block does not differ significantly between cryoablation and RFCA. The potential benefits of cryoenergy relative to ablation safety and pain perception are counterbalanced by longer procedure times, more device problems, and a high recurrence rate. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00196222.

Acute Effects and Long-Term Outcome of Pulmonary Vein Isolation in Combination With Electrogram-Guided Substrate Ablation for Persistent Atrial Fibrillation

Complex fractionated atrial electrographic (CFAE) catheter ablation is a new approach for the treatment of atrial fibrillation (AF). It is unclear if acute results of this approach correspond to long-term outcome. The purpose of this study was to prospectively assess acute and long-term successes of an ablation approach combining pulmonary vein isolation (PVI) and ablation of CFAE areas for treatment of persistent AF. PVI and ablation of CFAE areas were performed in 35 patients with persistent AF (30 men, 57+/-9 years of age). At the end of the ablation procedure AF had terminated in 23 of 35 patients (66%) by conversion to sinus rhythm (8 of 23 patients, 35%) or organization to atrial tachycardia (15 of 23 patients, 65%). AF persisted in 12 of 35 patients (34%). At the end of the follow-up period (19+/-12 months), sinus rhythm was present in 26 of 35 patients (74%), including 9 patients with a repeat procedure. This group of 26 patients consisted of 7 of 8 patients (88%) with acute sinus rhythm after the first ablation, 11 of 15 patients (73%) with organization, and 8 of 12 patients (66%) with ongoing AF (p=0.32). In conclusion, a combined approach of PVI and CFAE ablation in persistent AF leads to acute AF termination in 66% and long-term maintenance of sinus rhythm in 74% of cases. However, long-term outcome was not predictable by acute results of the ablation procedure.

Long-Term Results of Transapical Versus Transfemoral TAVI in a Real World Population of 1000 Patients With Severe Symptomatic Aortic Stenosis

Background—Transapical transcatheter aortic valve implantation is generally perceived to be associated with increased morbidity compared with transfemoral transcatheter aortic valve implantation. We aimed to compare access-related complications and survival using propensity score matching. Methods and Results—Prospective, single-center registry of 1000 consecutive patients undergoing transapical and transfemoral transcatheter aortic valve implantation between May 2008 and April 2012. Transapical was performed in 413 patients and transfemoral in 587 patients. Patients with transapical access were less often women and less had pulmonary hypertension. Further they had more peripheral arterial disease, coronary artery disease, carotid stenosis, and recurrent surgery and a higher logistic EuroSCORE I (24.3%±16.2% for transapical versus 22.2%±16.2% for transfemoral; P<0.01). After building 2 propensity score–matched groups of 354 patients each with either access route (total 708 patients), baseline characteristics were comparable. In this analysis, there was no significant difference in 30 day mortality (5.9% transapical versus 8.5% transfemoral; P=0.19), the rate of myocardial infarction (2.5% transapical versus 2.0% transfemoral; P=0.61), stroke (2.0% transapical versus 2.3% transfemoral; P=0.79), bleeding complications, pacemaker implantation rates, or moderate aortic insufficiency. Stage 1 renal complications were more common in transapical patients (odds ratio, 2.81; 95% confidence interval, 1.93–4.09), whereas major vascular complications were less common (odds ratio, 0.14; 95% confidence interval, 0.06–0.29). Survival probability over the long term was not statistically different (hazard ratio, 0.89; 95% confidence interval, 0.72–1.10; log-rank Test, P=0.27). Conclusions—The data demonstrate that in an experienced multidisciplinary heart team, either access route can be performed with comparable results.

Conduction Velocity Restitution of the Human Atrium—An Efficient Measurement Protocol for Clinical Electrophysiological Studies

Conduction velocity (CV) and CV restitution are important substrate parameters for understanding atrial arrhythmias. The aim of this work is to (i) present a simple but feasible method to measure CV restitution in-vivo using standard circular catheters, and (ii) validate its feasibility with data measured during incremental pacing. From five patients undergoing catheter ablation, we analyzed eight datasets from sinus rhythm and incremental pacing sequences. Every wavefront was measured with a circular catheter and the electrograms were analyzed with a cosine-fit method that calculated the local CV. For each pacing cycle length, the mean local CV was determined. Furthermore, changes in global CV were estimated from the time delay between pacing stimulus and wavefront arrival. Comparing local and global CV between pacing at 500 and 300 ms, we found significant changes in seven of eight pacing sequences. On average, local CV decreased by 20 ± 15% and global CV by 17 ± 13%. The method allows for in-vivo measurements of absolute CV and CV restitution during standard clinical procedures. Such data may provide valuable insights into mechanisms of atrial arrhythmias. This is important both for improving cardiac models and also for clinical applications, such as characterizing arrhythmogenic substrates during sinus rhythm.

