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OBJECTIVE To determine whether burden of multiple chronic conditions (MCCs) influences the risk of receiving inappropriate vs appropriate device therapies. DESIGN Retrospective cohort study. SETTING Seven US healthcare delivery systems. PARTICIPANTS Adults with left ventricular systolic dysfunction receiving an implantable cardioverter-defibrillator (ICD) for primary prevention. MEASUREMENTS Data on 24 comorbid conditions were captured from electronic health records and categorized into quartiles of comorbidity burden (0-3, 4-5, 6-7 and 8-16). Incidence of ICD therapies (shock and antitachycardia pacing [ATP] therapies), including appropriateness, was collected for 3 years after implantation. Outcomes included time to first ICD therapy, total ICD therapy burden, and risk of inappropriate vs appropriate ICD therapy. RESULTS Among 2235 patients (mean age = 69 ± 11 years, 75% men), the median number of comorbidities was 6 (interquartile range = 4-8), with 98% having at least two comorbidities. During a mean 2.2 years of follow-up, 18.3% of patients experienced at least one appropriate therapy and 9.9% experienced at least one inappropriate therapy. Higher comorbidity burden was associated with an increased risk of first inappropriate therapy (adjusted hazard ratio [HR] = 1.94 [95% confidence interval {CI} = 1.14-3.31] for 4-5 comorbidities; HR = 2.25 [95% CI = 1.25-4.05] for 6-7 comorbidities; and HR = 2.91 [95% CI = 1.54-5.50] for 8-16 comorbidities). Participants with 8-16 comorbidities had a higher total burden of ICD therapy (adjusted relative risk [RR] = 2.12 [95% CI = 1.43-3.16]), a higher burden of inappropriate therapy (RR = 3.39 [95% CI = 1.67-6.86]), and a higher risk of receiving inappropriate vs appropriate therapy (RR = 1.74 [95% CI = 1.07-2.82]). Comorbidity burden was not significantly associated with receipt of appropriate ICD therapies. Patterns were similar when separately examining shock or ATP therapies. CONCLUSIONS In primary prevention ICD recipients, MCC burden was independently associated with an increased risk of inappropriate but not appropriate device therapies. Comorbidity burden should be considered when engaging patients in shared decision making about ICD implantation.

As the new millennium opened, multimodality imaging techniques were united with the electrophysiological catheter techniques developed a generation before. These included traditional fluoroscopy, intracardiac ultrasound, and 4D electroanatomic or noncontact mapping. Detailed studies of cardiac anatomy allowed electrophysiology to transition into “electro-anatomic physiology.” Routine percutaneous access of the intact epicardial space was introduced.

The field of electrophysiology including electrocardiography, pacing, and invasive electrophysiology (EP) has been the subject of great interest since Henry Plummer had established an ECG laboratory at Mayo in 1914. The prelude to the 1980s included several years in the late 1970s during which experience in the field was accrued with both pacing and EP procedures (“HIS BUNDLE” recordings). Some of these focused on patients with SVT, specifically the Wolff-Parkinson-White syndrome (WPW), a condition that had been endlessly interesting, in part, because of the unusual ECGs and the tachycardia involved. There was robust growth of staff physicians and fellows coming from around the world who were extraordinarily productive in the field. Early publications tracked the Mayo pacing experience over two decades during which implantation moved from being a surgical specialty to being driven by cardiology operators in the Mayo catheterization laboratory. This two-decade experience also documented the rapid shift in pacing modalities as technology moved from single to dual chamber devices. Teaching, questioning, and problem-solving were eclectic and engaged. Favorite productive educational sessions were initiated, held every week at 5:00 pm in an establishment near the clinic campus which served liquid bread and popcorn. Out of these sessions came ideas for new studies, approaches, strategies of care, and intellectual property. Evaluation of the increasing number and complexity of pacing modes were the focus of study as well as early data on specific clinical circumstances such as the effect of MRI imaging on pacemaker function, the latter of which was studied in an animal model. Particularly noteworthy were studies on the hemodynamics of cardiac pacing including pacing-mediated tachycardia and the pacemaker syndrome. Of fundamental importance were the “HIS Books.” They were handwritten by the operators and included patient name, clinic number, indication for study, and diagnosis/diagnoses. These were the consecutive patient’s studies coming through the laboratory offering a wealth of information on indications for study and results, all tabulated into categories. They were used for manuscripts, presentations, and discussion. Looking at them now, the handwriting from the early physicians is readily identifiable; we can see who was doing what, well before the time of computerized records. The group was developing extensive experience with the WPW syndrome and what were called Kent bundles or now accessory AV nodal pathways. The earliest case in the operating room identified the specific location of the connection, transiently interrupted it, and stopped tachycardia. This set the stage for the extensive development of the surgical experience with patients with WPW which became a standard of care and then the migration to catheter ablation. Other surgical and catheter experiences included AVNRT from dual AV nodal pathways. Seminal studies included defining optimal strategies for infected pacemakers, the largest experience at that time of invasive assessment of syncope, and the effect of tilt table testing on rhythm disturbances. In an old GI room used for barium swallows, catheters could be placed in the supine position and tachycardia induced. Then the patient would be tipped upright to document the effects of position on the rhythm. That first example of this technology forms the basis for tilt table testing in use today. Other important observations included tachycardia-induced cardiomyopathy. The concept of inducing tachycardia with programmed electrical stimulation both SVT and VT was an essential part of the practice. This was used to evaluate symptoms, to test drugs for effectiveness, and to evaluate the possibility of implantable pacemakers that could be used to terminate tachycardia both SVT and VT. EP rounds in the CCU involved carrying a portable stimulator to identify if the medication the patient had received prevented re-induction of the tachycardia. Rounds were sometimes rather exciting both for the patient, the nursing staff, and the physicians involved. This use of electrical stimulation became a mainstay of the practice with its application perhaps for the first time in the field to ablate VT from the LV cavity using DC cardioversion.

