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BACKGROUND Implantable cardioverter defibrillators (ICDs) are indicated for the primary prevention of sudden cardiac death in patients with reduced left ventricular ejection fraction (LVEF). The ongoing risk/benefit profile of an ICD at generator replacement is unknown. This study aimed to identify predictors of appropriate ICD shocks and therapies after first ICD generator replacement, and its procedure-related complications. METHODS We conducted a multicenter, retrospective cohort study including patients with primary prevention ICDs who underwent generator replacement between April 2005 and July 2015 at three Canadian centers. The primary and secondary outcomes were appropriate ICD shock and any appropriate ICD therapy, respectively. Procedure-related complication rates were also reported. RESULTS Of the 219 patients in the cohort, 61 (28%) experienced an appropriate shock while 40 (18%) experienced appropriate antitachycardia pacing over a median follow up of 2.2 years. Independent predictors of appropriate ICD shocks included: LVEF at time of replacement (adjusted odds ratio [OR] 0.4 per 10% increase in LVEF, P

Background: The Hearts in Rhythm Organization (HiRO) is a team of Canadian inherited heart rhythm and cardiomyopathy experts, genetic counsellors, nurses, researchers, patients, and families dedicated to the detection of inherited arrhythmias and cardiomyopathies, provision of best therapies, and protection from the tragedy of sudden cardiac arrest. Methods: Recently, existing disease-specific registries were merged into the expanded National HiRO Registry, creating a single common data set for patients and families with inherited conditions that put them at risk for sudden death in Canada. Eligible patients are invited to participate in the registry and optional biobank from 20 specialized cardiogenetics clinics across Canada. Results: Currently, there are 4700 participants enrolled in the National HiRO Registry, with an average of 593 participants enrolled annually over the past 5 years. The capacity to enable knowledge translation of research findings is built into HiRO’s organizational infrastructure, with 3 additional working groups (HiRO Clinical Care Committee, HiRO Active Communities Committee, and HiRO Annual Symposium Committee), supporting the organization’s current goals and priorities as set alongside patient partners. Conclusion: The National HiRO Registry aims to be an integrated research platform to which researchers can pose novel research questions leading to a better understanding, detection, and clinical care of those living with inherited heart rhythm and cardiomyopathy conditions and ultimately to prevent sudden cardiac death. Résumé: Contexte: La Hearts in Rhythm Organization (HiRO) est une équipe d’experts canadiens en matière de rythmes cardiaques et de cardiomyopathies héréditaires, de conseillers en génétique, d’infirmières, de chercheurs, de patients et de familles qui se consacrent à la détection des arythmies et des cardiomyopathies héréditaires, à la mise en place des meilleures thérapies et à la protection contre la tragédie que représente une mort subite d’origine cardiaque. Méthodes: Récemment, les registres existants relatifs à des maladies spécifiques ont été fusionnés en un registre national élargi de l’HiRO, créant ainsi un ensemble de données commun unique à destination des patients et leurs familles, atteints de maladies héréditaires, qui sont à risque de mort subite au Canada. Les patients admissibles sont invités à s’associer au registre et à la biobanque facultative regroupant 20 cliniques spécialisées en cardiogénétique au Canada. Résultats: Actuellement, 4 700 participants sont inscrits au registre national de l’HiRO, avec une moyenne de 593 participants inscrits chaque année au cours des cinq dernières années. La capacité à favoriser l’application des connaissances issues de la recherche fait partie de la structure organisationnelle de l’HiRO, avec trois groupes de travail supplémentaires (comité des soins cliniques de l’HiRO, comité des communautés cctives de l’HiRO et comité du symposium annuel de l’HiRO), soutenant les objectifs et les priorités actuels de l’organisation tels qu’ils ont été fixés en partenariat avec les patients. Conclusion: Le registre national de l’HiRO vise à devenir une plateforme de recherche intégrée au sein de laquelle les chercheurs peuvent exposer des questions de recherche inédites permettant de mieux comprendre, détecter et soigner les personnes atteintes de troubles du rythme cardiaque et de cardiomyopathie héréditaires et, à terme, de prévenir la mort subite d’origine cardiaque.

The current definition of postural orthostatic tachycardia syndrome (POTS) dates back to a small case series of patients with a subacute illness who presented with excessive orthostatic tachycardia and orthostatic intolerance, in the absence of another recognized disease. Conventional POTS criteria require an excessive orthostatic tachycardia in the absence of substantial orthostatic hypotension, and predominant symptoms of orthostatic intolerance, worse with upright posture and better with recumbence. POTS is a heterogeneous syndrome with likely several underlying pathophysiological processes, and not a specific disease. The primary panel for this Canadian Cardiovascular Society position statement sought to provide a contemporary update of the best evidence for the evaluation and treatment of POTS. We performed a systemic review of evidence for the evaluation of treatment of POTS using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology, and developed recommendations on the basis of the Canadian Cardiovascular Society approach to position statements. One identified problem was that numerous patients who did not meet criteria for POTS would still be given that diagnoses by providers to validate the illness even though this diagnosis is incorrect. This includes patients with postural symptoms without tachycardia, orthostatic tachycardia without symptoms, and those with orthostatic tachycardia but another overt cause for excessive tachycardia. We developed a novel nomenclature ecosystem for orthostatic intolerance syndromes to increase clarity. We also provide more clarity on how to interpret the orthostatic vital signs. These concepts will need to be prospectively assessed.

