Jane Chen

Clinical Benefits of Remote Versus Transtelephonic Monitoring of Implanted Pacemakers

OBJECTIVES The purpose of this study was to evaluate remote pacemaker interrogation for the earlier diagnosis of clinically actionable events compared with traditional transtelephonic monitoring and routine in-person evaluation. BACKGROUND Pacemaker patient follow-up procedures have evolved from evaluating devices with little programmability and diagnostic information solely in person to transtelephonic rhythm strip recordings that allow monitoring of basic device function. More recently developed remote monitoring technology leverages expanded device capabilities, augmenting traditional transtelephonic monitoring to evaluate patients via full device interrogation. METHODS The time to first diagnosis of a clinically actionable event was compared in patients who were followed by remote interrogation (Remote) and those who were followed per standard of care with office visits augmented by transtelephonic monitoring (Control). Patients were randomized 2:1. Remote arm patients transmitted pacemaker information at 3-month intervals. Control arm patients with a single-chamber pacemaker transmitted at 2-month intervals. Control arm patients with dual-chamber devices transmitted at 2-month intervals with an office visit at 6 months. All patients were seen in office at 12 months. RESULTS The mean time to first diagnosis of clinically actionable events was earlier in the Remote arm (5.7 months) than in the Control arm (7.7 months). Three (2%) of the 190 events in the Control arm and 446 (66%) of 676 events in the Remote arm were identified remotely. CONCLUSIONS The strategic use of remote pacemaker interrogation follow-up detects actionable events that are potentially important more quickly and more frequently than transtelephonic rhythm strip recordings. The use of transtelephonic rhythm strips for pacemaker follow-up is of little value except for battery status determinations. (PREFER [Pacemaker Remote Follow-up Evaluation and Review]; NCT00294645).

Noninvasive Electroanatomic Mapping of Human Ventricular Arrhythmias with Electrocardiographic Imaging

Noninvasive imaging of cardiac electrical activity during ventricular arrhythmias enables superior diagnosis and treatment. A New View of the Beating Heart Just as a tree’s shadow is an oversimplification of branches and foliage, the electrocardiogram, a decades-old tool for measuring the electrical activity of the heart, captures only an approximate view of the heartbeat, distorted by the intervening tissues between the heart and the few electrodes on the skin. This poses a problem when trying to treat heart diseases such as dangerous ventricular arrhythmias, which destabilize the heartbeat and can lead to sudden cardiac death. Now, with a technique called electrocardiographic imaging (ECGI), Wang and colleagues have married multiple electrical recordings from the skin of patients who have ventricular tachycardia (VT) with detailed computerized axial tomography (CAT) scans of the anatomy of their torso. From these data, the authors can back calculate what is happening, electrically speaking, on the surface of the misbehaving hearts, yielding an individual portrait of that patient’s beating heart so that treatment can be more effectively deployed. Twenty-five patients with VT were scheduled to undergo electrical mapping of their hearts and then ablation of heart tissue to correct the electrical defect with an invasive catheter. The authors augmented this standard treatment by creating an image of their beating hearts with noninvasive ECGI, before the standard procedure. The ECGI and standard procedure identified the same origination point of the tachycardia in almost all of the patients, and ECGI was able to correctly categorize both focal and reentrant mechanisms of VT. The time resolution of ECGI enabled the authors to follow the response of the heart to different patterns of stimulation (or pacing), revealing presystolic activation near the site of origin. They could see variable beat-to-beat conduction patterns and showed that the abnormal conduction patterns often began in regions of scar tissue, relics of previous heart attacks. ECGI yields information comparable to the current procedure for mapping abnormal heart activity with a catheter-fed electrode, repeatedly placed on the heart surface. But it has significant advantages over the current approach: The spatial resolution of the ventricular arrhythmia on the heart surface is high, and it takes into account patient-to-patient variability in body size and shape. Further, it is noninvasive and can map single heartbeats, allowing unprecedented visualization of the anatomy of the electrical activation and beat-to-beat variability. These advantages should enable more effective diagnosis of VT and more appropriate drug or ablation therapy, which can now be directed to the specific characteristics of the patient’s heart instead of a simplified shadow. The rapid heartbeat of ventricular tachycardia (VT) can lead to sudden cardiac death and is a major health issue worldwide. Efforts to identify patients at risk, determine mechanisms of VT, and effectively prevent and treat VT through a mechanism-based approach would all be facilitated by continuous, noninvasive imaging of the arrhythmia over the entire heart. Here, we present noninvasive real-time images of human ventricular arrhythmias using electrocardiographic imaging (ECGI). Our results reveal diverse activation patterns, mechanisms, and sites of initiation of human VT. The spatial resolution of ECGI is superior to that of the routinely used 12-lead electrocardiogram, which provides only global information, and ECGI has distinct advantages over the currently used method of mapping with invasive catheter-applied electrodes. The spatial resolution of this method and its ability to image electrical activation sequences over the entire ventricular surfaces in a single heartbeat allowed us to determine VT initiation sites and continuation pathways, as well as VT relationships to ventricular substrates, including anatomical scars and abnormal electrophysiological substrate. Thus, ECGI can map the VT activation sequence and identify the location and depth of VT origin in individual patients, allowing personalized treatment of patients with ventricular arrhythmias.