Glenn N. Levine, MD, FACC, FAHA, Chair Patrick T. O’Gara, MD, MACC, FAHA, Chair-Elect Jonathan L. Halperin, MD, FACC, FAHA, Immediate Past Chair [¶][1] Sana M. Al-Khatib, MD, MHS, FACC, FAHA Joshua A. Beckman, MD, MS, FAHA Kim K. Birtcher, MS, PharmD, AACC Biykem Bozkurt, MD, PhD, FACC

Glenn N. Levine, MD, FACC, FAHA, Chair Patrick T. O’Gara, MD, MACC, FAHA, Chair-Elect Jonathan L. Halperin, MD, FACC, FAHA, Immediate Past Chair [¶][1] Sana M. Al-Khatib, MD, MHS, FACC, FAHA Joshua A. Beckman, MD, MS, FAHA Kim K. Birtcher, MS, PharmD, AACC Biykem Bozkurt, MD, PhD, FACC

Preamble e472 1. Introduction e473 2. General Principles e475 3. Sinus Tachyarrhythmias e480 4. Nonsinus Focal Atrial Tachycardia and MAT e481 5. Atrioventricular Nodal Reentrant Tachycardia e482 6. Manifest and Concealed Accessory Pathways e483 7. Atrial Flutter e485 8. Junctional Tachycardia e487 9. Special Populations e487

Jonathan L. Halperin, MD, FACC, FAHA, Chair Glenn N. Levine, MD, FACC, FAHA, Chair-Elect Jeffrey L. Anderson, MD, FACC, FAHA, Immediate Past Chair [¶][1] Nancy M. Albert, PhD, RN, FAHA[¶][1] Sana M. Al-Khatib, MD, MHS, FACC, FAHA Kim K. Birtcher, PharmD, AACC Biykem Bozkurt, MD, PhD, FACC

Background Primary prevention implantable cardioverter‐defibrillators (ICDs) reduce mortality in selected patients with left ventricular systolic dysfunction by delivering therapies (antitachycardia pacing or shocks) to terminate potentially lethal arrhythmias; inappropriate therapies also occur. We assessed device therapies among adults receiving primary prevention ICDs in 7 healthcare systems. Methods and Results We linked medical record data, adjudicated device therapies, and the National Cardiovascular Data Registry ICD Registry. Survival analysis evaluated therapy probability and predictors after ICD implant from 2006 to 2009, with attention to Centers for Medicare and Medicaid Services Coverage With Evidence Development subgroups: left ventricular ejection fraction, 31% to 35%; nonischemic cardiomyopathy Conclusions In this community cohort of primary prevention patients receiving ICD, therapy delivery varied across demographic and clinical characteristics, but did not differ meaningfully for Centers for Medicare and Medicaid Services Coverage With Evidence Development subgroups.

Background In US clinical practice, many patients who undergo placement of an implantable cardioverter‐defibrillator ( ICD ) for primary prevention of sudden cardiac death receive dual‐chamber devices. The superiority of dual‐chamber over single‐chamber devices in reducing the risk of inappropriate ICD shocks in clinical practice has not been established. The objective of this study was to compare risk of adverse outcomes, including inappropriate shocks, between single‐ and dual‐chamber ICD s for primary prevention. Methods and Results We identified patients receiving a single‐ or dual‐chamber ICD for primary prevention who did not have an indication for pacing from 15 hospitals within 7 integrated health delivery systems in the Longitudinal Study of Implantable Cardioverter‐Defibrillators from 2006 to 2009. The primary outcome was time to first inappropriate shock. ICD shocks were adjudicated for appropriateness. Other outcomes included all‐cause hospitalization, heart failure hospitalization, and death. Patient, clinician, and hospital‐level factors were accounted for using propensity score weighting methods. Among 1042 patients without pacing indications, 54.0% (n=563) received a single‐chamber device and 46.0% (n=479) received a dual‐chamber device. In a propensity‐weighted analysis, device type was not significantly associated with inappropriate shock (hazard ratio, 0.91; 95% confidence interval, 0.59–1.38 [ P =0.65]), all‐cause hospitalization (hazard ratio, 1.03; 95% confidence interval, 0.87–1.21 [ P =0.76]), heart failure hospitalization (hazard ratio, 0.93; 95% confidence interval, 0.72–1.21 [ P =0.59]), or death (hazard ratio, 1.19; 95% confidence interval, 0.93–1.53 [ P =0.17]). Conclusions Among patients who received an ICD for primary prevention without indications for pacing, dual‐chamber devices were not associated with lower risk of inappropriate shock or differences in hospitalization or death compared with single‐chamber devices. This study does not justify the use of dual‐chamber devices to minimize inappropriate shocks.

Background. Sudden cardiac death is the leading cause of death among end-stage kidney disease patients (ESKD) on dialysis, but the benefit of primary prevention implantable cardioverter defibrillators (ICDs) in this population is uncertain. We conducted this investigation to compare the mortality of dialysis patients receiving a primary prevention ICD with matched controls. Methods. We used data from the National Cardiovascular Data Registry’s ICD Registry to select dialysis patients who received a primary prevention ICD, and the Get with the Guidelines-Heart Failure Registry to select a comparator cohort. We matched ICD recipients and no-ICD patients using propensity score techniques to reduce confounding, and overall survival was compared between groups. Results. We identified 108 dialysis patients receiving primary prevention ICDs and 195 comparable dialysis patients without ICDs. One year (3-year) mortality was 42.2% (68.8%) in the ICD registry cohort compared with 38.1% (75.7%) in the control cohort. There was no significant survival advantage associated with ICD [hazard ratio (HR) 0.87, 95% confidence interval (CI) 0.66–1.13, log-rank P = 0.29]. After propensity matching, our analysis included 86 ICD patients and 86 matched controls. Comparing the propensity-matched cohorts, 1 year (3 years) mortality was 43.4% (74.0%) in the ICD cohort and 39.7% (76.6%) in the control cohort; there was no significant difference in mortality outcome between groups (HR = 0.94, 95% CI: 0.67– 1.31, log-rank P = 0.71). Conclusions. We did not observe a significant association between primary prevention ICDs and reduced mortality among ESKD patients receiving dialysis. Consideration of the potential risks and benefits of ICD implantation in these patients should be undertaken while awaiting the results of definitive clinical trials.