An 18 year old male with an incompletely healed clavicle fracture presented with unexplained syncope. Subsequent investigations were consistent with a diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC). A subcutaneous implantable cardioverter-defibrillator (S-ICD) was successfully implanted and defibrillation threshold (DFT) testing performed as per standard protocol. Shortly following the procedure, the patient complained of pain and swelling over the left clavicle. A radiograph revealed aggravation and displacement of the underlying clavicle fracture. Surgical reduction and internal fixation was performed one week later.

Visual Abstract, Highlights • The homozygous c.38T>G mutation in the LEMD2 gene causes arrhythmic cardiomyopathy with bilateral juvenile cataract in the Hutterite population. • The cardiac phenotype is characterized by localized inferior and inferolateral fibrosis of the left ventricle and mild impairment of left ventricular systolic function but severe ventricular arrhythmias leading to sudden cardiac death. • Affected heart tissue and fibroblasts exhibit abnormally shaped nuclei with condensed peripheral heterochromatin. • Functional assays on affected fibroblasts show decreased proliferation capacity, cellular senescence, and a prolonged G1 phase, suggesting premature aging and cellular senescence in proliferating cells., Summary Nuclear envelope proteins have been shown to play an important role in the pathogenesis of inherited dilated cardiomyopathy. Here, we present a remarkable cardiac phenotype caused by a homozygous LEMD2 mutation in patients of the Hutterite population with juvenile cataract. Mutation carriers develop arrhythmic cardiomyopathy with mild impairment of left ventricular systolic function but severe ventricular arrhythmias leading to sudden cardiac death. Affected cardiac tissue from a deceased patient and fibroblasts exhibit elongated nuclei with abnormal condensed heterochromatin at the periphery. The patient fibroblasts demonstrate cellular senescence and reduced proliferation capacity, which may suggest an involvement of LEM domain containing protein 2 in chromatin remodeling processes and premature aging.

Objectives This investigation was a retrospective study of catecholaminergic polymorphic ventricular tachycardia (CPVT) patients in Canada and the Netherlands to compare pregnancy, postpartum, and nonpregnant event rates. Background CPVT is characterized by life-threatening arrhythmias during exertion or emotional stress. The arrhythmic risk in CPVT patients during pregnancy is unknown. Methods Baseline demographics, genetics, treatment, and pregnancy complications were reviewed. Event rate calculations assumed a 40-week pregnancy and 24-week postpartum period. Results Ninety-six CPVT patients had 228 pregnancies (median 2 pregnancies per patient; range: 1 to 10; total: 175.4 pregnant patient-years). The median age of CPVT diagnosis was 40.7 years (range: 12 to 84 years), with a median follow-up of 2.9 years (range: 0 to 20 years; total 448.1 patient-years). Most patients had pregnancies before CPVT diagnosis (82%). Pregnancy and postpartum cardiac events included syncope (5%) and an aborted cardiac arrest (1%), which occurred in patients who were not taking beta-blockers. Other complications included miscarriages (13%) and intrauterine growth restriction (1 case). There were 6 cardiac events (6%) during the nonpregnant period. The pregnancy and postpartum event rates were 1.71 and 2.85 events per 100 patient-years, respectively, and the combined event rate during the pregnancy and postpartum period was 2.14 events per 100 patient-years. These rates were not different from the nonpregnant event rate (1.46 events per 100 patient-years). Conclusions The combined pregnancy and postpartum arrhythmic risk in CPVT patients was not elevated compared with the nonpregnant period. Most patients had pregnancies before diagnosis, and all patients with events were not taking beta-blockers at the time of the event.

Background Evidence regarding the incremental benefit of cardiac resynchronization therapy (CRT) with a defibrillator (CRT‐D) versus without (CRT‐P) in elderly patients with heart failure is limited. We compared mortality and cardiac hospitalisation between CRT‐D and CRT‐P in the elderly. Methods A retrospective chart review identified all consecutive patients with age ≥75 with CRT implantation over the last 10 years at a Canadian tertiary care cardiac centre. Kaplan‐Meier survival analyses and cumulative incidence curves were used to compare mortality and time to first cardiac hospitalisation, respectively, with CRT‐D versus CRT‐P over a 3 year period. Analyses were also repeated with propensity score matching based on age, sex, primary versus secondary prevention, date of implant, and Charlson Comorbidity Index. Results One hundred and seventy CRT patients were identified. A total of 128 received CRT‐D while 42 received CRT‐P. Median age was 79 (IQR 77‐81), and the majority were male (83%). CRT‐P patients had a higher burden of comorbidities (Charlson score 7, IQR 6‐8) than CRT‐D patients (Charlson score 5, IQR 5‐7; P

Research teams developing biobanks and/or genomic databases must develop policies for the disclosure and reporting of potentially actionable genomic results to research participants. Currently, a broad range of approaches to the return of results exist, with some studies opting for non-disclosure of research results while others follow clinical guidelines for the return of potentially actionable findings from sequencing. In this review, we describe current practices and highlight decisions a research team must make when designing a return of results policy, from informed consent to disclosure practices and clinical validation options. The unique challenges of returning incidental findings in cardiac genes, including reduced penetrance and the lack of clinical screening standards for phenotype-negative individuals are discussed. Lastly, the National Hearts in Rhythm Organization (HiRO) Registry approach is described to provide a rationale for the selective return of field-specific variants to those participating in disease-specific research. Our goal is to provide researchers with a resource when developing a return of results policy tailored for their research program, based on unique factors related to study design, research team composition and availability of clinical resources.

