Corticosteroid use during pulmonary vein isolation is associated with a higher prevalence of dormant pulmonary vein conduction

BACKGROUND

Atrial fibrillation (AF) recurrence after pulmonary vein isolation (PVI) is associated with PV to left atrium reconduction.

OBJECTIVE

The purpose of this study was to prospectively determine if the use of intraprocedural corticosteroids to limit the extent of tissue edema and/or inflammation alters the prevalence of spontaneous and adenosine-induced acute PV reconnection after PVI.

METHODS

Prior to wide circumferential PVI, 45 patients received a single intravenous (IV) bolus of hydrocortisone 250 mg immediately after transseptal access (steroid group). Another 45 consecutive patients underwent standard PVI without IV hydrocortisone (nonsteroid group). After PVI, all patients underwent adenosine testing to unmask dormant conduction. Patients were followed at 3, 6, and 12 months.

RESULTS

Dormant conduction was unmasked in a significantly higher proportion of PVs in the steroid group compared with the nonsteroid group (32.8% of PVs [60/183] vs 21.1% of PVs [37/175], P = .03). On multivariate generalized estimating equation analysis, steroid use remained independently associated with dormant PV conduction (P = .03). There was no difference in the segmental distribution of reconnection between the 2 groups. The 1-year freedom from recurrent AF did not differ between groups (P = .37). Radiofrequency time was significantly longer in the steroid group (58 ± 21 minutes vs 48 ± 18 minutes, P <.01), whereas procedure duration and fluoroscopy time were comparable (P = .55 and P = .44, respectively).

CONCLUSION

A single bolus of hydrocortisone 250 mg IV prior to PVI results in greater radiofrequency requirements for PVI and a higher prevalence of dormant PV conduction unmasked by adenosine. The utility of these approaches requires evaluation in a long-term prospective randomized study.

Procedural arrhythmia termination and long-term single-procedure clinical outcome in patients with non-paroxysmal atrial fibrillation

BACKGROUND

The influence of procedural arrhythmia termination on long-term single-procedure clinical outcome in patients with non-paroxysmal atrial fibrillation (AF) remains controversial.

METHODS

An individualized stepwise ablation strategy was used in 200 consecutive patients with non-paroxysmal AF who underwent first-time radiofrequency catheter ablation, with pulmonary vein isolation and sinus rhythm (SR) restoration as the primary endpoints.

RESULTS

SR was restored by ablation in 94 patients, including 32 with AF directly and 62 with intermediate atrial tachycardia (AT). Cardioversion was performed to restore SR in 106 patients, including 31 with intermediate AT, and 75 with sustained AF. During a mean follow-up of 50.0 ± 9.3 months, single-procedure success was achieved in 99 (49.5%) patients. There was a significant difference in long-term success between patients with SR restoration by ablation and by cardioversion (63.8% vs 36.8%; P < 0.001), but not between patients with AF termination by ablation and by cardioversion (53.6% vs 42.7%; P = 0.146). SR restoration by ablation (odds ratio = 3.032; 95% confidence interval = 1.703-5.398; P < 0.001) was the only predictor of single-procedure success by logistic regression analyses. In patients with intermediate AT (n = 93), AT termination by ablation was associated with a higher success rate than AT termination by cardioversion (62.9% vs 22.6%; P < 0.001).

CONCLUSIONS

SR restoration and AT termination by ablation were both associated with an improved long-term single-procedure clinical outcome in patients with non-paroxysmal AF.

Validation of novel 3-dimensional electrocardiographic mapping of atrial tachycardias by invasive mapping and ablation: a multicenter study

OBJECTIVES

This study prospectively evaluated the role of a novel 3-dimensional, noninvasive, beat-by-beat mapping system, Electrocardiographic Mapping (ECM), in facilitating the diagnosis of atrial tachycardias (AT).

BACKGROUND

Conventional 12-lead electrocardiogram, a widely used noninvasive tool in clinical arrhythmia practice, has diagnostic limitations.

METHODS

Various AT (de novo and post-atrial fibrillation ablation) were mapped using ECM followed by standard-of-care electrophysiological mapping and ablation in 52 patients. The ECM consisted of recording body surface electrograms from a 252-electrode-vest placed on the torso combined with computed tomography-scan-based biatrial anatomy (CardioInsight Inc., Cleveland, Ohio). We evaluated the feasibility of this system in defining the mechanism of AT-macro-re-entrant (perimitral, cavotricuspid isthmus-dependent, and roof-dependent circuits) versus centrifugal (focal-source) activation-and the location of arrhythmia in centrifugal AT. The accuracy of the noninvasive diagnosis and detection of ablation targets was evaluated vis-à-vis subsequent invasive mapping and successful ablation.

