Canadian Registry of Implantable Electronic Device Outcomes: Surveillance of High-Voltage Leads

Background

Cardiac implantable electrical devices (CIEDs) are subject to advisories and complications that can result in morbidity and mortality for patients; there is currently no system in Canada to track these.

Epidemiology of Kawasaki Disease in Canada 2004 to 2014: Comparison of Surveillance Using Administrative Data vs Periodic Medical Record Review

Background

We have previously documented an increase in the incidence of Kawasaki disease (KD) in Ontario followed by a stabilization from 1995 to 2006. We sought to validate the estimation of incidence of KD using administrative data and to describe the epidemiology of KD across Canada from 2004 to 2014.

A Population-Based Study of Adherence to Guideline Recommendations and Appropriate-Use Criteria for Implantable Cardioverter Defibrillators

Studies evaluating physician adherence to guideline recommendations for implantable cardioverter defibrillator (ICD) therapy are sparse, and none exist for the application of appropriate-use criteria (AUC) in clinical practice. As part of a quality improvement initiative, a review of all ICD procedures was performed from January 1, 2015 to December 31, 2016 in Alberta, Canada, to evaluate the proportion of patients receiving appropriate ICD therapy and to identify reasons for nonadherence. Our device-implant process involves an electrophysiologist or implanting cardiologist evaluation, reminders of ICD eligibility criteria on the device requisition, and peer-review consensus. Implants were classified according to the 2008 American College of Cardiology/American Heart Association/Heart Rhythm Society (ACC/AHA/HRS) ICD guidelines, 2013 Canadian Cardiovascular Society (CCS) Cardiac Resynchronization Therapy (CRT) guidelines, and 2013 AUC. There were 1,300 ICD procedures performed, and the mean age was 63.8 ± 12.9 years; 79% were male; the mean ejection fraction was 0.32 ± 0.13, and 69% were for primary prevention. Among all implants, < 1% were discordant with American College of Cardiology/American Heart Association/Heart Rhythm Society (ACC/AHA/HRS) recommendations. Among CRT implants, 10% were inconsistent with Canadian Cardiovascular Society (CCS) recommendations. According to AUC, 92% of implants were appropriate. Reasons for nonadherence to ACC/AHA/HRS recommendations included QRS width < 120 msec (n = 3), LVEF > 0.35 (n = 2) and recent myocardial infarction (MI) (n = 1). The most common reason for nonadherence to AUC was the absence of criteria for classification (n = 57, 4%). In this population-based study, we found that a process of specialist evaluation, eligibility reminders on device forms, and peer-review consensus may improve adherence to guideline recommendations and AUC for ICD therapy.     

Integrated Management Approach to Atrial Fibrillation Care: A Cost Utility Analysis

BackgroundAtrial fibrillation (AF) is a substantial burden on health care. Combined specialist and nurse-based AF clinics are associated with improved outcomes. However, Canadian data on the cost-effectiveness of this integrated management approach to AF care are lacking.MethodsWe evaluated health care costs and outcomes of 413 patients with newly-diagnosed AF in 3 emergency departments in Nova Scotia between January 1, 2011 and January 31, 2014. Using a before-after study design, patients were divided into usual care (228 patients) and intervention (185 patients) groups. The intervention was a nurse-run, physician-supervised AF clinic. Costs and quality-adjusted life years (QALYs) were compared between usual care and intervention. Costs were those incurred because of the clinical outcome, bleeding events, medications, and cardiovascular-related procedures. Probabilistic analysis was conducted to assess uncertainty.ResultsThe AF clinic was associated with an average cost reduction of CAD$210.83 and an average improvement in QALY of 0.0007 per patient. The AF clinic was dominant over usual care despite higher operational and medication costs over 1 year. It provided greater cost-saving in approximately 66% of probabilistic analysis simulations and generated more QALYs in approximately 92% of simulations. An incremental cost-effectiveness ratio < $50,000 was found in 68% of simulations.ConclusionsThe present study provides guidance regarding the cost-effectiveness of an integrated management approach compared with usual specialty care of AF in a Canadian setting. We recommend further study be undertaken that prospectively plans for economic evaluation before definitive assessments of cost-effectiveness can be made.     

Performance of re-used pacemakers and implantable cardioverter defibrillators compared with new devices at Groote Schuur Hospital in Cape Town,South Africa

Objectives

Little is known about the performance of re-used pacemakers and implantable cardioverter defibrillators (ICDs) in Africa. We sought to compare the risk of infection and the rate of malfunction of re-used pacemakers and ICDs with new devices implanted at Groote Schuur Hospital in Cape Town, South Africa.