Background: Following an unexplained cardiac arrest, clinical genetic testing is increasingly becoming standard of care. Periodic review of variant classification is required, as reinterpretation can change the diagnosis, prognosis, and management of patients and their relatives. Methods: This study aimed to develop and validate a standardized algorithm to facilitate clinical application of the 2015 American College of Medical Genetics and Association for Molecular Pathology guidelines for the interpretation of genetic variants. The algorithm was applied to genetic results in the Cardiac Arrest Survivors With Preserved Ejection Fraction Registry, to assess the rate of variant reclassification over time. Variant classifications were then compared with the classifications of 2 commercial laboratories to determine the rate and identify sources of variant interpretation discordance. Results: Thirty-one percent of participants (40 of 131) had at least 1 genetic variant with a clinically significant reclassification over time. Variants of uncertain significance were more likely to be downgraded (73%) to benign than upgraded to pathogenic (27%; P =0.03). For the second part of the study, 50% (70 of 139) of variants had discrepant interpretations (excluding benign variants), provided by at least 1 team. Conclusions: Periodic review of genetic variant classification is a key component of follow-up care given rapidly changing information in the field. There is potential for clinical care gaps with discrepant variant interpretations, based on the interpretation and application of current guidelines. The development of gene- and disease-specific guidelines and algorithms may provide an opportunity to further standardize variant interpretation reporting in the future. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT00292032.

Aims The term idiopathic ventricular fibrillation (IVF) describes survivors of unexplained cardiac arrest (UCA) without a specific diagnosis after clinical and genetic testing. Previous reports have described a subset of IVF individuals with ventricular arrhythmia initiated by short-coupled trigger premature ventricular contractions (PVCs) for which the term short-coupled ventricular fibrillation (SCVF) has been proposed. The aim of this article is to establish the phenotype and frequency of SCVF in a large cohort of UCA survivors. Methods and results We performed a multicentre study including consecutive UCA survivors from the CASPER registry. Short-coupled ventricular fibrillation was defined as otherwise unexplained ventricular fibrillation initiated by a trigger PVC with a coupling interval of Conclusion Short-coupled ventricular fibrillation is a distinct primary arrhythmia syndrome accounting for at least 6.6% of UCA. As documentation of ventricular fibrillation onset is necessary for the diagnosis, most cases are diagnosed at the time of recurrent arrhythmia, thus the true prevalence of SCVF remains still unknown. Quinidine is effective in SCVF and should be considered as first-line treatment for patients with recurrent episodes.

Objective: There is uncertainty about the incidence of and prognosis associated with atrial fibrillation that is documented for the first time in the setting of an acute stressor, such as surgery or medical illness. Our objective was to perform a systematic review of the incidence and long-term recurrence rates for atrial fibrillation occurring transiently with stress in the setting of acute medical illness. Data sources: Medline, Embase and Cochrane Central to September 2017. Study selection: We included retrospective and prospective observational studies, and randomised controlled trials. The population of interest included patients hospitalised for medical (i.e. non-surgical) illness who developed newly diagnosed atrial fibrillation. Studies were included if they included data on either the incidence of atrial fibrillation or the rate of atrial fibrillation recurrence in atrial fibrillation occurring transiently with stress patients following hospital discharge. Data extraction: Two reviewers collected data independently and in duplicate. We characterised each study’s methodology for ascertainment of prior atrial fibrillation history, atrial fibrillation during hospitalisation and atrial fibrillation recurrence after hospital discharge. Data synthesis: Thirty-six studies reported the incidence of atrial fibrillation. Ten used a prospective design and included a period of continuous electrocardiographic (ECG) monitoring. Atrial fibrillation incidence ranged from 1% to 44%, which was too heterogeneous to justify meta-analysis ( I2=99%). In post-hoc meta-regression models, the use of continuous ECG monitoring explained 13% of the variance in atrial fibrillation incidence, while care in an intensive care unit explained none. Two studies reported the long-term rate of atrial fibrillation recurrence following atrial fibrillation occurring transiently with stress. Neither of these studies used prospective, systematic monitoring. Recurrence rates at 5 years ranged from 42% to 68%. Conclusions: The incidence of atrial fibrillation with medical illness may be as high as 44%, with higher estimates in reports using continuous ECG monitoring. Within 5 years following hospital discharge, atrial fibrillation recurrence is documented in approximately half of patients; however, the true rate may be higher. Protocol registration PROSPERO CRD42016043240

Cold weather to 0°C has been implicated as a risk factor for ventricular arrhythmias and implantable cardioverter defibrillator (ICD) shocks. The effect of more extreme cold weather on the risk of ventricular arrhythmias and ICD shocks is unknown. We sought to describe the relationship between extreme cold weather and the risk of ICD shocks. We retrospectively identified patients seen at the Pacemaker and Defibrillator Clinic at St. Boniface Hospital in Winnipeg, Manitoba, Canada between 2010 and 2015 with an ICD shock. We excluded multiple shocks occurring on the same day in a single patient. We collected weather data, and evaluated the relationship between ICD shocks and weather on the same day as the shock using Negative Binomial regression. Three hundred and sixty patients experienced a total of 1,355 shocks. When excluding multiple shocks occurring in a single patient on the same day, there were 756 unique shocks. The daily high (DH) was the strongest predictor of receiving an ICD shock. Compared with the warmest days (DH above 10°C), shocks were 25% more common on the coldest days (DH below -10°C), and 8% more common on cold days (DH between -10°C and 10°C). This linear trend was statistically significant, with a p-value of 0.04. In conclusion, we found an association between extreme cold weather and ICD shocks.

