Heart Rhythm 2011: Meeting Highlights

Compiled by Jodie Elrod
Compiled by Jodie Elrod

Did you miss Heart Rhythm 2011? Enclosed below is a compilation of clinical news highlights from the meeting.

Endosense Reinforces Clinical Leadership in Contact-Force Sensing with a Range of New Study Data at Heart Rhythm 2011

Endosense, a Swiss medical technology company focused on improving the efficacy, safety and accessibility of catheter ablation for the treatment of cardiac arrhythmias, has further advanced its clinical leadership in the field of contact-force sensing with new study data supporting its TactiCath® ablation catheter.1 Presented in six separate abstracts at Heart Rhythm 2011 in San Francisco, the data included findings from the company’s EFFICAS I post-market clinical trial that shed fundamentally new insights into the relationship between catheter tip-to-tissue contact force and early pulmonary vein isolation (PVI) line reconduction.

“EFFICAS I represents the most rigorous and detailed investigation ever conducted on the role of contact force during catheter ablation, and its findings are truly remarkable,” said Karl-Heinz Kuck, MD, Asklepios Klinik St. Georg, Hamburg, Germany. “For the first time, we have clearly demonstrated a direct correlation between low contact force and post-operative PVI line reconduction at three-month follow-up. The implications are significant, as we now have the opportunity to use the information gathered in EFFICAS I to pinpoint optimal levels of contact force in EFFICAS II.”

The first in a series, EFFICAS I is a 45-patient, single-arm, prospective, multi-center European clinical trial designed to demonstrate the correlation between contact forces applied during pulmonary vein isolation (PVI) and atrial fibrillation (AF) treatment efficacy at three months. While investigators performed the procedure with the TactiCath, they were blinded to contact force measurements; however, the contact forces applied were recorded. Patients were re-assessed with a mapping catheter at three months to identify potential gaps in the PVI lines. Contact force parameters from initial procedures were then analyzed to determine the relationship with lesion formation.

In “Low Catheter-Tissue Contact Force Results in Late PV Reconnection - Initial Results from EFFICAS I,” study investigators unveiled data from 13 patients treated by seven operators at two centers with 926 radiofrequency ablations.2 At three-month follow-up, they found a predictive relationship between low force time integral (the accumulated energy delivered per ablation) at first ablation and early gap occurrence following PVI.2 They also concluded that the use of low contact force may result in early gap formation on the posterior heart wall.2

Full results from EFFICAS I will be applied to EFFICAS II, in which investigators will take full advantage of the real-time, objective TactiCath contact-force control features to improve their ablation technique during lesion creation. Now enrolling patients, the EFFICAS II study will measure reduction in PVI gaps as well as procedural improvements as compared to EFFICAS I.

Additional TactiCath study abstracts presented at Heart Rhythm 2011 further validated the relationship between contact force and procedure efficacy and safety while also exploring new modes of contact-force visualization. Among the key findings, investigators concluded that:

  • Parameters of low catheter tip-to-tissue contact force are associated with a higher rate of AF recurrence in patients at 12-month follow-up, as evidenced by long-term results of the TOCCATA clinical study3;
  • Contact-force measurement with the TactiCath is safe and effective, and it provides a significant reduction in radiofrequency (RF) time as compared to standard irrigated-tip catheters4;
  • The risk of steam pops when applying high contact force and moderate radiofrequency power is poorly predicted by a number of variables, including initial impedance, impedance, decrease during RF ablation, electrode tissue angle, systolic contact force, diastolic contact force and force-time integral5; and
  • New contact-force and force-time-integral mapping and visualization techniques may help EPs identify potential areas of PVI line reconduction that contribute to long-term AF recurrence.6,7

Endosense has a history of clinical leadership in the field of contact-force sensing. Since its first abstract on the TactiCath was presented at Heart Rhythm 2006, more than 30 clinical publications have appeared in peer-reviewed journals or been presented at major medical society meetings across the world. Endosense is currently conducting several post-market clinical studies of the TactiCath as well as the TOCCASTAR investigational device exemption clinical trial, which commenced in January 2011 and is rapidly enrolling patients.

