Publications by authors named "Conor D Barrett"

47 Publications

Specific Electrocardiograph Intervals Predict Hospitalization with Atrial Fibrillation in Those with Chronic Kidney Disease.

Am J Nephrol 2021 May 5:1-8. Epub 2021 May 5.

Division of Renal Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA.

Introduction: Atrial fibrillation (AF) is common in patients with chronic kidney disease (CKD) and is associated with higher rates of hospitalization compared to those without AF. Whether routine electrocardiographic parameters are predictive of future hospitalizations with AF is not clear.

Methods: The present study is an analysis of a prospective cohort of 2,759 patients without baseline AF from the Chronic Renal Insufficiency Cohort, a large prospective multicenter study of patients with nondialysis-dependent CKD. Unadjusted and adjusted Cox regression models were fit to examine the association of baseline categories of QTc, QRS, and PR intervals with time to first hospitalization with AF. Restricted cubic splines were used to display nonlinear associ-ations.

Results: The mean age of subjects at baseline was 58 ± 11 years, 55% were male, and 44% were Black. The mean follow-up was 6.6 years during which 224 participants experienced a hospitalization with AF. The association of baseline QTc interval with risk of AF hospitalization was nonlinear, such that the lowest and highest quartiles of QTc (<407 and >431 ms, respectively) had higher adjusted risk of AF hospitalization, compared with the second quartile (407-416 ms) (aHR Q1:Q2 1.58, 95% CI 1.03-2.41; p = 0.03; aHR Q4:Q2 1.84, 95% CI 1.22-2.78; p < 0.01). Longer QRS was associated with a higher risk of hospitalization with AF among the subgroup of patients with a history of heart failure (HF). PR interval was not associated with AF hospitalization.

Discussion/conclusion: The association of QTc with risk for hospitalization with AF among patients with CKD is nonlinear, while the association of longer QRS with AF hospitalization is restricted to patients with baseline HF. Electrocardiography may represent a simple and widely accessible method for risk stratification of future AF in patients with CKD.
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http://dx.doi.org/10.1159/000515670DOI Listing
May 2021

Comparison between TightRail rotating dilator sheath and GlideLight laser sheath for transvenous lead extraction.

Pacing Clin Electrophysiol 2021 May 27;44(5):895-902. Epub 2021 Mar 27.

Cardiac Arrhythmia Service, Corrigan Minehan Heart Center, Massachusetts General Hospital, Boston, Massachusetts, USA.

Background: There are limited data on the comparative analyses of TightRail rotating dilator sheath (Philips) and laser sheath for lead extraction.

Objective: To evaluate the effectiveness and safety of the TightRail sheath as a primary or secondary tool for transvenous lead extraction (TLE).

Methods: Retrospective cohort analysis of 202 consecutive patients who underwent TLE using either TightRail sheath and/or GlideLight laser sheath (Philips) in our hospital. The study population was divided into three groups: Group A underwent TLE with laser sheath only (N = 157), Group B with TightRail sheath only (N = 22), and Group C with both sheaths (N = 23).

Results: During this period, 375 leads in 202 patients were extracted, including 297 leads extracted by laser sheath alone, 45 leads by TightRail sheath alone, and 33 by both TightRail sheath and laser sheaths. The most common indications included device infection (44.6%) and lead-related complications (44.1%). The median age of leads was 8.9 years. TightRail sheath (Group B) achieved similar efficacy as a primary extraction tool compared with laser sheath (Group A), with complete procedure success rate of 93.3% (vs. 96.6%, P = .263) and clinical success rate of 100.0% (vs. 98.1%, P = .513). Among 32 leads in which Tightrail was used after laser had failed (Group C), the complete procedure success rate was 75.8%. No significant difference in procedural adverse events was observed.

Conclusion: Our single-center experience confirms that the TightRail system is an effective first-line and second-line method for TLE. Further investigation is required to guide the selection of mechanical and laser sheaths in lead extraction cases.
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http://dx.doi.org/10.1111/pace.14206DOI Listing
May 2021

Use of the inverse solution guidance algorithm method for RF ablation catheter guidance.

J Cardiovasc Electrophysiol 2021 May 8;32(5):1281-1289. Epub 2021 Mar 8.

Cardiac Arrhythmia Service, Massachusetts General Hospital, Boston, Massachusetts, USA.

Introduction: We previously introduced the inverse solution guidance algorithm (ISGA) methodology using a Single Equivalent Moving Dipole model of cardiac electrical activity to localize both the exit site of a re-entrant circuit and the tip of a radiofrequency (RF) ablation catheter. The purpose of this study was to investigate the use of ISGA for ablation catheter guidance in an animal model.

Methods: Ventricular tachycardia (VT) was simulated by rapid ventricular pacing at a target site in eleven Yorkshire swine. The ablation target was established using three different techniques: a pacing lead placed into the ventricular wall at the mid-myocardial level (Type-1), an intracardiac mapping catheter (Type-2), and an RF ablation catheter placed at a random position on the endocardial surface (Type-3). In each experiment, one operator placed the catheter/pacing lead at the target location, while another used the ISGA system to manipulate the RF ablation catheter starting from a random ventricular location to locate the target.

Results: The average localization error of the RF ablation catheter tip was 0.31 ± 0.08 cm. After analyzing approximately 35 cardiac cycles of simulated VT, the ISGA system's accuracy in locating the target was 0.4 cm after four catheter movements in the Type-1 experiment, 0.48 cm after six movements in the Type-2 experiment, and 0.67 cm after seven movements in the Type-3 experiment.

Conclusion: We demonstrated the feasibility of using the ISGA method to guide an ablation catheter to the origin of a VT focus by analyzing a few beats of body surface potentials without electro-anatomic mapping.
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http://dx.doi.org/10.1111/jce.14965DOI Listing
May 2021

Beyond the stethoscope: managing ambulatory heart failure during the COVID-19 pandemic.

