Cryoballoon pulmonary vein isolation versus radiofrequency ablation of the pulmonary veins and left atrial posterior wall: Patient-reported outcomes

BACKGROUND

Data are lacking on patient-reported outcomes (PRO) following cryoballoon ablation (CBA) versus radiofrequency ablation (RFA). We sought to evaluate QoL and clinical outcomes of cryoballoon pulmonary vein isolation only (CRYO-PVI-ONLY) versus RFA with PVI and posterior wall isolation (RF-PVI+PWI) in a large prospective PRO registry.

METHODS

Patients who underwent AF ablation (2013-2016) at our institution were enrolled in an automated, prospectively maintained PRO registry. CRYO-PVI-ONLY patients were matched (1:1) with RF-PVI+PWI patients based on age, gender, and type of AF (paroxysmal vs. persistent). QoL and clinical outcomes were assessed using PRO surveys at baseline and at 1-year. The atrial fibrillation symptom severity scale (AFSSS) was the measure for QoL. Additionally, we assessed patient-reported clinical improvement, arrhythmia recurrence, and AF burden (as indicated by AF frequency and duration scores).

RESULTS

A total of 296 patients were included (148 in each group, 72% paroxysmal). By PRO, a significant improvement in QoL was observed in the overall study population and was comparable between CRYO-PVI-ONLY and RF-PVI+PWI (baseline median AFSSS of 11.5 and 11; reduced to 2 and 4 at 1 year, respectively; p = 0.44). Similarly, the proportion of patients who reported improvement in their overall QoL and AF related symptoms was high and similar between the study groups [92% (CRYO-PVI-ONLY) vs. 92.8% (RF-PVI+PWI); p = 0.88]. Arrhythmia recurrence was significantly more common in the CRYO-PVI-ONLY group (39.7%) compared to RF-PVI+PWI (27.7 %); p = 0.03. Comparable results were observed in paroxysmal and persistent AF.

CONCLUSION

CRYO-PVI-ONLY and RF-PVI+PWI resulted in comparable improvements in patient reported outcomes including QoL and AF burden; with RF-PVI+PWI being more effective at reducing recurrences.

Atrial Fibrillation Ablation in Young Adults: Measuring Quality of Life Using Patient-Reported Outcomes Over 5 Years

BACKGROUND

Ablation is used for both rhythm control and improved quality of life (QoL) in atrial fibrillation (AF). It has been suggested that young adults may experience high recurrence rates after ablation and data remain lacking regarding QoL benefits. We aimed to investigate AF ablation outcomes and QoL benefits in young adults undergoing AF ablation using a large prospectively maintained registry and automated patient-reported outcomes (PRO).

METHODS

All patients undergoing AF ablation (2013-2016) at our center were prospectively enrolled. Patients aged 50 years or younger were included. For PROs, QoL measures and symptoms were assessed at baseline, 3 months after ablation, and every 6 months thereafter. The AF severity score served as the main assessment of QoL.

RESULTS

A total of 241 young adults (age, 16-50 years) were included (17% female, 40.3% persistent AF). In all, 77.2% of patients remained arrhythmia-free during the first year of follow-up (80% in nonstructural AF and 66% in structural AF). Using PROs, 90% of patients reported improvement in QoL throughout all survey time points up to 5 years postablation (P<0.0001). The baseline median AF severity score was 14 and improved to between 2 and 4 on all follow-up after ablation (P<0.0001). Patients also reported fewer and shorter AF episodes, fewer emergency room visits secondary to AF, and fewer hospitalizations (P<0.0001).

CONCLUSIONS

Ablation remains an effective rhythm-control strategy in young adults with AF. Young adults also experience significant improvement in QoL with reduction of the frequency and duration of AF episodes and AF-related healthcare utilization.

Novel Approaches for the Diagnosis of Concealed Nodo-Ventricular and His-Ventricular Pathways

BACKGROUND

Confirming the presence and participation of concealed nodo-ventricular (cNV) or His-ventricular (cHV) pathways in tachyarrhythmias is challenging. We describe novel observations to aid in diagnosing cNV or cHV pathways.

METHODS

We present 7 cases of cNV and cHV pathway-mediated arrhythmias and focus on several laboratory observations: (1) differential ventricular overdrive pacing (VOD) from the base versus apex, (2) response to His refractory premature ventricular complexes, (3) paradoxical atriohisian response (shorter atriohisian interval during tachycardia than that during sinus rhythm) in long RP tachycardia, and (4) the role of adenosine to aid in the diagnosis.

RESULTS

Three cases underwent differential VOD during tachycardia. All demonstrated a shorter postpacing interval minus tachycardia cycle length during basal pacing than apical pacing with one case exhibiting apical VOD results compatible with atrioventricular nodal reentrant tachycardia. Basal VOD was useful for localizing the ventricular connection in a case with cHV pathway. In 3 cases, His refractory premature ventricular complexes reset the tachycardia without conduction to the atrium, which excluded the involvement of an atrioventricular pathway or atrial tachycardia, or atrioventricular nodal reentrant tachycardia alone. One case had His refractory premature ventricular complexes followed by subsequent constant AA interval and then tachycardia termination, suggesting a bystander cNV pathway involvement. Two cNV pathway cases presented with long RP tachycardia had paradoxical atriohisian shortening of >15 ms, suggesting parallel activation of the atrium and the atrioventricular node. Adenosine terminated the tachycardia with retrograde block in 2 cases with cNV pathways but had no response on a cHV pathway.

CONCLUSIONS

cNV and cHV pathways mediated tachyarrhythmias can present with variable clinical presentations. We emphasize the important role of differential VOD sites, His refractory premature ventricular complexes that reset or terminate the tachycardia without conduction to the atrium, paradoxical atriohisian response in long RP tachycardia, and the use of adenosine for diagnosing cNV and cHV pathways.

Impact of redo ablation for atrial fibrillation on patient-reported outcomes and quality of life

INTRODUCTION

Catheter ablation for atrial fibrillation (AF) is frequently used for the purpose of rhythm control and improved quality of life (QoL). Although success rates are high, a significant proportion of patients require redo ablation. Data are scarce on patient-centered outcomes and QoL in patients undergoing redo AF ablation. We aimed to assess QoL and clinical outcomes using a large prospectively maintained patient-reported outcomes (PRO) registry.

METHODS

All patients undergoing redo AF ablation (2013-2016) at our center were enrolled in a prospective registry for outcomes and assessed for QoL using automated PRO surveys (baseline, 3 and 6 months after ablation, every 6 months thereafter). Data were collected over 3 years of follow-up. The atrial fibrillation symptom severity scale (AFSSS) was used as the main measure for QoL. Additional variables included patient-reported improvement, AF burden, and AF-related healthcare utilization including emergency room (ER) visits and hospitalizations.

