Association between high-density mapping of atypical atrial flutter, clinical outcomes and healthcare utilization.

BACKGROUND: Success of atypical atrial flutter (AAFL) ablation has historically been limited by difficulty mapping the complex re-entrant circuits involved. While high-density (HD) mapping has become commonplace in clinical practice, there are limited data on outcomes of HD versus non-HD mapping for AAFL ablation. OBJECTIVE: To compare clinical outcomes and healthcare utilization using HD mapping versus non-HD mapping for AAFL ablation. METHODS: Retrospective analysis of all AAFL procedures between 2005 and 2022 at an academic medical center was conducted. Procedures utilizing a 16-electrode HD Grid catheter and Precision mapping system were compared to procedures using prior generation 10-20 electrode spiral catheters and the Velocity system (Abbott, IL). Cox regression models and Poisson regression models were utilized to examine procedural and healthcare utilization outcomes. Models were adjusted for left ventricular ejection fraction, CHA2DS2-VASc, and history of prior ablation. RESULTS: There were 108 patients (62% HD mapping) included in the analysis. Baseline clinical characteristics were similar between groups. Use of HD mapping was associated with a higher rate of AAFL circuit delineation (92.5% vs. 76%; p = .014) and a greater adjusted procedure success rate, defined as non-inducibility at procedure end, (aRR (95% CI) 1.26 (1.02-1.55) p = .035) than non-HD mapping. HD mapping was also associated with a lower rate of ED visits (aIRR (95% CI) 0.32 (0.14-0.71); p = .007) and hospitalizations (aIRR (95% CI) 0.32 (0.14-0.68); p = .004) for AF/AFL/HF through 1 year. While there was a lower rate of recurrent AFL through 1 year among HD mapping cases (aHR (95% CI) 0.60 (0.31-1.16) p = .13), statistical significance was not met likely due to the low sample size and higher rate of ambulatory rhythm monitoring in the HD group (61% vs. 39%, p = .025). CONCLUSION: Compared to non-HD mapping, AAFL ablation with HD mapping is associated with improvements in the ability to define the AAFL circuit, greater procedural success, and a reduction in the number of ED visits and hospitalization for AF/AFL/HF.

Implementation of an intravenous sotalol initiation protocol: Implications for feasibility, safety, and length of stay.

INTRODUCTION: Oral sotalol initiation requires a multiple-day, inpatient admission to monitor for QT prolongation during loading. A 1-day intravenous (IV) sotalol loading protocol was approved by the United States Food and Drug Administration in March 2020, but limited data on clinical use and administration currently exists. This study describes implementation of an IV sotalol protocol within an integrated health system, provides initial efficacy and safety outcomes, and examines length of stay (LOS) compared with oral sotalol initiation. METHODS: IV sotalol was administered according to a prespecified initiation protocol to adult patients with refractory atrial or ventricular arrhythmias. Baseline characteristics, safety and feasibility outcomes, and LOS were compared with patients receiving oral sotalol over a similar time period. RESULTS: From January 2021 to June 2022, a total of 29 patients (average age 66.0 ± 8.6 years, 27.6% women) underwent IV sotalol load and 20 patients (average age 60.4 ± 13.9 years, 65.0% women) underwent oral sotalol load. The load was successfully completed in 22/29 (75.9%) patients receiving IV sotalol and 20/20 (100%) of patients receiving oral sotalol, although 7/20 of the oral sotalol patients (35.0%) required dose reduction. Adverse events interrupting IV sotalol infusion included bradycardia (seven patients, 24.1%) and QT prolongation (three patients, 10.3%). No patients receiving IV or oral sotalol developed sustained ventricular arrhythmias before discharge. LOS for patients completing IV load was 2.6 days shorter (mean 1.0 vs. 3.6, p < .001) compared with LOS with oral load. CONCLUSION: IV sotalol loading has a safety profile that is similar to oral sotalol. It significantly shortens hospital LOS, potentially leading to large cost savings.

Esophageal temperature management during cryoballoon ablation for atrial fibrillation.

