Apr-04

Biventricular Pacing Should be the Preferred Mode of Therapy for Atrial Fibrillation Patients who Undergo AV Node Ablation Biventricular pacing should be the preferred mode of therapy in chronic atrial fibrillation patients undergoing atrioventricular (AV) node ablation followed by pacemaker implantation, according to results of the Left Ventricular-Based Cardiac Stimulation Post AV Nodal Ablation Evaluation (PAVE) trial. Dr. Rahul Doshi from Sunrise Hospital and Medical Center in Las Vegas, Nevada, presented results from the PAVE study at the American College of Cardiology 2004 Scientific Sessions. PAVE is one of the first prospective, randomized trials of the ablate-and-pace strategy for atrial fibrillation patients. The trial, sponsored by St Jude Medical, examined exercise capacity, functional status, and quality-of-life outcomes in 102 patients randomized to cardiac resynchronization therapy using biventricular pacing following AV node ablation or to right ventricular (RV) pacing following AV node ablation. Patients were enrolled in the trial regardless of their left ventricular systolic function or NYHA classification. According to Doshi, patients randomized to the biventricular arm experienced significant improvements in six-minute walk time at six months, the primary endpoint of the trial. At six months, biventricular patients had increased their six-minute walk test by 82 m, compared with 56 m in the RV group, a statistically significant difference. In addition, biventricular pacing patients demonstrated significantly improved peak VO2 max and improved exercise duration at six months, whereas patients randomized to the RV arm did not experience statistically significant improvements. Quality-of-life measurements also indicated improvement. Surprisingly, patients randomized to biventricular pacing maintained a mean left ventricular ejection fraction of approximately 46% over the course of the trial, whereas patients who received RV pacing experienced deteriorating LV function, dropping from a mean LVEF of 44.9% at the start of the study to 40.7% at six months. The overall findings are congruent with previous trials that pointed to worsening left ventricular function in patients receiving RV pacing, Doshi stated. Pacing has been used for years and years, and some patients do just fine with RV pacing, but I think the trend is going toward a more physiological way to pace, Doshi commented. So even in patients who get a pacemaker for standard indications, physicians should perhaps try to avoid an RV pacemaker. I think that s a trend in the electrophysiological community. Doshi added that RV pacing, by altering the natural sequence of LV contraction, may make patients more symptomatic or hasten deterioration toward congestive heart failure. This is in theory corrected by biventricular pacing, he said. I think clearly many patients do very well on right ventricular pacing, but these are generally the patients who are less sick. The sicker patients, the patients who have baseline heart failure, they should be considered for biventricular pacing. Doshi commented that the number of ablate-and-pace procedures is only going to increase in the coming years as the population ages. Currently an estimated 30,000 patients per year undergo these procedures, and that number is expected to double within the next few years. Atrial fibrillation is predominantly a disease of the elderly, so these results are going to be increasingly relevant to a large number of patients. EP MedSystems Announces FDA Market Clearance for New EP-4 Cardiac Stimulation System EP MedSystems, Inc. announced the FDA market clearance for its new EP-4 Computerized Cardiac Stimulator. The EP-4 offers further advancements in cardiac stimulation, which is an essential component of nearly all electrophysiology (EP) procedures to diagnose and treat certain cardiac rhythm disorders. EP MedSystems also has received regulatory approval from its European Notified Body for the EP-4, allowing the sale of the EP-4 into the European Community. The EP-4 Computerized Cardiac Stimulator includes several features unique in the EP industry, consisting of a touch screen portable PC controlling a two- or four-channel dedicated EP stimulator. The stimulator is capable of single channel, simultaneous and sequential stimulation at programmed output settings. The EP-4 s four-channel constant current output provides increased versatility for site pacing and emergency backup pacing. The system is also compatible with the majority of the industry's EP recording systems. Reinhard Schmidt, President and CEO of EP MedSystems commented: We are very pleased to announce the EP-4 FDA market clearance. The EP-4 offers features that are unique in the EP industry, and will benefit patients, EP lab personnel and healthcare institutions alike and is a platform for expanded capabilities in the near future. With the EP-4, EP MedSystems continues in its promise to bring innovation