Poor prognosis for patients with chronic kidney disease despite ICD therapy for the primary prevention of sudden death.

Introduction: Chronic kidney disease (CKD) has been independently associated with increased cardiovascular mortality. Little is known about the benefit of implantable cardioverter defibrillator (ICD) therapy for prevention of sudden death in this large, high‐risk population. We sought to evaluate the impact of CKD on survival in patients who received an ICD for primary prevention of sudden death.

The azygos defibrillator lead for elevated defibrillation thresholds: implant technique, lead stability, and patient series.

Background: Conventional insertion of implantable cardioverter‐defibrillator (ICD) includes an evaluation of the defibrillation threshold (DFT). Implanting an ancillary defibrillation lead in the azygos vein has been introduced as a therapeutic option in patients with “high” DFT. This study reports the efficacy and stability of azygos defibrillation coils implanted for elevated DFTs.

Right Ventricular Lead Perforation Presenting as Left Chest Wall Muscle Stimulation

An 83-year-old man with a history of coronary artery disease and 3-vessel coronary artery bypass grafting underwent implantation of a pacemaker (Medtronic EnPulse E2DR01) at an outside facility because he experienced recurrent syncope and an abnormal response to tilt table testing. Active fixation leads were implanted in the right atrium (Medtronic 5076-52) and right ventricle (Medtronic 5076-58). At the time of implantation, all lead parameters were within normal limits, and the right ventricular lead was positioned in the apex. Twelve days after the implantation, the patient developed intermittent left …

Design of the Pacemaker REmote Follow-up Evaluation and Review (PREFER) trial to assess the clinical value of the remote pacemaker interrogation in the management of pacemaker patients

BackgroundAlthough pacemakers are primarily used for the treatment of bradycardia, diagnostic data available in current pacemakers allow them to be also used as sophisticated, continuous monitoring devices. Easy access to these stored data may assist clinicians in making diagnostic and therapeutic decisions sooner, thus avoiding potential long-term sequelae due to untreated clinical disorders. Internet-based remote device interrogation systems provide clinicians with frequent and complete access to stored data in pacemakers. In addition to monitoring device function, remote monitors may be a helpful tool in assisting physicians in the management of common arrhythmia disorders.MethodsThe Pacemaker Remote Follow-up Evaluation and Review (PREFER) trial is a prospective, randomized, parallel, unblinded, multicenter, open label clinical trial to determine the utility of remote pacemaker interrogation in the earlier diagnosis of clinically actionable events compared to the existing practice of transtelephonic monitoring. There have been 980 patients enrolled and randomized to receive pacemaker follow up with either remote interrogation using the Medtronic CareLink® Network (CareLink) versus the conventional method of transtelephonic monitoring (TTM) in addition to periodic in-person interrogation and programming evaluations. The purpose of this manuscript is to describe the design of the PREFER trial. The results, to be presented separately, will characterize the number of clinically actionable events as a result of pacemaker follow-up using remote interrogation instead of TTM.Trial registrationClinicalTrials.gov: NCT00294645.