RESULTS

A total of 848 patients were included (28% females, mean age 63.8, 51% persistent AF). By automated PRO, significant improvement in QoL was noted (baseline median AFSSS of 12 [5-18] and ranged between 2 and 4 on subsequent assessments; p < .0001), with ≥70%of patients reported remarkable improvement in their AF-related symptoms. The proportion of patients in AF at the time of baseline survey was 36%, and this decreased to <8% across all time points during follow-up (p < .0001). AF burden was significantly reduced (including frequency and duration of episodes; p < .0001), with an associated decrease in healthcare utilization after 6 months from the time of ablation (including ER visits and hospitalizations; p < .0001). The proportion of patients on anticoagulants or antiarrhythmics decreased on follow-up across all time points (p < .0001 for all variables).

CONCLUSION

Most patients derive significant QoL benefit from redo AF ablation; with reduction of both AF burden and healthcare utilization.

Early Experience with High-density Electroanatomical Mapping Using the Rhythmia™ Mapping System in Congenital and Pediatric Heart Disease

The Rhythmia™ system (Boston Scientific, Natick, MA, USA) facilitates the rapid acquisition of high-resolution electroanatomical and activation maps. However, there are limited data on its efficacy and safety in pediatric and adult congenital heart disease (CHD) patients. In a retrospective, observational cohort study, adult CHD and pediatric patients followed by pediatric cardiology underwent electrophysiologic study using the Rhythmia™ electroanatomic mapping system. Variables examined included the number of electroanatomical maps required, acquisition time, procedure time, fluoroscopy time, radiation dosage, and rate of recurrent arrhythmia. Twelve consecutive patients, including six male patients (50%), were included with an average age of 27.7 years (range: 11–64 years). Seven (58%) of these patients had a diagnosis of CHD [moderate complexity in two (17%) and great complexity in five patients (42%)] and 10 (83%) patients underwent ablation. A total of 37 high-density maps were created in 12 procedures, with a median of 8,140 mapping points, taking a median of 631 seconds. The median procedure time was 189.5 minutes. The median fluoroscopy time was 0.9 minutes, with eight (67%) patients receiving no fluoroscopy at all. Recurrence occurred in one patient (8%) over a median follow-up duration of 16 months (interquartile range: 12.8–17.3 months). No adverse periprocedural events were recorded. This study suggests the use of high-density electroanatomic mapping in adult CHD patients showed potential for rapid acquisition of highly detailed maps with minimal fluoroscopy time or risk of periprocedural events in the studied population.

Arrhythmias Utilizing Concealed Nodoventricular or His-Ventricular Pathways: A Structured Approach to Diagnosis and Management

OBJECTIVES

This study sought to describe the electrophysiologic characteristics, diagnostic maneuvers, and treatment of a series of arrhythmias using concealed nodoventricular (cNV) or His-ventricular (cHV) pathways.

BACKGROUND

Confirming the presence and participation of cNV or cHV pathways in tachyarrhythmias is challenging.

METHODS

We present 4 cases of tachycardias with a participatory cNV or cHV pathway.

RESULTS

The first patient had a narrow complex tachycardia with ventriculoatrial dissociation. Findings of an entrainment pacing from the right ventricle and fused premature ventricular complexes suggested cNV pathway involvement. The second patient had nonsustained narrow complex tachycardia with more ventricular than atrial complexes. The tachycardia exhibited an anterograde His-right bundle (RB) activation sequence and normal His-ventricular (HV) interval and consistently terminated with fused ventricular extra stimuli, suggesting cNV pathway participation. The third patient had a wide complex tachycardia (WCT) with either a right or left bundle branch block pattern. The WCT showed an eccentric His-RB activation sequence and short HV interval and terminated with fused premature ventricular complexes, suggesting a cHV (or concealed fasciculoventricular) pathway involvement. The fourth patient had a WCT with alternating bundle branch block morphologies with a short HV interval. Entrainment from the basal right ventricle demonstrated fusion and a short postpacing interval, suggesting cHV (or fasciculoventricular) pathway involvement. Ablation at the proximal RB rendered the tachycardia noninducible.

CONCLUSIONS

A structured approach can help diagnose and treat cNV or cHV pathways. We emphasize the importance of evaluating both the His-RB activation pattern and HV interval during sinus rhythm and tachycardia as well as the ventricular pacing study.

Super and Nonresponders to Catheter Ablation for Atrial Fibrillation: A Quality-of-Life Assessment Using Patient Reported Outcomes

[Figure: see text].

A new machine learning approach for predicting likelihood of recurrence following ablation for atrial fibrillation from CT

OBJECTIVE

To investigate left atrial shape differences on CT scans of atrial fibrillation (AF) patients with (AF+) versus without (AF-) post-ablation recurrence and whether these shape differences predict AF recurrence.

METHODS

This retrospective study included 68 AF patients who had pre-catheter ablation cardiac CT scans with contrast. AF recurrence was defined at 1 year, excluding a 3-month post-ablation blanking period. After creating atlases of atrial models from segmented AF+ and AF- CT images, an atlas-based implicit shape differentiation method was used to identify surface of interest (SOI). After registering the SOI to each patient model, statistics of the deformation on the SOI were used to create shape descriptors. The performance in predicting AF recurrence using shape features at and outside the SOI and eight clinical factors (age, sex, left atrial volume, left ventricular ejection fraction, body mass index, sinus rhythm, and AF type [persistent vs paroxysmal], catheter-ablation type [Cryoablation vs Irrigated RF]) were compared using 100 runs of fivefold cross validation.

RESULTS

Differences in atrial shape were found surrounding the pulmonary vein ostia and the base of the left atrial appendage. In the prediction of AF recurrence, the area under the receiver-operating characteristics curve (AUC) was 0.67 for shape features from the SOI, 0.58 for shape features outside the SOI, 0.71 for the clinical parameters, and 0.78 combining shape and clinical features.

CONCLUSION

Differences in left atrial shape were identified between AF recurrent and non-recurrent patients using pre-procedure CT scans. New radiomic features corresponding to the differences in shape were found to predict post-ablation AF recurrence.

Complex Re-Entrant Arrhythmias Involving the His-Purkinje System: A Structured Approach to Diagnosis and Management

OBJECTIVES

This study sought to characterize the presentations, electrophysiological features and diagnostic maneuvers for a series of unique arrhythmias involving the HPS.

BACKGROUND

By virtue of its unique anatomy and ion channel composition, the His-Purkinje system (HPS) is prone to a variety of arrhythmic perturbations.

METHODS

The authors present a collaborative multicenter case series of 6 patients with HPS-related arrhythmias. All patients underwent electrophysiological studies using standard multipolar catheters.

RESULTS

In 3 patients, both typical and reverse bundle branch re-entry were seen, with 1 patient demonstrating "figure of 8" re-entry likely involving the septal fascicle. One patient presented with systolic dysfunction associated with a high premature ventricular complex burden, with the mechanism being bundle-to-bundle re-entrant beats masquerading as dual response to a single sinus impulse. Two patients were diagnosed with interfascicular re-entry. Diagnosis was aided by careful assessment of HV interval in sinus rhythm and ventricular tachycardia, multipolar catheters to assess the activation sequence of the His-right bundle branch, and fascicles and entrainment of different components of the HPS. Cure of the arrhythmia was achieved by ablation of the right bundle branch block in 3 patients, the left septal fascicle in 2 patients, and the left posterior fascicle in 1 patient.