Background— Patients with heart failure and atrial fibrillation are at higher risk of thromboembolic events than patients with heart failure alone. Yet, the use of anticoagulation therapy varies in clinical practice, especially among older patients, for whom its effectiveness is poorly understood. Methods and Results— Using clinical registry data linked to Medicare claims from 2005 to 2011, we examined outcomes of older patients hospitalized with heart failure and atrial fibrillation who newly initiated anticoagulation therapy at discharge. We used Cox proportional hazards models and inverse probability-weighted treatment estimates to adjust for selection bias. Main outcomes were mortality and readmission at 1 and 3 years. Among 5105 patients in 195 hospitals, 1623 (31.8%) started anticoagulation therapy at discharge. Treated patients had lower unadjusted rates of all-cause mortality (26.4% versus 42.8%; P P Conclusions— Initiation of anticoagulation therapy at hospital discharge was associated with improved mortality at 1 and 3 years but was not associated with improved cardiovascular readmission among older patients with heart failure and atrial fibrillation.

ECG Lead I and Outflow Tract ArrhythmiaIntroduction Outflow tract ventricular arrhythmia (OTVA) can be complicated to target for ablation when originating from either the periaortic or pulmonary valve (PV) region. Both sites may present with a small R wave in lead V1. However, the utility of lead I in distinguishing these arrhythmia locations is unknown. Methods and Results Thirty-six consecutive patients (mean age 41 ± 14 years, 13 male) underwent catheter ablation for OTVA. OTVA origin was determined from intracardiac electrogram tracings and electroanatomic maps. Observers blinded to results measured QRS waveform amplitude and duration from standard 12-lead ECG tracings. Measurements with highest diagnostic performance were modeled into an algorithm. Sites of successful ablation were anterior right ventricular outflow tract (RVOT; n = 6), posterior RVOT (n = 4), PV (n = 18), and right coronary cusp (RCC; n = 8). Highest performing surface ECG discriminators were from lead I to V1 vectors: RCC, lead I R wave ≥ 1.5 mV, and V1 R wave ≥2.0 mV (sensitivity 87%, specificity 93%); PV, V1 R wave > 0 mV, and lead I R/(R+S) ≤ 0.75 (sensitivity 78%, specificity 72%); anterior RVOT, V1 R wave = 0 mV, and lead I R/(R+S) 0 mV, and lead I R/(R+S) > 0.75 (sensitivity 75%, specificity 84%). Sequential algorithmic application of these criteria resulted in an overall accuracy of 72% in predicting site of OTVA origin. Conclusions A relatively large R wave in lead I is seen with RCC origin but not PV origin. A sequential algorithm has limited but potentially significant value beyond assessment of lead I in approaching OTVA.

Objective Patients with chronic kidney disease (CKD) have higher risk of sudden cardiac death; however, they may not receive implantable cardioverter defibrillators (ICDs), in part due to higher risk of complications. We evaluated whether CKD is associated with greater risk of device-delivered shocks/antitachycardia pacing (ATP) therapies among patients receiving a primary prevention ICD. Methods We studied participants in the observational Cardiovascular Research Network Longitudinal Study of Implantable Cardioverter Defibrillators. CKD was defined as estimated glomerular filtration rate (eGFR) 2 . Outcomes included all delivered shocks/ATPs therapies and type of shock/ATP therapies (inappropriate or appropriate, determined by physician adjudication) within the 3 years. We evaluated the associations between CKD and time to first device therapy, burden of device therapy, and inappropriate versus appropriate device therapy, adjusting for demographics, comorbidity, laboratory values and medication use. Results Among 2161 participants, 1066 (49.3%) had CKD (eGFR 44±11 mL/min/1.73 m 2 ) at ICD implantation. During mean of 2.26±0.89 years, 9.8% and 18.5% of participants had at least one inappropriate and appropriate shock/ATP therapies, respectively. CKD was not associated with time to first shock/ATP therapies (adjusted HR 0.87, 95% CI 0.73 to 1.05), overall burden of shock/ATP therapies (adjusted relative rate 0.93, 95% CI 0.74 to 1.17) or inappropriate versus appropriate shock/ATP therapies (adjusted relative risk 0.88, 95% CI 0.68 to 1.14) compared with not having CKD. Conclusions In adults receiving a primary prevention ICD, mild-to-moderate CKD was not associated with the timing, burden or appropriateness of subsequent device therapy. Potential concern for inappropriate ICD-delivered therapies should not preclude ICDs among eligible patients with CKD.

Developed in Collaboration With the American Association for Thoracic Surgery, Heart Failure Society of America, and Society of Thoracic Surgeons

Andrew E. Epstein, MD, FACC, FAHA, FHRS, Chair; John P. DiMarco, MD, PhD, FACC, FHRS; Kenneth A. Ellenbogen, MD, FACC, FAHA, FHRS; N.A. Mark Estes III, MD, FACC, FAHA, FHRS; Roger A. Freedman, MD, FACC, FHRS; Leonard S. Gettes, MD, FACC, FAHA; A. Marc Gillinov, MD, FACC, FAHA; Gabriel Gregoratos, MD

Anatomy of Myocardial Extensions in Thoracic Veins. Introduction: Radiofrequency ablation for atrial fibrillation (AF) frequently involves energy delivery at the ostia of the thoracic veins. Detailed evaluation of the myocardium extending into the caval veins, vein of Marshall, as well as at the pulmonary vein ostia has not been completely evaluated. Methods and Results: Post-mortem assessment of 620 formalin-fixed hearts (mean age 60 ± 23 years, 44% female) was performed. The hearts were examined for integrity of venous structures and their atrial connections. Systematic gross anatomic evaluation including measurements on myocardial extensions in these veins was performed. Macroscopic myocardial extensions into pulmonary veins were noted in 99% of specimens evaluated and were circumferentially symmetric (99.6%). Myocardial extensions into the superior vena cava (SVC) occurred in 78% with the majority being circumferentially asymmetric (61%). Occasionally, myocardium extended into the azygos vein (6%). There were no myocardial extensions in the inferior vena cava (IVC). In some cases, the right atrial pectinate muscle extended into the coronary sinus (7%). The vein of Marshall was consistently located anterior to the left-sided pulmonary veins and posterior to the left atrial appendage, overlying the left atrial endocardial ridge. Conclusions: Myocardial extensions into the pulmonary veins are usually circumferential at the ostia validating the necessity for wide area rather than segmental ablation to isolate these veins during AF ablation. Myocardial extensions into the SVC are common and less likely to be circumferential, whereas extensions into the IVC are not present. The left atrial ridge is a reliable endocardial target for radiofrequency ablation of the vein of Marshall. (J Cardiovasc Electrophysiol, Vol. 23, pp. 1304-1309, December 2012)