BACKGROUND Up to 30% of medical spending in developed countries is unnecessary. Unnecessary testing is not only wasteful economically, but can be injurious to patients. Studies have shown that interventions such as education, auditing, and restrictive ordering can reduce unnecessary testing. However, these interventions are time- and resource-intensive. We conducted a study to determine if the passive intervention of placing signs on clinicians' computers was effective in reducing unnecessary testing. AIMS To determine the effectiveness of signage on physicians' computers to limit unnecessary testing. METHODS We identified two acute medicine wards on which all orders are placed via computer. On one ward (Ward A), we placed signs outlining recommendations regarding responsible test-ordering. Ward B acted as a control. Data was collected during a 6-month study period to determine whether test-ordering practices differed. RESULTS A total of 1645 patients accounting for 17 786 patient-days were included in the study. Fewer tests were ordered on Ward A than Ward B (7.38 vs 8.20 tests/patient-day; P

An increase in the duration of the QRS complex over time has been shown to be associated with poor clinical outcomes in specific subgroups of heart failure (HF) patients. There is a paucity of data on the clinical impact of increasing QRS duration on outcomes in HF with narrow QRS duration. This was a retrospective study of consecutive adult referrals to a tertiary outpatient HF clinic over a 2-year period. All patients with a narrow QRS, (130 ms) were included. The primary outcome was mortality. Secondary outcomes were HF hospitalization and a composite of HF hospitalization, implantation of cardiac resynchronization therapy or left ventricular assist device and cardiac transplant. A total of 253 patients with 2 or more QRS measurments were included. Death occurred in 41 patients (16%), 258 HF hospitalizations occurred in 116 patients (46%) and the composite occurred in 127 patients (50%). Multivariable analyses found that a rate of QRS duration change of ≥1 ms/month was independently associated with increased mortality (odds ratio [OR] 2.26, 95% confidence interval [CI] 1.04 to 4.91), HF hospitalization (relative risk [RR] 2.01, 95% CI 1.37 to 2.94), and the composite (OR 2.40, 95%CI 1.44 to 4.02). A new QRS130 ms was also independently associated with mortality (OR 3.27, 95%CI 1.29-8.32), HF hospitalization (RR 2.75, 95% CI 1.72 to 4.4) and the composite (OR 2.52, 95%CI 1.27 to 4.99). In conclusion, in patients with HF and a narrow baseline QRS, an increase in QRS duration of ≥1 ms per month is associated with increased mortality and HF hospitalization. HF patients may benefit from serial monitoring of QRS duration.

Background Despite the high sensitivity and negative predictive value of contemporary high-sensitivity troponin T assays (hsTnT), creatine kinase (CK) continues to be routinely tested for the diagnosis of acute coronary syndrome (ACS). We conducted a study to identify the clinical utility of routine CK measurement, its relevance in clinical decision making in the era of hsTnT, and the potential cost-savings achievable by limiting its use. Methods We conducted a retrospective review of all adult patients presenting to a tertiary care center in the year 2017. We identified patients presenting with cardiac complaints who had non-diagnostic hsTnT and positive CK. These patients underwent chart review to determine whether a diagnosis of AMI was made. Results A total of 36,251 presentations were reviewed. 9951 had cardiac complaints and 8150 had CK measured. 82% of these patients had hsTnT and CK measured; 2012 of these patients had non-diagnostic hsTnT with positive CK. Of these 2012 patients, only 1 was subsequently diagnosed with AMI (0.012%). CK provided no diagnostic benefit over hsTnT alone in > 99.9% of cases. With a cost for CK of $4/test, we estimated that routine CK testing costs at least $32,000 per year in our center, and over $100,000 per year across the region. Conclusion Routine CK testing does not provide a significant benefit to patient care and therefore represents an unnecessary system cost. Routine CK testing for the diagnosis of AMI should be eliminated from emergency departments in the era of hsTnT assays.

In patients with complete venous occlusion requiring venous access for cardiac device lead placement, venous revascularization is a viable option. A percutaneous approach to venous revascularization has gained popularity. This method reduces patient exposure to more invasive therapies. In this case series, we describe two cases of a total venous occlusion that were successfully revascularized using a “wire externalization” technique. This technique requires the use of antegrade and retrograde access.

Atrial fibrillation (AF) is the most common arrhythmia and is associated with an increase in the risk of ischemic stroke. The risk of stroke can be significantly decreased by oral anticoagulation (OAC). Our objective was to characterize the filling of OAC prescriptions for patients with actionable AF (new or existing AF with an indication for OAC but not prescribed) and determine the prevalence and predictors of guideline-appropriate therapy at 30 days.This is a multi-hospital, retrospective cohort study of patients who visited the Emergency Department (ED) and had a discharge diagnosis of AF. Patient records were examined to identify demographics, risk factors, and prescription data. Predictors of filling a prescription at 30 days were analyzed.788 patients with AF were reviewed. 257 patients had actionable AF. Forty one percent (104) had newly diagnosed AF. The mean CHADS2 score was 2 ± 1. At 30 days after discharge, 25.7% of patients filled a prescription for OAC therapy.Large numbers of patien...