CONCLUSIONS

Proper diagnosis of re-entrant arrhythmias involving the HPS may prove challenging. We emphasize a structured approach for diagnosis and effective therapy.

Proarrhythmic effects from competitive atrial pacing and potential programming solutions

BACKGROUND

Programmed long AV delays and intrinsic long first degree AV block may increase risk for competitive atrial pacing (CAP) in devices without CAP avoidance algorithms.

METHODS

Patients identified with CAP-induced mode switch episodes were followed clinically from September 2013 to August 2019. Attempts to avoid CAP included shortening of postventricular atrial refractory period (PVARP) or postventricular atrial blanking period (PVAB), or change to AAI or DDI modes. After observing associations with sensor-driven pacing, rate response was inactivated in a subset.

RESULTS

Among 23 patients identified with CAP (22 St Jude Medical [Abbott]; one Boston Scientific Corporation devices), atrial fibrillation (AF) was induced in 12 (52%), lasting 10 seconds to 28 hours and 32 minutes. In one patient with an ICD CAP-induced AF with rapid ventricular rates that triggered a shock, inducing ventricular fibrillation, syncope, and another shock. Changing AV delays and shortening of PVARP failed to resolve CAP. After noting that all had CAP during sensor-driven pacing, rate response was inactivated in seven, resolving further device-induced AF in the three of seven that had prior CAP-induced AF. In two patients with intact AV conduction, AAI(R) pacing resolved further documentation of CAP.

CONCLUSIONS

CAP predominantly occurs during sensor-driven atrial pacing that competes with intrinsic atrial events falling in PVARP. Inactivation of the activity sensor or change to atrial-based pacing modes (AAI/R) appears to effectively prevent induction of device-induced atrial proarrhythmia. Ultimately, a corrective algorithm is needed to avoid CAP-induced proarrhythmia.

Clinical Outcomes and Characteristics With Dofetilide in Atrial Fibrillation Patients Considered for Implantable Cardioverter-Defibrillator

BACKGROUND

Dofetilide is one of the only anti-arrhythmic agents approved for atrial fibrillation (AF) in patients with reduced left ventricular ejection fraction (LVEF). However, postapproval data and safety outcomes are limited. In this study, we assessed the incidence and predictors of LVEF improvement, safety, and outcomes in patients with AF with LVEF ≤35% without prior implantable cardioverter defibrillator, cardiac resynchronization therapy, or AF ablation.

METHODS

An analysis of 168 consecutive patients from 2007 to 2016 was performed. Incidences of adverse events, drug continuation, implantable cardioverter defibrillator and cardiac resynchronization therapy implantation, LVEF improvement (>35%) and recovery (≥50%), AF recurrence, and AF ablation were determined. Multivariable regression analysis to identify predictors of LVEF improvement/recovery was performed.

RESULTS

The mean age was 64±12 years. Dofetilide was discontinued before hospital discharge in 46 (27%) because of QT prolongation (14%), torsades de pointe or polymorphic ventricular tachycardia/fibrillation (6% [sustained 3%, nonsustained 3%]), ineffectiveness (5%), or other causes (3%). At 1 year, 43% remained on dofetilide. Freedom from AF was 42% at 1 year, and 40% underwent future AF ablation. LVEF recovered (≥50%) in 45% and improved to >35% in 73%. Predictors of LVEF improvement included presence of AF during echocardiogram (odds ratio, 4.22 [95% CI, 1.71-10.4], P=0.002), coronary artery disease (odds ratio, 0.35 [95% CI, 0.16-0.79], P=0.01), left atrial diameter (odds ratio, 0.52 per 1 cm increase [95% CI, 0.30-0.90], P=0.01), and LVEF (odds ratio, per 1% increase, 1.09 [95% CI, 1.02-1.16], P=0.006). The C statistic was 0.78.

CONCLUSIONS

In patients with LVEF ≤35%, who are potential implantable cardioverter defibrillator candidates, treated with dofetilide as an initial anti-arrhythmic strategy for AF, drug discontinuation rates were high, and many underwent future AF ablation. However, most patients had improvement in LVEF, obviating the need for primary prevention implantable cardioverter defibrillator.

Catheter Ablation in Patients With Cardiogenic Shock and Refractory Ventricular Tachycardia

BACKGROUND

There is paucity of data regarding radiofrequency ablation for ventricular tachycardia (VT) in patients with cardiogenic shock and concomitant VT refractory to antiarrhythmic drugs on mechanical support.

METHODS

Patients undergoing VT ablation at our center were enrolled in a prospectively maintained registry and screened for the current study (2010-2017).

RESULTS

All 21 consecutive patients with cardiogenic shock and concomitant refractory ventricular arrhythmia undergoing bailout ablation due to inability to wean off mechanical support were included. Median age was 61 years, 86% were men, median left ventricular ejection fraction was 20%, 81% had ischemic cardiomyopathy, and PAINESD score was 18±5. The type of mechanical support in place before the procedure was intra-aortic balloon pump in 14 patients (67%), Impella CP in 2, extracorporeal membrane oxygenation in 2, extracorporeal membrane oxygenation and intra-aortic balloon pump in 2, and extracorporeal membrane oxygenation and Impella CP in 1. Endocardial voltage maps showed myocardial scar in 19 patients (90%). The clinical VTs were inducible in 13 patients (62%), whereas 6 patients had premature ventricular contraction-induced ventricular fibrillation/VT (29%), and VT could not be induced in 2 patients (9%). Activation mapping was possible in all 13 with inducible clinical VTs. Substrate modification was performed in 15 patients with scar (79%). After ablation and scar modification, the arrhythmia was noninducible in 19 patients (91%). Seventeen (81%) were eventually weaned off mechanical support successfully, but 6 (29%) died during the index admission from persistent cardiogenic shock. Patients who had ventricular arrhythmia and cardiogenic shock on presentation had a trend toward lower in-hospital mortality compared with those who presented with cardiogenic shock and later developed ventricular arrhythmia.

CONCLUSIONS

Bailout ablation for refractory ventricular arrhythmia in cardiogenic shock allowed successful weaning from mechanical support in a large proportion of patients. Mortality remains high, but the majority of patients were discharged home and survived beyond 1 year.

Outcomes and Management of Patients With Severe Pulmonary Vein Stenosis From Prior Atrial Fibrillation Ablation

BACKGROUND

Pulmonary vein (PV) stenosis remains a feared complication of atrial fibrillation ablation. Little is known about outcomes in patients with severe PV stenosis, especially about repeat ablations.

METHODS

In 10 368 patients undergoing atrial fibrillation ablation (2000-2015), computed tomography scans were obtained 3 to 6 months after ablation. The clinical outcomes in severe PV stenosis were determined.

