Michael V. Orlov

Asymptomatic Atrial Fibrillation in Pacemaker Recipients: Incidence, Progression, and Determinants Based on the Atrial High Rate Trial

Background: The epidemiology and clinical implications of asymptomatic atrial tachyarrhythmias (AT) including both atrial fibrillation and flutter in pacemaker recipients with and without arrhythmia history are not well understood. The Atrial High Rate Episodes (A‐HIRATE) in Pacemaker Patients Trial was designed to identify and compare the incidence of AT in patients with and without previously diagnosed AT and a standard indication for dual chamber pacing, and to provide useful diagnostic information for clinical management.

Computed tomography-fluoroscopy overlay evaluation during catheter ablation of left atrial arrhythmia

AIMS Proper visualization of left atrial (LA) and pulmonary vein (PV) anatomy is of crucial importance during atrial fibrillation (AF) ablation. This two-centre study evaluated a new automatic computed tomography (CT)-fluoroscopy overlay system (EP navigator, Philips Medical Systems, Best, The Netherlands) and the accuracy of different registration methods. METHODS AND RESULTS Fifty-six consecutive patients (age: 56 +/- 14) with symptomatic AF underwent contrast CT of the LA/PV prior to ablation. Three registration methods were evaluated and validated by comparison with LA angiography: (i) catheter registration: the placement of catheters in identifiable anatomical structures; (ii) heart contour: based on aligning the fluoroscopy heart contours and the 3D-rendered CT volume; and (iii) spine registration: based on automatically aligning the segmented CT spine on fluoroscopy. Computed tomography segmentation was achieved in all but one patient due to motion artefacts. The mean duration of segmentation was 10 min and average registration lasted 7 min. Catheter and heart contour registration were highly accurate (discrepancy of 1.3 +/- 0.6 and 0.3 +/- 0.5 mm, respectively) when compared with spine registration (17 +/- 9 mm, P < 0.05). The EP navigator was helpful during trans-septal puncture, gave an internal view of the atria and allowed tracking of ablation lesions. CONCLUSION The EP navigator enabled accurate live integration of CT images and real-time fluoroscopy. Registration utilizing catheter placement or heart contours was stable and reliable.

Segmentation and registration of three-dimensional rotational angiogram on live fluoroscopy to guide atrial fibrillation ablation: A new online imaging tool

BACKGROUND Three-dimensional rotational atriography (3DATG) was developed to supplement two-dimensional fluoroscopy with 3D volume reconstruction of the left atrium (LA), pulmonary veins (PV), and other structures. Until recently, 3DATG images could only be viewed separately and were not suitable to directly guide atrial fibrillation (AF) ablation. OBJECTIVE The purpose of this study was to evaluate the feasibility and accuracy of intraprocedural 3DATG. METHODS Three-dimensional rotational atriography with right atrial contrast injection was obtained using a Philips Allura Xper FD10 system in 30 patients with symptomatic AF who also underwent preprocedural computed tomographic (CT) scan. RESULTS The majority (93%) of 3DATG image reconstructions were useful for guidance of catheter ablation. Nearly all PVs (94%), LA appendage (89%), and esophagus (100%) were successfully segmented. Measured PV ostial diameters compared using 3DATG and CT showed close concordance. Registration and re-registration of 3DATG overlay image was easily achieved with thoracic landmarks and validated by catheter placement demonstrating minimal discrepancy. Endoscopic views allowed for improved visualization of ostial position, dimensions, and navigation within the antrum. Lesion tagging on 3DATG overlay enhanced ablation guidance. Radiation exposure with 3DATG was significantly reduced compared with preprocedural CT scan (2.1 +/- 0.3 mSv vs 13.8 +/- 2.4 mSv, P <.001). CONCLUSION Intraprocedural 3DATG imaging during AF ablation with online segmentation and superimposition on live fluoroscopy is feasible. Overlay provides valuable and accurate information on 3D surface outline and endoscopic PV location. Three-dimensional rotational atriography overlay is a new imaging method with reduced radiation exposure that may replace preprocedural CT scan for catheter navigation and ablation of AF.

Biventricular pacing improves cardiac function and prevents further left atrial remodeling in patients with symptomatic atrial fibrillation after atrioventricular node ablation.