ESC Heart Fail 2021 04 27;8(2):999-1006. Epub 2021 Jan 27.

Cardiology Division, Department of Medicine, Massachusetts General Hospital, 55 Fruit Street, Boston, MA, 02114, USA.

There have been nearly 70 million cases of COVID-19 worldwide, with over 1.5 million deaths at the time of this publication. This global pandemic has mandated dramatic changes in healthcare delivery with a particular focus on social distancing in order to reduce viral transmission. Heart failure patients are among the highest utilizers of health care and are at increased risk for COVID-related vulnerabilities. Effectively managing this complex and resource-intensive patient population from a distance presents new and unique challenges. Here, we review relevant data on telemedicine and remote monitoring strategies for heart failure patients and provide a framework to help providers treat this population during the COVID-19 pandemic. This includes (i) dedicated pre-visit contact and planning (i.e. confirm clinical appropriateness, presence of compatible technology, and patient comfort); (ii) utilization of virtual clinic visits (use of telehealth platforms, a video-assisted exam, self-reported vital signs, and weights); and (iii) use of existing remote heart failure monitoring sensors when applicable (CardioMEMS, Optivol, and HeartLogic). While telemedicine and remote monitoring strategies are not new, these technologies are emerging as an important tool for the effective management of heart failure patients during the COVID-19 pandemic. In general, these strategies appear to be safe; however, additional data will be needed to determine their effectiveness with respect to both process and outcomes measures.
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http://dx.doi.org/10.1002/ehf2.13201DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8006709PMC
April 2021

Accuracy of cardiac ablation catheter guidance by means of a single equivalent moving dipole inverse algorithm to identify sites of origin of cardiac electrical activation.

J Interv Card Electrophysiol 2020 Sep 27;58(3):323-331. Epub 2019 Aug 27.

Institute for Medical Engineering and Science, Massachusetts Institute of Technology, 45 Carleton Street, Room E25-324, Cambridge, MA, 02142, USA.

We have developed a system that could potentially be used to identify the site of origin of ventricular tachycardia (VT) and to guide a catheter to that site to deliver radio-frequency ablation therapy. This system employs the Inverse Solution Guidance Algorithm based upon Single Equivalent Moving Dipole (SEMD) localization method. The system was evaluated in in vivo swine experiments. Arrays consisting of 9 or 16 bipolar epicardial electrodes and an additional mid-myocardial pacing lead were sutured to each ventricle. Focal tachycardia was simulated by applying pacing pulses to each epicardial electrode at multiple pacing rates during breath hold at the end-expiration phase. Surface potentials were recorded from 64 surface electrodes and then analyzed using the SEMD method to localize the position of the pacing electrodes. We found a close correlation between the locations of the pacing electrodes as measured in computational and real spaces. The reproducibility error of the SEMD estimation of electrode location was 0.21 ± 0.07 cm. The vectors between every pair of bipolar electrodes were computed in computational and real spaces. At 120 bpm, the lengths of the vectors in the computational and real space had a 95% correlation. Computational space vectors were used in catheter guidance simulations which showed that this method could reduce the distance between the real space locations of the emulated catheter tip and the emulated arrhythmia origin site by approximately 72% with each movement. We have demonstrated the feasibility of using our system to guide a catheter to the site of the emulated VT origin.
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http://dx.doi.org/10.1007/s10840-019-00605-zDOI Listing
September 2020

Case 24-2019: A 39-Year-Old Woman with Palpitations, Abdominal Pain, and Vomiting.

N Engl J Med 2019 Aug;381(6):567-577

From the Departments of Medicine (V.C., C.D.B., N.S.), Radiology (M.A.A.), and Pathology (M.N.A.), Massachusetts General Hospital, and the Departments of Medicine (V.C., C.D.B., N.S.), Radiology (M.A.A.), and Pathology (M.N.A.), Harvard Medical School - both in Boston.

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http://dx.doi.org/10.1056/NEJMcpc1900142DOI Listing
August 2019

Termination of persistent atrial fibrillation during pulmonary vein isolation: insight from the MAGIC-AF trial.

Europace 2017 Oct;19(10):1657-1663

Helmsley Cardiac Arrhythmia Service, Icahn School of Medicine at Mount Sinai, New York, NY, USA.

Aims: Controversy on the optimal ablation strategy for persistent atrial fibrillation (AF) exists with limited work evaluating a strategy of pulmonary vein isolation (PVI) alone when AF terminates during PVI. Thirty-five patients had AF termination during PVI in the Modified Ablation Guided by Ibutilide Use in Chronic Atrial Fibrillation (MAGIC-AF; ClinicalTrials.gov number: NCT01014741) study. The objective of the current study is to report the 1-year outcome after PVI alone in this unique patient group.

Methods And Results: The 1-year single procedure freedom from atrial arrhythmia off anti-arrhythmic drugs was reported for the 35 patients in the MAGIC-AF study with persistent AF termination during or upon completion of PVI. Freedom from recurrent atrial arrhythmia was achieved in 60% of patients where AF terminated during PVI. Cavotricuspid isthmus flutter was common when AF terminated to a macro re-entrant flutter during PVI, and responsible for 92% of all flutter circuits with AF termination.

Conclusions: Persistent AF termination during PVI may identify a subgroup of patients who experience a similar long-term clinical outcome with PVI ablation alone when compared with other more extensive persistent AF ablation strategies. Pulmonary vein isolation alone may be an appropriate tactic in this subgroup of persistent AF patients.
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http://dx.doi.org/10.1093/europace/euw266DOI Listing
October 2017

Persistent Atrial Fibrillation Ablation in Females: Insight from the MAGIC-AF Trial.

J Cardiovasc Electrophysiol 2016 Nov 30;27(11):1259-1263. Epub 2016 Aug 30.

Helmsley Cardiac Arrhythmia Service, Icahn School of Medicine at Mount Sinai, New York, New York, USA.