Wave-Direction and Conduction-Velocity Analysis From Intracardiac Electrograms–A Single-Shot Technique

Atrial arrhythmias, such as atrial flutter or fibrillation, are frequent indications for catheter ablation. Recorded intracardiac electrograms (EGMs) are, however, mostly evaluated subjectively by the physicians. In this paper, we present a method to quantitatively extract the wave direction and the local conduction velocity from one single beat in a circular mapping catheter signal. We simulated typical clinical EGMs to validate the method. We then showed that even with noise, the average directional error was below 10^ and the average velocity error was below 5.4 cm/s. In a realistic atrial simulation, the method could clearly distinguish between stimuli from different pulmonary veins. We further analyzed eight clinical data segments from three patients in normal sinus rhythm and with stimulation. We obtained stable wave directions for each segment and conduction velocities between 70 and 115 cm/s. We conclude that the method allows for easy quantitative analysis of single macroscopic wavefronts in intracardiac EGMs, such as during atrial flutter or in typical clinical stimulation procedures after termination of atrial fibrillation. With corresponding simulated data, it can provide an interface to personalize electrophysiological (EP) models. Furthermore, it could be integrated into EP navigation systems to provide quantitative data of high diagnostic value to the physician.

A survey of German centres performing invasive electrophysiology: structure, procedures, and training positions.

AIMS To provide a nationwide survey (and reference for the future) on cardiac electrophysiologists, types and numbers of invasive electrophysiological procedures, and training opportunities in 2010. METHODS AND RESULTS German cardiology centres performing invasive electrophysiology were identified from quality reports and contacted to fill a questionnaire. A majority of 122 centres (65%) responded. Electrophysiology (ablation procedures and device therapy) was mainly part of a cardiology department (82%), and only in 9% independent (own budget). In only 58% of the centres, (at least) two physicians were present during catheter ablations. Although in 2010, women represented 59.4% of physicians <35 years old, only 26% of physicians in electrophysiology training were female. In total, 33 420 catheter ablations were performed with a median number of 180 per centre. Atrial fibrillation (AF) was the most common arrhythmia invasively treated (35%). At least 50 AF ablations were performed in 53% of the centres. Of the centres performing AF ablations, consecutive left atrial arrhythmias were treated by catheter ablation only in 75%, and only 44% had in-house surgical backup. Only one-fourth of the 122 centres fulfilled all requirements for training centre accreditation according to the European Heart Rhythm Association and the German Cardiac Society. CONCLUSION The results indicate a high number of electrophysiology centres and procedures in Germany. Atrial fibrillation was the most common arrhythmia invasively treated. An increasing demand for catheter ablation is likely, but training opportunities are limited. Women are clearly underrepresented. A co-operation of higher and lower volume electrophysiology centres may be necessary for training purposes.

Rationale and design of the FreezeAF trial: A randomized controlled noninferiority trial comparing isolation of the pulmonary veins with the cryoballoon catheter versus open irrigated radiofrequency ablation in patients with paroxysmal atrial fibrillation

BACKGROUND Atrial fibrillation is the most commonly encountered clinical arrhythmia, and there are an increasing number of patients with paroxysmal atrial fibrillation treated by catheter ablation. The criterion standard is the isolation of the pulmonary veins (PVs) using radiofrequency (RF) energy in combination with an open irrigated tip catheter. The procedure remains technically challenging with a significant number of complications. So far, no randomized comparisons between the outcome of cryoballoon versus RF ablation are available. STUDY DESIGN The object of this randomized clinical trial is to compare the efficacy of isolating the PVs with either the cryoballoon or the open irrigated tip RF catheter. Two hundred forty-four patients with paroxysmal atrial fibrillation will be randomized for either RF or cryoballoon. With both techniques, PV isolation will be performed. Primary end point of the study is freedom from atrial fibrillation without antiarrhythmic drugs and without persistent complications at 6 and 12 months. Clinical success will be evaluated using Holter electrocardiogram and event recordings for at least 7 days. Within 6 months, no redo procedure is performed; and a redo after 6 months is performed with the previously used energy source. Secondary end points include the mid- and long-term clinical success, procedural data, and cost-effectiveness. CONCLUSION The FreezeAF trial will examine for the first time in a randomized trial whether PV isolation with the cryoballoon is not relevantly inferior to open irrigated RF ablation in patients with paroxysmal atrial fibrillation during follow-up. It will additionally directly compare acute procedural success and safety of the procedures.