BACKGROUND Randomized trials have demonstrated benefits of biventricular (BiV) pacing in patients with advanced heart failure, intraventricular conduction delay, and atrial fibrillation (AF) post-atrioventricular (AV) node ablation. The AV Node Ablation with CLS and CRT Pacing Therapies for Treatment of AF trial (AVAIL CLS/CRT) was designed to demonstrate superiority of BiV pacing in patients with AF after AV node ablation, to evaluate its effects on cardiac structure and function, and to investigate additional benefits of Closed Loop Stimulation (CLS) (BIOTRONIK, Berlin, Germany). METHODS Patients with refractory AF underwent AV node ablation and were randomized (2:2:1) to BiV pacing with CLS, BiV pacing with accelerometer, or right ventricular (RV) pacing. Echocardiography was performed at baseline and 6 months, with paired data available for 108 patients. RESULTS The RV pacing contributed to significant increase in left atrial volume, left ventricular (LV) end-systolic volume, and LV mass compared to BiV pacing. Ejection fraction decreased insignificantly with RV pacing compared to significant increase with BiV pacing. Interventricular dyssynchrony significantly decreased with BiV compared with RV pacing. Closed Loop Stimulation did not result in additional echocardiographic changes; heart rate distribution was significantly wider with CLS. All groups showed significant improvement in 6-minute walk distance, quality-of-life score, and New York Heart Association class. CONCLUSION In conclusion, RV pacing results in significant increase in left atrial volume, LV mass, and worsening of LV contractility compared to patients receiving BiV pacing post-AV node ablation for refractory AF. Closed Loop Stimulation was not associated with additional structural changes but resulted in significantly wider heart rate distribution.

Prospective randomized comparison between the conventional electroanatomical system and three-dimensional rotational angiography during catheter ablation for atrial fibrillation

BACKGROUND Theoretically, the use of electroanatomical mapping systems may reduce radiation exposure, while three-dimensional rotational atriography (3DATG) may increase exposure. Anatomical representation and image registration using 3DATG are likely to be superior, but the net clinical benefit of either system is unknown. OBJECTIVE The purpose of this prospective randomized two-center study was to compare the procedural and clinical outcome of patients with atrial fibrillation (AF) treated by catheter ablation using either three-dimensional (3D) electroanatomical mapping (Carto) or 3DATG. METHODS From November 2007 to November 2008, 91 consecutive patients with AF (mean age 58 +/- 10 years; 63% paroxysmal AF, 37% persistent AF) from two centers (Bordeaux and Boston) were randomized to ablation using either 3DATG (44 patients) or Carto (47 patients). RESULTS Of the 47 left atrial shells acquired with 3DATG, one was uninterpretable. There was no difference in total radiofrequency applications (72 +/- 23 vs. 79 +/- 33 minutes, respectively, P = .296), procedural duration (232 +/- 65 vs. 218 +/- 67 minutes; P = .335), fluroroscopic duration (75 +/- 28 vs. 67 +/- 26 minutes; P = .151), or radiation exposure (71,810 +/- 42,954 vs. 68,009 +/- 38,345 mGy cm(2); P = .719) between procedures performed with 3DATG or Carto. After a mean follow-up of 10 +/- 4 months, there was no difference in clinical outcome using either Carto or 3DATG concerning total arrhythmia recurrence (34% versus 38%; P = .668) or AF recurrence (20% vs. 15%; P = .555). CONCLUSION Three-dimensional ATG-guided AF ablation has similar radiation exposure and procedural and outcome characteristics compared with Carto-guided ablation. The ease of use and accurate 3D representation of the left atrium make 3DATG a reasonable alternative to conventional 3D electroanatomical mapping systems, however, without advanced mapping functions.

Magnesium therapy in new-onset atrial fibrillation

Abstract In new-onset atrial fibrillation (AF), digoxin has a limited ability to control ventricular response, is no better than placebo for facilitating conversion to sinus rhythm, and has a slow onset of action with a narrow toxic-therapeutic ratio.1,2 Magnesium (Mg) has been shown to slow and sometimes normalize the heart rhythm in supraventricular tachyarrhythmias.3,4 A randomized trial found Mg prevents AF in patients after cardiac surgery.5 Because of these factors, we conducted a prospective, randomized, double-blind, placebo-controlled study addressing whether Mg and digoxin were superior to digoxin alone in controlling the ventricular response of AE.

Remote Magnetic Versus Manual Catheter Navigation for Ablation of Supraventricular Tachycardias: A Randomized, Multicenter Trial

Introduction: The potential benefits of remote robotic navigation for catheter ablation procedures have not been demonstrated in controlled clinical trials. The purpose of this study was to compare remote magnetic catheter navigation to manual navigation for the ablation of common supraventricular arrhythmias.