Providing care to the elderly patient with syncope poses problems that are unusual in their complexity. The differential diagnosis is broad, and sorting through it is made more difficult by the relative lack of symptoms surrounding the faint. Indeed, distinguishing faints from falls is often problematic. Many elderly patients are frail and are at risk of trauma if they should have an unprotected faint or fall to the ground. However, not all elderly patients are frail, and definitions of frailty vary. Providing accurate, effective, and appropriate care for the frail elderly patient who faints may require a multidisciplinary approach.

Background There is limited evidence whether being on fludrocortisone prevents vasovagal syncope. Objectives The authors sought to determine whether treatment with fludrocortisone reduces the proportion of patients with recurrent vasovagal syncope by at least 40%, representing a pre-specified minimal clinically important relative risk reduction. Methods The multicenter POST 2 (Prevention of Syncope Trial 2) was a randomized, placebo-controlled, double-blind trial that assessed the effects of fludrocortisone in vasovagal syncope over a 1-year treatment period. All patients had >2 syncopal spells and a Calgary Syncope Symptom Score >−3. Patients received either fludrocortisone or matching placebo at highest tolerated doses from 0.05 mg to 0.2 mg daily. The main outcome measure was the first recurrence of syncope. Results The authors randomized 210 patients (71% female, median age 30 years) with a median 15 syncopal spells over a median of 9 years equally to fludrocortisone or placebo. Of these, 96 patients had ≥1 syncope recurrences, and only 14 patients were lost to follow-up before syncope recurrence. There was a marginally nonsignificant reduction in syncope in the fludrocortisone group (hazard ratio [HR]: 0.69: 95% confidence interval [CI]: 0.46 to 1.03; p = 0.069). In a multivariable model, fludrocortisone significantly reduced the likelihood of syncope (HR: 0.63; 95% CI: 0.42 to 0.94; p = 0.024). When the analysis was restricted to outcomes after 2 weeks of dose stabilization, there was a significant benefit due to fludrocortisone (HR: 0.51; 95% CI: 0.28 to 0.89; p = 0.019). Conclusions The study did not meet its primary objective of demonstrating that fludrocortisone reduced the likelihood of vasovagal syncope by the specified risk reduction of 40%. The study demonstrated a significant effect after dose stabilization, and there were significant findings in post hoc multivariable and on-treatment analyses. (A randomised clinical trial of fludrocortisone for the prevention of vasovagal syncope; ISRCTN51802652 ; Prevention of Syncope Trial 2 [POST 2]; NCT00118482 )

It is estimated that nearly 500,000 Canadians are currently living with heart failure, a disease process associated with considerable morbidity and mortality. Despite significant evidence for effective medical therapies, heart failure remains one of the leading causes of hospitalization in Canada and patients with the disease experience an annual mortality of up to 10%. Approximately one in three patients with systolic heart failure have some degree of intraventricular conduction delay, manifest as increased QRS duration on electrocardiogram (ECG), the most common of which is left bundle branch block (LBBB). This conduction delay, or electrical dyssynchrony, can lead to mechanical uncoupling and inefficiency, which, in turn, can lead to exacerbation of systolic dysfunction, altered myocardial metabolism, functional mitral regurgitation, negative remodeling and worsening clinical outcomes.Cardiac resynchronization therapy (CRT), also known as biventricular pacing, involves coordinating contraction between the left (LV) and right ventricles (RV) through programmed pacing of both ventricles. CRT is an established non-pharmacological therapy for patients with systolic heart failure due to a low ejection fraction, who have a QRS >130 ms and who are symptomatic despite optimal medical therapy. In carefully selected patients, CRT has been shown to promote positive LV remodeling, increase functional capacity, improve quality of life, reduce heart failure hospitalizations and reduce mortality.2 CRT systems can include defibrillator capabilities (CRT-D) or act as a stand-alone pacemaker (CRT-P). The insertion of a CRT system consumes significant resource (costs), requires a commitment to regular clinical follow-up, and the acceptance of permanent implantation of a large medical device. Clinicians are tasked with identifying patients who would be expected to benefit from CRT and making the decision whether to proceed with CRT implantation. Therefore a careful consideration of the risks and benefits of this technology is required by both the healthcare providers and the patient. Herein we hope to offer guidance on identifying ideal candidates for CRT and to remind health care providers that the patients’ goals must be taken into consideration when counseling a patient for treatment with CRT.

Background Anti-platelet therapy is commonly used in patients receiving oral anticoagulation and may increase bleeding risk among patients undergoing cardiac implantable electronic device (CIED) surgery. We sought to determine the proportion of anticoagulated patients who are concomitantly receiving anti-platelet therapy, the associated risk of clinically significant hematoma (CSH), and the proportion of patients in whom anti-platelet usage is guideline-indicated. Methods A secondary analysis of the Bridge or Continue Coumadin for Device Surgery Randomized Controlled Trial (BRUISE CONTROL). Patients who were receiving warfarin, had an annual predicted risk of thromboembolism of ≥5% and were scheduled to undergo non-emergent CIED surgery were randomized to continued warfarin versus heparin bridging. In the current analysis, patients were divided into those receiving anti-platelet therapy and those not receiving anti-platelet therapy. The incidence of CSH was compared in both groups. The proportion of patients on potentially inappropriate and potentially interruptible antiplatelet therapy was estimated. Results All 681 patients enrolled in BRUISE CONTROL were included, of whom 280 received and 401 did not receive anti-platelet therapy. Anti-platelet therapy increased the risk of CSH (relative risk, 1.72; 95% confidence interval (CI), 1.09 to 2.72; P = 0.02). Of the 280 patients receiving anti-platelet therapy, 97 (34.6%) had no guideline indication for concomitant anti-platelet therapy and an additional 146 (52.1%) were on anti-platelet therapy that could potentially have been interrupted around CIED surgery. Conclusions Concomitant anti-platelet therapy in patients receiving anticoagulation is associated with a significant risk of CSH. The majority of concomitant anti-platelet therapy is potentially inappropriate or interruptible. Trial registration clinicaltrials.gov Identifier: (NCT00800137)