to the fields of cardiology and electrophysiology. EP MedSystems develops and markets cardiac electrophysiology products used to diagnose and treat certain cardiac rhythm disorders. The company's EP product line includes the EP-WorkMate ® Electrophysiology Workstation with RPM Real-time Position Management navigation technology, the EP-3 Stimulator, diagnostic electrophysiology catheters and related disposable supplies, the ALERT ® System and ALERT family of internal cardioversion catheters, the ViewMate ® intracardiac ultrasound catheter imaging system and now the EP-4 Computerized Cardiac Stimulator. Implantable Defibrillators Reduce Death by 23 Percent in Landmark Heart Failure Trial NIH Study Indicates Need to More Aggressively Identify and Protect Patients at Risk for SCA People with heart failure live longer when they receive an implantable cardioverter-defibrillator (ICD), according to results of the landmark Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT). The 2,521-patient study showed that ICDs reduced death by 23 percent in people with moderate heart failure compared to those who did not receive defibrillators. Study Director and Principal Investigator Gust H. Bardy, MD, who presented the results at the 53rd Annual Scientific Session of the American College of Cardiology in New Orleans said, The results of the trial show definitively that simple implantable defibrillator therapy will prolong life in patients with congestive heart failure. The study also shows that amiodarone, when used as a prophylactic medication, does not improve survival. Sudden cardiac arrest (SCA) takes the lives of approximately 450,000 people in the United States each year, more than lung cancer, breast cancer, stroke and AIDS combined. Current medical evidence allows identification of 150,000 of those 450,000 and, with ICDs, protects them from sudden cardiac death. Implantable defibrillators have been vastly underutilized, even though they are 99 percent effective in preventing sudden cardiac death, and often provide pain-free therapy that is typically undetectable by the patient. Despite their proven benefit, approximately 20 percent of U.S. patients currently indicated actually get them. The result has been an epidemic of unnecessary deaths from cardiac arrest. The important thing to remember about this trial is that it greatly enhances physicians' ability to identify and treat heart failure patients at risk for sudden cardiac death, said Steve Mahle, President of Medtronic Cardiac Rhythm Management. SCD-HeFT was a placebo-controlled, three-arm trial examining the use of ICD therapy and anti-arrhythmic drug therapy in patients who have moderate heart failure (New York Heart Association Class II or III), plus impaired pumping function of the left ventricle, the heart's main pumping chamber. It's critical to understand that this trial was aggressively powered to test whether or not ICDs are effective in heart failure patients who are already receiving optimal medical therapy. We achieved that goal, said Dr. Bardy. While there are some interesting observations in the major sub-populations, one must be cautious about over-interpreting sub-group analyses. Based on these data, all patients with moderate heart failure, with or without a history of coronary artery disease, should be evaluated for an ICD. One-third of the patients enrolled in the study received an ICD provided by Medtronic. Another third received amiodarone, a medication used to manage fast heart rhythms, and one-third received a placebo. All patients in the trial received optimal conventional heart failure medications when appropriate and tolerated, such as ACE inhibitors, beta-blockers, diuretics, statins and aspirin. Sponsored by the NIH, with funding from Medtronic and Wyeth Pharmaceuticals, patient enrollment began in 1997 and continued through 2001. Heart failure is a progressive condition affecting at least 5 million Americans that causes the lower chambers of the heart to lose the ability to pump sufficient blood to meet the needs of the circulatory system. Approximately 1 million Americans suffer from the potentially lethal combination of heart failure and a high risk of sudden cardiac arrest. According to the American Heart Association, sudden cardiac arrest occurs six to nine times more frequently in people with heart failure than in the general population. FDA Clears the Completely Automatic Pacemaker from Medtronic Device Automatically Adjusts Pacing Energy Levels without Physician Intervention Medtronic, Inc. announced U.S. Food and Drug Administration (FDA) clearance and U.S. commercial launch of a fully automatic pacemaker for slowly beating hearts. The Medtronic EnPulse system is a medical device that regularly measures the minimum energy needed to stimulate the heart's upper and lower chambers and automatically adjusts the intensity of electrical impulses delivered to both chambers without physician intervention. With other