  1. Caution: In the United States, the TactiCath is an investigational device. Limited by Federal (or Uni ted States) law to investigational use.
  2. Reddy V, et al. “Low Catheter-Tissue Contact Force Results in Late PV Reconnection - Initial Results from EFFICAS I.” Heart Rhythm 2011, AB12-1.
  3. Shah D, et al. “Contact Force During Ablation Predicts AF Recurrence at 12 Months.” Heart Rhythm 2011, PO6-61.
  4. Dello Russo A, et al. “Catheter Contact Force in Atrial Fibrillation Ablation: What Benefit Can We Learn?” Heart Rhythm 2011, PO5-135.
  5. Ikeda A, et al. “Predictors of Steam Pop During Radiofrequency Ablation at High Contact Force and Moderate RF Power in Canine Beating Heart.” Heart Rhythm 2011, PO2-156.
  6. Rashed K, et al. “Magnetic Resonance Imaging Analysis of Tissue-contact Force Following Catheter Ablation for Paroxysmal Atrial Fibrillation.” Heart Rhythm 2011, AB15-1
  7. Vijaykumar R, et al. “Spatiotemporal Distribution of Catheter-Tissue Contact Force Across the Left Atrium During Pulmonary Vein Isolation.” Heart Rhythm 2011, PO6-85.

New Studies Support CardioFocus HeartLight™ Endoscopic Ablation System’s Notable Treatment Results for Paroxysmal AF

CardioFocus, Inc., developer of the HeartLight Endoscopic Ablation System for the transcatheter treatment of atrial fibrillation, announced its technology enables a pulmonary vein (PV) acute isolation rate of nearly 99%, with approximately 86% of PVs remaining persistently isolated after three months. Additional research also suggests that 65% of patients achieve durable freedom from AF after a single procedure.

New clinical results supporting the safety and efficacy of the HeartLight System were presented at Heart Rhythm 2011, the Heart Rhythm Society’s 32nd Annual Scientific Sessions. The presentations included data from both a 200-patient international, multicenter clinical experience with the CardioFocus device (15 sites across four countries) and from a unique study that employed intracardiac diagnostic remapping on 56 paroxysmal AF patients, whether or not they were symptomatic, to determine the rate of persistent PV isolation.

“These recent clinical experiences support the promise of the HeartLight technology to help patients achieve lasting freedom from paroxysmal AF,” commented Stephen Sagon, President and CEO of CardioFocus, Inc. “As shown by the robust data across multiple clinical centers, our proprietary technology, including endoscopic visualization, a compliant balloon catheter and the delivery of light energy, is helping to enhance the reproducibility and efficacy of atrial fibrillation ablation.”

In the 200-patient study, titled “Pulmonary Vein Isolation Using the Visually-Guided Laser Balloon: The First 200-Patient Multicenter Clinical Experience” and presented on May 6th, researchers reported nearly 99% of all PVs were isolated following the HeartLight ablation procedure. Of the 107 patients that reached at least 6 months follow-up, 65% remained free from AF after a single ablation procedure. The procedure also demonstrated low complication rates including freedom from strokes, PV stenosis or atrial esophageal fistulae.

“A historical concern with catheter ablation therapy for paroxysmal AF is the inability to create durable lesions in a single procedure to adequately isolate the pulmonary veins,” said lead investigator Vivek Y. Reddy, MD, of Mount Sinai School of Medicine, New York. “This study demonstrates that a high rate of PV isolation can be reproducibly achieved across multiple sites with a visually-guided laser balloon catheter.”

The remapping study, presented on May 4th and titled “Persistent Pulmonary Vein Isolation Using the Visually-Guided Laser Balloon: Results of a Multicenter PV Remapping Study,” revealed that 86% of all PVs were persistently isolated at three months. The study included 56 paroxysmal AF patients who underwent initial ablation with the HeartLight catheter at three centers. After three months nearly all patients were remapped (52), regardless of symptoms, to determine the incidence of persistent PV isolation.

“This data is significant because diagnostic remapping in asymptomatic patients is rarely attempted. In this case, remapping has enabled us to clearly confirm quality outcomes, demonstrating that the visually-guided laser balloon catheter can achieve persistent, long-lasting PV isolation in paroxysmal AF patients,” said lead investigator Srinivas R. Dukkipati, MD, of Mount Sinai School of Medicine, New York.