Introduction: Atrial fibrillation (AF) ablation is less frequently performed in women when compared to men. There are conflicting data on the safety and efficacy of AF ablation in women. The objective of this study was to compare the clinical characteristics and outcomes in a contemporary cohort of men and women undergoing persistent AF ablation procedures.

Methods And Results: A total of 182 men and 53 women undergoing a first-ever persistent AF catheter ablation procedure in The Modified Ablation Guided by Ibutilide Use in Chronic Atrial Fibrillation (MAGIC-AF) trial were evaluated. Clinical and procedural characteristics were compared between each gender. The primary efficacy endpoint was the 1-year single procedure freedom from atrial arrhythmia off anti-arrhythmic drugs. Women undergoing catheter ablation procedures were older than men (P < 0.001). The duration of AF and associated co-morbidities were similar between both genders. Single procedure drug-free atrial arrhythmia recurrence occurred in 53% of the cohort with no difference based on gender (men = 54%, women = 53%; P = 1.0). Procedural (P = 0.04), fluoroscopic (P = 0.02), and ablation times (P = 0.003) were shorter in women compared to men. Periprocedural complications and postablation improvement in quality of life were similar between men and women.

Conclusion: Women undergoing a first-ever persistent AF ablation procedure were older but had similar clinical outcomes and complications when compared with men.
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http://dx.doi.org/10.1111/jce.13051DOI Listing
November 2016

The modified stepwise ablation guided by low-dose ibutilide in chronic atrial fibrillation trial (The MAGIC-AF Study).

Eur Heart J 2016 May 4;37(20):1614-21. Epub 2016 Feb 4.

Helmsley Cardiac Arrhythmia Service, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, PO Box 1030, New York, NY 10029, USA

Aims: Complex fractionated atrial electrograms (CFAE) are targeted during persistent atrial fibrillation (AF) ablation. However, many CFAE sites are non-specific resulting in extensive ablation. Ibutilide has been shown to reduce left atrial surface area exhibiting CFAE. We hypothesized that ibutilide administration prior to CFAE ablation would identify sites critical for persistent AF maintenance allowing for improved procedural efficacy and long-term freedom from atrial arrhythmias.

Methods And Results: Two hundred patients undergoing a first-ever persistent AF catheter ablation procedure were randomly assigned to receive either 0.25 mg of intravenous ibutilide or saline placebo upon completion of pulmonary vein isolation. Complex fractionated atrial electrogram sites were then targeted with ablation. The primary efficacy endpoint was the 1-year single procedure freedom from atrial arrhythmia off anti-arrhythmic drugs. Similar procedural characteristics (procedure, fluoroscopy, and ablation times) were observed with both strategies despite a greater reduction in left atrial surface area with CFAE sites (8 vs. 1%, P < 0.0001) and AF termination during CFAE ablation with ibutilide compared with placebo (75 vs. 57%, P = 0.007). The primary efficacy endpoint was achieved in 56% of patients receiving ibutilide and 49% receiving placebo (P = 0.35). No significant differences in peri-procedural complications were observed in both groups.

Conclusion: Despite a reduction in CFAE area and greater AF termination during CFAE ablation, procedural characteristics and clinical outcomes were unchanged when CFAE ablation was guided by ibutilide administration.

Clinical Trial Registration Information: ClinicalTrials.gov number: NCT01014741.
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http://dx.doi.org/10.1093/eurheartj/ehw003DOI Listing
May 2016

Non-Vitamin K Antagonist Oral Anticoagulants and Antiplatelet Therapy for Stroke Prevention in Patients With Atrial Fibrillation: A Meta-Analysis of Randomized Controlled Trials.

Cardiol Rev 2016 Sep-Oct;24(5):218-23

From the *Department of Medicine, Memorial Hospital, Rome, NY; †Division of Cardiology, Mount Sinai St. Luke's Hospital and Mount Sinai West Hospital, New York, NY; ‡Division of Cardiology, Massachusetts General Hospital, Boston, MA; §Division of Cardiology, Centre for Cardiovascular Sciences, City Hospital, University of Birmingham, Birmingham, United Kingdom; ¶Division of Cardiology, Brookwood Medical Center, Birmingham, AL; ‖Division of Cardiology, Texas Cardiac Arrhythmia Institute, St. David's Medical Center, Austin, TX; and **Division of Preventive Medicine, Brigham and Women's Hospital, Boston, MA.

Non-vitamin K antagonist oral anticoagulants (NOACs) are frequently used to prevent stroke in patients with atrial fibrillation. These patients are often also on aspirin or other antiplatelet agents. It is possible that treatment with both NOACs and aspirin or other antiplatelet drug may be effective in decreasing stroke, but data are sparse regarding the efficacy and safety of using both agents for stroke prevention. To address these issues, data were pooled from the 4 recent randomized, controlled trials of NOACs: apixaban, rivaroxaban, dabigatran, and edoxaban, which included 42,411 patients; 14,148 (33.4%) were also on aspirin or other antiplatelet drug. The number of thromboembolic events among participants on NOAC and aspirin/antiplatelet was compared with the number of events in patients on NOAC alone. Bleeding rates were also compared between those on NOAC + aspirin/antiplatelet and on NOAC alone. These results were compared with thromboembolic and bleeding events in the warfarin + aspirin/antiplatelet versus warfarin alone. No greater risk for thromboembolism was seen in patients on NOACs compared with patients on both NOACs and aspirin/antiplatelet drug. In this nonrandomized comparison, there was initially a signal toward higher thromboembolic rates among NOAC users also on aspirin/antiplatelet drugs (relative risk, 1.16; 95% confidence intervals, 1.05, 1.29) when compared with NOAC alone. This likely reflected the higher CHADS2 scores of those on aspirin/antiplatelet drugs. When the analysis was limited to studies that included aspirin rather than other antiplatelet drugs, no difference was seen for thromboembolic rates comparing dual therapy to NOAC alone (relative risk, 1.02; 95% confidence intervals, 0.90, 1.15). Higher rates of bleeding were seen with aspirin/antiplatelet drug in conjunction with NOAC. In this meta-analysis and nonrandomized comparison of aspirin/antiplatelet users and nonusers also on anticoagulation, there was no additional benefit seen of anticoagulation and antiplatelet therapy for stroke prevention when compared with anticoagulation alone. There was, however, an increased risk of bleeding. Careful assessment of the indications for antiplatelet drugs in patients with atrial fibrillation who are also receiving oral anticoagulants is warranted, and future randomized comparisons are needed.
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http://dx.doi.org/10.1097/CRD.0000000000000088DOI Listing
March 2017