INTRODUCTION: Esophageal thermal injury (ETI) is a well-recognized complication of atrial fibrillation (AF) ablation. Previous studies have demonstrated that direct esophageal cooling reduces ETI during radiofrequency AF ablation. The purpose of this study was to evaluate the use of an esophageal warming device to prevent ETI during cryoballoon ablation (CBA) for AF. METHODS: This prospective, double-blinded study enrolled 42 patients with symptomatic AF undergoing CBA. Patients were randomized to the treatment group with esophageal warming (42°C) using recirculated water through a multilumen, silicone tube inserted into the esophagus (EnsoETM®; Attune Medical) (WRM) or the control group with a luminal single-electrode esophageal temperature monitoring probe (LET). Patients underwent upper endoscopy esophagogastroduodenoscopy (EGD) the following day. ETI was classified into four grades. RESULTS: Baseline patient characteristics were similar between groups. Procedural characteristics including number of freezes, total freeze time, early freeze terminations, coldest balloon temperature, procedure duration, posterior wall ablation, and proton pump inhibitor and transesophageal echocardiogram use before procedure were not different between groups. The EGD was completed in 40/42 patients. There was significantly more ETI in the WRM group compared to the LET group (n = 8 [38%] vs. n = 1 [5%], p = 0.02). All ETI lesions were grade 1 (erythema) or 2 (superficial ulceration). Total freeze time in the left inferior pulmonary vein was predictive of ETI (360 vs. 300 s, p = 0.03). CONCLUSION: Use of a luminal heat exchange tube for esophageal warming during CBA for AF was paradoxically associated with a higher risk of ETI.

Patient-reported outcomes after cryoballoon ablation are equivalent between moderate sedation and general anesthesia.

INTRODUCTION: Moderate sedation (MS) during cryoballoon ablation (CBA) avoids risks of general anesthesia (GA) and improves electrophysiology (EP) lab throughput. However, one barrier to the use of MS is the potential for patient discomfort. The objective of this study was to compare patient-reported outcome measures following CBA for paroxysmal atrial fibrillation (pAF) under MS and GA. METHODS AND RESULTS: Consecutive patients undergoing a first CBA for pAF under GA or MS were prospectively enrolled. The sedation method was assigned based on patient and provider preference, and perceived airway risk. The primary outcomes were quality of recovery (measured using a validated 40 question survey; QoR-40) and likelihood to recommend (LTR) the procedure and sedation method (measured by Likert scale). Secondary outcomes were acute pulmonary vein (PV) isolation rate, procedure, fluoroscopy and ablation times, and complication rates. Forty-seven GA and 53 MS patients were included. The mean age was 64.9 ± 9.4 years and mean CHA2 DS2 -VASc score was 2.0 ± 1.4. QoR-40 scores were 184.6 ± 16.4 for GA and 187.6 ± 10.2 for MS (P = .28). LTR responses were similar between groups. Mean procedure times were 148.2 ± 56.0 minutes for GA and 129.4 ± 31.4 minutes for MS (P = .038). Fluoroscopy and ablation times were similar between groups. A total of 100% (409/409) of PVs were acutely isolated. One hemopericardium occurred in the MS group requiring pericardiocentesis. CONCLUSION: MS for CBA offers an alternative to GA that is safe and well-tolerated by patients with comparable success rates and improved EP lab throughput.

Long-term electrical performance of Attain Performa quadripolar left ventricular leads with all steroid-eluting electrodes: Results from a large worldwide clinical trial.

