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This international multidisciplinary document is intended to guide electrophysiologists, cardiologists, other clinicians, and health care professionals in caring for patients with arrhythmic complications of neuromuscular disorders (NMDs). The document presents an overview of arrhythmias in NMDs followed by detailed sections on specific disorders: Duchenne muscular dystrophy, Becker muscular dystrophy, and limb-girdle muscular dystrophy type 2; myotonic dystrophy type 1 and type 2; Emery-Dreifuss muscular dystrophy and limb-girdle muscular dystrophy type 1B; facioscapulohumeral muscular dystrophy; and mitochondrial myopathies, including Friedreich ataxia and Kearns-Sayre syndrome, with an emphasis on managing arrhythmic cardiac manifestations. End-of-life management of arrhythmias in patients with NMDs is also covered. The document sections were drafted by the writing committee members according to their area of expertise. The recommendations represent the consensus opinion of the expert writing group, graded by class of recommendation and level of evidence utilizing defined criteria. The recommendations were made available for public comment; the document underwent review by the Heart Rhythm Society Scientific and Clinical Documents Committee and external review and endorsement by the partner and collaborating societies. Changes were incorporated based on these reviews. By using a breadth of accumulated available evidence, the document is designed to provide practical and actionable clinical information and recommendations for the diagnosis and management of arrhythmias and thus improve the care of patients with NMDs. [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ahj.2010.07.032 Byline: Deepak Bhakta, Miriam R. Groh, Changyu Shen, Robert M. Pascuzzi, William J. Groh Abstract: Myotonic dystrophy type 1 (DM1) is a neurologic disorder with known cardiac involvement, including left ventricular systolic dysfunction (LVSD), heart failure (HF), atrioventricular and intraventricular conduction system disease, and sudden death. We studied the prevalence of these conditions and associated findings in a large population with DM1. Article History: Received 29 March 2010; Accepted 28 July 2010 Article Note: (footnote) Clinical Trial Registration: clinicaltrials.gov NCT00622453.

Background: Utilization rates (URs) for implantable cardioverter-defibrillators (ICDs) for primary prevention of sudden cardiac death (PPSCD) are lacking in the community. Objective: The purpose of this study was to establish the ICD UR in central Indiana. Methods: A query run on 2 hospitals in a health information exchange database in Indianapolis identified patients between 2011 and 2012 with left ventricular ejection fraction (EF) ≤0.35. ICD eligibility and utilization were determined from chart review. Results: We identified 1863 patients with at least 1 low EF study. Two cohorts were analyzed: 1672 patients without and 191 patients with International Classification of Diseases, Ninth Revision, Clinical Modification procedure code 37.94 for ICD placement. We manually reviewed a stratified (by hospital) random sample of 300 patients from the no-ICD procedure code cohort and found that 48 (16%) had no ICD but had class I indications for ICD. Eight of 300 (2.7%) actually had ICD implantation for PPSCD. Review of all 191 patients in the ICD procedure code cohort identified 70 with ICD implantation for PPSCD. The ICD UR (ratio between patients with ICD for PPSCD and all with indication) was 38% overall (95% confidence interval [CI] 28%–49%). URs were 48% for males (95% CI 34%–61%), 21% for females (95% CI 16%–26%, P = .0002 vs males), 40% for whites (95% CI 27%–53%), and 37% for blacks (95% CI 28%–46%, P = .66 vs whites). Conclusion: ICD UR is 38% among patients meeting class I indications, suggesting further opportunities for improving guideline compliance. This study also illustrates limitations in calculating ICD UR using large electronic repositories without hands-on chart review. [Copyright &y& Elsevier]