RESULTS

Severe PV stenosis was diagnosed in 52 patients (0.5%). This involved mostly the left superior PV (51% of severely stenosed veins). Percutaneous interventions were performed in 43 patients, and complications occurred in 5: 3 PV ruptures, 1 stroke, and 1 phrenic injury. Over a median follow-up of 25 months, 41 (79%) patients remained arrhythmia free. Repeat ablation was performed in 15 patients (7 from the main series and 8 from prior ablation at other institutions); of whom 10 had PV stents in place. Conduction recovery was noted in all but 2 of the stenosed or stented PVs, and areas with recovery were targeted with antral ablation. Lasso entrapment within stents occurred in 2 patients but eventually freed without complications. After redo ablation, preplanned stenting was performed in 3 patients and computed tomographic scans showed progression of concomitant stenoses in 1 patient (moderate to severe). No procedure-related deaths occurred.

CONCLUSIONS

The incidence of severe PV stenosis is low but remains associated with significant morbidity. In patients with recurrent arrhythmia, conduction recovery at the stenosed or stented veins is common. Care must be taken to ablate antrally to avoid stenosis progression. In patients with prior PV stents, we suggest to avoid using Lasso.

Safety of Oral Dofetilide Reloading for Treatment of Atrial Arrhythmias

BACKGROUND

Although dofetilide labeling states that the drug must be initiated or reinitiated with continuous electrocardiographic monitoring and in the presence of trained personnel, the risks of dofetilide reloading justifying repeat hospitalization have not been investigated.

METHODS AND RESULTS

Patients admitted for dofetilide reloading for atrial arrhythmias were retrospectively reviewed. The need for dose adjustment and the incidence of torsades de pointes (TdP) were identified. The incidence of TdP in dofetilide reloading was compared with patients admitted for dofetilide initial loading. Of 138 patients admitted for dofetilide reloading for atrial arrhythmias, 102 were reloaded at a previously tolerated dose, 30 with a higher dose from a previously tolerated dose and 2 at a lower dose; prior dosage was unknown in 4 patients. Dose adjustment or discontinuation was required in 44 patients (31.9%). No TdP occurred in the same dose reloading group, but TdP occurred in 2 patients admitted to increase dofetilide dosage (0% versus 6.7%; P=0.050). Dofetilide dose adjustment or discontinuation was required in 30 of 102 patients (29.4%) reloaded at a previously tolerated dose and in 11 of 30 patients (36.7%) admitted for an increase in dose.

CONCLUSIONS

Although no TdP occurred in patients admitted to reload dofetilide at the same dose as previously tolerated, dosage adjustments or discontinuation was frequent and support the need for hospitalization for dofetilide reloading. Patients admitted for reloading with a higher dose tended to be at higher risk for TdP than patients reloaded at a prior tolerated dose.

Incidence of Thromboembolic Complications Within 30 Days of Electrical Cardioversion Performed Within 48 Hours of Atrial Fibrillation Onset

OBJECTIVES

This study sought to compare the risk of thromboembolism after cardioversion within 48 h of atrial fibrillation (AF) onset in patients therapeutically versus not therapeutically anticoagulated.

BACKGROUND

Although guidelines do not mandate anticoagulation for cardioversion within 48 h of AF onset, risk of thromboembolism in this group has been understudied.

METHODS

Patients undergoing cardioversion within 48 h after AF onset were identified from a prospectively collected database and retrospectively reviewed to determine anticoagulation status and major thromboembolic events within 30 days of cardioversion.

RESULTS

Among 567 cardioversions in 484 patients without therapeutic anticoagulation (mean CHA₂DS₂-VASc score, 2.3 ± 1.7), 6 had neurological events (1.06%), all in patients on aspirin alone. Among 898 cardioversions in 709 patients on therapeutic anticoagulation (mean CHA₂DS₂-VASc score, 2.6 ± 1.7; p = 0.017), 2 neurological events occurred (0.22%; OR: 4.8; p = 0.03), both off anticoagulation at the time of stroke. No thromboembolic events occurred in patients with CHA₂DS₂-VASc score <2 (p = 0.06) or in patients with postoperative AF.

CONCLUSIONS

In patients with acute-onset AF, odds of thromboembolic complications were almost 5 times higher in patients without therapeutic anticoagulation at the time of cardioversion. However, no events occurred in post-operative patients and in those with CHA₂DS₂-VASc scores of <2, supporting the utility of accurate assessment of AF onset and risk stratification in determining the need for anticoagulation for cardioversion of AF <48 h in duration.

Early Changes in QRS Frequency Following Cardiac Resynchronization Predict Hemodynamic Response in Left Bundle Branch Block Patients

INTRODUCTION

QRS characteristics are the cornerstone of patient selection in cardiac resynchronization therapy (CRT) and the presence of left bundle branch block (LBBB) and baseline QRS ≥150 milliseconds portends a good outcome. We previously showed that baseline QRS frequency analysis adds predictive value to LBBB alone and have hypothesized that a change in frequency characteristics following CRT may produce additional predictive value.

METHODS

We examined the QRS frequency characteristics of 182 LBBB patients before and soon after CRT. Patients were assigned to responder and nonresponder groups. Responders were defined by a decrease in left ventricular end-systolic volume (LVESV) ≥15% following CRT. We analyzed the QRS in ECG leads I, AVF, and V3 before and soon after CRT using the discrete Fourier transform algorithm. The percentage of total QRS power within discrete frequency intervals before and after CRT was calculated. The reduction in lead V3 power <10 Hz was the best indicator of response.

RESULTS

Baseline QRS width was similar between the responders and nonresponders (162.2 ± 17.2 milliseconds vs. 158 ± 22.1 milliseconds, respectively; P = 0.180). Responders exhibited a greater reduction in QRS power <10 Hz (-17.0 ± 11.9% vs. -6.6 ± 12.5%; P < 0.001) and a significant AUC (0.743; P < 0.001). A ≥8% decline in QRS power <10 Hz produced the best predictive values (PPV = 84%, NPV = 59%). Importantly, when patients with baseline QRS <150 milliseconds were compared, the AUC improved (0.892, P < 0.001).

CONCLUSIONS

Successful CRT produces a significant reduction in QRS power below 10 Hz, particularly when baseline QRS <150 milliseconds. These results indicate that QRS frequency changes after CRT provide additional predictive value to QRS alone.

Outcome of cardiac sarcoidosis after radiofrequency ablation and placement of AICD- A propensity matched analysis

BACKGROUND

Cardiac Sarcoidosis (CS) can lead to life-threatening ventricular dysrhythmias and sudden death. Immunosuppressive medications, radiofrequency ablation (RFA), and implantable cardioverter defibrillators (ICD) have been utilized to manage ventricular dysrhythmias but their benefits remain poorly defined.

OBJECTIVE

The aim of this study is to assess the durability of RFA in CS population and to determine outcome predictors after RFA.

METHODS

We compared the CS patients who had RFA±ICD against those with only ICD placement and contemporaneous patients with arrhythmogenic right ventricular dysplasia (ARVD) who had RFA. We analyzed time to a composite first event of appropriate ICD therapy, subsequent RFA, cardiac transplantation or death. We also evaluated variables predicting recurrence of ventricular dysrhythmias, including LVEF, cardiac involvement on PET scan, percent of ventricular ectopic beats, number of inducible VT foci and success of the RFA procedure. We used propensity matching and multivariable regression to adjust for baseline differences between the groups to identify outcome predictors.