BACKGROUND: Steroid-eluting (SE) electrodes suppress local inflammation and lower pacing capture thresholds (PCT); however, their effectiveness on quadripolar left ventricular (LV) leads in the cardiac vein is not fully studied. We evaluated the effectiveness of SE on all four LV pacing electrodes in human subjects enrolled in the Medtronic Attain® Performa™ quadripolar LV lead study. METHODS: A total of 1,097 subjects were included in this evaluation. At each follow-up visit (1, 3, 6, and 12 months), LV PCT and pacing impedance were measured using either manual or automated testing methods. Summary statistics for PCT and impedance values were obtained for implant and each scheduled follow-up visit for all lead models. RESULTS: Average extended bipolar (LV electrode to right ventricular Coil) PCTs for the four LV SE pacing electrodes (LV1, LV2, LV3, and LV4) on the three shapes of the quadripolar LV leads were 1.06 ± 0.97 V, 1.38 ± 1.26 V, 1.51 ± 1.33 V, and 2.25 ± 1.63 V, respectively, at 0.5-ms pulse width. PCTs remained low and stable throughout the 12-month follow-up period. CONCLUSION: This clinical trial demonstrated that SE on all LV pacing electrodes is associated with low and stable PCTs for all quadripolar LV lead electrodes, resulting in multiple viable vectors for LV pacing. The large number of available vectors facilitates basal pacing, avoidance of PNS, and potentially prolongs generator longevity due to lower PCTs.

What Is the Role of Left Atrial Appendage Closure in the Rhythm Control of Atrial Fibrillation?

Interventional catheter ablation approaches to the rhythm control of atrial fibrillation (AF) have advanced significantly in the past decade. The foundation of the catheter ablation in AF is electrical isolation of the pulmonary veins (PVI). However, PVI only in more advanced stages of AF (persistent AF) has only modest to poor success rates prompting a search for alternative and adjunctive procedures to improve the outcomes of ablation in persistent AF. The left atrial appendage (LAA) is well understood to be a primary source of emboli in AF but less well known be a trigger or driver for AF. Therefore, LAA exclusion is an attractive target to potentially improve AF ablation outcomes in more advanced stages of AF and possibly as an alternative to chronic oral anticoagulation in the prevention of stroke and systemic embolism in AF. However, the precise role of LAA closure in the interventional approach to AF is still to be elucidated with ongoing clinical investigations.

Reconnection Rate and Long-Term Outcome with Adenosine Provocation During Cryoballoon Ablation for Pulmonary Vein Isolation.

BACKGROUND: Adenosine can unmask dormant conduction during pulmonary vein isolation (PVI) for atrial fibrillation (AF). Studies of adenosine use in radiofrequency PVI show high reconnection rates and conflicting results for long-term success, however there is limited data with cryoballoon ablation (CBA). METHODS: A prospectively maintained database of patients undergoing first CBA at a single institution was analyzed. Adenosine use was at the discretion of the primary operator. Additional freezes were delivered for reconnected veins until dormant conduction was eliminated. The primary endpoint, time to AF recurrence defined as any episode < 30 seconds after a 3-month blanking period, was assessed by Kaplan-Meier analysis. RESULTS: From 2011 to 2015, 406 patients underwent CBA, 361 of whom had > 3 months follow-up. The mean age was 61.7 years, 69% were male, and the prevalence of paroxysmal AF was 79% with no significant difference between those that did and did not receive adenosine (77% vs 86%, respectively, p = 0.23). Adenosine testing was performed in 78 patients (21.6%) with a mean dose of 10.6 mg/vein. Of the 306 veins evaluated, 17 (6%) demonstrated dormant conduction. Over a median 14.4 months follow-up, there was no significant difference in freedom from AF with adenosine use (p= 0.86). CONCLUSIONS: Dormant conduction with adenosine is uncommon following CBA and its use does not improve long-term success rates.

Bronchial effects of cryoballoon ablation for atrial fibrillation.