Myocardial scar imaging by standard single-energy and dual-energy late enhancement CT: Comparison with pathology and electroanatomic map in an experimental chronic infarct porcine model.

J Cardiovasc Comput Tomogr 2015 Jul-Aug;9(4):313-20. Epub 2015 Mar 24.

Al-Sabah Arrhythmia Institute, Mount Sinai St. Luke's-Roosevelt Hospital Center, New York, NY, USA.

Background: Myocardial scar is a substrate for ventricular tachycardia and sudden cardiac death. Late enhancement CT imaging can detect scar, but it remains unclear whether newer late enhancement dual-energy (LE-DECT) acquisition has benefit over standard single-energy late enhancement (LE-CT).

Objective: We aim to compare late enhancement CT using newer LE-DECT acquisition and single-energy LE-CT acquisitions with pathology and electroanatomic map (EAM) in an experimental chronic myocardial infarction (MI) porcine study.

Methods: In 8 pigs with chronic myocardial infarction (59 ± 5 kg), we performed dual-source CT, EAM, and pathology. For CT imaging, we performed 3 acquisitions at 10 minutes after contrast administration: LE-CT 80 kV, LE-CT 100 kV, and LE-DECT with 2 postprocessing software settings.

Results: Of the sequences, LE-CT 100 kV provided the best contrast-to-noise ratio (all P ≤ .03) and correlation to pathology for scar (ρ = 0.88). LE-DECT overestimated scar (both P = .02), whereas LE-CT images did not (both P = .08). On a segment basis (n = 136), all CT sequences had high specificity (87%-93%) and modest sensitivity (50%-67%), with LE-CT 100 kV having the highest specificity of 93% for scar detection compared to pathology and agreement with EAM (κ = 0.69).

Conclusions: Standard single-energy LE-CT, particularly 100 kV, matched better to pathology and EAM than dual-energy LE-DECT for scar detection. Larger human trials as well as more technical studies that optimize varying different energies with newer hardware and software are warranted.
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http://dx.doi.org/10.1016/j.jcct.2015.03.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4475424PMC
March 2016

Management of refractory atrial fibrillation post surgical ablation.

Ann Cardiothorac Surg 2014 Jan;3(1):91-7

Texas Cardiac Arrhythmia Institute, St. David's Medical Center, Austin, TX, USA ; ; Department of Biomedical Engineering, University of Texas, Austin, TX, USA ; ; Division of Cardiology, Stanford University, California, USA ; ; Case Western Reserve University, Cleveland, Ohio, USA ; ; EP Services, California Pacific Medical Center, San Francisco, California, USA ; ; Interventional Electrophysiology, Scripps Clinic, San Diego, California, USA.

Over the past two decades, invasive techniques to treat atrial fibrillation (AF) including catheter-based and surgical procedures have evolved along with our understanding of the pathophysiology of this arrhythmia. Surgical treatment of AF may be performed on patients undergoing cardiac surgery for other reasons (concomitant surgical ablation) or as a stand-alone procedure. Advances in technology and technique have made surgical intervention for AF more widespread. Despite improvements in outcome of both catheter-based and surgical treatment for AF, recurrence of atrial arrhythmias following initial invasive therapy may occur.Atrial arrhythmias may occur early or late in the post-operative course after surgical ablation. Early arrhythmias are generally treated with prompt electrical cardioversion with or without antiarrhythmic therapy and do not necessarily represent treatment failure. The mechanism of persistent or late occurring atrial arrhythmias is complex, and these arrhythmias may be resistant to antiarrhythmic drug therapy. The characterization and management of recurrent atrial arrhythmias following surgical ablation of AF are discussed below.
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http://dx.doi.org/10.3978/j.issn.2225-319X.2013.12.08DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3904336PMC
January 2014

Feasibility and safety of uninterrupted rivaroxaban for periprocedural anticoagulation in patients undergoing radiofrequency ablation for atrial fibrillation: results from a multicenter prospective registry.

J Am Coll Cardiol 2014 Mar 8;63(10):982-8. Epub 2014 Jan 8.

Texas Cardiac Arrhythmia Institute, Austin, Texas; Department of Biomedical Engineering, University of Texas, Austin, Texas.

Objectives: The purpose of this study was to evaluate the feasibility and safety of uninterrupted rivaroxaban therapy during atrial fibrillation (AF) ablation.

Background: Optimal periprocedural anticoagulation strategy is essential for minimizing bleeding and thromboembolic complications during and after AF ablation. The safety and efficacy of uninterrupted rivaroxaban therapy as a periprocedural anticoagulant for AF ablation are unknown.

Methods: We performed a multicenter, observational, prospective study of a registry of patients undergoing AF ablation in 8 centers in North America. Patients taking uninterrupted periprocedural rivaroxaban were matched by age, sex, and type of AF with an equal number of patients taking uninterrupted warfarin therapy who were undergoing AF ablation during the same period.