Methods

This was a retrospective case comparison study of the performance of re-used pacemakers and ICDs in comparison with new devices implanted at Groote Schuur Hospital over a 10-year period. The outcomes were incidence of device infection, device malfunction, early battery depletion, and device removal due to infection, malfunction, or early battery depletion.

Results

Data for 126 devices implanted in 126 patients between 2003 and 2013 were analysed, of which 102 (81%) were pacemakers (51 re-used and 51 new) and 24 (19%) were ICDs (12 re-used and 12 new). There was no device infection, malfunction, early battery depletion or device removal in either the re-used or new pacemaker groups over the median follow up of 15.1 months [interquartile range (IQR), 1.3–36.24 months] for the re-used pacemakers, and 55.8 months (IQR, 20.3–77.8 months) for the new pacemakers. In the ICD group, no device infection occurred over a median follow up of 35.9 months (IQR, 17.0–70.9 months) for the re-used ICDs and 45.7 months (IQR, 37.6–53.7 months) for the new ICDs. One device delivered inappropriate shocks, which resolved without intervention and with no harm to the patient. This re-used ICD subsequently needed generator replacement 14 months later. In both the pacemaker and ICD groups, there were no procedure-non-related infections documented for the respective follow-up periods.

Conclusion

No significant differences were found in performance between re-used and new pacemakers and ICDs with regard to infection rates, device malfunction, battery life and device removal for complications. Pacemaker and ICD re-use is feasible and safe and is a viable option for patients with bradyarrhythmias and tachyarrthythmias.     

Arrhythmias in Adults With Congenital Heart Disease: What the Practicing Cardiologist Needs to Know

The expanding population of adults with congenital heart disease (CHD) combined with the pervasiveness of arrhythmias has resulted in the rapid growth of a dedicated sector of cardiology at the intersection between 2 subspecialties: electrophysiology and adult CHD. Herein, practical considerations are offered regarding urgent referral for catheter ablation of atrial arrhythmias, anticoagulation, and primary prevention implantable cardioverter-defibrillators (ICDs). Patients with Ebstein anomaly and ventricular pre-excitation should be referred promptly due to the high prevalence of multiple accessory pathways and increased incidence of atrial tachyarrhythmias, which may be poorly tolerated. In patients with transposition of the great arteries and atrial switch surgery, atrial arrhythmias should be managed without delay because they could provoke ventricular arrhythmias and sudden death. Other settings in which atrial arrhythmias can be poorly tolerated include single ventricle physiology and Eisenmenger syndrome. Long-term anticoagulation is generally indicated in patients with sustained intra-atrial reentrant tachycardia or atrial fibrillation and a mechanical valve, moderate or severe systemic atrioventricular valve stenosis, traditional risk factors for stroke, and/or moderate or complex CHD. The only class I indication for a primary prevention ICD is a systemic left ventricular ejection fraction ≤ 35%, with biventricular physiology, and New York Heart Association class II or III symptoms. ICD therapy is reasonable in selected adults with tetralogy of Fallot and multiple risk factors for sudden death identified by observational studies. Indications for ICDs in patients with systemic right ventricles and univentricular hearts are less well established, underscoring the need for future research to inform risk stratification.     

Pacemakers and implantable cardioverter-defibrillators in pediatric patients

The use of pacemakers and implantable cardioverter-defibrillators (ICDs) in infants, children, and patients with congenital heart disease presents unique challenges and considerations. They include uncommon indications for device implantation, innovative approaches to lead implantation and configuration, and age-dependent and disease-specific aspects of device programming. In this review, the current indications for pacemaker and ICD implantation in young patients are discussed, followed by consideration of the approaches to lead and device placement in very small patients and those with complex congenital heart disease, in whom unique problems may be encountered. The limitations of programmability of current pacemakers and ICDs when used in young patients are discussed, followed by an analysis of long-term device follow-up and potential late complications.     

Magnetic resonance imaging in individuals with cardiovascular implantable electronic devices.

