Multicenter, randomized comparison between magnetically navigated and manually guided radiofrequency ablation of atrioventricular nodal reentrant tachycardia (the MagMa-AVNRT-trial).

BACKGROUND: Remote magnetic navigation (RMN) is attributed to diminish radiation exposure for both patient and operator performing catheter ablation for different arrhythmia substrates. The purpose of this prospective, randomized study was to compare RMN with manually guided catheter ablation for AV nodal reentrant tachycardia (AVNRT) regarding fluoroscopy time/dosage, acute and long-term efficacy as well as safety. METHODS AND RESULTS: A total of 218 patients with AVNRT undergoing catheter ablation at three centers (male 34%, mean age 50 ± 17 years) were randomized to a manual approach (n = 113) or RMN (n = 105) using the Niobe® magnetic navigation system. The primary study endpoint was total fluoroscopy time/dosage for patient and operator at the end of the procedure. Secondary endpoints included acute success, procedure duration, complications and success rate after 6 months. Fluoroscopy time and dosage for the patient were significantly reduced in the RMN group compared to the manual group (6 ± 6 vs. 11 ± 10 min; p < 0.001 and 425 ± 558 vs. 751 ± 900 cGycm2, p = 0.002). A reduction in fluoroscopy time/dose also applied to the operator (3 ± 5 vs. 7 ± 9 min 209 ± 444 vs. 482 ± 689 cGycm2, p < 0.001). Procedure duration was significantly longer in the RMN group (88 ± 29 vs. 79 ± 29 min; p = 0.03) and crossover from the RMN group to manual ablation occurred in 7.6% of patients (7.6 vs. 0.1%; p = 0.02). Acute success was achieved in 100% of patients in both groups. Midterm success after 6 months was 97 vs. 98% (p = 0.67). No complications occurred in both groups. CONCLUSION: The use of RMN for catheter ablation of AVNRT compared to a manual approach results in a reduction of fluoroscopy time and dosage of about 50% for both patients and physicians. Acute and midterm success and safety are comparable. RMN is a good alternative to a manual approach for AVNRT ablation.

First-line catheter ablation of paroxysmal atrial fibrillation: outcome of radiofrequency vs. cryoballoon pulmonary vein isolation.

AIMS: First-line ablation prior to antiarrhythmic drug (AAD) therapy is an option for symptomatic paroxysmal atrial fibrillation (PAF); however, the optimal ablation technique, radiofrequency (RF), or cryoballoon (CB) has to be determined. METHODS AND RESULTS: The FREEZE Cohort Study compares RF and CB ablation. Treatment-naïve patients were documented in the FREEZEplus Registry. Periprocedural data and outcome were analysed. From 2011 to 2014, a total of 373/4184 (8.9%) patients with PAF naïve to AAD were identified. Pulmonary vein isolation (PVI) was performed with RF (n = 180) or CB (n = 193). In the RF group, patients were older (65 vs. 61 years, P < 0.01) compared with the CB group. The procedure time was significantly shorter and radiation exposure higher in the CB group. Major adverse events occurred in 1.6% (CB) and 3.7% (RF) of patients (P = 0.22). AF/atrial tachycardia (AT) recurrence until discharge was 4.5% (RF) and 8.5% (CB, P = 0.2). Follow-up (FU) ≥12 months was available in 99 (RF) and 107 (CB) patients. After 1.4 years of FU, freedom from AF/atrial tachycardia (AT) was 61% (RF) and 71% (CB, P = 0.11). In the RF group, more patients underwent cardioversion, and a trend for more repeat ablations was observed. Persistent phrenic nerve palsy was observed in one patient treated by CB. CONCLUSION: First-line ablation for PAF is safe and effective with either RF or CB. The procedure was faster with the CB, but the radiation exposure was higher. Although there was a trend for more recurrences and complications in the RF group, a more favourable risk profile in patients undergoing CB ablation might have biased the results. CLINICALTRIALSGOV IDENTIFIER: NCT01360008.

Evaluation of a new very low dose imaging protocol: feasibility and impact on X-ray dose levels in electrophysiology procedures.