Background Adverse events during donation negatively impact the likelihood of subsequent donation. Syncope is a possible complication of blood donation in healthy individuals. This systematic review aims to identify risk factors for syncope in healthy blood donors. Study design and methods Medline, Embase, Cochrane, CINAHL, Web of Science, Transfusion Evidence Library, and PubMed libraries up to November 2016 were searched. Inclusion criteria were observational and interventional trials, case series including more than 10 participants, randomized controlled trials, and clinical trials. Papers required data pertaining to syncopal events separate from presyncope for inclusion. Incomplete text or non-English language versions were excluded. Papers were evaluated using the CHARMS 2014 checklist. Results From 3316 papers, 1297 unique citations were identified, and 11 were selected for data extraction. Sex, estimated blood volume, age, donor status, blood pressure, heart rate, weight, previous reaction, caffeine, sleep, and donation site were identified as risk factors for syncope during blood donation. Conclusion Possible risk factors for syncope in healthy blood donors have been identified that could allow for improved screening prior to donation and potential reduction in donor attrition due to negative experiences.

Background An implantable loop recorder (ILR) assists in the diagnosis of unexplained syncope and atrial fibrillation (AF). Both become prevalent with age. Limited data exist describing the incidence of AF as the diagnostic rhythm underlying syncope in the elderly. This study aims to report the incidence of AF in older adults with ILRs for unexplained syncope and identify clinical characteristics associated with AF in this population. Methods Retrospective observational study on patients with unexplained syncope seen in syncope clinics from two Canadian centers. Participants were ≥65 years old, without a history of AF, and received an ILR for unexplained syncope. Data were collected from patient's clinic charts. Arrhythmia diagnosis was based on ILR electrocardiogram reading during syncope (symptom-rhythm correlation). Fisher's exact test and the Student's t test were used to compare participants with and without AF. Results In our cohort of 222 patients, 124 were females and 98 were males. Mean age at implant was 80 ± 8 years. Arrhythmia was diagnosed in 98 patients (44.1%). Median time to diagnosis was 18 months. AF was diagnosed in 17 (7.7%) participants. There were fewer males in the AF group than the no AF group (11.8%, 46.8%, p = 0.01). Age, baseline EKG, and prevalence of hypertension, diabetes, stroke, or ischemic heart disease were not statistically different between patients with AF and without AF. Conclusions Atrial fibrillation was a common diagnostic rhythm in this cohort of adults, aged 65 and older, with ILRs for unexplained syncope. It was observed more frequently in females.

Objectives: The objectives of this study were to evaluate the effectiveness of a physician notification system for atrial fibrillation (AF) detected on cardiac devices, and to assess predictors of anticoagulation in patients with device-detected AF. Methods: In 2013, a physician notification system for AF detected on a patient’s CIED [including pacemakers, implantable cardioverter defibrillators (ICD) or cardiac resynchronization therapy (CRT) devices] was implemented, with a recommendation to consider oral anticoagulation in high-risk patients. We prospectively investigated the effectiveness of this system, and evaluated both patient and physician predictors of anticoagulation, as well as factors influencing physician decision making in prescribing anticoagulation. Both uni- and multivariable analysis as well as descriptive statistics were used in the analysis. Results: We identified 177 patients with device-detected AF, 126 with a CHADS2 ⩾2. Only 41% were prescribed anticoagulation at any point within 12 months. On multivariable analysis, stroke risk as predicted by CHADS2 was not a predictor of anticoagulation. ASA use predicted a lower rate of anticoagulation (OR 0.39, 95% CI 0.16–0.97, p = 0.04); physicians in practice for Conclusions: Patients on aspirin were less likely to be anticoagulated. Physicians in practice for

Implantable loop recorders (ILRs) are increasingly being used for ambulatory electrocardiography. We sought to evaluate ILR indications, diagnostic yield, ILR-guided interventions, and complications in two Canadian centers. This was a retrospective study using electronic medical records to identify ILR implants at Queen’s University and the University of Manitoba. Information was collected on patient characteristics, medications, indication for implant, results of prior investigations, diagnostic outcome, and subsequent management. A total of 540 patients were identified; 386 had completed monitoring at time of analysis. Forty patients were lost to follow-up. Indications were unexplained syncope 84.8%, palpitations 12.8%, and suspected atrial fibrillation 11.7%. For syncope, ILRs documented arrhythmia or conduction disorder in 46%. Most common conditions were asystole/sinus pause (22%), complete heart block (10.4%), and atrial fibrillation (AF) (6.9%). After ILR diagnosis, 39.9% of implanted patients received pacemaker/ICD and 2.7% underwent catheter ablation. For palpitations, ILRs documented arrhythmia or conduction disorder in 60.4%. Most common conditions were AVNRT, AF, complete heart block, and ventricular tachycardia. After diagnosis, 25% underwent catheter ablation and 22.9% received pacemaker/ICD. For suspected AF, AF was diagnosed in 40%. Complications were observed in 3.3% of implanted patients: implant site infection 1.5%, non-infectious implant site pain requiring device removal or pocket revision 1.5%, 0.2% hypertrophic scar, and 0.2% device malfunction. An ILR has excellent diagnostic yield for syncope, palpitations, and suspected AF, and a considerable proportion of patients undergo ILR-directed interventions following monitoring. ILR implantation is a low-risk procedure.