Clinical Implications of Brief Device-Detected Atrial Tachyarrhythmias in a Cardiac Rhythm Management Device Population: Results from the Registry of Atrial Tachycardia and Atrial Fibrillation Episodes

Background: The RATE Registry (Registry of Atrial Tachycardia and Atrial Fibrillation Episodes) is a prospective, outcomes-oriented registry designed to document the prevalence of atrial tachycardia and/or fibrillation (AT/AF) of any duration in patients with pacemakers and implantable cardioverter defibrillators (ICDs) and evaluate associations between rigorously adjudicated AT/AF and predefined clinical events, including stroke. The appropriate clinical response to brief episodes of AT/AF remains unclear. Methods: Rigorously adjudicated electrogram (EGM) data were correlated with adjudicated clinical events with logistic regression and Cox models. Long episodes of AT/AF were defined as episodes in which the onset and/or offset of AT/AF was not present within a single EGM recording. Short episodes of AT/AF were defined as episodes in which both the onset and offset of AT/AF were present within a single EGM recording. Results: We enrolled 5379 patients with pacemakers (N=3141) or ICDs (N=2238) at 225 US sites (median follow-up 22.9 months). There were 359 deaths. There were 478 hospitalizations among 342 patients for clinical events. We adjudicated 37 531 EGMs; 50% of patients had at least one episode of AT/AF. Patients with clinical events were more likely than those without to have long AT/AF (31.9% vs. 22.1% for pacemaker patients and 28.7% vs. 20.2% for ICD patients; P<0.05 for both groups). Only short episodes of AT/AF were documented in 9% of pacemaker patients and 16% of ICD patients. Patients with clinical events were no more likely than those without to have short AT/AF (5.1% vs. 7.9% for pacemaker patients and 11.5% vs. 10.4% for ICD patients; P=0.21 and 0.66, respectively). Conclusions: In the RATE Registry, rigorously adjudicated short episodes of AT/AF, as defined, were not associated with increased risk of clinical events compared with patients without documented AT/AF. Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00837798.

Evaluation of left atrial and posterior mediastinal anatomy by multidetector helical computed tomography imaging: Relevance to ablation

IntroductionIncreasing use of catheter ablation in the left atrium (LA) requires understanding of substrate anatomy, especially with regard to potential damage to adjacent structures.Methods and resultsWe reviewed multidetector helical computed tomography (MDCT) imaging on 42 subjects, 26 imaged before planned LA ablation for atrial fibrillation (AF), and 16 without AF. LA volume and dimensions were larger in patients with AF (p < 0.05) and the spine and aorta (Ao) impressed the LA more frequently in the AF group. The esophagus (Eo) was the predominant feature on the posterior LA wall, contacting it in all patients. The Ao was in contact with the LA body or the left inferior pulmonary vein (PV) in 32 (76%) of 42 cases, and in 10 it ran along an indentation on the posterior aspect of the LA. The coronary sinus was adjacent to LA ablation sites, the azygos vein was rarely adjacent to those sites, and the left bronchus abutted the PV ostium but not the LA. Two patients had findings that directly impacted the ablation procedure: one patient had a dilated fluid filled Eo with esophageal stricture and underwent nasogastric decompression before ablation, and one was discovered to have an anomalous PV and underwent surgical repair.ConclusionsMDCT imaging identifies structures adjacent to the LA, which could be affected by ablation. Posterior LA topography can be influenced by the position of the Ao or by the proximity of the spine. Preprocedural imaging can characterize anatomic structures that could be vulnerable during ablation, and detect unusual pathology that can affect the treatment plan.

Results of the Multicenter RENEWAL® 3 AVT Clinical Study of Cardiac Resynchronization Defibrillator Therapy in Patients with Paroxysmal Atrial Fibrillation

Introduction: Atrial fibrillation impacts the clinical course of up to 50% of patients with advanced heart failure (HF) who are eligible for cardiac resynchronization therapy with a defibrillator (CRT‐D). While RV‐based defibrillators are available with advanced atrial diagnostics and therapies that provide rapid diagnosis and treatment of spontaneously occurring atrial tachycardia/fibrillation (AT/AF) episodes, there is no CRT‐D device that combines atrial/ventricular and CRT therapies.