BACKGROUND: Damage to extracardiac structures, including the esophagus and phrenic nerve, is a known complication of cryoballoon ablation (CBA) during pulmonary vein (PV) isolation for atrial fibrillation (AF). Other adjacent structures, including the pulmonary bronchi and lung parenchyma, may be affected during CBA at the PV ostia. OBJECTIVE: The purpose of this study was to prospectively study the bronchial effects of CBA in humans undergoing CBA for PV isolation. METHODS: Ten patients undergoing CBA for AF under general anesthesia were enrolled in an institutional review board-approved prospective observational study. Real-time bronchoscopy was performed during cryoablation of PVs adjacent to pulmonary bronchi to monitor for thermal injury. Patients were followed for the development of respiratory complaints postprocedure. RESULTS: In 7 of 10 patients (70%) and in 13 of 22 freezes (59%), ice formation was visualized in the left mainstem bronchus during CBA in the left upper PV. Ice formation was not seen in the right mainstem bronchus during right upper PV CBA. The average time to ice formation was 89 seconds. There was no significant difference (P = -.45) in average minimum balloon temperature during freezes with ice formation (-48.5°C) and freezes without ice formation (-46.3°C). No patients went on to develop respiratory complications. CONCLUSION: Unrecognized ice formation occurs frequently in the left mainstem bronchus during CBA for AF. This information helps explain the source of cough and hemoptysis in some patients who undergo CBA. The long-term consequences of this novel finding and the implications for procedural safety are unknown.

Moderate Sedation Reduces Lab Time Compared to General Anesthesia during Cryoballoon Ablation for AF Without Compromising Safety or Long-Term Efficacy.

BACKGROUND: Cryoballoon ablation (CBA) for paroxysmal atrial fibrillation (pAF) can be performed under general anesthesia (GA) or moderate sedation (MS). Our objective was to compare the effectiveness, safety, procedure duration, and time spent in the electrophysiology (EP) laboratory for CBA performed under GA and MS. METHODS: Patients undergoing a first CBA for pAF were identified. Patients received either GA administered by an anesthesiologist or MS with midazolam and fentanyl administered by EP laboratory staff. Total time in laboratory (sum of procedure and nonprocedure time); fluoroscopy time; freedom from documented AF, atrial flutter, and atrial tachycardia (FFAF); acute pulmonary vein isolation (PVI) rate; and 30-day complication rate were assessed. RESULTS: A total of 55 patients received GA and 119 patients received MS. PVI success rate was 100% in GA and 98.1% in MS (P = 0.04). Total laboratory time was longer for GA (280.4 ± 54.1 minutes vs 245.5 ± 54.7 minutes; P < 0.001), related to longer nonprocedure time (92.2 ± 28.8 minutes GA vs 71.0 ± 30.0 minutes MS; P < 0.001), but not procedure time (188.3 ± 49.3 minutes GA vs 174.5 ± 50.2 minutes MS; P = 0.09). FFAF was not significantly different over a median follow-up duration of 0.9 (interquartile range 0.4-1.9) years (61.8% GA vs 63.0% MS; log-rank P = 0.90). There was no significant difference in complication rate. CONCLUSION: Compared to GA, MS during CBA for pAF was independently associated with shorter total EP laboratory time without compromising FFAF or complication rates.

The Safety of Cardiac and Thoracic Magnetic Resonance Imaging in Patients with Cardiac Implantable Electronic Devices.

RATIONALE AND OBJECTIVES: Studies reporting the safety of magnetic resonance imaging (MRI) in patients with a cardiac implantable electronic device (CIED) have mostly excluded examinations with the device in the magnet isocenter. The purpose of this study was to describe the safety of cardiac and thoracic spine MRI in patients with a CIED. MATERIALS AND METHODS: The medical records of patients with a CIED who underwent a cardiac or thoracic spine MRI between January 2011 and December 2014 were reviewed. Devices were interrogated before and after imaging with reprogramming to asynchronous pacing in pacemaker-dependent patients. The clinical interpretability of the MRI and peak and average specific absorption rates (SARs, W/kg) achieved were determined. RESULTS: Fifty-eight patients underwent 51 cardiac and 11 thoracic spine MRI exams. Twenty-nine patients had a pacemaker and 29 had an implantable cardioverter defibrillator. Seventeen percent (n = 10) were pacemaker dependent. Fifty-one patients (89%) had non-MRI-conditional devices. There were no clinically significant changes in atrial and ventricular sensing, impedance, and threshold measurements. There were no episodes of device mode changes, arrhythmias, therapies delivered, electrical reset, or battery depletion. One study was prematurely discontinued due to a patient complaint of chest pain of which the etiology was not determined. Across all examinations, the average peak SAR was 2.0 ± 0.85 W/kg with an average SAR of 0.35 ± 0.37 W/kg. Artifact significantly limiting the clinical interpretation of the study was present in 33% of cardiac MRI studies. CONCLUSIONS: When a comprehensive CIED magnetic resonance safety protocol is followed, the risk of performing 1.5-T magnetic resonance studies with the device in the magnet isocenter, including in patients who are pacemaker dependent, is low.