Implantable cardioverter–defibrillator (ICD) coverage was expanded by the Center for Medicare and Medicaid Services (CMS) on Jan. 27, 2005, based on the results of the Sudden Cardiac Death and Heart Failure Trial (SCD-HeFT). A requirement of expanded coverage included use of a registry to track ICD’s implanted for primary prevention of sudden cardiac death in Medicare beneficiaries. CMS selected the National ICD Registry as the sole repository for ICD implantation data for Medicare beneficiaries April 1, 2006. The registry was developed through a partnership of the Heart Rhythm Society (HRS) and American College of Cardiology Foundation (ACCF) using the expertise of the National Cardiovascular Data Registry (NCDR). The registry has made substantial progress toward several predefined goals, which will be discussed in this review

Endocavitary Structures and Ventricular Tachycardia Ablation. Background: Radiofrequency (RF) ablation for ventricular tachycardia (VT) has high failure rates. Whether endocavitary structures (ECS) such as the papillary muscles (PMs), moderator bands (MBs), or false tendons (FTs) impact VT ablation is unknown. Methods and Results: We retrospectively reviewed records of 190 consecutive patients presenting for VT ablation and identified 46 (24%) where ECS affected ablation. In 31 of 46 patients (67%), the ECS created difficulty with catheter manipulation (n = 20), interpretation of pace map data (n = 7), or with accurately defining a scar (n = 4). In 15 of 46 (33%), specific mapping and RF energy delivery targeting the ECS itself was necessary to eliminate the arrhythmia. Detailed electroanatomic mapping was performed in 11 of 15 (73%), noncontact mapping in 3 of 15 (20%), multielectrode catheter mapping in 1 of 15 (7%), and intracardiac ultrasound in 14 of 15 (93%) patients. The ablated ECS was a PM in 5 of 15, the MB in 7 of 15, and an FT in 3 of 15. The arrhythmogenic substrate on the ECS was a focus of automatic tachycardia in 9 of 15 and the slow zone responsible for reentrant arrhythmia in the remaining 6 of 15. Successful elimination of tachycardia without recurrence was obtained in all 15 cases. There was no evidence of valvular damage or disruption of the valvular apparatus. Conclusion: During VT ablation procedures, ECS should be considered for specific mapping and targeted ablation. Once recognized, these structures can be successfully targeted for ablation without valve damage. (J Cardiovasc Electrophysiol, Vol. 21, pp. 245–254, March 2010)

Electrophysiological Anatomy of Typical Atrial Flutter.Background: The electrophysiological anatomy of cavotricuspid isthmus-dependent atrial flutter (CVTI-AFL) has not been fully elucidated. Methods: We studied 602 autopsied human hearts from individuals aged 0 to 103 years. We measured morphological features of the right atrium, including the crista terminalis (CT), pectinate muscles, sub-Eustachian pouch, Thebesian valve (TV), and the coronary sinus (CS) ostium. Results: In adults, the mean right atrium dimensions were 4.7 cm × 4.5 cm × 4.4 cm. Pectinate muscles extended medial to the CT in 54% of hearts. In 19% of hearts, these ended in another ridge termed the second CT. Pectinate muscles extended into the CVTI in 70% of hearts. A sub-Eustachian pouch was present in 16% of hearts, was always located on the septal CVTI, and was more likely when a prominent TV was also present. A TV, present in 62% of all hearts, covered the inferior quadrant of the CS ostium in 9% of these hearts. Conclusion: The posterior boundary of the reentrant circuit of CVTI-AFL comprises the Eustachian ridge and CT, but in some patients may also include a second CT. Sub-Eustachian pouches on the septal CVTI are strongly associated with a prominent TV. The lateral CVTI can have prominent pectinate muscles. This comprehensive characterization of the electrophysiological anatomy of the reentrant circuit of CVTI-AFL may provide guidance and improve success during difficult ablations. (J Cardiovasc Electrophysiol, Vol. 21, pp. 144-149, February 2010)

Risk Factors for ICD Lead Fracture. Introduction: The Medtronic Sprint Fidelis® implantable cardioverter defibrillator (ICD) lead was “recalled” in October 2007 after 268,000 implants worldwide due to increased failure risk. Manufacturer suggested monitoring has not been shown effective at preventing adverse events. Only limited data exist regarding clinical predictors of Fidelis® lead fracture. We sought to identify risk factors for Fidelis® fracture to guide clinical monitoring and compare its performance with a control lead. Methods: Fractured lead cases were retrospectively reviewed for demographic data, implant technique, radiographic appearance and clinical presentation was analyzed. Lead survival was compared using Kaplan-Meir curves. Results: Study patients (n = 1314) experienced 18 Fidelis® and 6 Quattro™ lead fractures. Patients with failed Fidelis® leads were younger than those with surviving leads (49.5 vs 64.6 years, P = 0.0066). Fidelis® lead fractures often occurred around the time of physical activity. No other measured demographic or technique related factors were associated with lead fracture. Fidelis® leads had significantly decreased survival compared with Quattro™ leads (89.3 vs 98.9% at 30 months). Patients less than 50 years old had significantly decreased lead survival compared with those older than 50 in both Fidelis® (79.6% vs 96.5% at 24 months) and Quattro™ (93.4 vs 99.8%, P < 0.001 at 24 months) leads. Conclusions: Patients under age 50, with either Fidelis® or Quattro™ ICD leads, are at increased risk of lead fracture compared with patients over 50, particularly around the time of intense physical activity. Aggressive monitoring and advisory programming appears warranted in patients with Fidelis® leads as well as especially in younger patients. (J Cardiovasc Electrophysiol, Vol. 21, pp. 671-677, June 2010)

ntroduction he National ICD Registry became the sole repository of CD implantation data for Medicare beneficiaries on April , 2006, and as of June 2009 had collected data from ,432 hospitals in the United States totaling over 380,000 mplants. The registry was developed through a partnership f the Heart Rhythm Society (HRS [www.HRSonline.org]) nd the American College of Cardiology Foundation ACCF [www.acc.org]) utilizing the expertise of the ational Cardiovascular Data Registry (NCDR [www. ccncdr.com]) and has made substantial progress toward everal predefined goals