Results: A total of 642 patients were included in the study, with 321 in each group. Mean age was 63 ± 10 years, with 442 (69%) males and 328 (51%) patients with paroxysmal AF equally distributed between the 2 groups. Patients in the warfarin group had a slightly higher mean HAS- BLED (hypertension, abnormal renal/liver function, stroke, bleeding history or predisposition, labile international normalized ratio, elderly, drugs/alcohol concomitantly) score (1.70 ± 1.0 vs. 1.47 ± 0.9, respectively; p = 0.032). Bleeding and embolic complications occurred in 47 (7.3%) and 2 (0.3%) patients (both had transient ischemic attacks) respectively. There were no differences in the number of major bleeding complications (5 [1.6%] vs. 7 [1.9%], respectively; p = 0.772), minor bleeding complications (16 [5.0%] vs. 19 [5.9%], respectively; p = 0.602), or embolic complications (1 [0.3%] vs. 1 [0.3%], respectively; p = 1.0) between the rivaroxaban and warfarin groups in the first 30 days.

Conclusions: Uninterrupted rivaroxaban therapy appears to be as safe and efficacious in preventing bleeding and thromboembolic events in patients undergoing AF ablation as uninterrupted warfarin therapy.
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http://dx.doi.org/10.1016/j.jacc.2013.11.039DOI Listing
March 2014

Ventricular fibrillation cardiac arrest due to 5-fluorouracil cardiotoxicity.

Tex Heart Inst J 2013 ;40(4):472-6

Divisions of Cardiology (Drs. Barrett, Fradley, and Francis) and Hematology and Oncology (Dr. Clark), Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114.

The antimetabolite chemotherapeutic agent 5-fluorouracil is used to treat a variety of cancers. Although 5-fluorouracil is generally well tolerated, its toxicity profile includes potential cardiac ischemia, vasospasm, arrhythmia, and direct myocardial injury. These actual or potential toxicities are thought to resolve upon cessation of the medication; however, information about the long-term cardiovascular effects of therapy is not sufficient. We present the case of a 58-year-old man who had 2 ventricular fibrillation cardiac arrests, with evidence of coronary vasospasm and myocarditis, on his 4th day of continuous infusion with 5-fluorouracil. External defibrillation and cessation of the 5-fluorouracil therapy resolved the patient's electrocardiographic abnormalities. In addition to reporting the clinical manifestations of 5-fluorouracil-associated cardiotoxicity in our patient, we discuss management challenges in patients who develop severe 5-fluorouracil-induced ventricular arrhythmias.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3783134PMC
May 2014

The Riata lead recall--more data, but do we now know what we need to know?

Heart Rhythm 2013 Dec 20;10(12):1783-4. Epub 2013 Sep 20.

Arrhythmia Institute, St Luke's Roosevelt Hospital Centers, New York, New York.

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http://dx.doi.org/10.1016/j.hrthm.2013.09.063DOI Listing
December 2013

Ventricular arrhythmias and left ventricular assist device.

Int J Cardiol 2013 Sep 24;168(2):e81-3. Epub 2013 Jul 24.

Cardiac Arrhythmia Service, Massachusetts General Hospital, Boston, MA, USA; Division of Cardiovascular Medicine, University at Buffalo School of Medicine and Biomedical Sciences, Buffalo, NY, USA. Electronic address:

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http://dx.doi.org/10.1016/j.ijcard.2013.07.045DOI Listing
September 2013

Multi-sensor esophageal temperature probe used during radiofrequency ablation for atrial fibrillation is associated with increased intraluminal temperature detection and increased risk of esophageal injury compared to single-sensor probe.

J Cardiovasc Electrophysiol 2013 Sep 7;24(9):958-64. Epub 2013 Jun 7.

Department of Medicine.

Background: Radiofrequency (RF) ablation in the posterior left atrium has risk of thermal injury to the adjacent esophagus. Increased intraluminal esophageal temperature has been correlated with risk of esophageal injury. The objective of this study was to compare esophageal temperature monitoring (ETM) using a multi-sensor temperature probe with 12 sensors to a single-sensor probe during catheter ablation for atrial fibrillation (AF).

Methods And Results: We compared the detection of intraluminal esophageal temperature rises in 543 patients undergoing RF ablation for AF with ETM. Esophageal endoscopy (EGD) was performed on all patients with maximum esophageal temperature ≥ 39°C. Esophageal lesions were classified by severity as mild or severe ulcerations. Four hundred fifty-five patients underwent RF ablation with single-sensor ETM and 88 patients with multi-sensor ETM. Thirty-nine percent of patients with single-sensor versus 75% with multi-sensor ETM reached a maximum detected esophageal temperature ≥ 39°C (P < 0.0001). Esophageal injury was detected by EGD in 29% of patients with maximum temperature ≥ 39°C by single-sensor versus 46% of patients with multi-sensor ETM (P = 0.021). Thirty-nine percent of patients with lesions in the single-sensor probe group had severe ulcerations compared to 33% of patients in the multi-sensor probe group (P = 0.641).

Conclusions: Intraluminal esophageal temperature ≥ 39°C is detected more frequently by the multi-sensor temperature probe versus the single-sensor probe, with more frequent esophageal injury and with comparable severity of injury. Despite detecting esophageal temperature rises in more patients, the multi-sensor probe may not have any measurable benefit compared to a single-sensor probe.
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http://dx.doi.org/10.1111/jce.12180DOI Listing
September 2013

Uncontrolled forward motion of an ablation catheter through a recently available deflectable sheath.

Europace 2013 Jun 29;15(6):786. Epub 2013 Jan 29.

Cardiac Arrhythmia Service, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.

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http://dx.doi.org/10.1093/europace/eut008DOI Listing
June 2013

A novel pacing method to suppress repolarization alternans in vivo: implications for arrhythmia prevention.

Heart Rhythm 2013 Apr 28;10(4):564-72. Epub 2012 Dec 28.

Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts; Division of Cardiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02129, USA.