The muscular dystrophies are a group of inherited diseases affecting skeletal muscle that also affect cardiac muscle. Cardiac involvement occurs as a degenerative process with fibrosis and fatty replacement of the myocardium. Electrophysiologists are asked to participate in the care of muscular dystrophy patients because of the risk of atrial arrhythmias, conduction disease, bradycardia, ventricular arrhythmias, and sudden death. Duchenne, Becker, and limb-girdle types 2C−2F and 2I are muscular dystrophies in which the development of a dilated cardiomyopathy is common. Arrhythmias and conduction disease occur after the development of the dilated cardiomyopathy. Patients are considered for pacemakers or implantable cardioverter-defibrillators on the basis of guidelines used for nonischemic cardiomyopathies. Myotonic types 1 and 2, Emery-Dreifuss, limb-girdle type 1B, and facioscapulohumeral muscular dystrophies present with conduction disease and associated arrhythmias and variably with a dilated cardiomyopathy. In myotonic type 1, Emery-Dreifuss, and limb-girdle type 1B muscular dystrophies, conduction abnormalities are frequent and often require pacing. Recent studies support the use of prophylactic implantable cardioverter-defibrillators rather than pacemakers. In all the muscular dystrophies, respiratory muscle involvement can impact quality and quantity of life and needs to be factored in when considering a prophylactic device. [ABSTRACT FROM AUTHOR]

Background: There is controversy whether proceduralist-directed, nurse-administered propofol sedation (PDNAPS) is safe. Objective: To assess the frequency of adverse events when PDNAPS is used for implantable cardioverter-defibrillator (ICD)-related procedures and to determine the patient and procedural characteristics associated with adverse events. Methods: Consecutive ICD-related procedures using PDNAPS from May 2006 to July 2009 at a tertiary-care hospital were evaluated. Serious adverse events were defined as procedural death, unexpected transfer to an intensive care unit, respiratory failure requiring intubation/bag-mask ventilation, or hypotension requiring vasoconstrictor/inotrope support. Nonserious adverse events were defined as hypotension requiring fluid resuscitation or hypoxemia requiring augmented respiratory support with non-rebreather mask, oral airway, or jaw lift. Results: Of 582 patients (age 64 ± 14 years, 72.3% males) undergoing ICD-related procedures using PDNAPS, 58 (10.0%) patients had serious adverse events with no procedural death and 225 (38.7%) had nonserious adverse events. Longer procedure duration (relative risk [RR] = 2.1 per hour; 95% confidence interval [CI] = 1.6–2.8; P < .001) and biventricular implant (RR = 2.7; CI = 1.4–5.3; P = .003) were independent predictors of serious adverse events. A longer procedure duration (RR = 1.4 per hour; CI = 1.1–1.7; P = .001), heart failure class (RR = 1.4 per 1 class; CI = 1.1–1.7; P = .002), and use of propofol infusion (RR = 3.5; CI = 2.2–5.7; P < .001) were independent predictors of nonserious adverse events. Conclusion: PDNAPS for shorter ICD procedures including single- and dual-chamber implants, generator changes, and defibrillation threshold testing have acceptable rates of serious adverse events and manageable nonserious adverse events and should be considered for further study. Biventricular implants and other complex procedures should be done with an anesthesiologist. [Copyright &y& Elsevier]

Summary: Objectives: To evaluate the characteristics of volunteers responding to emergencies in the North American Public Access Defibrillation (PAD) Trial. Methods: The PAD Trial was a prospective evaluation of cardiac arrest survival in community facilities randomized to cardiopulmonary resuscitation (CPR) or to CPR with automated external defibrillators (AEDs). The PAD volunteers’ characteristics were analyzed using Poisson regression clustered on the facility and offset by the number of emergency episodes to which volunteers were exposed. Results: A total of 19,320 volunteers in 1260 facilities were trained to provide emergency care. Of these, 8169 volunteers were participating actively at their facility during a time when one or more emergency episodes occurred. There were 1971 emergency episodes responded to by 1245 volunteers. The treatment arm (CPR-only versus CPR+AED) was not associated with the likelihood of volunteer participation in an episode. Likewise, the volunteers’ age or sex did not affect response. Volunteers more likely to respond were supervisory/management or security personnel, non-minority participants, volunteers with previous CPR training, volunteers with previous experience in emergency care and those who passed the PAD CPR skills follow-up test. Volunteers who had a formal education beyond a high school level were less likely to respond. Conclusions: Volunteers with previous emergency training and positions of responsibility in their facility had a greater likelihood of participation in medical emergencies in the PAD Trial. [Copyright &y& Elsevier]