Background— Unexplained cardiac arrest may be because of an inherited arrhythmia syndrome. The role of genetic testing in cardiac arrest survivors without a definite clinical phenotype is unclear. Methods and Results— The CASPER (Cardiac Arrest Survivors with Preserved Ejection Fraction Registry) is a large registry of cardiac arrest survivors where initial assessment reveals normal coronary arteries, left ventricular function, and resting ECG. Of 375 cardiac arrest survivors in CASPER from 2006 to 2015, 174 underwent genetic testing. Patients were classified as phenotype-positive (n=72) or phenotype-negative (n=102). Genetic testing was performed at treating physicians’ discretion in line with contemporary guidelines and availability. All genetic variants identified from original laboratory reports were reassessed by the investigators in line with modern criteria. Pathogenic variants were identified in 29 (17%) patients (60% channelopathy-associated and 40% cardiomyopathy-associated genes) and 70 variants of unknown significance were identified in 32 (18%) patients. Prior syncope (odds ratio, 4.0; 95% confidence interval, 1.6–9.7) and a family history of sudden death (odds ratio, 3.2; 95% confidence interval, 1.1–9.4) were independently associated with the presence of a pathogenic variant. In phenotype-negative patients, broad multiphenotype genetic testing led to higher yields (21% versus 8%; P =0.04) but was associated with more variants of unknown significance (55% versus 5%; P Conclusions— Genetic testing identifies a pathogenic variant in a significant proportion of unexplained cardiac arrest survivors. Prior syncope and family history of sudden death are predictors of a positive genetic test. Both arrhythmia and cardiomyopathy genes are implicated. Broad, multiphenotype testing revealed the highest frequency of pathogenic variants in phenotype-negative patients. Clinical Trial Registration— https://www.clinicaltrials.gov . Unique Identifier: NCT00292032

We report an unusual complication of permanent pacemaker (PPM) implantation in a patient with a temporary transvenous pacemaker (TVP) in situ, in which the TVP lead formed a knot around the newly-placed right ventricular (RV) lead, complicating TVP removal. The case underscores the fact that suboptimal TVP lead placement, such as looping in the RV, can result in complications during implantation of a permanent pacemaker. How to cite this article Wiens EJ, Seifer CM et al. Inadvertent Removal of a Right Ventricular Pacemaker Lead by a Knotted Transvenous Pacing Wire. Indian J of Crit Care Med 2019;23(2):102-103.

Magnetic resonance imaging (MRI) has historically been considered contraindicated for individuals with cardiac implantable electronic devices (CIEDs) such as pacemakers and implantable defibrillators. Magnetic resonance scanners produce magnetic fields that can interact negatively with the metallic components of CIEDs. However, as CIED technology has advanced, newer MRI conditional devices have been developed that are now in clinical use and these systems have had demonstrated safety in the MRI environment. Despite the supportive data of such CIED systems, physicians remain reluctant to perform MRI scanning of conditional devices. This joint statement by the Canadian Heart Rhythm Society and the Canadian Association of Radiologists describes a collaborative process by which CIED specialists and clinics can work with radiology departments and specialists to safely perform MRI in patients with MRI conditional CIED systems. The steps required for patient and scanning preparation and the roles and responsibilities of the CIED and radiology departments are outlined. We also briefly outline the risks and a process by which patients with nonconditional CIEDs might also receive MRI in highly specialized centres. This document supports MRI in patients with MRI conditional CIEDs and offers recommendations on how this can be implemented safely and effectively.

BACKGROUND: Right ventricular (RV) pacing has been associated with increased risk of pacemaker‐induced cardiomyopathy, hospitalization and death among patients with implantable cardioverter defibrillators (ICDs). Little is known about its association with ventricular tachyarrhythmias. We hypothesize that RV pacing is associated with increased incidence of appropriate ICD shocks and death. METHODS: Retrospective study of consecutive patients with de novo ICD insertion (excluding cardiac resynchronization therapy devices) from a single tertiary care center. Patients were classified into

Carotid sinus hypersensitivity was first reported more than 200 years ago. Nevertheless, a complete understanding of this relatively common clinical finding in older patients has proven elusive. There is evidence to support an association between symptoms, particularly syncope, and a hypersensitive response to carotid sinus massage. However, the clinical implication of a high prevalence in asymptomatic healthy older persons is not known. A central degenerative process likely underlies the pathophysiology, but this is as yet unproven. Although selected patients have had symptom improvement with treatment, particularly permanent pacing, there is a dearth of randomized controlled trial data to guide management.