Introduction: Defining whether retrograde ventriculoatrial (V-A) conduction is via the AV node (AVN) or an accessory pathway (AP) is important during ablation procedures for supraventricular tachycardia (SVT). With the introduction of ventricular extrastimuli (VEST), retrograde right bundle branch block (RBBB) may occur, prolonging the V-H interval, but only when AV node conduction is present. We hypothesized that when AP conduction was present, the V-A interval would increase less than the V-H interval, whereas with retrograde nodal conduction, the V-A interval would increase at least as much as the V-H interval. Methods and Results: We retrospectively reviewed the electrophysiological studies of patients undergoing ablation for AVN reentrant tachycardia (AVNRT) (55) or AVRT (50), for induction of retrograde RBBB during the introduction of VEST, and the change in the measured V-H and V-A intervals. Results were found to be reproducible between independent observers. Out of 105 patients, 84 had evidence of induced retrograde RBBB. The average V-H interval increase with induction of RBBB was 53.7 ms for patients with AVRT and 54.4 ms for patients with AVNRT (P = NS). The average V-A interval increase with induction of RBBB was 13.6 ms with AVRT and 70.1 ms with AVNRT (P < 0.001). All patients with a greater V-H than V-A interval change had AVRT, and those with a smaller had AVNRT. Conclusions: Induction of retrograde RBBB during VEST is common during an electrophysiological study for SVT. The relative change in the intervals during induction of RBBB accurately differentiates between retrograde AVN and AP conduction.

Background With the increased number of implantable cardioverter-defibrillator (ICD) recipients and the frequent need for device upgrading, lead malfunction is a concern, but the optimal approach to managing nonfunctioning leads is unknown. Objective The purpose of this study was to determine the rate and characteristics of complications related to abandoned ICD leads. Methods Patients with abandoned leads were identified by retrospective review of the Mayo Clinic ICD database from August 1993 to May 2002. We reviewed the medical records to assess long-term follow-up for venous thromboembolic complications, device sensing malfunction, appropriateness of delivered shocks, defibrillation threshold (DFT) values before and after lead abandonment, and subsequent surgical procedures related to devices or leads. Results We identified 78 ICD patients (81% males; mean age 63 ± 14 years) with 101 abandoned leads (69 in the right ventricle, 31 in the right atrium or superior vena cava, 1 in the coronary sinus). During a mean follow-up of 3.1 ± 2.0 years, neither sensing malfunction nor venous thromboembolic complications were detected. DFT values were high in 13 patients (17%), but there was no significant increase in mean DFT values before and after lead abandonment in 43 patients for whom both values were available (16.2 ± 9.2 J before abandonment vs 14.1 ± 5.5 J after; P = .24). Fourteen patients (18%) required further ICD-related surgery; none of these operations were attributed to abandoned leads. Five-year rates of appropriate and inappropriate shocks were 25.9% and 20.5%, respectively. Conclusion Abandoning a nonfunctioning lead appears to be safe and does not pose a clinically significant additional risk of future complications.

UNLABELLED Flutter Ablation and Subsequent Arrhythmia. INTRODUCTION Patients with atrial flutter (AFL) treated medically are at high risk for subsequent development of atrial fibrillation (AF). Whether curative radiofrequency ablation of AFL can modify the natural history of arrhythmia progression is not clear. We aimed to determine whether ablation of AFL decreases the subsequent development of AF in patients without previous AF. METHODS AND RESULTS Patients with AFL as the sole atrial arrhythmia were selected from patients who underwent successful AFL ablation at Mayo Clinic between 1997 and 2003 (N = 137). The cohort was divided by presence (n = 50) or absence (n = 87) of structural heart disease. A control group comprised 59 patients with AFL and no history of paroxysmal AF, who received only medical therapy. Occurrence of AF after AFL ablation was compared among study groups and controls. Symptomatic AF occurred in 49 patients during 5 years of follow-up after AFL ablation, with similar frequency in both study groups. The cumulative probability of paroxysmal and chronic AF was similar in controls and each study group. By multivariate analysis, the AFL ablation procedure carries significant risk of AF occurrence during follow-up. Fifty patients discontinued antiarrhythmic drugs after AFL ablation, and the rate of cardioversions decreased. CONCLUSION Successful ablation of AFL does not improve the natural history of atrial arrhythmia progression; postablation AF is frequent. This suggests that AFL may be initiated by bursts of AF and that in the absence of AFL substrate the AF continues to progress.

We reviewed our experience in managing intracardiac ultrasound-detected left atrial thrombus and analyzed the impact of the timing of heparin therapy on thrombus incidence.We identified 508 patients undergoing ablation procedures for atrial fibrillation in which intracardiac ultrasound was used. All patients received unfractionated heparin during the procedure: 31 patients before the first transseptal puncture (preTS1), 257 between the first and second transseptal punctures (TS1-TS2), and 220 following both punctures (postTS2). By using intracardiac echocardiography (ICE), thrombus was detected in 30 of these 508 patients (5.9%). Of these, 29 were in the left atrium and constituted our study group. In 21 patients, the thrombi were successfully aspirated from the left atrium using strong suction through the transseptal sheath. All patients in whom thrombi were aspirated did well without neurological event or death. When patients received heparin therapy either preTS1 or TS1-TS2, there was a significant decrease in the occurrence of ICE-detected left atrial thrombus compared with those who received heparin postTS2 (0 of 31 patients (0%) preTS, 9 of 257 (3.5%) TS1-TS2, and 20 of 220 (9.1%) postTS2; (preTS1 vs postTS2, p = 0.01; preTS2 [preTS1 and TS1-TS2] vs postTS2, p0.001).Early administration of intravenous heparin, specifically before transseptal puncture, decreases the incidence of left atrial thrombi.