Background: Intrathecal clonidine (ITC) is used clinically to manage neuropathic pain but frequently causes hypotension and bradycardia due to centrally mediated sympatholytic effects.Objectives: The purpose of this study was to evaluate the cardiac electrophysiologic effects of thoracic ITC and its effects on ischemia-provoked ventricular arrhythmias.Methods: Twelve mongrel dogs with healed myocardial infarctions and heart failure were evaluated. ITC was delivered locally via catheter to the T2-T4 spinal segments and was dosed to reduce heart rate (HR) by >20% to 25%. Electrophysiologic testing was performed before and after ITC. Transient (4-minute) myocardial ischemia was induced via left circumflex coronary artery occlusion on two separate occasions to provoke ventricular arrhythmias (ventricular tachycardia [VT]/ventricular fibrillation [VF]). Ischemic episodes were separated by 1 to 2 days, and dogs were randomly assigned to receive ITC or intrathecal saline flush (control) prior to the first or the second ischemic episode.Results: ITC produced significant decrease in HR (31%) and increases in PR interval (22%), Wenckebach cycle length (122%), and atrial and ventricular effective refractory periods (19% and 9%, respectively) but had no significant effect on systemic blood pressure. The occurrence of VT/VF was reduced from 9 of 12 to 3 of 12 dogs when ITC was administered prior to transient myocardial ischemia (P = .04). ITC also blunted ischemia-induced HR increase by 74%.Conclusion: ITC reduced ischemia-induced VT/VF in a canine model of healed myocardial infarction with superimposed heart failure and acute ischemia. Results from electrophysiologic testing were consistent with a clonidine-induced reduction in cardiac sympathetic activity from the spinal cord. These data suggest that ITC administration may be a novel approach to treating ventricular arrhythmias. [ABSTRACT FROM AUTHOR]

Background: Development of experimental animal models has played an invaluable role in understanding the mechanisms of ventricular arrhythmias. Objectives: The purpose of this study was to evaluate a new canine model of myocardial infarction (MI), heart failure, and ischemic ventricular arrhythmias in an attempt to replicate clinical conditions. Methods: Thirty-six mongrel dogs underwent placement of a permanent ventricular pacemaker and induction of an anterior MI by percutaneous transcatheter embolization of polyvinyl foam particles into the left anterior descending coronary artery (just distal to the first septal branch). After a 2-week recovery period, heart failure was induced by continuous rapid ventricular pacing at 200 to 240 ppm for 3 weeks. Transient (4-minute) myocardial ischemia was induced via balloon occlusion of the proximal left circumflex coronary artery. Echocardiographic and electrophysiologic testing was performed before MI creation and repeated prior to acute ischemia induction. Results: Seven dogs (19%) died within several hours of MI creation. All surviving dogs developed severe left ventricular systolic dysfunction. Significant increases in the intraatrial and intraventricular conduction intervals were observed following MI creation and heart failure induction compared with baseline values, as evidenced by increases in the duration of the P wave and QRS complex. Significant increases in corrected QT interval and ventricular refractoriness were observed. Acute transient ischemia induced sustained ventricular tachycardia or ventricular fibrillation in 21 of 29 dogs (72%). Conclusion: This canine model can serve as a useful tool for studying ventricular arrhythmias during the interactions of healed infarction, heart failure, increased sympathetic tone, and myocardial ischemia. [ABSTRACT FROM AUTHOR]