pacemakers, physicians manually measure and update device threshold levels during in-person patient appointments. In contrast, the EnPulse device can automatically adjust the level of pacing on an hourly or daily basis, which may help patients feel better and minimize the amount of time patients spend in a physician's office. Approximately 250,000 Americans receive pacemakers each year. An earlier version of the EnPulse pacemaker was cleared by the FDA on Dec. 18, 2003. Now, physicians can use the device with a pioneering feature called Atrial Capture Management (ACM), which enables the pacemaker to automatically adjust electrical impulses delivered to the heart's upper right chamber. The EnPulse pacemaker with ACM has been available in Europe since October 2003. The FDA has also approved the use of the EnPulse pacemaker with the Medtronic CareLink ® Network, the company's Internet-based, remote cardiac device monitoring system. To date, the service has been used by patients with various Medtronic implantable cardioverter-defibrillator (ICD) models, and the company plans to make the service available in the next couple of months to many pacemaker patients whose clinics currently use the Medtronic CareLink Network. This enables patients to transmit device information from home or while traveling instead of making trips to the clinic for device evaluation. Physicians review the data on a secure Internet website and, if needed, make adjustments to the patient's medication or prescribe additional therapy. The Medtronic EnPulse system incorporates an array of unique features to help physicians improve pacing therapy and streamline the patient follow-up process, including: Atrial Capture Management: This enables the automatic adjustment of the pacing impulse level for optimal stimulation of the atrium. It is the pairing of ACM with Ventricular Capture Management, a similar function that may optimize stimulation in the ventricle, that enables the EnPulse device to automatically and regularly adapt to necessary threshold levels in both chambers of the heart. Post Mode-Switch Overdrive Pacing: With advanced sensing and detection capabilities, this automatically recognizes and responds to potential atrial tachyarrhythmia (AT) triggers with specialized therapies that may reduce the onset or continuation of AT episodes, including atrial fibrillation (AF). Search AV+: This automatic and expanded search method senses the patient's natural heartbeats before delivering pacing therapy, which may reduce unnecessary electrical impulses in the ventricle and allow the heart to beat on its own as often as possible. Recent clinical studies have suggested that reducing this pacing stimulation may reduce the patient's risk of developing heart failure and AF. A reduction in pacing also may preserve the pacemaker battery and extend the life of the device. Quick Look ® II interface: This innovative data display allows clinicians to instantly access complete information about the patient's heart rhythm and device activity on a single, easy-to-understand screen, which simplifies the device follow-up process and may allow physicians to spend more quality time with the patient instead of performing lengthy pacemaker tests. In addition, new trend monitoring capabilities may reduce the amount of time needed to gather key information and shorten patient office visits. SCD-HeFT Lays out a Bright Future for ICD Makers Positive results from the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT), reported at the American College of Cardiology 2004 Scientific Sessions, could double the use of defibrillators and, in return, boost sales of the $25,000 device, according to media reports. However, a surge in ICD implantations depends on forces beyond the heart device industry, as reported on Dow Jones. Most ICD recipients depend on Medicare coverage for the expensive device. Experts anticipate the Centers for Medicare & Medicaid Services (CMS) to extend government reimbursement for ICDs as a result of the positive outcomes of the SCD-HeFT and MADIT II studies to include patients with QRS of 120 or below. Currently, only 25% of people who would benefit from an ICD actually receive the device, Dr. Michael Cain said in a statement, as reported by the Minneapolis Star Tribune. The article details the profile of possible future ICD recipients: Patients who were doing well, said Dr. Richard Luceri from Florida Arrhythmia Consultants in Ft. Lauderdale. In SCD-HeFT, his team implanted ICDs in patients who were playing golf and tennis and leading normal lives. Dr. Stephen Hammill from the Mayo Clinic in Rochester, Minnesota, also called for a greater use of ICDs in an interview with Dow Jones. We've been looking for data that would corroborate the results of MADIT II, and SCD-HeFT does that. The more data that are out there, the more physicians will refer patients, and we'll see wider penetration [of ICDs]. The more ICDs are implanted, the greater profits will