Dynamic Approximate Entropy Electroanatomic Maps Detect Rotors in a Simulated Atrial Fibrillation Model

There is evidence that rotors could be drivers that maintain atrial fibrillation. Complex fractionated atrial electrograms have been located in rotor tip areas. However, the concept of electrogram fractionation, defined using time intervals, is still controversial as a tool for locating target sites for ablation. We hypothesize that the fractionation phenomenon is better described using non-linear dynamic measures, such as approximate entropy, and that this tool could be used for locating the rotor tip. The aim of this work has been to determine the relationship between approximate entropy and fractionated electrograms, and to develop a new tool for rotor mapping based on fractionation levels. Two episodes of chronic atrial fibrillation were simulated in a 3D human atrial model, in which rotors were observed. Dynamic approximate entropy maps were calculated using unipolar electrogram signals generated over the whole surface of the 3D atrial model. In addition, we optimized the approximate entropy calculation using two real multi-center databases of fractionated electrogram signals, labeled in 4 levels of fractionation. We found that the values of approximate entropy and the levels of fractionation are positively correlated. This allows the dynamic approximate entropy maps to localize the tips from stable and meandering rotors. Furthermore, we assessed the optimized approximate entropy using bipolar electrograms generated over a vicinity enclosing a rotor, achieving rotor detection. Our results suggest that high approximate entropy values are able to detect a high level of fractionation and to locate rotor tips in simulated atrial fibrillation episodes. We suggest that dynamic approximate entropy maps could become a tool for atrial fibrillation rotor mapping.

Non-Linear Energy Operator for the Analysis of Intracardial Electrograms

The curative therapy of atrial fibrillation (AF) is still challenging. Although the electrophysiologists know many strategies to cure AF, the underlying mechanisms are still mostly unknown. Also the optimal ablation strategy for paroxysmal and long-lasting persistent AF is not known. Complex fractionated atrial electrograms (CFAEs) are becoming more and more important in the ablation strategies, especially for longlasting persistant AF. Automated detection and signal analysis of CFAEs is essential in supporting the physicians during the ablation procedure. The robust algorithm to locate CFAEs presented in the contribution by Nguyen, Schilling and Dossel delivers a good bases for postprocessing and signal analysis of CFAEs. It is employing a non-linear energy operator combined with thresholding. In this paper this new algorithm is tested on clinical data and compared to clinically accepted algorithms.

Ablation of perimitral flutter: acute and long-term success of the modified anterior line

AIMS The modified anterior line (MAL) is an alternative to the mitral isthmus (MI) line for the treatment of perimitral atrial flutter (PMFL). We sought to investigate acute and long-term efficacy of this line if routinely used for PMFL. METHODS AND RESULTS The cohort included 77 consecutive patients who underwent catheter ablation of PMFL. The anterior line was deployed between the anterolateral mitral annulus and the ostium of the left superior pulmonary vein. Perimitral atrial flutter was either the presenting arrhythmia after persistent atrial fibrillation (AF) ablation (Group 1, n = 42, 54.5%), occurring during AF ablation (Group 2, n = 25, 35%) or presenting as primary arrhythmia (Group 3, n = 8, 10%). Acute success was defined as PMFL termination during MAL deployment with demonstration of bidirectional line block. Acute success was achieved in 68 of 77 patients (88%) without difference between the three groups. In five patients an additional MI line was necessary to terminate PMFL and in four patients both lines failed to achieve termination. During follow-up (16 ± 7 months), 38 of 77 (49%) patients underwent a repeat procedure for a recurrent arrhythmia. During reablation, 13 of 38 (34%) patients were identified to have a PMFL recurrence. Persistent MAL block was demonstrated in 22 of 38 (58%) patients during the repeat ablation. CONCLUSION The MAL is effective for acute and long-term treatment of PMFL. Maintenance of bidirectional MAL block was shown in 58% of patients during a repeat ablation.