Objectives: The purpose of this study was to determine whether gender differences exist in the characteristics and outcomes for out-of-hospital cardiac arrest (OHCA) occurring in a rural setting.Background: In urban settings, women have a lower incidence of OHCA than men but otherwise a comparable survival for ventricular fibrillation (VF) OHCA. Whether OHCA gender differences exist in rural settings is not clear.Methods: The study consisted of a prospective collection and analysis of nontraumatic, adult OHCA prompting a 911 call in six rural Indiana counties.Results: Over an average period of 2.2 years, 138 women and 250 men experienced OHCA (annual incidence rate: 56.4 per 100,000 men and 29.3 per 100,000 women). Women were older, less likely to experience OHCA in a public setting, more likely to be in an extended care facility, and less likely to have a witnessed arrest than were men. Women were less likely to present with an initial rhythm of VF than men (33.3% vs 53.6%, P < .001). Women in VF had a longer time interval from 911 call to first shock compared with men. Women had poorer survival to hospital discharge for all OHCA (2.2% vs 7.2%, P = .04) and VF OHCA (2.2% vs 13.4%, P = .05) compared with men. After age adjustment, female gender remained associated with a poorer OHCA survival outcome. With adjustment for all significant arrest characteristics, female gender was no longer associated with survival.Conclusions: In a rural population, women suffering OHCA have a dismal survival rate likely because of multiple unfavorable arrest characteristics. [ABSTRACT FROM AUTHOR]

Objectives: We used optical mapping to characterize the reentrant circuit of ventricular tachycardia (VT) during acute myocardial infarction (MI) in isolated canine left ventricular preparations.Background: The nature of the reentrant circuit that underlies VT during acute MI is not well understood.Methods: Using optical mapping in isolated canine left ventricular preparations, we characterized the reentrant circuit of monomorphic VT (mean cycle length 245.3 +/- 15.6 ms, n = 7) induced by programmed stimulation during acute MI.Results: Optical mapping during VT revealed a functional reentrant circuit consisting of four components: (1) a protected isthmus located between the infarction area and the functional line of block; (2) an entrance site located at one end of the isthmus; (3) an exit site located at the other end of the isthmus; and (4) an outer loop consisting of nonischemic normal tissue, connecting the exit and entrance sites. Rate-dependent slow conduction within the border zone was associated with significant changes (n = 6) in action potential amplitude (99.1 +/- 0.4 vs 71.4 +/- 0.6 mV, P < .01), maximal diastolic potential (-80.6 +/- 0.2 vs -65.4 +/- 0.6 mV, P < .05), action potential duration at 90% repolarization (APD(90); 188.4 +/- 1.0 vs 164.3 +/- 3.1 ms, P < .05), and dV/dt (302.4 +/- 7.9 vs 168.5 +/- 3.6 V/s, P < .05). Compared to preparations with no inducible VT (n = 7), formation of a functional line of block was the key mechanism for initiation of functional reentry in preparations with VT. When comparing preparations with sustained and nonsustained VT, preservation of slow conduction over the isthmus was the key component for maintenance of sustained VT.Conclusions: The reentrant circuit of monomorphic VT in the setting of acute MI involved both the infarction border zone and nonischemic normal tissue. The underlying mechanism is related to the presence of rate-dependent slow conduction and the development of a functional line of block in the border zone. [ABSTRACT FROM AUTHOR]

Evaluates the use of implantable cardioverter-defibrillators in patients with the long QT syndrome. Consideration of death as sudden cardiac death; Presence in the patients of an echocardiogram or cardiac catheterization; Absence in the patients of structural heart disease.

Summary: The adverse event (AE) profile of lay volunteer CPR and public access defibrillation (PAD) programs is unknown. We undertook to investigate the frequency, severity, and type of AE''s occurring in widespread PAD implementation. Design: A randomized-controlled clinical trial. Setting: One thousand two hundred and sixty public and residential facilities in the US and Canada. Participants: On-site, volunteer, lay personnel trained in CPR only compared to CPR plus automated external defibrillators (AEDs). Intervention: Persons experiencing possible cardiac arrest receiving lay volunteer first response with CPR+AED compared with CPR alone. Main outcome measure: An AE is defined as an event of significance that caused, or had the potential to cause, harm to a patient or volunteer, or a criminal act. AE data were collected prospectively. Results: Twenty thousand three hundred and ninety six lay volunteers were trained in either CPR or CPR+AED. One thousand seven hundred and sixteen AEDs were placed in units randomized to the AED arm. There were 26,389 exposure months. Only 36 AE''s were reported. There were two patient-related AEs: both patients experienced rib fractures. There were seven volunteer-related AE''s: one had a muscle pull, four experienced significant emotional distress and two reported pressure by their employee to participate. There were 27 AED-related AEs: 17 episodes of theft involving 20 devices, three involved AEDs that were placed in locations inaccessible to the volunteer, four AEDs had mechanical problems not affecting patient safety, and three devices were improperly maintained by the facility. There were no inappropriate shocks and no failures to shock when indicated (95% upper bound for probability of inappropriate shock or failure to shock=0.0012). Conclusions: AED use following widespread training of lay-persons in CPR and AED is generally safe for the volunteer and the patient. Lay volunteers may report significant, usually transient, emotional stress following response to a potential cardiac arrest. Within the context of this prospective, randomized multi-center study, AEDs have an exceptionally high safety profile when used by trained lay responders. [Copyright &y& Elsevier]