Background: Repolarization alternans (RA), a pattern of ventricular repolarization that repeats on an every other beat basis, has been closely linked with the substrate associated with ventricular tachycardia/ventricular fibrillation.

Objective: To evaluate a novel method to suppress RA.

Methods: We have developed a novel method to dynamically (on R-wave detection) trigger pacing pulses during the absolute refractory period. We have tested the ability of this method to control RA in a structurally normal swine heart in vivo.

Results: RA induced by triggered pacing can be measured from both intracardiac and body surface leads and the amplitude of R-wave triggered pacing-induced alternans can be locally modulated by varying the amplitude and width of the pacing pulse. We have estimated that to induce a 1 μV change in alternans voltage on the body surface, coronary sinus, and left ventricle leads, a triggered pacing pulse delivered in the right ventricle of 0.04±0.02, 0.05±0.025, and 0.06±0.033 μC, respectively, is required. Similarly, to induce a 1 unit change in Kscore (ratio of alternans peak to noise), a pacing stimulus of 0.93±0.73, 0.32±0.29, and 0.33±0.37 μC, respectively, is required. We have been able to demonstrate that RA can be suppressed by R-wave triggered pacing from a site that is within or across ventricles. Lastly, we have demonstrated that the proposed method can be used to suppress spontaneously occurring alternans in the diseased heart.

Conclusion: We have developed a novel method to suppress RA in vivo.
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http://dx.doi.org/10.1016/j.hrthm.2012.12.026DOI Listing
April 2013

The anatomic and electrical location of the left ventricular lead predicts ventricular arrhythmia in cardiac resynchronization therapy.

Heart Rhythm 2013 May 28;10(5):668-75. Epub 2012 Dec 28.

Cardiac Arrhythmia Service, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.

Background: Both anatomic and electrical locations of the left ventricular (LV) lead have been identified as important predictors of clinical outcomes in cardiac resynchronization therapy (CRT). The impact of LV lead location on incident device-treated ventricular arrhythmia (VA), however, is not well understood.

Objective: To assess the relationship between electrical and anatomic LV lead location and device treated VAs in CRT.

Methods: Sixty-nine patients undergoing CRT implantation for standard indications were evaluated. Anatomic LV lead location was assessed by means of coronary venography and chest radiography and categorized as apical or nonapical. Electrical LV lead location was assessed by LV electrical delay (LVLED) and was calculated as the time between the onset of the native QRS on the surface electrocardiogram and sensed signal on the LV lead during implantation and corrected for native QRS. Incident appropriate device-treated VA was assessed via device interrogation.

Results: Apical lead placement was an independent predictor of VAs (hazard ratio 5.29; 95% confidence interval 1.69-16.5; P = .004). Among patients with a nonapical lead, LVLED<50% native QRS was an independent predictor of VAs (hazard ratio 6.90; 95% confidence interval 1.53-31.1; P = .012). Those with a nonapical lead and LVLED ≥ 50% native QRS were at substantially lower risk for first incident and recurrent VAs when compared to all other patients.

Conclusions: The apical lead position is associated with an increased risk of VAs in CRT patients. Among patients with a nonapical lead position, an LVLED of<50% of the native QRS is associated with an increased risk of VAs.
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http://dx.doi.org/10.1016/j.hrthm.2012.12.025DOI Listing
May 2013

Rapid acquisition of high-resolution electroanatomical maps using a novel multielectrode mapping system.

J Interv Card Electrophysiol 2013 Apr 22;36(3):233-42. Epub 2012 Nov 22.

MGH Heart Center, Cardiac Arrhythmia Service, Massachusetts General Hospital, Boston, MA 02114, USA.

Purpose: Conventional electroanatomical mapping systems employ roving catheters with one or a small number of electrodes. Maps acquired using these systems usually contain a small number of points and take a long time to acquire. Use of a multielectrode catheter could facilitate rapid acquisition of higher-resolution maps through simultaneous collection of data from multiple points in space; however, a large multielectrode array could potentially limit catheter maneuverability. The purpose of this study was to test the feasibility of using a novel, multielectrode catheter to map the right atrium and the left ventricle.

Methods: Electroanatomical mapping of the right atrium and the left ventricle during both sinus and paced rhythm were performed in five swine using a conventional mapping catheter and a novel, multielectrode catheter.

Results: Average map acquisition times for the multielectrode catheter (with continuous data collection) ranged from 5.2 to 9.5 min. These maps contained an average of 2,753 to 3,566 points. Manual data collection with the multielectrode catheter was less rapid (average map completion in 11.4 to 18.1 min with an average of 870 to 1,038 points per map), but the conventional catheter was slower still (average map completion in 28.6 to 32.2 min with an average 120 to 148 points per map).

Conclusions: Use of this multielectrode catheter is feasible for mapping the left ventricle as well as the right atrium. The multielectrode catheter facilitates acquisition of electroanatomical data more rapidly than a conventional mapping catheter. This results in shorter map acquisition times and higher-density electroanatomical maps in these chambers.
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http://dx.doi.org/10.1007/s10840-012-9733-yDOI Listing
April 2013

Usefulness of hemoglobin A(1c) to predict outcome after cardiac resynchronization therapy in patients with diabetes mellitus and heart failure.

Am J Cardiol 2012 Sep 25;110(5):683-8. Epub 2012 May 25.

Cardiology Division, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.