New Study Demonstrates Accuracy of Microvolt T-Wave Alternans in Predicting SCA

Cambridge Heart Inc., a developer of non-invasive diagnostic tests for cardiac disease, announced that new data presented at the Heart Rhythm Society’s 32nd Annual Scientific Sessions in San Francisco confirm the diagnostic value of Microvolt T-wave Alternans (MTWA) testing in identifying patients at risk of sudden cardiac arrest (SCA). The pooled analysis of 2,883 patients shows that MTWA is a statistically significant predictor of SCA in patients whose heart muscle is damaged (ejection fraction ≤ 35%), as well as those with more preserved cardiac function (ejection fraction > 35%).

“In this pooled analysis of patients without ICDs, MTWA testing is a powerful predictor of SCD in patients with a broad range of ejection fractions. In the future, prospective studies should be designed to specifically assess the value of ICD therapy in patients with a negative/positive MTWA test result,” said Dr. Antonis Armoundas, senior author of the study.

“This new data further confirms the prognostic value of MTWA testing,” noted Ali Haghighi-Mood, CEO of Cambridge Heart. Mr. Haghighi-Mood added, “These results have important implications for management strategies designed to prevent sudden cardiac arrest in 10–12 million patients with heart disease who are considered to be at risk for SCA.”

SCA is the leading cause of death in the U.S. accounting for an estimated 300,000 deaths each year — more than stroke, lung cancer and breast cancer combined. Out-of-hospital survival is less than 8%, making prediction and prevention critically important. Microvolt T-Wave Alternans is a marker of SCA risk which is measured during a non-invasive treadmill test.

Cook Medical Announces Addition to Liberator® Locking Stylet with Beacon® Tip Technology to Support Physician Control in Lead Extraction 

A new version of the Liberator Locking Stylet with Beacon® Tip Technology, a distinct radiopaque tip marker, was unveiled at Heart Rhythm 2011, and is now available to physicians worldwide, officials at Cook Medical's Lead Management division said. Locking stylets play a fundamental role in lead extraction procedures by providing internal support to the cardiac lead targeted for removal. The addition of the new radiopaque tip marker should allow for users to better track the progress of the Liberator locking stylet as it is being positioned prior to engagement within the lead. Enhanced visualization of the Liberator locking stylet should help physicians achieve their goal of locking a stylet as close to the lead’s distal tip as possible so that lead control is maintained during subsequent extraction sheath manipulations.

The Liberator Locking Stylet now includes a tip made of two highly radiopaque materials, which have been selected to make the stylet visible under fluoroscopy throughout the procedure. The Liberator’s popular locking system and its twisted wire handle will remain unchanged, and the new tip marker has been incorporated into the existing Liberator design in a manner that does not affect the look of the device or the mechanical functionality.

“The Liberator has been a standard tool in the lead extraction process for nearly ten years. The newly updated Liberator locking stylet is designed to offer physicians greater procedural control by helping them optimize the position of the Liberator locking stylet within the lead,” said Lou Goode, global leader of Cook’s Lead Management business unit. 

New Data Shows Clinical Benefit of Cardiac Resynchronization Therapy in Atrial Fibrillation

Data presented as a Late Breaking Clinical Trial at Heart Rhythm 2011 shows the clinical benefit of cardiac resynchronization therapy (CRT) versus conventional right-ventricle (RV) pacing in improving heart failure (HF) in patients undergoing atrioventricular (AV) junction ablation for permanent AF. In the clinical trial, patients receiving CRT had a 26 percent reduction in the primary composite endpoint of death from HF, hospitalization from HF, or worsening HF when compared to patients undergoing RV pacing (11 percent).

The APAF (Assessment of Cardiac Resynchronization Therapy in Patients with Permanent Atrial Fibrillation) clinical trial was supported by Medtronic. The use of Medtronic CRT devices in permanent AF patients with depressed LV function undergoing AV nodal ablation is investigational and not an approved use in the United States.