RESULTS

Thirty ablations for VT were performed in 20 CS patients (13 had concomitant ICD placement); 12 ablations were done in eight ARVD patients and 33 CS patients with only ICD placements were included in this cohort. The median follow-up period was 48 (9-173) months. Fourteen (70%) patients reached composite end points after RFA compared to 13 (63%) following ICD placement and five (87%) in the ARVD cohort. There was a significant time difference to reach composite end points (p=0.02) in favor of ICD only cohort. The median number of ICD therapies were higher in the CS-RFA group (p=0.01). The requirement for ICD therapy increased over time following RFA, especially after 12 months. Variables predicting earlier time-to-event were EF &lt;40% (OR=13.2) and unsuccessful RFA procedure (OR=7.9). The presence of more than one inducible VT morphology was associated with higher likelihood of unsuccessful RFA (p=0.03).

CONCLUSION

RFA can be an effective modality for the short-term treatment of ventricular dysrhythmias in cardiac sarcoidosis; however, after more than 12 months, the number of appropriate therapies escalates. Accordingly, ICD placement is recommended for all patients who undergo RFA for VT associated with CS, whether it is successful or not. Low LVEF and unsuccessful ablation were strong predictors of future events.

QRS frequency characteristics help predict response to cardiac resynchronization in left bundle branch block less than 150 milliseconds

BACKGROUND

Baseline QRS duration (QRSd) ≥150 ms is a recognized predictor of clinical improvement by cardiac resynchronization therapy (CRT), particularly for those with left bundle branch (LBBB). Patients with QRSd <150 ms are considered less likely to respond.

OBJECTIVE

The purpose of this study was to test our theory that left ventricular dyssynchrony, although usually associated with wider QRSd, also exhibits lower QRS frequency characteristics and that low-frequency content predicts CRT response in LBBB patients.

METHODS

We retrospectively examined the QRS frequency content of 170 heart failure patients with LBBB and QRSd ≥120 ms using Fourier transformation. Ninety-four responders to CRT (defined as reduction in left ventricular end-systolic volume by ≥15% from baseline) were compared to 76 nonresponders (<15% reduction). Analysis of 3 standard ECG leads (I, aVF, and V3) representing the 3 dimensions of depolarization was performed, and V3 provided the best predictive value.

RESULTS

The QRSd of responders (160.3 ± 17.8 ms) and nonresponders (161.8 ± 21.1 ms, P = .604) were similar. We found that the percentage of total QRS frequency power below 10 Hz that exceeded 52% was most predictive of CRT response compared to other cutoff values. However, the percentage of patients with total QRS power >52% below 10 Hz was especially predictive of response in those with QRSd <150 ms. In these patients, this power threshold was highly predictive of CRT response (positive predictive value 85.7%, negative predictive value 71.4%).

CONCLUSION

In this group of CRT recipients with LBBB, retrospective analysis of QRS frequency content below 10 Hz had greater predictive value for CRT response than baseline QRSd, particularly in those with QRSd <150 ms.

Left ventricular hypertrophy and antiarrhythmic drugs in atrial fibrillation: impact on mortality

BACKGROUND

Despite sparse clinical data, current atrial fibrillation (AF) guidelines favor amiodarone as a drug of choice for patients with left ventricular hypertrophy (LVH).

OBJECTIVE

This study tested the hypothesis that patients with persistent AF and LVH on nonamiodarone antiarrhythmics have higher mortality compared to patients on amiodarone.

METHODS

In an observational cohort analysis of patients who underwent cardioversion for AF, patients with LVH, defined as left ventricular wall thickness ≥1.4 cm, by echocardiogram prior to their first cardioversion, were included; clinical data, including antiarrhythmic drugs and ejection fraction (LVEF), were collected. Mortality, determined via the Social Security Death Index, was analyzed using Kaplan-Meier and Cox proportional hazards models to determine whether antiarrhythmic drugs were associated with higher mortality.

RESULTS

In 3,926 patients, echocardiographic wall thickness was available in 1,399 (age 66.8 ± 11.8 years, 67% male, LVEF 46 ± 15%, septum 1.3 ± 0.4, posterior wall 1.2 ± 0.2 cm), and 537 (38%) had LVH ≥1.4 cm. Among 537 patients with LVH, mean age was 67.5 ± 11.7 years, 76.4% were males, and mean LVEF was 48.3 ± 13.3%. Amiodarone was associated with lower survival (log rank P = 0.001), including after adjusting for age, LVEF, and coronary artery disease (P = 0.023). In propensity-score matched cohorts with LVH treated with no drugs, nonamiodarone antiarrhythmic drugs (non-AADs), or amiodarone (N = 65 each group), there was early lower survival in patients on amiodarone (P = 0.05).

CONCLUSIONS

Patients with persistent AF and LVH on non-AADs do not have higher mortality compared to patients on amiodarone. Importantly, these findings do not support amiodarone as a superior choice in patients with LVH.

Use of dabigatran for periprocedural anticoagulation in patients undergoing catheter ablation for atrial fibrillation

BACKGROUND

Pulmonary vein isolation (PVI) for atrial fibrillation is associated with a transient increased risk of thromboembolic and hemorrhagic events. We hypothesized that dabigatran can be safely used as an alternative to continuous warfarin for the periprocedural anticoagulation in PVI.

METHODS AND RESULTS

A total of 999 consecutive patients undergoing PVI were included; 376 patients were on dabigatran (150 mg), and 623 patients were on warfarin with therapeutic international normalized ratio. [corrected] Dabigatran was held 1 to 2 doses before PVI and restarted at the conclusion of the procedure or as soon as patients were transferred to the nursing floor. Propensity score matching was applied to generate a cohort of 344 patients in each group with balanced baseline data. Total hemorrhagic and thromboembolic complications were similar in both groups, before (3.2% versus 3.9%; P=0.59) and after (3.2% versus 4.1%; P=0.53) matching. Major hemorrhage occurred in 1.1% versus 1.6% (P=0.48) before and 1.2% versus 1.5% (P=0.74) after matching in the dabigatran versus warfarin group, respectively. A single thromboembolic event occurred in each of the dabigatran and warfarin groups. Despite higher doses of intraprocedural heparin, the mean activated clotting time was significantly lower in patients who held dabigatran for 1 or 2 doses than those on warfarin.

CONCLUSIONS

Our study found no evidence to suggest a higher risk of thromboembolic or hemorrhagic complications with use of dabigatran for periprocedural anticoagulation in patients undergoing PVI compared with uninterrupted warfarin therapy.

Early risk of mortality after coronary artery revascularization in patients with left ventricular dysfunction and potential role of the wearable cardioverter defibrillator

BACKGROUND

Implantation of implantable cardioverter defibrillator for prevention of sudden cardiac death is deferred for 90 days after coronary revascularization, but mortality may be highest early after cardiac procedures in patients with ventricular dysfunction. We determined mortality risk in postrevascularization patients with left ventricular ejection fraction ≤35% and compared survival with those discharged with a wearable cardioverter defibrillator (WCD).