Magnetic resonance (MR) imaging has unparalleled soft-tissue imaging capabilities. The presence of devices such as pacemakers and implantable cardioverter-defibrillators (ICDs), however, was historically considered a contraindication to MR imaging. We summarize the potential hazards of the device-MR environment interaction, and present updated information regarding in vitro and in vivo experiments suggesting that certain pacemaker and ICD systems may indeed be MR-safe. Recent reports on several hundred patients with implantable pacemakers and ICDs who underwent MR scan safely indicate that, under certain conditions, individuals with these implanted systems may benefit from MR imaging. We believe that, on a case-by-case basis, the diagnostic benefit from MR imaging outweighs the presumed risks for some pacemaker and ICD patients. Thus for some patients, the risks presented by MR imaging under specific, characterized scanning and monitoring conditions may be acceptable given the diagnostic benefit of this powerful imaging modality. This may have major clinical implications on current imaging practice. A strategy for the performance of MR imaging in these individuals is proposed.     

Biventricular implantable cardioverter defibrillators improve survival compared with biventricular pacing alone in patients with severe left ventricular dysfunction

INTRODUCTION: Biventricular cardiac pacemakers provide important hemodynamic benefit in selected patients with heart failure and severe left ventricular (LV) dysfunction. Nevertheless, these patients remain at high mortality risk. To address this issue, we examined mortality outcome in patients with heart failure treated with biventricular pacemakers alone and those treated with biventricular implantable cardioverter defibrillators (ICDs). METHODS AND RESULTS: The study population consisted of 126 consecutive patients with LV dysfunction and heart failure who received either a biventricular ICD (n = 62) or a biventricular pacemaker (n = 64) between January 1998 and December 2002. A minimum 12 months of follow-up was obtained in all survivors. ICD indications were conventional in all patients. Kaplan-Meier actuarial method and log rank statistics were used to calculate and compare survival rates in both groups. Comparison of mortality rates utilized Chi-square test. The two groups had similar clinical and demographic features, LV ejection fraction, and medication use. Average follow-up times were 13 +/- 11.8 months (range 4-60) and 18 +/- 13.2 months (range 0.5-53) for biventricular ICD and pacemaker groups, respectively. Overall mortality rate was significantly lower in the biventricular ICD group (13%, 8 deaths) compared to the pacemaker group (41%, 26 deaths) (P = 0.01). Further, the predominant survival benefit for ICD-treated patients becomes evident after the first 12 months of follow-up. CONCLUSION: The findings in this study, although necessarily limited in their interpretation by the absence of treatment randomization, suggest that biventricular ICDs offer a survival benefit compared to biventricular pacing alone. Furthermore, this benefit may be most apparent if other clinical factors do not preclude patient survival >1 year postimplant.     

Pacemaker and implantable cardioverter-defibrillator use in a US myotonic dystrophy type 1 population

Pacemakers and ICDs in Myotonic Dystrophy. Introduction: We assessed implant rates, indications, characteristics, and outcomes in patients with the neuromuscular disease, myotonic dystrophy type 1 (DM1) receiving a pacemaker or an implantable cardioverter‐defibrillator (ICD). Methods and Results: Device use was evaluated in a prospective, multicenter registry of 406 genetically confirmed adult patients followed for 9.5 ± 3.2 years. Forty‐six (11.3%) had or received a pacemaker and 21 (5.2%) received an ICD. Devices were primarily implanted for asymptomatic conduction abnormalities and left ventricular (LV) systolic dysfunction. However, 7 (15.2%) pacemakers were implanted for third‐degree atrioventricular block and 6 (28.6%) ICDs were implanted for ventricular tachyarrhythmias (ventricular tachycardia [VT] or fibrillation [VF]). Patients receiving devices were older and more frequently had heart failure, LV systolic dysfunction, atrial tachyarrhythmias, and ECG conduction abnormalities compared to nondevice patients. Five (10.9%) pacemaker patients underwent upgrade to an ICD, 3 for LV systolic dysfunction, 1 for VT/VF, and 1 for progressive conduction disease. Seventeen (27.4%) of the 62 patients with devices were pacemaker‐dependent at last follow‐up. Three (14.3%) ICD patients had appropriate therapies. Twenty‐four (52.2%) pacemaker patients died including 13 of respiratory failure and 7 of sudden death. Seven (33.3%) ICD patients died including 2 of respiratory failure and 3 of sudden death. The patients with ICDs and sudden death all had LV systolic dysfunction and 1 death was documented due to inappropriate therapies. Conclusions: DM1 patients commonly receive antiarrhythmia devices. The risk of VT/VF and sudden death suggests that ICDs rather than pacemakers should be considered for these patients. (J Cardiovasc Electrophysiol, Vol. 22, pp. 1369‐1375, December 2011)     