Heart failure is a significant public health concern around the world. Implantable cardioverter defibrillators with or without cardiac resynchronization therapy (CRT-D) have proven survival benefit. As patients progress to end-stage disease, management shifts to palliative care, and cardiologists are often confronted with how to best manage these devices.Studies suggest that up to one-third of patients with an implantable cardioverter defibrillator receive painful shocks in the last 24 h of life. Disabling pacing or resynchronization devices may further weaken the heart function and expedite death, particularly if the patient has no underlying ventricular rhythm. Is it ethical or legal to discontinue functions of the implantable device? The discussion and the decision to be made are whether to continue both pacing and tachyarrhythmia therapies, disable tachyarrhythmia therapies while maintaining pacing, or discontinue both.The decision to disable all or parts of the device function is ultimately up to the patient. To avoid painful shocks near the end of life, it is recommended that tachyarrhythmia therapies be turned off when the patient is being treated palliatively. After informed discussion, withdrawing the resynchronization or pacing device option is also acceptable if requested by the patient regardless of the potential outcomes.

Background— Unexplained cardiac arrest (UCA) may be explained by inherited arrhythmia syndromes. The Cardiac Arrest Survivors With Preserved Ejection Fraction Registry prospectively assessed first-degree relatives of UCA or sudden unexplained death victims to screen for cardiac abnormalities. Methods and Results— Around 398 first-degree family members (186 UCA, 212 sudden unexplained death victims’ relatives; mean age, 44±17 years) underwent extensive cardiac workup, including ECG, signal averaged ECG, exercise testing, cardiac imaging, Holter-monitoring, and selective provocative drug testing with epinephrine or procainamide. Genetic testing was performed when a mutation was identified in the UCA survivor or when the diagnostic workup revealed a phenotype suggestive of a specific inherited arrhythmia syndrome. The diagnostic strength was classified as definite, probable, or possible based on previously published definitions. Cardiac abnormalities were detected in 120 of 398 patients (30.2%) with 67 of 398 having a definite or probable diagnosis (17%), including Long-QT syndrome (13%), catecholaminergic polymorphic ventricular tachycardia (4%), arrhythmogenic right ventricular cardiomyopathy (4%), and Brugada syndrome (3%). The detection yield was similar for family members of UCA and sudden unexplained death victims (31% versus 27%; P =0.59). Genetic testing was performed more often in family members of UCA patients (29% versus 20%; P =0.03). Disease-causing mutations were identified in 20 of 398 relatives (5%). The most common pathogenic mutations were RyR2 (2%), SCN5A (1%), and KNCQ1 (0.8%). Conclusions— Cardiac screening revealed abnormalities in 30% of first-degree relatives of UCA or sudden unexplained death victims, with a clear working diagnosis in 17%. Long-QT, arrhythmogenic right ventricular cardiomyopathy, and catecholaminergic polymorphic ventricular tachycardia were the most common diagnoses. Systematic cascade screening and genetic testing in asymptomatic individuals will lead to preventive lifestyle and medical interventions with potential to prevent sudden cardiac death. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT00292032.

Background Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a complex and clinically heterogeneous arrhythmic condition. Incomplete penetrance and variable expressivity are particularly evident in ARVC, making clinical decision-making challenging. Methods Pediatric and adult cardiologists, geneticists, genetic counsellors, ethicists, nurses, and qualitative researchers are collaborating to create the Canadian ARVC registry using a web-based clinical database. Biological samples will be banked and systematic analysis will be performed to examine potentially causative mutations, variants, and biomarkers. Outcomes will include syncope, ventricular arrhythmias, defibrillator therapies, heart failure, and mortality. Results Preliminary recruitment has enrolled 365 participants (aged 42.7 ± 17.1 years; 50% women), including 129 probands and 236 family members. Previous cardiac arrest occurred in 28 (8%) participants, syncope occurred in 43 (12%) participants, and 46% of probands had a family history of sudden death. Overall yield of genetic testing was 36% for a disease-causing mutation and 20% for a variant of unknown significance. Target enrollment is 1000 affected patients and 500 unaffected family member controls over 7 years. The cross-sectional and longitudinal data collected in this manner will allow a robust assessment of the natural history and clinical course of genetic subtypes. Conclusions The Canadian ARVC Registry will create a population-based cohort of patients and their families to inform clinical decisions regarding patients with ARVC.

Multimodality cardiac imaging is useful for the non-invasive characterization of infective endocarditis and its complications prior to surgical intervention.

Syncope is a very common presentation in the emergency department, and the combination of a wide differential diagnosis, a range of prognoses, and infrequent documentation of the faint leads to a high proportion of patients being admitted. These problems are mirrored in the investigation of inpatients with syncope, for which the high proportion of patients with benign outcomes and the profound risk aversion of health care providers make for expensive and inefficient assessment. Difficulties such as this in health services delivery can be improved by standardized approaches, such as guidelines, pathways, and checklists. Accordingly, emergency department decision rules, specialized syncope-monitoring units, and formal diagnostic algorithms have been developed to provide standardized approaches to the investigation of syncope. To provide guidance in the management of syncope, the Canadian Cardiovascular Society commissioned a position paper on standardized approaches to syncope investigation in adults. A primary panel first reviewed the literature systematically, then undertook iterative syntheses of data, and finally took positions with specific recommendations according to the GRADE framework. This paper summarizes the evidence and its quality and makes recommendations on the specific approaches meriting adoption. The position paper was then reviewed by a secondary panel, which provided suggestions for revisions leading to the final document as presented here. Overall, the position group concluded that there is little persuasive evidence that emergency department syncope rules and diagnostic syncope units provide efficient care and improved outcomes but that formal diagnostic algorithms with specialist support show promise.