Left atrial appendage closure.

Stroke or systemic embolism is a devastating consequence of atrial fibrillation (AF) due to thrombus formation in the left atrial appendage (LAA). AF causes thrombus formation in the LAA due to both the loss of atrial systole and the unique anatomic features of the LAA. Oral anticoagulation is a well established and effective therapy to reduce the risk of stroke in AF patients, albeit with a risk of bleeding. LAA closure is a possible alternative to oral anticoagulation in the prevention of stroke or systemic embolism in AF.

Cryoballoon versus radiofrequency catheter ablation for paroxysmal atrial fibrillation.

BACKGROUND: Catheter ablation is an established treatment for atrial fibrillation (AF). Cryoballoon ablation (CBA) has emerged as an alternative to radiofrequency ablation (RFA). However, there are few data comparing these modalities for treatment of paroxysmal AF (pAF) in the U.S. POPULATION: The purpose of this study was to compare procedural times, safety, and efficacy of CBA against RFA. METHODS: A single-center prospective cohort study evaluated patients who underwent catheter ablation for pAF using CBA or RFA between January 1, 2010 and October 31, 2013. Patients with prior ablation and those without rhythm follow-up for at least 3 months were excluded. The primary end point was freedom from AF, atrial flutter, and atrial tachycardia (FFAF) >30 seconds after a 3-month blanking period without requirement for antiarrhythmic drugs. We also compared rates of successful pulmonary vein isolation (PVI), fluoroscopy and procedure times, and major complication rates. RESULTS: A total of 201 patients were included (CBA = 101, RFA = 100). The rate of successful PVI was 99.3% in CBA versus 97.4% in RFA (P = 0.08). Procedure times were shorter with CBA (192.9 ± 44.0 minutes vs 283.7 ± 78.0 minutes, P < 0.001) as well as total fluoroscopy times (46.0 ± 22.4 minutes vs 73.0 ± 30.1 minutes, P < 0.001). Overall complication rates were equivalent; however, fewer cardiac perforations occurred with CBA (0% vs 4%, P = 0.042). The 1-year FFAF rates were 60.3% for CBA and 61.1% for RFA (log rank P = 0.93). CONCLUSION: CBA was associated with equivalent 1-year FFAF rate as RFA for pAF. Procedure and fluoroscopy times were shorter for CBA and fewer cardiac perforations occurred.

Early safety and efficacy of percutaneous left atrial appendage suture ligation: results from the U.S. transcatheter LAA ligation consortium.

BACKGROUND: Transcatheter left atrial appendage (LAA) ligation may represent an alternative to oral anticoagulation for stroke prevention in atrial fibrillation. OBJECTIVES: This study sought to assess the early safety and efficacy of transcatheter ligation of the LAA for stroke prevention in atrial fibrillation. METHODS: This was a retrospective, multicenter study of consecutive patients undergoing LAA ligation with the Lariat device at 8 U.S. sites. The primary endpoint was procedural success, defined as device success (suture deployment and <5 mm leak by post-procedure transesophageal echocardiography), and no major complication at discharge (death, myocardial infarction, stroke, Bleeding Academic Research Consortium bleeding type 3 or greater, or cardiac surgery). Post-discharge management was per operator discretion. RESULTS: A total of 154 patients were enrolled. Median CHADS2 score (congestive heart failure, hypertension, age ≥ 75 years, diabetes mellitus, prior stroke, transient ischemic attack, or thromboembolism [doubled]) was 3 (interquartile range: 2 to 4). Device success was 94%, and procedural success was 86%. A major complication occurred in 15 patients (9.7%). There were 14 major bleeds (9.1%), driven by the need for transfusion (4.5%). Significant pericardial effusion occurred in 16 patients (10.4%). Follow-up was available in 134 patients at a median of 112 days (interquartile range: 50 to 270 days): Death, myocardial infarction, or stroke occurred in 4 patients (2.9%). Among 63 patients with acute closure and transesophageal echocardiography follow-up, there were 3 thrombi (4.8%) and 13 (20%) with residual leak. CONCLUSIONS: In this initial multicenter experience of LAA ligation with the Lariat device, the rate of acute closure was high, but procedural success was limited by bleeding. A prospective randomized trial is required to adequately define clinical efficacy, optimal post-procedure medical therapy, and the effect of operator experience on procedural safety.