29例起搏器和置入式心脏复律除颤器导线断裂的临床分析

目的分析心脏起搏器和置入式心脏复律除颤器(ICD)导线断裂可能的原因、部位和处理方法。方法回顾性分析1982年1月至2004年11月置入的永久起搏器和ICD,通过随访症状、程控测试、检查X线胸片及心电图,及时发现导线断裂,给予相应处理,并随访观察疗效。结果分析置入的起搏器4698台和ICD161台,共发现导线断裂29例、导线31支,发生率0.6%;其中经锁骨下静脉置入组导线断裂发生率0.9%,头静脉置入组0.4%,P=0.04。断裂部位锁骨下22例,囊袋内6例,心室内1例。29例患者中,24例置入新导线。3例心房导线断裂,将起搏器由DDD程控为VVI工作方式。处理后平均随访(55.6±16.1)个月。1例因保留的断裂导线露出皮肤,引发感染,开胸取出导线。结论起搏器和ICD导线置入应首选头静脉切开途径,其次选择经锁骨下静脉外侧端穿刺置管。导线断裂部位主要发生在锁骨下,定期复查可以及时发现导线断裂,妥善处理。     

Potential interference of small neodymium magnets with cardiac pacemakers and implantable cardioverter-defibrillators

BACKGROUND: Magnetic fields may interfere with the function of cardiac pacemakers and implantable cardioverter-defibrillators (ICDs). Neodymium-iron-boron (NdFeB) magnets, which are small in size but produce strong magnetic fields, have become widely available in recent years. Therefore, NdFeB magnets may be associated with an emerging risk of device interference. OBJECTIVE: We conducted a clinical study to evaluate the potential of small NdFeB magnets to interfere with cardiac pacemakers and ICDs. METHODS: The effect of four NdFeB magnets (two spherical magnets 8 and 10 mm in diameter, a necklace made of 45 spherical magnets, and a magnetic name tag) was tested in forty-one ambulatory patients with a pacemaker and 29 patients with an ICD. The maximum distance at which the magnetic switch of a device was influenced was observed. RESULTS: Magnetic interference was observed in all patients. The maximum distance resulting in device interference was 3 cm. No significant differences were found with respect to device manufacturer and device types. CONCLUSION: Small NdFeB magnets may cause interference with cardiac pacemakers and ICDs. Patients should be cautioned about the interference risk associated with NdFeB magnets during daily life.     

ICD-Antiarrhythmic Drug and ICD-Pacemaker Interactions

Implantable Cardioverter Defibrillators. Antiarrhythmic drugs and separate bradycardia pacing systems are prescribed commonly in patients with implantable cardioverter defibrillators (ICDs). Adverse effects of antiarrhythmic drugs on ICD function and adverse interactions between ICDs and pacemakers have been documented. The effect of antiarrhythmic drugs on the defibrillation threshold (DFT) in patients has not been well assessed. Most studies have been performed in animal models in which cardiac function was normal and drug doses were supraphysiologic. In addition, most studies have utilized monophasic defibrillation shock waveforms and epicardial lead systems. Despite the lack of clinical data applicable to current defibrillation systems, it appears that chronic amiodarone administration causes a significant DFT increase. In addition, antiarrhythmic drugs can influence antitachycardia pacing and tachycardia sensing. Defibrillation shocks can cause transient failure of pacemaker sensing and pacing, and cause spurious pacemaker reprogramming. Pacemaker function can result in ICD oversensing, leading to inappropriate therapy, or cause ICD undersensing, potentially resulting in failure to deliver therapy during ventricular fibrillation. The susceptibility of an ICD to undersensing appears related to the amplitude of the pacing stimulus artifact recorded by the ICD rate-sensing circuit and to the characteristics of the fibrillation electrogram. Preliminary data suggest that undersensing of ventricular fibrillation by current ICDs is an unlikely event.     

经静脉拔除心内膜导线:目前认识和处理建议

心脏起搏器和植入型心律转复除颤器（ICD）卓越的治疗效果已为仍们所公认，随着起搏工程技术的发展，起搏治疗的适应证也不断拓宽，植入起搏器和ICD的患者越来越多，随之而来的起搏系统和ICD系统的感染，轻者植入部位皮肤局部红肿、疼痛，重者脉冲发生器囊袋积血，化脓溃破流脓，伤口经久不愈，发热，引 起菌血症或心内膜炎，拔除心内膜导和取出脉冲发生器是唯一有效的根治方法。本文对心内膜导线拔除的适应证，禁忌证，手术方法，治疗效果，并发症进行讲座，并提出建议。     

How different from pacemaker patients are recipients of implantable cardioverter-defibrillators with respect to psychosocial adaptation,affective disorders,and quality of life?