RESULTS

Comparison between ECM and electrophysiological diagnosis could be accomplished in 48 patients (48 AT) but was not possible in 4 patients where the AT mechanism changed to another AT (n = 1), atrial fibrillation (n = 1), or sinus rhythm (n = 2) during the electrophysiological procedure. ECM correctly diagnosed AT mechanisms in 44 of 48 (92%) AT: macro-re-entry in 23 of 27; and focal-onset with centrifugal activation in 21 of 21. The region of interest for focal AT perfectly matched in 21 of 21 (100%) AT. The 2:1 ventricular conduction and low-amplitude P waves challenged the diagnosis of 4 of 27 macro-re-entrant (perimitral) AT that can be overcome by injecting atrioventricular node blockers and signal averaging, respectively.

CONCLUSIONS

This prospective multicenter series shows a high success rate of ECM in accurately diagnosing the mechanism of AT and the location of focal arrhythmia. Intraprocedural use of the system and its application to atrial fibrillation mapping is under way.

Atrial flutter following pulmonary vein isolation: what is the mechanism?

A 70-year-old man with atrial flutter (AFL) following pulmonary vein (PV) isolation (PVI) underwent electrophysiologic testing. The AFL exhibited positive P waves in the inferior leads and lead V1. Left atrial activation mapping revealed 2 remote sites with early activation that were located at the antrum of the left superior PV roof and the left inferior PV bottom. A single irrigated radiofrequency ablation targeting the earliest PV activation at the left PV carina eliminated the AFL. This case demonstrated that PV carina tachycardia with multiple conduction gaps and inter-PV conduction after PVI might mimic double focal atrial tachycardias.

Pattern and timing of the coronary sinus activation to guide rapid diagnosis of atrial tachycardia after atrial fibrillation ablation

BACKGROUND

Atrial tachycardias (AT) during or after ablation of atrial fibrillation frequently pose a diagnostic challenge. We hypothesized that both the patterns and the timing of coronary sinus (CS) activation could facilitate AT mapping.

METHODS AND RESULTS

A total of 140 consecutive postpersistent atrial fibrillation ablation patients with sustained AT were investigated by conventional mapping. CS activation pattern was defined as chevron or reverse chevron when the activations recorded on both the proximal and the distal CS dipoles were latest or earliest, respectively. The local activation of mid-CS was timed with reference to Ppeak-Ppeak (P-P) interval in lead V1. A ratio, mid-CS activation time to AT cycle length, was computed. Of 223 diagnosed ATs, 124 were macroreentrant (56%) and 99 were centrifugal (44%). When CS activation was chevron/reverse chevron (n=44; 20%), macroreentries were mostly roof dependent. With reference to P-P interval, mid-CS activation timing showed specific consistency for peritricuspid and perimitral AT. Proximal to distal CS activation pattern and mid-CS activation at 50% to 70% of the P-P interval (n=30; 13%) diagnosed peritricuspid AT with 81% sensitivity and 89% specificity. Distal to proximal CS activation and mid-CS activation at 10% to 40% of the P-P interval (n=44; 20%) diagnosed perimitral AT with 88% sensitivity and 75% specificity.

CONCLUSIONS

The analysis of the patterns and timing of CS activation provides a rapid stratification of most likely macroreentrant ATs and points toward the likely origin of centrifugal ATs. It can be included in a stepwise diagnostic approach to rapidly select the most critical mapping maneuvers.

Advanced ablation strategies for management of post-surgical atrial arrhythmias

Post-surgical arrhythmias include a wide range of arrhythmias occurring late after cardiac surgery and represent a complex substrate for catheter ablation either because of extended scar and remodeling or because of limited access to the area of interest. Novel image integration and ablation tools have made the catheter ablation in this population both feasible and successful. We review a structured approach to catheter ablation of post-surgical atrial arrhythmias in various patient cohorts including the most common congenital heart defects.

An introduction to murine models of atrial fibrillation

Understanding the mechanism of re-entrant arrhythmias in the past 30 years has allowed the development of almost curative therapies for many rhythm disturbances. The complex, polymorphic arrhythmias of atrial fibrillation (AF) and sudden death are, unfortunately, not yet well understood, and hence still in need of adequate therapy. AF contributes markedly to morbidity and mortality in aging Western populations. In the past decade, many genetically altered murine models have been described and characterized. Here, we review genetically altered murine models of AF; powerful tools that will enable a better understanding of the mechanisms of AF and the assessment of novel therapeutic interventions.