increase for the device industry. The much-anticipated SCD-HeFT results intrigued not only Medtronic, the sponsor of the trial, but also two other ICD makers, Guidant and St Jude Medical. Shares of all three Minnesota-based companies went up after the trial results were released. Dow Jones reports that trades in shares of the big three were even halted by the New York Stock Exchange in anticipation of the positive trial outcome and that Medtronic anticipated ICD implantations to double as a result of SCD-HeFT, with 600,000 additional patients who might benefit from the device. Many cardiologists think along the same lines. I think there will be a potential explosion of defibrillator use in all kinds of patients with heart failure, said Dr. Emanuel Kostacos from the University of Pennsylvania, Philadelphia. Dr. Eric Prystowsky from St. Vincent Hospital in Indianapolis, Indiana is quoted by Dow Jones, saying that the SCD-HeFT data confirm we were doing the right thing. It means we ought to be implanting ICDs prophylactically in non-ischemic patients with ejection fractions of 35% or less. However, he is not sure how the CMS is going to react to the evidence from the two trials to expand its coverage. Is it good enough for CMS? he said. I don't know. I m not a regulator. That s their call, not ours. U.S. FDA Approves New Devices for Use with Medtronic s Internet-Based Heart Device Monitoring System New Offerings will mean Enhanced Convenience and Peace of Mind for many with Heart Disease Medtronic, Inc. has reached a significant milestone in its ability to enhance the ongoing clinical management of patients with implantable cardioverter-defibrillators (ICDs). The company announced that it has added three additional devices to its Medtronic CareLink ® Network, its Internet-based, remote cardiac device monitoring system. Physicians now can offer the Medtronic CareLink Network to more than 130,000 persons whose heart conditions are being treated with Medtronic ICDs and cardiac resynchronization therapy/ICD (CRT-ICD) systems, now including the InSync II Marquis CRT-ICD device or the single- or dual-chamber model of the Maximo ICD device. The company recently received U.S. Food and Drug Administration approval to allow use of these implantable devices with the Medtronic CareLink ® Monitor, which patients use at home or while traveling to transmit data to their clinics. These additions fulfill the company's plans to offer the Medtronic CareLink Network to its most current market-leading ICDs and CRT-ICD systems. Future ICDs and CRT-ICDs will be added to the Network shortly after they are released for commercial implant. Hospitals and clinics in 42 states plus the District of Columbia are following more than 6,000 ICD recipients who use the Medtronic CareLink Network from home, work or on vacation. Patients transmit data from their ICD or CRT-ICD using a portable monitor that is connected to a standard telephone line as instructed by their physician. Within minutes, the patient's physician and nurses can view the data on a secure Internet website. The information, which is comparable to the information provided during an in-clinic device follow-up visit, provides the physician with a view of how the device is working. If needed, the physician can make adjustments to the patient's medication or prescribe additional therapy. Remote follow-up of CRT-ICD devices allows clinicians to review the status of and changes to a patient's heart condition, and it can help facilitate a timely exchange of device information between various physicians involved in treating heart failure patients - electrophysiologists who implant and monitor CRT devices and cardiologists who follow the patient's heart failure condition. Information about the Medtronic CareLink Network can be found at www.medtronic.com/carelink. As clinicians use the Medtronic CareLink Network for longer periods of time and with more patients, we regularly are told that it's becoming an absolute necessity to their business, not to mention a great source of satisfaction for their patients. They can't imagine going back to the often-inefficient system of providing all device checks in the clinic, said Reggie Groves, Vice President and General Manager of Medtronic Patient Management. We're extremely pleased with the feedback we're receiving from our customers, and we are working closely with them to understand how we can quickly adapt the Medtronic CareLink Network to add significant value to their management of a wide range of patient conditions. The InSync II Marquis system, available in the United States since August 2003, helps re-coordinate the beating of the heart with features that can be tailored to individual patients, such as the ability to independently program the level of energy delivered to each ventricle. It also can painlessly terminate up to 75 percent of fast ventricular tachycardia episodes with antitachycardia pacing instead of delivering unnecessary