Use of an electrocardiographic screening tool to determine candidacy for a subcutaneous implantable cardioverter-defibrillator.

BACKGROUND: An electrocardiographic (ECG) screening test has been developed to identify patients being considered for a totally subcutaneous implantable cardioverter-defibrillator (S-ICD) at risk for T-wave oversensing. OBJECTIVE: The purpose of this study was to determine the proportion of potential S-ICD recipients who fail the ECG screening test and to identify predictors of failure. METHODS: Patients who already have an ICD but are not receiving antibradycardia pacing are representative of patients who might be considered for an S-ICD. One hundred such outpatients were enrolled in the study. Surface rhythm strips were recorded along the sensing vectors of the S-ICD system and the screening template applied. Clinical and standard ECG characteristics of patients who failed the test were compared to those who passed. RESULTS: Patients had the following characteristics: 72% male, age 57 ± 16 years, body mass index 29 ± 6 kg/m(2), left ventricular ejection fraction 43% ± 17%, QRS duration 109 ± 23 ms, QTc interval 447 ± 39 ms, 44% had coronary disease, and 55% had heart failure. Among the 100 patients, 8% failed the screening test. There were no differences in patient clinical characteristics and most standard ECG measurements. However, patients with T-wave inversions in standard ECG leads I, II, and aVF had a 45% chance of failing. CONCLUSION: Eight percent of potential S-ICD patients were not eligible for the S-ICD after failing the screening test designed to identify patients susceptible to T-wave oversensing. Patients with T-wave inversions in leads I, II, and aVF on a standard ECG were 23 times more likely to fail. More work is needed in S-ICD sensing algorithms to increase patient eligibility for the S-ICD.

Prevalence and predictors of cable extrusion and loss of electrical integrity with the Riata defibrillator lead.

INTRODUCTION: Recently, a medical advisory was issued regarding the Riata and Riata ST silicone endocardial defibrillator leads (St. Jude Medical, Sylmar, CA, USA) addressing the issue of conductor cables extruding in an "inside-out" fashion from the main body of the lead. However, little data exist to guide our management of patients with these leads. METHODS AND RESULTS: A retrospective analysis was performed of 84 patients with a Riata lead who underwent cine-fluoroscopy and electrical evaluation as part of a screening program to assess for cable extrusion. All leads screened were dual-coil except for one single-coil lead. Of 84 patients, 23 patients (27.4%) had fluoroscopic evidence of cable extrusion. Multivariate analysis showed that the duration of time since lead implant and the presence of multiple right ventricular leads were significantly associated with cable extrusion. All 23 patients had normal electrical parameters on routine device interrogation. Fifteen of these 23 patients (65%) with extruded cables had high-voltage shocks within 12 months of lead screening; only one patient demonstrated postshock electrical abnormalities. CONCLUSIONS: The prevalence of cable extrusion in dual-coil Riata leads is significantly higher at 27.4% than previously reported. The duration of time since implantation and the presence of multiple right ventricular leads are associated with cable extrusion. High-energy shocks did not reveal electrical abnormalities in most patients with cable extrusion.