METHODS AND RESULTS

Hospital survivors after surgical (coronary artery bypass graft surgery) or percutaneous (percutaneous coronary intervention [PCI]) revascularization with left ventricular ejection fraction ≤35% were included from Cleveland Clinic and national WCD registries. Kaplan-Meier, Cox proportional hazards, propensity score-matched survival, and hazard function analyses were performed. Early mortality hazard was higher among 4149 patients discharged without a defibrillator compared with 809 with WCDs (90-day mortality post-coronary artery bypass graft surgery 7% versus 3%, P=0.03; post-PCI 10% versus 2%, P<0.0001). WCD use was associated with adjusted lower risks of long-term mortality in the total cohort (39%, P<0.0001) and both post-coronary artery bypass graft surgery (38%, P=0.048) and post-PCI (57%, P<0.0001) cohorts (mean follow-up, 3.2 years). In propensity-matched analyses, WCD use remained associated with lower mortality (58% post-coronary artery bypass graft surgery, P=0.002; 67% post-PCI, P<0.0001). Mortality differences were not attributable solely to therapies for ventricular arrhythmia. Only 1.3% of the WCD group had a documented appropriate therapy.

CONCLUSIONS

Patients with left ventricular ejection fraction ≤35% have higher early compared to late mortality after coronary revascularization, particularly after PCI. As early hazard seemed less marked in WCD users, prospective studies in this high-risk population are indicated to confirm whether WCD use as a bridge to left ventricular ejection fraction improvement or implantable cardioverter defibrillator implantation can improve outcomes after coronary revascularization.

Implantable cardioverter-defibrillator FDA safety advisories: Impact on patient mortality and morbidity

BACKGROUND

A significant proportion of implantable cardioverter-defibrillators (ICDs) have been subject to Food and Drug Administration (FDA) advisories. The impact of device advisories on mortality or patient care is poorly understood. Although estimated risks of ICD generators under advisory are low, dependency on ICD therapies to prevent sudden death justifies the assessment of long-term mortality.

OBJECTIVE

To test the association of FDA advisory status with long-term mortality.

METHODS

The study was a retrospective, single-center review of clinical outcomes, including device malfunctions, in patients from implantation to either explant or death. Patients with ICDs first implanted at Cleveland Clinic between August 1996 and May 2004 who became subject to FDA advisories on ICD generators were identified. Mortality was determined by using the Social Security Death Index.

RESULTS

In 1644 consecutive patients receiving first ICD implants, 704 (43%) became subject to an FDA advisory, of which 172 (10.5%) were class I and 532 (32.3%) were class II. ICDs were explanted before advisory notifications in 14.0% of class I and 10.1% of class II advisories. Among ICDs under advisory, 28 (4.0%) advisory-related and 15 non-advisory- related malfunctions were documented. Over a median follow-up of 70 months, 814 patients died. Kaplan-Meier 5-year survival rate was 65.6% overall, and 64.2, 61.1, and 69.3% in patients with no, class I, and class II advisories, respectively (P = .17).

CONCLUSIONS

ICD advisories impacted 43% of the patients. Advisory-related malfunctions affected 4% within the combined advisory group. Based on a conservative management strategy, ICDs under advisory were not associated with increased mortality over a background of significant disease-related mortality.

Predictors of response to cardiac resynchronization therapy in patients with a non-left bundle branch block morphology

Patients with non-left bundle branch block (LBBB) morphologies are thought to derive less benefit from cardiac resynchronization therapy (CRT) than those with LBBB. However, some patients do exhibit improvement. The characteristics associated with a response to CRT in patients with non-LBBB morphologies are unknown. Clinical, electrocardiographic, and echocardiographic data were collected from 850 consecutive patients presenting for a new CRT device. For inclusion, all patients had a left ventricular ejection fraction of ≤35%, a QRS duration of ≥120 ms, and baseline and follow-up echocardiograms available. Patients with a paced rhythm or LBBB were excluded. The response was defined as an absolute decrease in left ventricular end-systolic volume of ≥10% from baseline. Multivariate models were constructed to identify variables significantly associated with the response and long-term outcomes. A total of 99 patients met the inclusion criteria. Of these 99 patients, 22 had right bundle branch block and 77 had nonspecific intraventricular conduction delay; 52.5% met the criteria for response. On multivariate analysis, the QRS duration was the only variable significantly associated with the response (odds ratio per 10-ms increase 1.23, 95% confidence interval 1.01 to 1.52, p = 0.048). During a mean follow-up of 5.4 ± 0.9 years, 65 patients died or underwent heart transplant or left ventricular assist device placement. On multivariate analysis, the QRS duration was inversely associated with poor long-term outcomes (hazard ratio per 10-ms increase 0.79, 95% confidence interval 0.66 to 0.94, p = 0.005). In patients with advanced heart failure and non-LBBB morphologies, a wider baseline QRS duration is an important determinant of enhanced reverse ventricular remodeling and improved long-term outcomes after CRT.

The relationship between ventricular electrical delay and left ventricular remodelling with cardiac resynchronization therapy

Aims

The aim of the present study was to evaluate the relationship between left ventricular (LV) electrical delay, as measured by the QLV interval, and outcomes in a prospectively designed substudy of the SMART-AV Trial.

Methods and results

This was a multicentre study of patients with advanced heart failure undergoing cardiac resynchronization therapy (CRT) defibrillator implantation. In 426 subjects, QLV was measured as the interval from the onset of the QRS from the surface ECG to the first large peak of the LV electrogram. Left ventricular volumes were measured by echocardiography at baseline and after 6 months of CRT by a blinded core laboratory. Quality of life (QOL) was assessed by a standardized questionnaire. When separated by quartiles based on QLV duration, reverse remodelling response rates (>15% reduction in LV end systolic volume) increased progressively from 38.7 to 68.4% and QOL response rate (>10 points reduction) increased from 50 to 72%. Patients in the highest quartile of QLV had a 3.21-fold increase (1.58–6.50, P = 0.001) in their odds of a reverse remodelling response after correcting for QRS duration, bundle branch block type, and clinical characteristics by multivariate logistic regression analysis.

Conclusion

Electrical dyssynchrony, as measured by QLV, was strongly and independently associated with reverse remodelling and QOL with CRT. Acute measurements of QLV may be useful to guide LV lead placement.

Aggregate national experience with the wearable cardioverter-defibrillator: event rates, compliance, and survival

OBJECTIVES

The purpose of this study was to determine patient compliance and effectiveness of antiarrhythmic treatment by the wearable cardioverter-defibrillator (WCD).

BACKGROUND

Effectiveness of the WCD for prevention of sudden death is dependent on event type, patient compliance, and appropriate management of ventricular tachycardia/ventricular fibrillation (VT/VF).

METHODS

Compliance and events were recorded in a nationwide registry of post-market release WCDs. Survival, using the Social Security Death Index, was compared with survival in implantable cardioverter-defibrillator (ICD) patients.