the American College of Cardiology Foundation Board of ssociation Science Advisory and Coordinating Committee, oard of Trustees in February 2008. iology Foundation, American Heart Association, and Heart s document be cited as follows: Epstein AE, DiMarco JP, I, Freedman RA, Gettes LS, Gillinov AM, Gregoratos G, y MA, Newby LK, Page RL, Schoenfeld MH, Silka MJ, CC/AHA/HRS 2008 guidelines for device-based therapy of report of the American College of Cardiology/American n Practice Guidelines (Writing Committee to Revise the deline Update for Implantation of Cardiac Pacemakers and oll Cardiol 2008;51:e1–62. This article h 2008 issue of H Copies: Thi College of C americanheart.o document, plea reprints@elsevie Permissions: tion of this doc College of Ca Society. Pleas elsevier.com. avid L. Hayes, MD, FACC, FAHA, FHRS* ark A. Hlatky, MD, FACC, FAHA . Kristin Newby, MD, FACC, FAHA ichard L. Page, MD, FACC, FAHA, FHRS ark H. Schoenfeld, MD, FACC, FAHA, FHRS ichael J. Silka, MD, FACC ynne Warner Stevenson, MD, FACC, FAHA‡ ichael O. Sweeney, MD, FACC*

Background— Obesity is a risk factor for atrial fibrillation and other cardiovascular conditions. Our objective was to determine whether catheter-based ablation effectively treated atrial fibrillation in obese patients. Methods and Results— Five hundred twenty-three consecutive patients with symptomatic, medication-refractory atrial fibrillation underwent catheter ablation. Patients were grouped by body mass index (lean, 2 ; overweight, 25 to 29.9 kg/m 2 ; obese, ≥30 kg/m 2 ). Outcome and quality of life were measured with a general health survey (Medical Outcomes Study 36-item Short-Form General Health Survey [SF-36]); patients were assessed before ablation and at 3 and 12 months after the procedure. Two hundred twenty-eight study patients (44%) were overweight, and 201 (38%) were obese. Twelve months after curative ablation, 72% of patients were free of atrial fibrillation without the use of antiarrhythmic agents; 84% were arrhythmia free when those receiving medication were included. Atrial fibrillation was eliminated in 75%, 72%, and 70% of the lean, overweight, and obese patients, respectively, at 12 months ( P =0.41, trend test). SF-36 scores were lower for patients with higher body mass index ( P P P Conclusions— Catheter ablation of atrial fibrillation was effective in obese patients. Coexistence of atrial fibrillation and obesity indicated lower SF-36 scores, but the improvement in quality of life was consistent across all body mass index categories.

Background: Cardiac resynchronisation therapy (CRT) improves outcomes in selected patients with heart failure and left ventricular dysfunction. One mechanism of benefit is believed to be favourable ventricular remodelling. Whether CRT also decreases the frequency of ventricular arrhythmias and risk of sudden death is unknown. Objective: To determine the effect of CRT on frequency of ventricular arrhythmias and appropriate ICD therapies. Design: Retrospective cohort study. Setting: Single-centre, tertiary care facility (Mayo Clinic). Patients: 52 patients (46 male), aged 70 (SD 10) years, who underwent upgrade from an implantable cardioverter defibrillator (ICD) to a CRT-defibrillator were included. Interventions: Upgrade of ICD to CRT-defibrillator. Main Outcome Measures: Frequency of ventricular arrhythmias prior to and following upgrade to CRT device. Results: Ejection fraction increased from 22% (SD 8%) to 27% (SD 11%) following CRT. However, the frequency of non-sustained ventricular arrhythmias, sustained ventricular arrhythmias, and ventricular fibrillation was not significantly changed prior to and following CRT (2.38 (SD 9.78) vs 58.51 (SD 412.73) per patient per month, p = 0.66; 0.07 (SD 0.17) vs 0.16 (SD 0.52), p = 0.70; 0.05 (SD 0.12) vs 0.25 (SD 1.40), p = 0.12). Conclusions: CRT is not associated with a decrease in the frequency of ventricular arrhythmia or appropriate device therapy. Thus, use of CRT alone is not beneficial in decreasing the frequency of ventricular arrhythmias or the risk of appropriate ICD therapies.

Ventricular conduction blocks (VCBs) identified on a 12-lead electrocardiogram (ECG) are associated with poor outcomes in patients with known cardiac disease. The prognostic implications of uncomplicated VCB (right or left bundle branch block [RBBB or LBBB], left anterior hemiblock) in patients without cardiac diagnoses, however, need to be reevaluated in the current therapeutic era. The purpose of this study was to determine long-term cardiac morbidity and mortality in a community-based population with electrocardiographically-identified VCB, documented normal left ventricular ejection fraction, and no diagnoses of cardiac disease at the time of the index ECG. A retrospective observational cohort study was undertaken of patients in Olmsted County, Minnesota, evaluated from 1975 to 1999. Kaplan-Meier survival analysis post-index electrocardiography was performed with median follow-up of 9.0 years; 706 patients (mean age 64 +/- 16 [SE] years) were identified. Of those, 12% had LBBB with left-axis deviation (LAD); 20% had LBBB without LAD; 26% had left anterior hemiblock; and 42% had RBBB. Kaplan-Meier analysis indicated a significant difference in cardiovascular morbidity risk among the VCB groups (p = 0.017) with left anterior hemiblock and LBBB with LAD, and these were associated with the highest 10-year cardiovascular morbidity risk (58% and 68%, respectively). The incidence of dilated cardiomyopathy was 3% in patients with LBBB with LAD compared with 0.85% in the overall cohort. Significant mortality differences were also demonstrated between LBBB with LAD compared with LBBB without LAD (p = 0.048), left anterior hemiblock compared with LBBB without LAD (p0.0001), and left anterior hemiblock compared with RBBB (p = 0.0007). In conclusion, the identification of uncomplicated VCB with LAD is associated with increased long-term cardiac morbidity/mortality risk, including the development of dilated and ischemic cardiomyopathy. Isolated VCB is an early marker of cardiac co-morbidities and potentially identifies a high-risk group of patients who warrant preventive intervention.