AIMS: This study presents and evaluates the impact of a new lowest-dose fluoroscopy protocol (Siemens AG), especially designed for electrophysiology (EP) procedures, on X-ray dose levels. METHODS AND RESULTS: From October 2014 to March 2015, 140 patients underwent an EP study on an Artis zee angiography system. The standard low-dose protocol was operated at 23 nGy (fluoroscopy) and at 120 nGy (cine-loop), the new lowest-dose protocol was operated at 8 nGy (fluoroscopy) and at 36 nGy (cine-loop). Procedural data, X-ray times, and doses were analysed in 100 complex left atrial and in 40 standard EP procedures. The resulting dose-area products were 877.9 ± 624.7 µGym² (n = 50 complex procedures, standard low dose), 199 ± 159.6 µGym² (n = 50 complex procedures, lowest dose), 387.7 ± 36.0 µGym² (n = 20 standard procedures, standard low dose), and 90.7 ± 62.3 µGym² (n = 20 standard procedures, lowest dose), P < 0.01. In the low-dose and lowest-dose groups, procedure times were 132.6 ± 35.7 vs. 126.7 ± 34.7 min (P = 0.40, complex procedures) and 72.3 ± 20.9 vs. 85.2 ± 44.1 min (P = 0.24, standard procedures), radiofrequency (RF) times were 53.8 ± 26.1 vs. 50.4 ± 29.4 min (P = 0.54, complex procedures) and 10.1 ± 9.9 vs. 12.2 ± 14.7 min (P = 0.60, standard procedures). One complication occurred in the standard low-dose and lowest-dose groups (P = 1.0). CONCLUSION: The new lowest-dose imaging protocol reduces X-ray dose levels by 77% compared with the currently available standard low-dose protocol. From an operator standpoint, lowest X-ray dose levels create a different, reduced image quality. The new image quality did not significantly affect procedure or RF times and did not result in higher complication rates. Regarding radiological protection, operating at lowest-dose settings should become standard in EP procedures.

Transseptal Puncture Guided by CT-Derived 3D-Augmented Fluoroscopy.

BACKGROUND: Transseptal puncture for left atrial (LA) access is still mainly performed using fluoroscopy and transesophageal or intracardiac echocardiography. We present an easily applicable approach for the guidance of transseptal puncture that uses the combination of a 3D-mapping system and CT-derived 3D-overlayed anatomy. METHODS AND RESULTS: A computer tomographic (CT) LA-angiography was performed in n = 65 patients prior to a scheduled atrial fibrillation ablation procedure. The CARTO3 (Biosense Webster, Diamond Bar, CA, USA) segmentation tool was used to create a 3D-reconstruction of cardiac anatomy and the spine. The CARTO UNIVU module was then used to overlay and register the segmented 3D-anatomy onto fluoroscopy. The 3D-reconstructed spine and cardiac anatomy were congruently aligned to their fluoroscopic counterparts in fluoroscopic views. The feasibility of the technique, its safety, and accuracy (assessed as contour offsets between 3D-overlay and angiographic LA anatomy) were evaluated. Overlay registration accuracy was analyzed by CARTO3 registration matrices. Transseptal puncture was feasible without complications in all 65 patients using the new 3D-overlay technique. Three-dimensional-overlay contour offsets were 1.6 ± 1.2 mm in left PV, 1.7 ± 1.2 mm in right PV, and 1.3 ± 1.0 mm in the LA roof region. Overlay registration accuracy was 4.9 ± 2.7 mm. The average time needed for anatomy segmentation was 204 ± 61 seconds, time needed for overlay registration was 18 ± 8 seconds. CONCLUSIONS: Three-dimensional-augmented fluoroscopy is feasible, safe, and easy to apply as guidance for transseptal puncture and demonstrates a high level of accuracy.

Sensor-Based Electromagnetic Navigation (Mediguide®): How Accurate Is It? A Phantom Model Study.

BACKGROUND: Data about localization reproducibility as well as spatial and visual accuracy of the new MediGuide® sensor-based electroanatomic navigation technology are scarce. We therefore sought to quantify these parameters based on phantom experiments. METHODS AND RESULTS: A realistic heart phantom was generated in a 3D-Printer. A CT scan was performed on the phantom. The phantom itself served as ground-truth reference to ensure exact and reproducible catheter placement. A MediGuide® catheter was repeatedly tagged at selected positions to assess accuracy of point localization. The catheter was also used to acquire a MediGuide®-scaled geometry in the EnSite Velocity® electroanatomic mapping system. The acquired geometries (MediGuide®-scaled and EnSite Velocity®-scaled) were compared to a CT segmentation of the phantom to quantify concordance. Distances between landmarks were measured in the EnSite Velocity®- and MediGuide®-scaled geometry and the CT dataset for Bland-Altman comparison. The visualization of virtual MediGuide® catheter tips was compared to their corresponding representation on fluoroscopic cine-loops. Point localization accuracy was 0.5 ± 0.3 mm for MediGuide® and 1.4 ± 0.7 mm for EnSite Velocity®. The 3D accuracy of the geometries was 1.1 ± 1.4 mm (MediGuide®-scaled) and 3.2 ± 1.6 mm (not MediGuide®-scaled). The offset between virtual MediGuide® catheter visualization and catheter representation on corresponding fluoroscopic cine-loops was 0.4 ± 0.1 mm. CONCLUSIONS: The MediGuide® system shows a very high level of accuracy regarding localization reproducibility as well as spatial and visual accuracy, which can be ascribed to the magnetic field localization technology. The observed offsets between the geometry visualization and the real phantom are below a clinically relevant threshold.