shocks, while also providing effective defibrillation protection when necessary. Introduced in October 2003, the Maximo family of ICDs includes high-output ICDs with the most advanced combination of delivered energy and features in the industry. It combines the clinical benefits of 35 joules of delivered energy with a small size, fast charge times throughout the life of the device, and multiple patient safety features doctors need to optimally manage their ICD patients. Brugada Syndrome Delved into in the New York Times An extensive New York Times article chronicles the early mystery surrounding Brugada syndrome, described as one of the most lethal diseases imaginable, and highlights the recent attempts to identify a genetic basis of the disease. In discussing the story of Brian Nelson, a Seattle resident recently diagnosed with Brugada syndrome, the article, written by reporter Sandeep Jauhar, notes that as many as 12% of all sudden deaths and roughly 20% of deaths in patients with structurally normal hearts are attributed to the disease. According to the Times, most victims die in their sleep. Moreover, once patients develop symptoms unexplained fainting being the most common there is a 50% chance patients will die within 10 years if they do not receive treatment. Currently, an implantable cardioverter defibrillator (ICD) is the only effective treatment. The typical patient is 40 years old, in the best moment of his life, very active, very productive, with no previous history of anything, and all of a sudden one night he never wakes up, said Dr. Ramon Brugada from Masonic Medical Research Laboratory in Utica, New York. Jauhar reports that the number of diagnosed cases of Brugada syndrome has grown exponentially over the past 10 years. In Southeast Asia, the disease is endemic and is the most second most common cause of death, after motor-vehicle accidents, in men under age 40. In some areas, it affects 2% of the population, writes Jauhar. In the United States, Dr. Charles Antzelvitch, director of the Masonic Medical Research Laboratory where much of the research on the syndrome has been done, told the Times that one in 5,000 people may be at risk for sudden death from Brugada syndrome. The article also goes on to describe some of the earliest known theories about the disease. The paper notes that Dr. Gonzalo Aponte, a pathologist at the Naval Hospital in Guam, first wrote a paper in 1960 describing 11 cases of young Filipino men who had died in their sleep. In each case, the manner of their deaths was similar, with victims moaning, gasping for breath, and thrashing violently before dying. With nothing to explain the deaths, Aponte learned that sudden death of apparently healthy men was not uncommon in the Philippines. According to the Times, villagers called it bangungot, the Tagalog word for nightmares, and the syndrome was described in a Philippine medical journal as far back as 1917. In Thailand, it has been called lai-tai. Quoting local legend, the Times explains that many believe widow ghosts take men away in the dead of night, leading some men to disguise themselves as women at bedtime in hopes of staving off such deadly specters. In the US, the disease first came to the attention of public-health authorities during the late 1970s. In 1986, Dr. Pedro Brugada saw the first case in Europe, although the case was not recognized as such at the time; on examining the patient's ECG, he saw an unusual pattern, the signal shaped almost like a shark's fin. After collecting eight of these highly unusual ECGs, Brugada and his brother, Dr. Josep Brugada, published their results in the Journal of the American College of Cardiology, where the new clinical entity was later named Brugada syndrome. During the late 1990s, a consortium led by Antzelvitch and the Brugada brothers set out to discover the genetic basis of the disease. Basing their research on the genetic pool of three families with the disease, the scientists identified a mutation in SCN5a, a gene that controls the flow of sodium ions into heart cells. When the gene was sequenced in 200 control patients, none had the mutation, Jauhar reports. The Times explains that, unlike most heart-rhythm abnormalities, those that accompany Brugada are set off by a slow heartbeat, explaining why the deaths usually occur at night. The paper notes that the first randomized trial of ICDs in Brugada patients was published last year in Circulation. The small study was stopped early as ICDs appeared to extend patients' lives, the Times reports. The paper notes that experts believe most cases of Brugada syndrome remain undiagnosed and screening should begin early in the teenage years. The sooner you get it, the more likely you are to catch something before it becomes a problem, Antzelvitch told the Times. Anger, Hostility Linked to Atrial Fibrillation in Men Men who explode with anger or expect the worst from people are more likely to develop an irregular heart rhythm called