Abstract: The high-affinity choline transporter (CHT1) system is an attractive target for the development of positron emission tomography (PET) biomarkers to probe brain, cardiac, and cancer diseases. An efficient and convenient synthesis of new radiolabeled CHT1 inhibitors [11C]hemicholinium-3 and [18F]hemicholinium-3 by solid-phase extraction (SPE) technique using a cation-exchange CM Sep-Pak cartridge has been well developed. The preliminary evaluation of both tracers through biodistribution studies in 9L-glioma rats has been performed, and the uptakes in the heart and tumor were observed, while very low brain uptake was seen. [Copyright &y& Elsevier]

Abstract: [11C]Hemicholinium-15 ([11C]HC-15) and [18F]hemicholinium-15 ([18F]HC-15) have been synthesized as new potential PET tracers for the heart high-affinity choline uptake (HACU) system. [11C]HC-15 was prepared by N-[11C]methylation of the appropriate precursor, 4-methyl-2-phenyl-morpholin-2-ol, using [11C]CH3OTf in 55–70% radiochemical yield decay corrected to end of bombardment (EOB) and 2–3Ci/μmol specific activity at end of synthesis (EOS). [18F]HC-15 was prepared by N-[18F]fluoromethylation of the precursor using [18F]FCH2OTf in 20–30% radiochemical yield decay corrected to EOB and >1.0Ci/μmol specific activity at EOS. The biodistribution of both compounds was determined in rats at 20min post-intravenous injection, and the results show the heart region uptakes 1.32±0.75%ID/g in R-ventricle for [11C]HC-15 and 1.28±0.81%ID/g in L-ventricle for [18F]HC-15, respectively. The dynamic PET imaging studies of [11C]HC-15 in rats were acquired 60min post-intravenous injection of the tracer using the IndyPET-II scanner. For the blocking experiments, the rats were intravenously pretreated with 3.0mg/kg of unlabeled HC-15 prior to [11C]HC-15 injection. [11C]HC-15 rat heart PET studies show rapid heart uptake to give clear heart images. The rat heart PET blocking studies found no significant blocking effect. The dynamic PET studies in normal and ablated dogs were performed using Siemens PET scanner with [13N]NH3, [11C]HC-15, and [18F]HC-15. PET studies in dogs of both [11C]HC-15 and [18F]HC-15 also show significant heart uptake and give images of the heart. However, there is no significant change in [11C]HC-15 L-ventricle uptake following radiofrequency ablation in the dog. These results suggest that the localization of HC-15 tracers in the heart is mediated by non-specific processes, and the visualization of HC-15 tracers on the heart is related to non-specific binding of HACU. [Copyright &y& Elsevier]

Despite substantial progress in the diagnosis and treatment of acute ST-segment elevation myocardial infarction (STEMI), implementation of this knowledge into routine clinical practice has been variable. It has become increasing clear that primary percutaneous coronary intervention (PCI) is the preferred method of reperfusion if it can be performed in a timely manner. Recent European data suggest that transfer for direct PCI may also be preferable to fibrinolytic therapy. We believe it is time to establish a national policy for treatment of patients with STEMI to develop a coordinated system of care similar to that of the level 1 trauma system. [Copyright &y& Elsevier]