Although current evidence supporting a more precise strategy for identifying patients at highest risk for sudden cardiac death (SCD) is sparse, strategies for translating existing and future evidence into clinical practice and policy are needed today. A great many unanswered questions exist. Examples include the following: At what level of risk for SCD should we pursue further testing or therapy? How should clinical strategies ethically and economically balance alternative outcomes? How can we best translate optimal strategies into clinical practice so as to prevent tomorrow's SCDs? On July 20 and 21, 2006, a group of individuals with expertise in clinical cardiovascular medicine, biostatistics, economics, and health policy was joined by government (Food and Drug Administration; Centers for Medicare and Medicaid Services; National Heart, Lung, and Blood Institute; Agency for Healthcare Research and Quality), professional societies (Heart Rhythm Society), and industry to discuss strategies for risk assessment and prevention of SCD. The meeting was organized by the Duke Center for the Prevention of Sudden Cardiac Death and the Duke Clinical Research Institute. This article, the second of 2 documents, summarizes the policy discussions of that meeting, discusses an analytic framework for evaluating the risks and benefits associated with SCD prevention and risk stratification, and addresses the translation of SCD risk assessment strategies into practice and policy.

Accurate and timely prediction of sudden cardiac death (SCD) is a necessary prerequisite for effective prevention and therapy. Although the largest number of SCD events occurs in patients without overt heart disease, there are currently no tests that are of proven predictive value in this population. Efforts in risk stratification for SCD have focused primarily on predicting SCD in patients with known structural heart disease. Despite the ubiquity of tests that have been purported to predict SCD vulnerability in such patients, there is little consensus on which test, in addition to the left ventricular ejection fraction, should be used to determine which patients will benefit from an implantable cardioverter defibrillator. On July 20 and 21, 2006, a group of experts representing clinical cardiology, cardiac electrophysiology, biostatistics, economics, and health policy were joined by representatives of the US Food and Drug administration, Centers for Medicare Services, Agency for Health Research and Quality, the Heart Rhythm Society, and the device and pharmaceutical industry for a round table meeting to review current data on strategies of risk stratification for SCD, to explore methods to translate these strategies into practice and policy, and to identify areas that need to be addressed by future research studies. The meeting was organized by the Duke Center for the Prevention of SCD at the Duke Clinical Research Institute and was funded by industry participants. This article summarizes the presentations and discussions that occurred at that meeting.

Introduction: Primary prevention implantable cardioverter defibrillators (ICDs) reduce mortality in select patients with left ventricular systolic dysfunction (LVSD). The occurrence of device therapies after ICD implantation in contemporary clinical practice is not well described, especially in patient subgroups designated in the Centers for Medicare and Medicaid Services (CMS) 2005 Coverage with Evidence Development (CED). Methods: The Longitudinal Study of ICDs assessed rates and correlates of device therapies (overall and those requiring shock) up to 3 years post-implant among 2540 patients with LVSD receiving first-time primary prevention ICDs in 7 US health care systems from 2006-2009. Implant data from the National Cardiovascular Data Registry ICD Registry were linked to electronic longitudinal health care system data and a novel centrally adjudicated repository of device therapies abstracted from medical records. Proportional hazard models evaluated associations with device therapies by appropriateness, adjusted for demographic and clinical factors. Results: Subjects were 26% women, 35% =65 years (1.40, 1.04-1.88), and lower among 2009 implants compared to 2006 (0.66, 0.46-0.95). Regarding the 3 CMS CED patient subgroups, neither ejection fraction nor heart failure symptom severity was associated with device therapy; for LVSD etiology, the rate of inappropriate therapy was nominally but not significantly higher among subjects with non-ischemic cardiomyopathy of < 9 months duration (1.38, 0.88-2.18). Conclusions: In a representative cohort of primary prevention ICD patients in usual care, rates of device therapies were somewhat lower than in landmark trials, differed by some patient characteristics, but did not differ meaningfully for CMS CED subgroups.

Preamble e472 1. Introduction e473 2. General Principles e475 3. Sinus Tachyarrhythmias e480 4. Nonsinus Focal Atrial Tachycardia and MAT e481 5. Atrioventricular Nodal Reentrant Tachycardia e482 6. Manifest and Concealed Accessory Pathways e483 7. Atrial Flutter e485 8. Junctional Tachycardia e487 9. Special Populations e487

Jonathan L. Halperin, MD, FACC, FAHA, Chair Glenn N. Levine, MD, FACC, FAHA, Chair-Elect Jeffrey L. Anderson, MD, FACC, FAHA, Immediate Past Chair [¶][1] Nancy M. Albert, PhD, RN, FAHA[¶][1] Sana M. Al-Khatib, MD, MHS, FACC, FAHA Kim K. Birtcher, PharmD, AACC Biykem Bozkurt, MD, PhD, FACC

Background Patient sex and age may influence rates of death after receiving an implantable cardioverter‐defibrillator for primary prevention. Differences in outcomes other than mortality and whether these differences vary by heart failure symptoms, etiology, and left ventricular ejection fraction are not well characterized. Methods and Results We studied 2954 patients with left ventricular ejection fraction ≤0.35 undergoing first‐time implantable cardioverter‐defibrillator for primary prevention within the Cardiovascular Research Network; 769 patients (26%) were women, and 2827 (62%) were aged >65 years. In a median follow‐up of 2.4 years, outcome rates per 1000 patient‐years were 109 for death, 438 for hospitalization, and 111 for heart failure hospitalizations. Procedure‐related complications occurred in 8.36%. In multivariable models, women had significantly lower risks of death (hazard ratio 0.67, 95% CI 0.56 to 0.80) and heart failure hospitalization (hazard ratio 0.82, 95% CI 0.68 to 0.98) and higher risks for complications (hazard ratio 1.38, 95% CI 1.01 to 1.90) than men; patients aged >65 years had higher risks of death (hazard ratio 1.55, 95% CI 1.30 to 1.86) and heart failure hospitalization (hazard ratio 1.25, 95% CI 1.05 to 1.49) than younger patients. Age and sex differences were generally consistent in strata according to symptoms, etiology, and severity of left ventricular systolic dysfunction, except the higher risk of complications in women, which differed by New York Heart Association classification ( P =0.03 for sex–New York Heart Association interaction), and the risk of heart failure hospitalization in older patients, which differed by etiology of heart failure ( P =0.05 for age–etiology interaction). Conclusions The burden of adverse outcomes after receipt of an implantable cardioverter‐defibrillator for primary prevention is substantial and varies according to patient age and sex. These differences in outcome generally do not vary according to baseline heart failure characteristics.