atrial fibrillation (AF), according to a report in Circulation. This is the first study to show that certain measures of anger and hostility are related to the development of atrial fibrillation in men, said lead author Elaine D. Eaker, ScD, of Eaker Epidemiology Enterprises, LLC in Chili, Wisconsin. She conducted the study with colleagues at Boston University and the Framingham Heart Study. AF affects about 2 million Americans and is increasing as the population ages. Previous research has suggested a possible link between atrial fibrillation and psychosocial stress. Researchers tried to determine whether anger, hostility and Type A behavior are independently associated with the development of coronary heart disease, AF or death. The analysis includes 1,769 men and 1,913 women in the Framingham Offspring Study, which involves the adult children and their spouses of the original participants in the National Heart, Lung, and Blood Institute s Framingham Heart Study, begun in 1948. The Offspring participants completed psychological surveys during the third examination of the study, when their average age was 48.5 years and they had no signs of heart disease. Afterward, they were followed for 10 years for the incidence of coronary heart disease, atrial fibrillation, and death from any cause (total mortality). After adjusting for known risk factors such as age and high blood pressure, researchers found several traits significantly increased the risk of AF in men. Those with higher feelings of hostility were 30 percent more likely to develop AF compared with men with lower hostility levels. Hostility, as measured by the Minnesota Multiphasic Personality Inventory, is a generally contemptuous attitude toward other people. Hostile people expect the worst from others and feel a need to defend against it, agreeing with statements such as: I have often met people who were supposed to be experts who were no better than me; I frequently have worked under people who arrange things so they get all the credit; or Some of my family members have habits that bother me and annoy me very much. As for anger, men who scored high in trait-anger had a 10 percent greater risk of developing atrial fibrillation compared with men without increased anger. Participants scoring high on trait-anger described themselves as fiery- or quick-tempered, hot-headed, annoyed when slighted, furious when criticized, and wanting to hit someone when frustrated. Men high in trait-anger were also 20 percent more likely to have died from any cause during the study. There has been a perception that you can dissipate the negative health effects of anger by letting anger out instead of bottling it up, Eaker said. But that is definitely not the case in the men in this study they were at higher risk not only of atrial fibrillation but of death from all causes. Also, men had a 20 percent increased chance of developing atrial fibrillation if they were rated high in symptoms of anger, reporting that their anger is often accompanied by bodily sensations such as shaking, headaches, and muscle tension. In contrast, the researchers found no increased risk in men who rated high on Type A behavior. In this study, Type A behavior was assessed by the Bortner Rating Scale, which does not include anger and hostility but focuses on time urgency (always in a rush, hate having to wait) and competitiveness (hard-driving, strong need to excel, thinking about work all the time). Rather than concentrating on Type A behavior as a risk factor, it is probably more fruitful to start thinking about anger and hostility in men, Eaker said. Researchers found no significant association between anger, hostility or Type A behavior in a woman s risk of dying or developing coronary heart disease or atrial fibrillation. We failed to find an association in women, but that may be because women develop heart disease later than men and our population was fairly young, with few instances of atrial fibrillation in women during the follow-up period, Eaker said. Without a larger or longer study, we cannot say definitely that the personality traits are not related to health outcomes in women. The known risks for atrial fibrillation are largely mechanical anything that scars, stretches, or distorts the shape of the heart muscle can eventually result in arrhythmia, such as rheumatic fever, high blood pressure or heart surgery. The peak ages for developing atrial fibrillation are between 70 and 84. However, because this study was based on a middle-aged population, 66 percent of the cases occurred before age 60 and almost all were in people with no known heart disease. Though these results need confirmation, Eaker said healthcare providers should know that some personality traits may be detrimental to health. Co-authors are Lisa M. Sullivan, PhD; Margaret Kelly-Hayes, EdD, RN; Ralph B. D Agostino, Sr., PhD; and Emelia J. Benjamin, MD, ScM. The National Heart, Lung and Blood Institute funded the study.