RESULTS

Of 3,569 patients wearing the WCD (age 59.3+/-14.7 years, duration 52.6+/-69.9 days), daily use was 19.9+/-4.7 h (>90% of the day) in 52% of patients. More days of use correlated with higher daily use (p<0.001). Eighty sustained VT/VF events occurred in 59 patients (1.7%). First-shock success was 76 of 76 (100%) for unconscious VT/VF and 79 of 80 (99%) for all VT/VF. Eight patients died after successful conversion of unconscious VT/VF (89.5% survival of VT/VF events). Asystole occurred in 23 (17 died), pulseless electrical activity in 2, and respiratory arrest in 1 (3 died), representing 24.5% of sudden cardiac arrests. During WCD use, 3,541 of 3,569 patients (99.2%) survived overall. Survival occurred in 72 of 80 (90%) VT/VF events and 78 of 106 (73.6%) for all events. Long-term mortality was not significantly different from first ICD implant patients but highest among patients with traditional ICD indications.

CONCLUSIONS

Compliance was satisfactory with 90% wear time in >50% of patients and low sudden death mortality during use. Survival was comparable to that of ICD patients. However, asystole was an important cause of mortality in sudden cardiac arrest events.

Left atrial epicardial adiposity and atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) has been linked to inflammatory factors and obesity. Epicardial fat is a source of several inflammatory mediators related to the development of coronary artery disease. We hypothesized that periatrial fat may have a similar role in the development of AF.

METHODS AND RESULTS

Left atrium (LA) epicardial fat pad thickness was measured in consecutive cardiac CT angiograms performed for coronary artery disease or AF. Patients were grouped by AF burden: no (n=73), paroxysmal (n=60), or persistent (n=36) AF. In a short-axis view at the mid LA, periatrial epicardial fat thickness was measured at the esophagus (LA-ESO), main pulmonary artery, and thoracic aorta; retrosternal fat was measured in axial view (right coronary ostium level). LA area was determined in the 4-chamber view. LA-ESO fat was thicker in patients with persistent AF versus paroxysmal AF (P=0.011) or no AF (P=0.003). LA area was larger in patients with persistent AF than paroxysmal AF (P=0.004) or without AF (P<0.001). LA-ESO was a significant predictor of AF burden even after adjusting for age, body mass index, and LA area (odds ratio, 5.30; 95% confidence interval, 1.39 to 20.24; P=0.015). A propensity score-adjusted multivariable logistic regression that included age, body mass index, LA area, and comorbidities was also performed and the relationship remained statistically significant (P=0.008).

CONCLUSIONS

Increased posterior LA fat thickness appears to be associated with AF burden independent of age, body mass index, or LA area. Further studies are necessary to examine cause and effect, and if inflammatory, paracrine mediators explain this association.

Cardiac-resynchronization therapy in heart failure with narrow QRS complexes

BACKGROUND

Indications for cardiac-resynchronization therapy (CRT) in patients with heart failure include a prolonged QRS interval (> or =120 msec), in addition to other functional criteria. Some patients with narrow QRS complexes have echocardiographic evidence of left ventricular mechanical dyssynchrony and may also benefit from CRT.

METHODS

We enrolled 172 patients who had a standard indication for an implantable cardioverter-defibrillator. Patients received the CRT device and were randomly assigned to the CRT group or to a control group (no CRT) for 6 months. The primary end point was the proportion of patients with an increase in peak oxygen consumption of at least 1.0 ml per kilogram of body weight per minute during cardiopulmonary exercise testing at 6 months.

RESULTS

At 6 months, the CRT group and the control group did not differ significantly in the proportion of patients with the primary end point (46% and 41%, respectively). In a prespecified subgroup with a QRS interval of 120 msec or more, the peak oxygen consumption increased in the CRT group (P=0.02), but it was unchanged in a subgroup with a QRS interval of less than 120 msec (P=0.45). There were 24 heart-failure events requiring intravenous therapy in 14 patients in the CRT group (16.1%) and 41 events in 19 patients in the control group (22.3%), but the difference was not significant.

CONCLUSIONS

CRT did not improve peak oxygen consumption in patients with moderate-to-severe heart failure, providing evidence that patients with heart failure and narrow QRS intervals may not benefit from CRT. (ClinicalTrials.gov number, NCT00132977 [ClinicalTrials.gov].).

Incidence of Atrial Arrhythmias Detected by Permanent Pacemakers (PPM) Post-Pulmonary Vein Antrum Isolation (PVAI) for Atrial Fibrillation (AF): Correlation with Symptomatic Recurrence

BACKGROUND

Studies examining AF recurrences post-PVAI base recurrence on patient reporting of symptoms. However, whether asymptomatic recurrences are common is not well known.

OBJECTIVE

To assess the incidence of atrial tachycardia/fibrillation post-PVAI as detected by a PPM and whether these recurrences correlate to symptomatic recurrence.

METHODS

Eighty-six consecutive patients with symptomatic AF and PPMs with programmable mode-switch capability underwent PVAI. Mode switching was programmed post-PVAI to occur at an atrial-sensed rate of >170 bpm. Patients were followed with clinic visits, ECG, and PPM interrogation at 1, 3, 6, and 9 months post-PVAI. The number and duration of mode-switching episodes (MSEs) were recorded at each visit and is presented as median (interquartile range).

RESULTS

The patients (age 57 +/- 8 years, EF 54 +/- 10%) had paroxysmal (65%) and persistent (35%) AF pre-PVAI. Sensing, pacing, and lead function were normal for all PPMs at follow-up. Of the 86 patients, 20 (23%) had AF recurrence based on symptoms. All 20 of these patients had appropriate MSEs detected. Of the 66 patients without symptomatic recurrence, 21 (32%) had MSEs detected. In 19 of these patients, MSEs were few in number, compared with patients with symptomatic recurrence (16 [4-256] vs 401 [151-2,470], P < 0.01). The durations were all <60 seconds. All of these nonsustained MSEs occurred within the first 3 months post-PVAI, gradually decreasing over time. The other 2 of 21 remaining patients had numerous (1,343 [857-1,390]) and sustained (18 +/- 12 minutes) MSEs that also persisted beyond 3 months (1 beyond 6 months). Therefore, the incidence of numerous, sustained MSEs in asymptomatic patients post-PVAI was 2 of 66 (3%).

CONCLUSIONS

Detection of atrial tachyarrhythmias by a PPM occurred in 30% of patients without symptomatic AF recurrence. Most of these episodes were <60 seconds and waned within 3 months. Sustained, asymptomatic episodes were uncommon.

Vagal responses induced by endocardial left atrial autonomic ganglion stimulation before and after pulmonary vein antrum isolation for atrial fibrillation

BACKGROUND

Elimination of vagal inputs into the left atrium (LA) may be necessary for successful catheter ablation of atrial fibrillation (AF). These vagal inputs are clustered in autonomic ganglia (AG) that are close to the pulmonary vein antrum (PVA) borders, but whether standard intracardiac echocardiography (ICE)-guided PVA isolation (PVAI) affects these inputs is unknown.

OBJECTIVE

The purpose of this study was to assess whether standard ICE-guided PVAI affects vagal responses induced by endocardial AG stimulation in the LA.