Continuous ECGI mapping of spontaneous VT initiation, continuation, and termination with antitachycardia pacing

A 40-year-old woman with nonischemic cardiomyopathy and a left ventricular (LV) ejection fraction of 35% was referred for recurrent ventricular tachycardia (VT). She experienced 248 VT episodes treated by antitachycardia pacing (ATP) over 14 days. In 2005, she received an implantable cardioverter defibrillator for an episode of syncope and nonsustained VT. She later underwent an invasive electrophysiology study (EPS) with inducible VT and an ablation of the AV nodal reentrant tachycardia. Since then, she experienced symptomatic VT, terminated by ATP. Her VT was unresponsive to sotalol and mexiletine. Two EPS in early 2010 failed to induce VT despite intravenous isoproterenol and triple extrastimuli at two right ventricular (RV) sites; therefore, no ablations were performed.

Sustained Polymorphic Arrhythmias Induced by Programmed Ventricular Stimulation have Prognostic Value in Patients Receiving Defibrillators

Background: Patients with ischemic cardiomyopathy (ICM) who have monomorphic ventricular tachycardia (VT) induced by programmed ventricular stimulation (PVS) are at increased risk of sudden cardiac death (SCD). Among a primary prevention population, the prognostic significance of induced polymorphic ventricular arrhythmias is unknown.

Speech‐Induced Atrial Tachycardia: An Unusual Presentation of Supraventricular Tachycardia

A 63‐year‐old male radio announcer was admitted with a narrow complex, long RP tachycardia. While in the awake state, the patient spoke in his radio voice, initiating and maintaining the tachycardia. Three‐dimensional electroanatomic mapping during electrophysiology study localized the tachycardia to the ostium of the right superior pulmonary vein. After single radiofrequency energy application, no further arrhythmias were inducible with speech. At more than 1 year of follow‐up, the patient had no recurrences and continues to work as a radio announcer.

Narrow QRS complex tachycardia: what is the mechanism?

A 43-year-old woman with normal left ventricular ejection fraction presented with a history of repeated episodes of palpitations for over 20 years. The baseline 12-lead electrocardiogram showed normal sinus rhythm with no evidence of preexcitation. An event monitor recording showed a rapid, narrow complex tachycardia, and she underwent an electrophysiology study to assess the tachycardia mechanism. The patient’s baseline rhythm was sinus with a normal axis, an AH interval of 64 ms, and HV interval of 39 ms. During the electrophysiological study, a regular, narrow complex tachycardia at a rate of 240 beats/min was reproducibly induced with a single extrastimulus from the high right atrium at a critical AH interval of 200 ms. One to one atrioventricular (AV) association was present during the tachycardia with the earliest atrial activation seen at the distal His-bundle bipoles. The tachycardia was not inducible from the right ventricle. The tachycardia was terminated with overdrive pacing from the atrium or the ventricle. A single ventricular extrastimulus delivered from the right ventricle when the His bundle was refractory did not advance or delay the atrial activation timing. Pacing from the right ventricle resulted in an identical atrial activation pattern as seen during tachycardia. The tachycardia became noninducible after radiofrequency ablation in the mid-posterior region of the triangle of Koch, despite provocation with intravenous isoproterenol and aggressive stimulation with single and double atrial extrastimuli. On several occasions during the electrophysiological study, a tachycardia at exactly half the ventricular rate of the initial tachycardia was noted. Figure 1 shows the 12-lead electrocardiogram of this tachycardia. This tachycardia, at a ventricular rate of 120 beats/min, correlated with the intracardiac electrograms on one (Fig. 2) and then another (Fig. 3) induction. What is the mechanism of the tachycardia shown in these figures,