“These findings suggest CRT should be considered as the preferred treatment approach for patients that require the ‘ablate and pace’ procedure,” said Michele Brignole, MD, lead investigator and electrophysiologist, Ospedali del Tigullio, Lavagna, Italy. “While these results provide evidence supporting the potential expansion of indications regarding the use of CRT as a first-line treatment for all permanent AF patients who must undergo AV junction ablation, we look forward to conducting additional studies to provide further confirmation that will ultimately result in the modification of treatment guidelines.”

Often referred to as “ablate and pace” therapy, AV junction ablation, which produces complete AV block to assure heart rate control and rhythm regulation, followed by implantation of a cardiac pacing device, is a routine, clinically validated treatment for patients with symptomatic, drug-refractory permanent AF. Additionally, CRT is a well-established treatment for heart failure that uses a specialized cardiac pacing device to improve the pumping efficiency of the heart. While heart failure and AF are increasingly common, life-threatening diseases that often predispose one another, CRT has not been extensively studied in the treatment of AF. Based on current U.S. and European treatment guidelines, CRT is not currently recommended as a treatment for all patients with permanent AF and refractory heart failure.

Approximately 25 percent of patients in the APAF trial met the current CRT indication criteria set forth in the treatment guidelines, while 75 percent did not. The findings showed that the relative clinical benefit of CRT over RV pacing was significant and independent of whether the patients were indicated for CRT in the guidelines.

“This Medtronic-supported research builds upon the growing body of evidence suggesting guideline changes for the use of CRT therapy in patients with permanent AF,” said Pat Mackin, president of the Cardiac Rhythm Disease Management business and senior vice president at Medtronic.

Heart Rhythm Society Releases Expert Consensus Statement on Perioperative Management of Patients with Cardiovascular Implantable Electronic Devices

The Heart Rhythm Society (HRS) issued the first consensus statement for the perioperative management of patients with cardiovascular implantable electronic devices (CIEDs). The HRS Expert Consensus Statement on the Perioperative Management of Patients with Implantable Defibrillators, Pacemakers and Arrhythmia Monitors: Facilities and Patient Management was developed as a joint project with the American Society of Anesthesiologists (ASA), and in collaboration with the American College of Cardiology (ACC), the American Heart Association (AHA) and the Society of Thoracic Surgeons (STS). The HRS expert consensus statement was presented at Heart Rhythm 2011, the Society’s 32nd Annual Scientific Sessions.

The perioperative period for patients with pacemakers and defibrillators poses unique challenges in assuring a high degree of patient safety. There are factors such as rapid changes in CIED technology, expanded use of potential sources of electromagnetic interference (EMI) and out-dated recommendations based upon limited data that highlight the need for a consensus statement. The HRS expert consensus statement is the first to offer clinicians and industry guidance on the management of CIEDs during and after surgical or medical procedures.

“With the increasing number of cardiac devices being implanted around the world, it’s crucial that recommendations are frequently reviewed, updated and shared to ensure optimal patient care,” stated co-lead author of the statement, George Crossley, MD, FHRS, at St. Thomas Research Institute and University of Tennessee College of Medicine in Nashville, TN. “While the ultimate judgment of care must be made by the individual patient and his or her health care provider, this document aims to provide clinicians with the best possible guidance available.”

HRS and ASA brought together a diverse panel of experts in pacemaker and defibrillator management to focus on medical procedures that might interfere with CIED function. To address the topic, a multidisciplinary group convened, including cardiac electrophysiologists, anesthesiologists, a cardiothoracic surgeon and an allied health professional.

The statement provides the following:

  • Evaluation of the potential problems that can occur in patients with CIEDs within the perioperative setting;
  • Recommendations for the appropriate preoperative evaluation of patients with a CIED;
  • Management of the CIED during the surgical or medical procedure;
  • Postoperative care of the patient with a CIED who has undergone certain surgical or medical procedures.

Furthermore, a primary recommendation from the expert consensus writing committee is that the patient’s CIED team, or another available CIED team, provides the operative team with guidance on the perioperative management of the CIED. According to the expert panel, the best possible outcome will result when advice from the patient’s CIED team is effectively communicated to the procedural team, and executed during the patient’s perioperative care.