METHODS

Twenty consecutive patients undergoing first-time PVAI (group 1) and 20 consecutive patients undergoing repeat PVAI for AF recurrence (group 2) were enrolled in the study. Before ablation, electrical stimulation (20 Hz, pulse duration 10 ms, voltage range 12-20 V) was performed through an 8-mm-tip ablation catheter. Based on prior data, regions around all four PVA borders were carefully mapped and stimulated to localize AG inputs. A positive stimulated vagal response was defined as atrioventricular (AV) block, asystole, or increase in mean RR interval by >50%. Locations of positive vagal responses were recorded wth biplane fluoroscopy and CARTO. All patients then underwent standard ICE-guided PVAI by an operator blinded to the locations of vagal responses. Stimulation of the AG locations was then repeated postablation.

RESULTS

Patients (age 54 +/- 11 years, 30% female, ejection fraction 54% +/- 7%) had a history of paroxysmal (75%) and persistent (25%) AF. In group 1, vagal responses were induced in all 20 patients around a mean of 3.8 +/- 0.4 PVAs per patient. The most common response was asystole (53%), mean RR slowing >50% (28%), and AV block (20%). Postablation, vagal responses could no longer be induced in all 20 patients. A diminished response was induced (RR slowing <50%) in 2/20 patients around one PVA each. In group 2, vagal responses were not induced in any of the 20 repeat patients. Stimulation capture postablation was confirmed because transient, nonsustained (<30 seconds) AF or atrial flutter was induced in all 40 patients with stimulation, whether vagal responses were induced or not.

CONCLUSIONS

Standard ICE-guided PVAI eliminates vagal responses induced by AG stimulation. Responses are not seen in patients presenting for repeat PVAI, despite clinical recurrence of AF.

Efficacy of Adjuvant Anterior Left Atrial Ablation During Intracardiac Echocardiography-Guided Pulmonary Vein Antrum Isolation for Atrial Fibrillation

BACKGROUND

Recent data have shown that the septum and anterior left atrial (LA) wall may contain "rotor" sites required for AF maintenance. However, whether adding ablation of such sites to standard ICE-guided PVAI improves outcome is not well known.

OBJECTIVE

To determine if adjuvant anterior LA ablation during PVAI improves the cure rate of paroxysmal and permanent AF.

METHODS

One hundred AF patients (60 paroxysmal, 40 persistent/permanent) undergoing first-time PVAI were enrolled over three months to receive adjuvant anterior LA ablation (Group I). These patients were compared with 100 randomly selected, matched first-time PVAI controls from the preceding three months who did not receive adjuvant ablation (Group II). All 200 patients underwent ICE-guided PVAI during which all four PV antra and SVC were isolated. In group I, a decapolar lasso catheter was used to map the septum and anterior LA wall during AF (induced or spontaneous) for continuous high-frequency, fractionated electrograms (CFAE). Sites where CFAE were identified were ablated until the local EGM was eliminated. A complete anterior line of block was not a requisite endpoint. Patients were followed up for 12 months. Recurrence was assessed post-PVAI by symptoms, clinic visits, and Holter at 3, 6, and 12 months. Patients also wore rhythm transmitters for the first 3 months. Recurrence was any AF/AFL >1 min occurring >2 months post-PVAI.

RESULTS

Patients (age 56 +/- 11 years, 37% female, EF 53%+/- 11%) did not differ in baseline characteristics between group I and II by design. Group I patients had longer procedure time (188 +/- 45 min vs 162 +/- 37 min) and RF duration (57 +/- 12 min vs 44 +/- 20 min) than group II (P < 0.05 for both). Overall recurrence occurred in 15/100 (15%) in group I and 20/100 (20%) in group II (P = 0.054). Success rates did not differ for paroxysmal patients between group I and II (87% vs 85%, respectively). However, for persistent/permanent patients, group I had a higher success rate compared with group II (82% vs 72%, P = 0.047).

CONCLUSIONS

Adjuvant anterior LA ablation does not appear to impact procedural outcome in patients with paroxysmal AF but may offer benefit to patients with persistent/permanent AF.

Effects of Cocaine Intoxication on the Threshold for Stun Gun Induction of Ventricular Fibrillation

OBJECTIVES

This study sought to assess cocaine's effects on Taser-induced ventricular fibrillation (VF) threshold in a pig model.

BACKGROUND

Stun guns are increasingly used by law enforcement officials to restrain violent subjects, who are frequently intoxicated with cocaine and other drugs of abuse. The interaction of cocaine and the stun gun on VF induction is unknown.

METHODS

We tested five adult pigs using a custom device built to deliver multiples of standard neuromuscular incapacitating (NMI) discharge that matched the waveform of a commercially available electrical stun gun (Taser X-26, Taser International, Scottsdale, Arizona). The NMI discharges were applied in a step-up and step-down fashion at 5 body locations. End points included determination of maximum safe multiple, minimum VF-inducing multiple, and ventricular fibrillation threshold (VFT) before and after cocaine infusion.

RESULTS

Standard NMI discharges (x1) did not cause VF at any of the 5 locations before or after cocaine infusion. The maximum safe multiple, minimum VF-inducing multiple, and VFT of NMI application increased with increasing electrode distance from the heart. There was a 1.5- to 2-fold increase in these values at each position after cocaine infusion, suggesting decreased cardiac vulnerability for VF. Cocaine increased the required strength of NMI discharge that caused 2:1 or 3:1 ventricular capture ratios at all of the positions. No significant changes in creatine kinase-MB and troponin-I were seen.

CONCLUSIONS

Cocaine increased the VFT of NMI discharges at all dart locations tested and reduced cardiac vulnerability to VF. The application of cocaine increased the safety margin by 50% to 100% above the baseline safety margin.

Present Understanding of Shock Polarity for Internal Defibrillation: The Obvious and Non-Obvious Clinical Implications

BACKGROUND

Uncertainty about the best electrode configuration has combined with the programming flexibility in modern implantable cardioverter-defibrillators (ICDs) to result in routine polarity reversal during an implant to deal with a high defibrillation threshold (DFT). We feel that this practice is not always supported by the clinical data and the present scientific understanding of defibrillation.

METHOD

A meta-analysis of the clinical studies on ICD shock polarity was performed. Subgroup analyses were also performed to test the impact of high DFTs, various tilts, and the use of the hot can electrode. A review of the basic research surrounding the effects of polarity in defibrillation is also presented.

RESULTS

A total of 224 patients were studied. The use of an anodal right ventricular (RV) coil lowers the mean DFT by 14.8% (P = 0.00001). It provides thresholds equal to or lower than cathodal defibrillation in 83% of patients. The fraction of patients with lower anodal DFTs was 94/224 versus 38/224 for cathodal polarity. This phenomenon may be explained by virtual electrode effects. In particular, anodal electrodes tend to produce collapsing wavefronts while cathodal electrodes tend to produce expanding proarrhythmic wavefronts.

CONCLUSION

In an ICD implant, the RV coil should be the anode. Furthermore, DFT testing beginning with cathodal defibrillation is most likely unnecessary and needlessly extends the procedure's duration and increases the risks for the patient.