Patients with diabetes and heart failure (HF) have worse clinical outcomes compared to patients with HF without diabetes after cardiac resynchronization therapy (CRT). Patients with HF and diabetes represent a growing population at high risk for cardiovascular events and are increasingly treated with CRT. Although patients with diabetes and HF appear to benefit from CRT, their clinical outcomes are worse than those of patients without diabetes after CRT. The aim of this study was to identify clinical predictors that explain the differential hazard in patients with diabetes. We studied 442 patients (169 with diabetes) with systolic HF referred to the Massachusetts General Hospital CRT clinic from 2003 to 2010 to identify predictors of outcomes after CRT in patients with HF and diabetes. Patients with diabetes were more likely to have ischemic causes of HF than those without diabetes, but there was no difference in the left ventricular ejection fraction or HF classification at implantation. Patients with diabetes had poorer event-free survival (death or HF hospitalization) compared to those without diabetes (log-rank p = 0.04). The presence of diabetes was the most important independent predictor of differential outcomes in the entire population (hazard ratio 1.65, 95% confidence interval 1.10 to 2.51). Patients with diabetes receiving insulin therapy had poorer survival, whereas those not receiving insulin therapy had similar survival to patients without diabetes. Patients with peri-implantation glycosylated hemoglobin >7% had worse outcomes, whereas patients with glycosylated hemoglobin ≤7% had improved survival (hazard ratio 0.36, 95% confidence interval 0.15 to 0.86) equivalent to that of patients without diabetes. In conclusion, although the presence of diabetes, independent of other variables, increases the hazard of worse outcomes after CRT, there is additional risk conferred by insulin use and suboptimal peri-implantation glycemic control.
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http://dx.doi.org/10.1016/j.amjcard.2012.04.056DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3483789PMC
September 2012

Multidisciplinary care of patients receiving cardiac resynchronization therapy is associated with improved clinical outcomes.

Eur Heart J 2012 Sep 21;33(17):2181-8. Epub 2012 May 21.

Cardiac Arrhythmia Service, Massachusetts General Hospital Heart Center, Harvard Medical School, Boston, MA 02114, USA.

Aims: Although cardiac resynchronization therapy (CRT) reduces morbidity and mortality in patients with heart failure, a significant minority of patients do not respond adequately to this therapy. The objective of this study was to examine the impact of a 'multidisciplinary care' (MC) approach on the clinical outcome in CRT patients.

Methods And Results: The clinical outcome in patients prospectively receiving MC (n = 254) was compared with a control group of patients who received conventional care (CC, n = 173). The MC group was followed prospectively in an integrated clinic setting by a team of subspecialists from the heart failure, electrophysiology, and echocardiography service at 1-, 3-, and 6-months post-implant. All patients had echocardiographic-guided optimization at their 1-month visit. The proportional hazards model (adjusting for all covariates) and Kaplan-Meier time to first event curves were compared between the two groups, over a 2-year follow-up. The long-term outcome was measured as a combined endpoint of heart failure hospitalization, cardiac transplantation, or all-cause mortality. The clinical characteristics between the MC and CC groups at baseline were comparable (age, 68 ± 13 vs. 69 ± 12; NYHA III, 90 vs. 82%; ischaemic cardiomyopathy 55 vs. 64%, P = NS, respectively). The event-free survival was significantly higher in the multidisciplinary vs. the CC group (P = 0.0015). A significant reduction in clinical events was noted in the MC group vs. the CC group (hazard ratio: 0.62, 95% CI: 0.46-0.83, P = 0.001).

Conclusion: Integrated MC may improve 2-year event-free survival in patients receiving cardiac resynchronization therapy. Prospective randomized studies are needed to validate our findings.
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http://dx.doi.org/10.1093/eurheartj/ehs107DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3634395PMC
September 2012

The missing left atrial appendage.

J Cardiovasc Comput Tomogr 2012 Jan-Feb;6(1):60-1. Epub 2011 Nov 18.

Division of Cardiology, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA.

A 34 year old man underwent a transesophageal echocardiogram (TEE) prior to implantation of a biventricular ICD and DC cardioversion, to exclude left atrium and left atrial appendage thrombus. He had a history of repaired tetralogy of Fallot as a child, Stickler syndrome, atrial flutter and was status post recent mitral valve replacement, pulmonary valve replacement and tricuspid valve repair. The left atrial appendage was not visualized on TEE. A cardiac CT clarified that there was a left atrial appendage and provided an explanation as to why it was not visualized on TEE, highlighting the importance of multimodality imaging in patients with complex congenital heart disease.
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http://dx.doi.org/10.1016/j.jcct.2011.07.002DOI Listing
May 2012

Unpredictable battery depletion of St Jude Atlas II and Atlas+ II HF implantable cardioverter-defibrillators.

Heart Rhythm 2012 May 13;9(5):717-20. Epub 2011 Dec 13.

Cardiac Arrhythmia Service, Massachusetts General Hospital, Boston, MA, USA.

Background: Predictable progression to battery depletion is necessary for device management in patients with pacemakers or implantable cardioverter-defibrillators, particularly in patients who either are pacemaker dependent or have required implantable cardioverter-defibrillator therapies.

Objective: To determine the incidence and characteristics of unexpected battery depletion in patients implanted with a cardiac resynchronization therapy - defibrillator (CRT-D) device.

Methods: All patients with a St Jude Atlas+ HF or Atlas II HF CRT-D device implanted between 2004 and 2007 at the Massachusetts General Hospital and the Nashville VA Medical Center (Vanderbilt University) were studied. All patients with early generator depletion (transition of generator voltage above specified elective replacement indicator [ERI] to end of life [EOL] in less than 90 days) were evaluated further.

Results: Eight cases (mean age 69.6 ± 9 years) with abrupt battery depletion were identified among 191 patients (4.2%) implanted with a St Jude Atlas CRT-D device. The longevity of 8 premature depletion devices was 46.4 ± 10 months (median 45 months). The battery voltage in these 8 devices decreased from a mean of 2.48 ± 0.03 V (above ERI) to 2.3 ± 0.08 V (below ERI) over 33.3 ± 23 days (range 1-59 days; median 38.5 days). One device reached EOL status within 1 day of having battery voltage above ERI and another device within 12 days.