OBJECTIVE—To assess differences in psychosocial adaptation, quality of life, and incidence of affective disorders between patients with pacemakers and those with implantable cardioverter-defibrillators (ICDs).
DESIGN—Patients aged 40-70 years who underwent a first pectoral implantation of a pacemaker or an ICD system were studied. All subjects were asked to complete the hospital anxiety and depression scale (HAD), the short form general health survey (SF-36), and a specially designed device related questionnaire. Data analysis was performed for three patient groups: pacemaker (n = 76), ICD patients who received therapeutic shocks (n = 45), and ICD patients who did not receive shocks (n = 31).
RESULTS—There were no differences between the three patient groups in HAD scores or in any of the SF-36 subscales or summary ratings. Probable depressive disorder (depression score > 10) was observed in 5.2%, 6.5%, and 6.6%, and probable anxiety disorder (anxiety score > 10) in 13.1%, 9.7%, 13.3% of the pacemaker, non-shocked ICD, and shocked ICD patients, respectively. There were no sex differences. However, patients in the shocked ICD group were more likely than those in the other groups to report limitations in their leisure activities, to perceive their device as a "life extender," and to admit anxiety about battery depletion and technical problems. Forty per cent of shocked ICD patients would be interested in joining a support group.
CONCLUSIONS—Despite having distinctly different medical histories and treatments, patients with pacemakers and ICDs responded similarly to validated tools of health status assessment. ICD patients who had received shocks perceived their device as prolonging their life and had greater anxiety about technical problems. Their endorsement of the potential benefits of a support group warrants further investigation.


Keywords: pacemaker; implantable cardioverter-defibrillator; affective disorder; quality of life     

Surgical treatment of pacemaker and defibrillator lead endocarditis: the impact of electrode lead extraction on outcome

BACKGROUND: Cardiac device (CD) endocarditis is an infrequent but potentially lethal infectious complication of permanent pacemakers or implantable cardioverter-defibrillators (ICDs), and mortality rates of 30 to 35% have been reported. Medical treatment has been suggested for the treatment of CD endocarditis, but there is increasing evidence that surgical treatment is to be preferred as the best approach to achieve eradication of the infection and reduce mortality. OBJECTIVE: To evaluate the following: (1) the clinical and echocardiographic characteristics of patients with pacemaker or ICD endocarditis, (2) the outcome of this population depending on the mode of treatment (medical vs surgical treatment), and (3) the clinical, microbiological, echocardiographic, and therapeutic variables associated with patient outcome. DESIGN: Prospective cohort study. SETTING: Tertiary referral center in Barcelona, Spain. PATIENTS: All consecutive patients with infectious endocarditis (IE) admitted to the study institution between 1990 and 2001 were prospectively evaluated by a multidisciplinary treatment team, and a definite diagnosis of CD endocarditis was established when cases met pathologic or clinical criteria according to the Duke criteria. RESULTS: A total of 31 patients, 25 men and 6 women aged 61 +/- 15 years (mean +/- SD), with pacemaker or ICD endocarditis were identified among 669 consecutive patients (4.6%) with IE. During the study period, a total of 3,768 pacemakers and 460 ICDs were implanted in the study institution. In 22 cases of pacemaker endocarditis, the pacemaker was implanted in our institution, and 9 cases were referred from other institutions (incidences of endocarditis on pacemaker and ICD implanted in our institution of 0.58% and 0.65%, respectively). Medical treatment without removal of the pacing system was initially performed on seven patients; all of them (100%) had relapses of endocarditis, and one patient died. The remaining 24 patients underwent surgical removal of the pacing system; 1 patient had one relapse, 3 patients died after surgical treatment, and the others were successfully cured with no relapses after a mean follow-up of 38 +/- 9 months. Clinical, echocardiographic, microbiological, and therapeutic variables were evaluated in association with prognosis. The only prognostic factor for failure of treatment or mortality was the absence of surgical treatment (p < 0.0001). CONCLUSIONS: Electrode lead endocarditis occurred in < 1% of pacemaker and ICD implants. Conservative treatment without explantation of all hardware failed in all patients, and surgical treatment during antibiotic therapy was effective in eradication of infection but was associated with a 12.5% mortality. The only patient characteristic associated with treatment failure or death was the absence of surgical removal of all infected hardware. Complete extraction of the pacemaker or ICD should be considered as standard therapy for most patients with CD endocarditis.     