Abstract: A new AChE tracer N-[11C]methyl-3-[[(dimethylamino)carbonyl]oxy]-2-(2′,2′-diphenylpropionoxymethyl)pyridinium ([11C]MDDP, [11C]1) has been synthesized in 40–65% radiochemical yield. Initial PET dynamic studies of [11C]MDDP in rat heart showed rapid heart uptake and blood pool clearance to give high-quality heart images. Blocking studies of [11C]MDDP with pretreatment drug neostigmine in rats found only minor reductions in rat heart [11C]MDDP retention. The results suggest that [11C]MDDP delineates the heart very clearly, and the uptakes of [11C]MDDP in rat heart might be related to non-specific binding. [Copyright &y& Elsevier]

A series of 11C-labeled analogs of the acetylcholinesterase (AChE) inhibitor pyridostigmine have been synthesized for evaluation as new potential positron emission tomography (PET) imaging agents for heart AChE. The appropriate precursors for radiolabeling were slightly modified from commercial reagents. The new tracers [11C]pyridostigmine (1), [11C]para-pyridostigmine (2) and [11C]ortho-pyridostigmine (3) were prepared by N-[11C]methylation of the precursors using [11C]methyl triflate. Pure target compounds were isolated by a solid-phase extraction (SPE) purification procedure with 60–85% radiochemical yields (decay corrected to end of bombardment), and a synthesis time of 10–15 min. The initial PET dynamic studies of compounds (1–3) in rat heart showed rapid heart uptake and blood pool clearance to give high quality heart images. These results suggest the new tracers delineate the heart very clearly and could be potential heart AChE imaging agents. [Copyright &y& Elsevier]

Background: Measuring survival from sudden out-of-hospital cardiac arrest (OOH-CA) is often used as a benchmark of the quality of a community’s emergency medical service (EMS) system. The definition of OOH-CA survival rates depends both upon the numerator (surviving cases) and the denominator (all cases). Purpose: The purpose of the public access defibrillation (PAD) trial was to measure the impact on survival of adding an automated external defibrillator (AED) to a volunteer response system trained in CPR. This paper reports the definition of OOH-CA developed by the PAD trial investigators, and it evaluates alternative statistical methods used to assess differences in reported “survival.” Methods: Case surveillance was limited to the prospectively determined geographic boundaries of the participating trial units. The numerator in calculating a survival rate should include only those patients who survived an event but who otherwise would have died except for the application of some facet of emergency medical care—in this trial a defibrillatory shock. Among denominators considered were: total population of the study unit, all deaths within the study unit, and documented ventricular fibrillation cardiac arrests. The PAD classification focused upon cases that might have benefited from the early use of an AED, in addition to the likely benefit from early recognition of OOH-CA, early access of EMS, and early cardiopulmonary resuscitation (CPR). Results of this classification system were used to evaluate the impact of the PAD definition on the distribution of cardiac arrest case types between CPR only and CPR + AED units. Results: Potential OOH-CA episodes were classified into one of four groups: definite, probable, uncertain, or not an OOH-CA. About half of cardiac arrests in the PAD units were judged to be definite OOH-CA events and therefore potentially treatable with an AED. However, events that occurred in CPR-only units were less likely to be classified as definite or probable OOH-CA events than those in CPR + AED units (43% versus 55%, odds ratio 0.78, 95% confidence interval 0.57–1.07). The study retained sufficient power to permit a statistical analysis of the alternative hypothesis that the CPR + AED method results in twice as many survivors as a CPR-only approach. The result is critically dependent on the denominator used for calculating survival rates; but the analysis does not require a denominator as the numerators will have identical Poisson distributions (counts for rare events) under the null hypothesis since randomization distributes the risk of cardiac arrest evenly between the two arms. Conclusion: Reported OOH-CA rates and survival rates vary widely, depending upon the definitions applied to events. Rigorous assessment of treatments applied to improve survival can be obscured by inappropriate definitions. Large-scale randomized interventions designed to improve survival from OOH-CA can be evaluated based upon the absolute numbers of patients surviving, rather than a change in the proportion surviving. [Copyright &y& Elsevier]