Conclusion: The incidence of abrupt battery depletion was 4.2% in patients implanted with a St Jude Atlas CRT-D device. No common mechanism has been identified for this failure. Close monitoring of battery voltage and timely generator replacement are required in patients with these devices.
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http://dx.doi.org/10.1016/j.hrthm.2011.12.009DOI Listing
May 2012

The Modified Ablation Guided by Ibutilide Use in Chronic Atrial Fibrillation (MAGIC-AF) Study: clinical background and study design.

J Cardiovasc Electrophysiol 2012 Apr 28;23(4):352-8. Epub 2011 Oct 28.

Schulich Heart Program, Division of Cardiology, Sunnybrook Health Science Center, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.

Background: Beyond pulmonary vein isolation (PVI), adjuvant ablation at the sites of complex fractionated atrial electrograms (CFAE) has been shown to improve the long-term success of catheter ablation of persistent atrial fibrillation (AF). However, this approach often requires extensive ablation due to the widespread distribution of CFAE within the left atrium. An optimal strategy would identify areas of CFAE which, when selectively targeted with ablation, result in AF termination with an acceptable long-term freedom from AF. It is possible that the intraprocedural administration of an antiarrhythmic drug may help accomplish this.

Objective: The Modified Ablation Guided by Ibutilide Use in Chronic AF (MAGIC-AF) Study is an international multicenter prospective randomized double-blinded clinical trial assessing the utility of the intraprocedural administration of 0.25 mg of intravenous ibutilide before performing CFAE ablation. The primary efficacy endpoint of this study will be the freedom from AF at 1 year after a single procedure off antiarrhythmic agents. Safety endpoints will include procedural and radiofrequency ablation time as well as overall procedural complication rate.

Methods: Patients undergoing a first ever catheter ablation procedure for persistent AF will be included. Individuals with hypertrophic cardiomyopathy, complex congenital heart disease including atrial septal defects, and ejection fraction <35% will be excluded from the study. All patients will first undergo PVI. Those patients who remain in AF will then be randomized in a 1:1 fashion to receive either 0.25 mg intravenous ibutilide or saline placebo followed by a CFAE based ablation strategy. Two hundred randomized patients will be enrolled in this study-100 in each study arm.

Conclusion: The MAGIC-AF study will assess the utility of a combined pharmaco-ablative strategy in patients with persistent AF undergoing a CFAE based ablation strategy.
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http://dx.doi.org/10.1111/j.1540-8167.2011.02198.xDOI Listing
April 2012

Severity of esophageal injury predicts time to healing after radiofrequency catheter ablation for atrial fibrillation.

Heart Rhythm 2011 Dec 23;8(12):1862-8. Epub 2011 Jul 23.

Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.

Background: The delivery of radiofrequency (RF) energy to the posterior left atrium creates a risk of injury to the adjacent esophagus. Esophageal endoscopy (EGD) is used to screen patients at risk for esophageal thermal injury after RF ablation.

Objective: The purpose of this study was to analyze the macroscopic features of the severity of esophageal injuries induced by RF ablation to the left atrium as seen by EGD and evaluate the association of these descriptions with the time elapsed until complete healing.

Methods: This study analyzed 219 patients undergoing RF ablation for atrial fibrillation. Esophageal temperature probes were used during each ablation, and EGD was performed in cases with intraesophageal temperature ≥39°C. Repeat EGD was obtained at 10 days to evaluate for healing in all cases demonstrating esophageal injury. Serial endoscopies were repeated every 2 weeks until complete healing was documented. Lesions were classified according to severity as superficial or deep ulceration; size and shape were also noted.

Results: We found 37.4% of patients (82 of 219) with esophageal intraluminal temperatures ≥39°C. Of these, 22 patients (27%) were identified with esophageal injury, with 68% being superficial ulcerations and 32% deep. On repeat EGD at 10 days, only 29% of deep ulcerations were healed, as compared with 87% of the superficial injuries (P = .0136). No difference in healing was found when analyzed for size or shape.

Conclusions: The macroscopic severity of esophageal lesions detected on endoscopy the day after RF ablation can predict the time to resolution, with severe, deep ulcerations requiring a longer time to heal.
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http://dx.doi.org/10.1016/j.hrthm.2011.07.022DOI Listing
December 2011

Respiratory compensation improves the accuracy of electroanatomic mapping of the left atrium and pulmonary veins during atrial fibrillation ablation.

J Interv Card Electrophysiol 2011 Nov 24;32(2):105-10. Epub 2011 May 24.

Heart Center, Massachusetts General Hospital, Boston, MA, USA.

Background: The creation of accurate electroanatomic maps (EAM) of the left atrium and pulmonary veins is important for atrial fibrillation (AF) ablation to guide ablative lesions and improve the safety and efficacy of the procedure. Respiratory motion of the heart and the pulmonary veins affects the accuracy of these maps.

Purpose: This study aims to assess changes in the left atrial and pulmonary venous anatomy due to respiration and to evaluate their implication for EAM acquisition.

Methods: Two separate EAM were created using the CARTO 3 mapping system in 22 consecutive patients (63% males; mean age, 63 ± 8 years) undergoing AF ablation at our center: a non-respiratory compensation (RC) map in which endocardial points were collected irrespective of respiratory phase and an RC map in which the points were collected during end expiration only. These maps were compared to pre-procedural cardiac CT/MRI images.

Results: Non-RC mapping required 3.2 ± 1.0 min versus 7.8 ± 2.1 min for the maps with RC. In comparison to the pre-procedural CT/MRI images, maps without RC significantly overestimated the dimensions of the pulmonary veins' ostia compared to maps with RC in both long and short axes. Distances between the pulmonary veins were not significantly different when comparing non-RC to RC mapping at the left atrial roof or floor.

Conclusions: Respiratory compensation at the time of EAM acquisition during AF ablation more accurately represents the true anatomical dimensions of the pulmonary vein ostia. The resulting more accurate maps may improve the safety and efficacy of atrial fibrillation ablation.
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http://dx.doi.org/10.1007/s10840-011-9583-zDOI Listing
November 2011