“The collaborative nature of the writing committee allowed clinicians and professionals of varied medical backgrounds to discuss and evaluate the complexity of CIED patient management,” stated co-lead author of the statement, Jeanne Poole, MD, University of Washington in Seattle, WA. “The combined experience of the experts and the results of this document provide a unique, first-of-its-kind consensus on the perioperative care of these patients.”

The expert consensus statement will be published in the June edition of HeartRhythm, the official journal of the Heart Rhythm Society.

Heart Rhythm Society and European Heart Rhythm Association Release Expert Consensus Statement on the State of Genetic Testing for the Channelopathies and Cardiomyopathies

Genetic testing is increasingly important in determining potential cardiac conditions in patients and is used in clinical settings more than ever before. To ensure that physicians have up-to-date knowledge of the evolving role of genetic testing for sudden death predisposing, genetic heart diseases in cardiology, which can be life-saving for some patients, the Heart Rhythm Society and the European Heart Rhythm Association have prepared HRS/EHRA Expert Consensus Statement on the State of Genetic Testing for the Channelopathies and Cardiomyopathies. The consensus statement was released at Heart Rhythm 2011, the Heart Rhythm Society’s 32nd Annual Scientific Sessions.

“With the significant complexities of genetic testing present today, it is essential that heart rhythm specialists specifically and cardiologists in general address and bridge any knowledge gaps that may exist with respect to genetic testing for heritable heart diseases,” said co-lead author of the statement Michael J. Ackerman, MD, PhD, of the Mayo Clinic in Rochester, MN. “As genetic testing evolves, we must continue to develop and recognize the appropriate clinical applications to ensure the best possible patient care.”

The Heart Rhythm Society and the European Heart Rhythm Association formed an international writing group in order to evaluate the use and role of genetic testing for potentially heritable cardiac conditions, based on the analysis of literature and their own experience in treating patients. The statement focuses primarily on the state of genetic testing for 13 distinct entities and the relative diagnostic, prognostic and therapeutic impact of the genetic test result for each entity. The statement is directed to all health care professionals who are involved with genetic testing for channelopathies and cardiomyopathies.

It is important to note that it is ultimately the health care provider who must consider all circumstances presented by a patient in determining diagnoses and care, as there are no absolutes in clinical situations. Genetic testing for heart diseases is just one component of a comprehensive cardio-genetic evaluation. With these considerations in mind, the international writing group developed the following overarching recommendations on the state of genetic testing for heritable cardiac conditions:

  • Genetic counseling is recommended for all patients and relatives with the familial heart diseases detailed in the document and should include discussion of the risks, benefits and options available for clinical testing and/or genetic testing.
  • Treatment decisions should not rely solely on his/her genetic test result but should be based on an individuals’ comprehensive clinical evaluation.
  • It can be useful for pre-genetic test counseling, genetic testing, and the interpretation of genetic test results to be performed in centers experienced in the genetic evaluation and family-based management of the heritable arrhythmia syndromes and cardiomyopathies described in the document.

Primary recommendations were considered when evaluating the state of genetic testing for each of the 13 heritable cardiac conditions discussed in the document, including Long QT Syndrome, Catecholaminergic Polymorphic Ventricular Tachycardia, Brugada Syndrome, Progressive Cardiac Conduction Disease, Short QT Syndrome, Atrial Fibrillation, Hypertrophic Cardiomyopathy, Arrhythmogenic Cardiomyopathy/Arrhythmogenic Right Ventricular Cardiomyopathy, Dilated Cardiomyopathy, Left Ventricular Noncompaction and Restrictive Cardiomyopathy. The document includes guidance on the use and role of genetic testing for out-of-hospital cardiac arrest survivors and post-mortem testing in sudden unexpected death cases.

“Genetic testing cannot be viewed as a one size fits all solution, but should be considered for each disease state,” said co-lead author of the statement Silvia G. Priori, MD, PhD, of Fondazione Salvatore Maugeri University in Pavia, Italy. “The recommendations outlined in this document can and should be used as guidance on how each potential disease is evaluated with respect to genetic testing, keeping in mind that each patient is different.”

The complete guidelines will be published in the August issue of the HeartRhythm Journal, the official journal of the Heart Rhythm Society, and Europace.