ObjectivesThe purpose of this study was to assess the benefit of primary prevention implantable cardioverter defibrillators (ICDs) in women.BackgroundClinical trials of primary prevention ICDs enrolled a limited number of women.MethodsUsing a propensity score method, we matched 490 women≥65 years of age who received an ICD during a hospitalization for heart failure in the National Cardiovascular Data Registry ICD Registry from January 1, 2006, through December 31, 2007, to 490 ICD-eligible women without an ICD hospitalized for heart failure in the Get With The Guidelines for Heart Failure database from January 1, 2006, through December 31, 2009. The primary endpoint was all-cause mortality obtained from the Medicare Claims Database. An identical analysis was conducted in men.ResultsMedian follow-up for patients with an ICD was 4.6 years versus 3.2 years for patients with no ICD. Compared with women with no ICD, those with an ICD were younger and less frequently white. In the matched cohorts, the survival of women with an ICD was significantly longer than that of women without an ICD (adjusted hazard ratio: 0.79, 95% confidence interval: 0.66 to 0.95; p= 0.013). Similarly, men with an ICD had longer survival than men without an ICD (adjusted hazard ratio: 0.73, 95% confidence interval: 0.65 to 0.83; p< 0.0001). There was no interaction between sex and the presence of an ICD with respect to survival (p= 0.44).ConclusionsAmong older women with left ventricular dysfunction, a primary prevention ICD was associated with a significant survival benefit that was nearly identical to that seen in men. These findings support the use of primary prevention ICDs in eligible patients regardless of sex.

Background— Racial and ethnic minorities are under-represented in clinical trials of primary prevention implantable cardioverter-defibrillators (ICDs). This analysis investigates the association between primary prevention ICDs and mortality among Medicare, racial/ethnic minority patients. Methods and Results— Data from Get With The Guidelines-Heart Failure Registry and National Cardiovascular Data Registry’s ICD Registry were used to perform an adjusted comparative effectiveness analysis of primary prevention ICDs in Medicare, racial/ethnic minority patients (nonwhite race or Hispanic ethnicity). Mortality data were obtained from the Medicare denominator file. The relationship of ICD with survival was compared between minority and white non-Hispanic patients. Our analysis included 852 minority patients, 426 ICD and 426 matched non-ICD patients, and 2070 white non-Hispanic patients (1035 ICD and 1035 matched non-ICD patients). Median follow-up was 3.1 years. Median age was 73 years, and median ejection fraction was 23%. Adjusted 3-year mortality rates for minority ICD and non-ICD patients were 44.9% (95% confidence interval [CI], 44.2%–45.7%) and 54.3% (95% CI, 53.4%–55.1%), respectively (adjusted hazard ratio, 0.79; 95% CI, 0.63–0.98; P =0.034). White non-Hispanic patients receiving an ICD had lower adjusted 3-year mortality rates of 47.8% (95% CI, 47.3%–48.3%) compared with 57.3% (95% CI, 56.8%–57.9%) for those with no ICD (adjusted hazard ratio, 0.75; 95% CI, 0.67%–0.83%; P P =0.70). Conclusions— Primary prevention ICDs are associated with lower mortality in nonwhite and Hispanic patients, similar to that seen in white, non-Hispanic patients. These data support a similar approach to ICD patient selection, regardless of race or ethnicity.

Aims Trials of rate control vs. rhythm control for atrial fibrillation or flutter included few patients with new-onset arrhythmia. Our objective was to assess the relapse rate and the effect of the relapse of newonset atrial arrhythmias on mortality after direct-current cardioversion (DCCV). Methods and results A cohort of 351 patients with atrial fibrillation (new onset in 179) and 126 patients with atrial flutter (new onset in 78) was followed-up after DCCV. Cox proportional hazard models were used. Median age was 74.6 years. Mean follow-up for relapse was 7.7 months; for death, 29.4 months. Patients with new-onset atrial flutter [adjusted hazard ratio (HR) ¼ 1] were more likely to maintain sinus rhythm than the patients with recurrent atrial flutter (adjusted HR ¼ 2.5, P , 0.01), new-onset atrial fibrillation (adjusted HR ¼ 2.4, P , 0.01), or recurrent atrial fibrillation (adjusted HR ¼ 2.7, P , 0.01). Patients with new-onset atrial fibrillation were as likely to have relapses as patients with recurrent atrial fibrillation or flutter. Relapse of atrial arrhythmia after DCCV was associated with increased mortality (adjusted HR ¼ 3.1, P , 0.01). Conclusion DCCV is more successful in maintaining sinus rhythm in patients with new-onset atrial flutter than in patients with new-onset atrial fibrillation. Relapse of atrial arrhythmia after cardioversion is associated with increased mortality.

The clinical presentation of recurrent atrial fibrillation (AF) has been categorized into 3 general patterns: paroxysmal, persistent, and permanent AF. This community-based cohort study characterized the effect of the AF pattern on survival. Community residents in Olmsted County, Minnesota, with electrocardiographically proven new-onset AF during 1996 and 1997 were retrospectively identified and prospectively followed. Observed survival was estimated using the Kaplan-Meier method and compared with the expected survival. Log-rank tests were used for group comparisons. The association between the baseline variables and mortality was assessed using Cox proportional hazards models. Of 270 patients (mean +/- SD age 73 +/- 14 years; 148 men [55%]), 143 had paroxysmal AF, 40 had persistent AF, and 87 had permanent AF. The cohort's observed survival was significantly worse than expected (p0.001). The factors associated with increased mortality included older age, concomitant heart failure, and concomitant chronic obstructive pulmonary disease (all p0.001). Permanent AF was associated with higher mortality than paroxysmal AF (hazard ratio 1.6, 95% confidence interval 1.1 to 2.3). Persistent AF was associated with better survival (hazard ratio 0.3, 95% confidence interval 0.1 to 0.8). In conclusion, survival among patients with persistent AF was significantly better than that among patients with paroxysmal AF or permanent AF. The ability to maintain sinus rhythm may be associated with better survival.