Pitx2 prevents susceptibility to atrial arrhythmias by inhibiting left-sided pacemaker specification

Atrial fibrillation (AF), the most prevalent sustained cardiac arrhythmia, often coexists with the related arrhythmia atrial flutter (AFL). Limitations in effectiveness and safety of current therapies make an understanding of the molecular mechanism underlying AF more urgent. Genome-wide association studies implicated a region of human chromosome 4q25 in familial AF and AFL, approximately 150 kb distal to the Pitx2 homeobox gene, a developmental left-right asymmetry (LRA) gene. To investigate the significance of the 4q25 variants, we used mouse models to investigate Pitx2 in atrial arrhythmogenesis directly. When challenged by programmed stimulation, Pitx2(null+/-) adult mice had atrial arrhythmias, including AFL and atrial tachycardia, indicating that Pitx2 haploinsufficiency predisposes to atrial arrhythmias. Microarray and in situ studies indicated that Pitx2 suppresses sinoatrial node (SAN)-specific gene expression, including Shox2, in the left atrium of embryos and young adults. In vivo ChIP and transfection experiments indicated that Pitx2 directly bound Shox2 in vivo, supporting the notion that Pitx2 directly inhibits the SAN-specific genetic program in left atrium. Our findings implicate Pitx2 and Pitx2-mediated LRA-signaling pathways in prevention of atrial arrhythmias.

Successful catheter ablation of atrial tachycardia originating from the non-coronary aortic sinus

We report a rare case of atrial tachycardia originating from the non-coronary aortic sinus. After failed radiofrequency (RF) energy applications at right His-bundle region, the complete elimination of atrial tachycardia was achieved with an RF energy application in the non-coronary aortic sinus. With the review of other papers, this report emphasizes the importance of mapping in the non-coronary aortic sinus in focal atrial tachycardia near the atrioventricular node or near the His-bundle.

Clinical application of pacemakers in atrial tachyarrhythmias

The diagnostic programmes of modern pacemakers have increased our knowledge of atrial tachyarrhythmias (ATAs) in chronically paced patients. These programmes also support the evaluation of the effects of pharmacological treatment of ATAs. The success of interruption and/or prevention of ATAs with pacemakers depends strongly on the diagnostic accuracy and the properties of the pacing algorithms, their individual programming and the site and configuration of the pacing leads. Atrial septum pacing can be beneficial in patients with paroxysmal atrial fibrillation and prolonged P wave duration. Recent large-scale studies on preventive and interruptive atrial pacing of ATAs show modestly positive or no results. Therefore, atrial pacing therapy for ATAs should be considered cautiously, serving as an adjuvant to pharmacological treatment rather than as a primary intervention. This also applies for pacing interventions for ATAs in cardiac resynchronisation therapy. The pacemaker algorithms for the detection of ATAs and atrial lead configuration are crucial for the success of pacemaker-mediated prevention or interruption of ATAs. The success of these interventions is dependant on future improvements of pacemaker technology. (Neth Heart J 2008;16(Suppl1):S20-S24.).

Multiple arrhythmogenic substrate for tachycardia in a patient with frequent palpitations

We report a 26-year-old woman with frequent episodes of palpitation and dizziness. Resting electrocardiography showed no evidence of ventricular preexcitation. During electrophysiologic study, a concealed right posteroseptal accessory pathway was detected and orthodromic atrioventricular reentrant tachycardia incorporating this pathway as a retrograde limb was reproducibly induced. After successful ablation of right posteroseptal accessory pathway, another tachycardia was induced using a concealed right posterolateral accessory pathway in tachycardia circuit. After loss of retrograde conduction of second accessory pathway with radiofrequency ablation, dual atrioventricular nodal physiology was detected and typical atrioventricular nodal reentrant tachycardia was repeatedly induced. Slow pathway ablation was done successfully. Finally sustained self-terminating atrial tachycardia was induced under isoproterenol infusion but no attempt was made for ablation. During 8-month follow-up, no recurrence of symptoms attributable to tachycardia was observed.

An unusual tachycardia

The following article presents an unusual case of atrial tachycardia, initially misdiagnosed due to a lack of clear P waves. The diagnosis was eventually confirmed using the atrial electrogram from the patient's pacemaker.

Figure-8 tachycardia confined to the anterior wall of the left atrium

Incisional atrial tachycardias have been described most frequently in patients with previous corrective surgery for congenital heart defects and mitral valve disease. Less information is available on atrial tachycardias appearing late after isolated aortic valve surgery. We report the case of a patient who developed a left figure-8 tachycardia after undergoing aortic valve replacement. During electrophysiologic study the entire cycle length of the tachycardia was mapped within a low voltage area confined to the left anterior atrial wall. However, during ablation a transmural lesion could not be attained. The mapping and ablation strategy along with the mechanism of the tachycardia are discussed.