The Effect of Cardiac Rehabilitation and a Specialized Clinic on Outcomes of Patients With Atrial Fibrillation

Background

Cardiac rehabilitation (CR) intervention programs are currently not part of management in patients with atrial fibrillation (AF). We sought to determine the effect of CR compared with a specialized AF clinic (AFC) and usual care on outcomes in patients with AF.

Combined use of non-thoracotomy cardioverter defibrillators and endocardial pacemakers.

OBJECTIVE: To study the potential interactions in patients with endocardial permanent pacemakers and non-thoracotomy implantable cardioverter defibrillator (ICD) systems. DESIGN: Case series and cohort study. SETTING: Tertiary referral centre. PATIENTS: Fifteen consecutive patients with both endocardial pacemakers (12 dual chamber and three single chamber) and non-thoracotomy ICD systems. MAIN OUTCOME MEASURES: Detection inhibition of induced ventricular fibrillation; double counting; and pacemaker function after shocks. In the evaluation of detection inhibition, 124 VF inductions were analysed for detection duration compared with induced VF episodes in controls with an ICD but without a pacemaker. RESULTS: Two patients (13%) showed detection inhibition of VF and required pacemaker system change at the time of the ICD implant. With the final lead position, despite frequent pacemaker undersensing of VF, ICD detection of VF was not inhibited during any induction, and neither initial detection nor redetection times for VF were different from controls. Double/triple counting of pacemaker artefact and evoked electrogram was noted in three patients (20%). In two, this was remedied during the implantation procedure, and in the other it was abolished when amiodarone treatment was discontinued. Pacemaker function was affected by ICD discharges in two patients, one who showed postshock atrial undersensing and loss of capture, and another whose pacemaker reverted to VVI mode. CONCLUSIONS: When careful testing is performed at implantation to detect and remedy device interactions, non-thoracotomy ICD treatment and endocardial pacemakers can be used safely in combination.     

Poor Adherence to Dietary Guidelines Among French-Speaking Adults in the Province of Quebec,Canada: The PREDISE Study

Background

Regular monitoring of the population’s food and nutrient intake is essential to develop effective nutrition-focused public health policies. The aim of this study was to provide dietary intake estimates using an age- and sex-representative sample of French-speaking adults with Internet access from 5 administrative regions in the province of Quebec, Canada.

Left Atrial Function Using Cardiovascular Magnetic Resonance Imaging Independently Predicts Life-Threatening Arrhythmias in Patients Referred to Receive a Primary Prevention Implantable Cardioverter Defibrillator

BackgroundIn this study we aimed to investigate left atrial (LA) function, measured from routine cine cardiovascular magnetic resonance imaging, to determine its value for the prediction of sudden cardiac death (SCD) or appropriate implantable cardioverter defibrillator (ICD) shock in patients who received primary prevention ICD implantation.MethodsWe studied 203 patients with ischemic or idiopathic nonischemic dilated cardiomyopathy who underwent cardiovascular magnetic resonance imaging before primary prevention ICD implantation. LA volumes were measured at end-diastole and end-systole from 4- and 2-chamber cine images, and LA emptying function (LAEF) calculated. Patients were followed for the primary composite end point of SCD or appropriate ICD shock.ResultsMean age was 61 ± 12 years with a mean left ventricular ejection fraction of 24 ± 7%. The mean LAEF was 27 ± 15% (range, 0.9%-73%). At a median follow-up of 1639 days, 35 patients (17%) experienced the primary composite outcome. LAEF was strongly associated with the primary outcome (P = 0.001); patients with an LAEF ≤ 30% experienced a cumulative event rate of 26.1% vs 5.7% (hazard ratio, 5.5; P < 0.001) in patients above this cutoff. This finding was maintained in multivariable analysis (hazard ratio, 4.7; P = 0.002) and was consistently shown in the ischemic and nonischemic dilated cardiomyopathy subgroups.ConclusionsLAEF is a simple, powerful, and independent predictor of SCD in patients being referred for primary prevention ICD implantation.