Rhythm Society Research Articles

Influence of different electrode placement patterns on electromagnetic interference generated by Left Ventricular Assist Devices (LVADs) during electrocardiogram performance

Abstract Background Heart failure (HF), with an incidence of approximately 3/1000 person-years, often progresses to advanced stages where symptoms persist despite treatment. In such cases, mechanical circulatory assist devices, particularly left ventricular assist devices (LVADs) in ambulatory patients, enhance survival and quality of life. These LVADs generate electromagnetic interference, resulting in noise artefacts in conventional electrocardiograms (ECGs). The conventional ECG should be configured with a low-pass filter of 150 Hz and a high-pass filter of 0.05 Hz, as recommended by the American Heart Association/American College of Cardiology/Heart Rhythm Society. LVADs, such as the HeartMate 3 (Abbott®), typically operate at a rotational speed of 5000 to 6000 rpm, corresponding to oscillatory frequencies of 83.3 to 100 Hz. Objective To assess the impact of various surface electrode placement strategies and modifications to the low-pass filter on the electromagnetic interference produced by LVADs. Methods We conducted an observational study involving seven patients with HeartMate 3 adjusted to various rotational speeds (refer to Table 1). Three distinct electrode placement schemes (AHA, Mason Likar, and modified Torso) were employed for the frontal plane leads. The horizontal plane leads remained unmodified. Each patient underwent a total of 6 ECGs, corresponding to each of the aforementioned schemes. ECG recordings were performed using a high-pass filter set at 0.05 Hz and a low-pass filter set at 150 Hz. Additionally, a set of ECGs was obtained by modifying the low-pass filter to 40 Hz for further analysis. Results Figure 1 displays ECGs obtained from a male with a HeartMate 3 operating at 4600 rpm or 76.6 Hz. This device employs an algorithm to generate an "artificial pulse" by cyclically accelerating and decelerating the pump speed by 2000 rpm every 2 seconds, resulting in rotational speeds of 2600 rpm and 6600 rpm (43.3 Hz and 110 Hz, respectively). No specific placement scheme demonstrated consistent noise reduction across all cases, likely due to inter-individual variability resulting from factors such as the final position of the LVAD the rpm in each case, and the thoracic impedance of each patient. However, the modification of the low-pass filter to 40 Hz yielded a noteworthy improvement in noise reduction across all cases. In our limited sample, this adjustment did not pose issues for ECG interpretation. Nevertheless, it is essential to acknowledge that excessively low filter settings may not only eliminate noise but also potentially discard clinically relevant high-frequency signals (e.g., pacemaker spikes, large amplitude Rs, QRS notches). Conclusions Individualizing the electrode placement scheme is crucial for minimizing noise generated by LVADs. The adjustment of the low-pass filter to 40 Hz could generally prove beneficial in reducing artifact generation, despite the clinical limitations it may entail.

A Revised Definition of Left Bundle Branch Block Using Time to Notch in Lead I

Current left bundle branch block (LBBB) criteria are based on animal experiments or mathematical models of cardiac tissue conduction and may misclassify patients. Improved criteria would impact referral decisions and device type for cardiac resynchronization therapy. To develop a simple new criterion for LBBB based on electrophysiological studies of human patients, and then to validate this criterion in an independent population. In this diagnostic study, the derivation cohort was from a single-center, prospective study of patients undergoing electrophysiological study from March 2016 through November 2019. The validation cohort was assembled by retrospectively reviewing medical records for patients from the same center who underwent transcatheter aortic valve replacement (TAVR) from October 2015 through May 2022. Patients were classified as having LBBB or intraventricular conduction delay (IVCD) as assessed by intracardiac recording. Sensitivity and specificity of the electrocardiography (ECG) criteria assessed in patients with LBBB or IVCD. A total of 75 patients (median [IQR] age, 63 [53-70.5] years; 21 [28.0%] female) with baseline LBBB on 12-lead ECG underwent intracardiac recording of the left ventricular septum: 48 demonstrated complete conduction block (CCB) and 27 demonstrated intact Purkinje activation (IPA). Analysis of surface ECGs revealed that late notches in the QRS complexes of lateral leads were associated with CCB (40 of 48 patients [83.3%] with CCB vs 13 of 27 patients [48.1%] with IPA had a notch or slur in lead I; P = .003). Receiver operating characteristic curves for all septal and lateral leads were constructed, and lead I displayed the best performance with a time to notch longer than 75 milliseconds. Used in conjunction with the criteria for LBBB from the American College of Cardiology/American Heart Association/Heart Rhythm Society, this criterion had a sensitivity of 71% (95% CI, 56%-83%) and specificity of 74% (95% CI, 54%-89%) in the derivation population, contrasting with a sensitivity of 96% (95% CI, 86%-99%) and specificity of 33% (95% CI, 17%-54%) for the Strauss criteria. In an independent validation cohort of 46 patients (median [IQR] age, 78.5 [70-84] years; 21 [45.7%] female) undergoing TAVR with interval development of new LBBB, the time-to-notch criterion demonstrated a sensitivity of 87% (95% CI, 74%-95%). In the subset of 10 patients with preprocedural IVCD, the criterion correctly distinguished IVCD from LBBB in all cases. Application of the Strauss criteria performed similarly in the validation cohort. The findings suggest that time to notch longer than 75 milliseconds in lead I is a simple ECG criterion that, when used in conjunction with standard LBBB criteria, may improve specificity for identifying patients with LBBB from conduction block. This may help inform patient selection for cardiac resynchronization or conduction system pacing.

Paced QRS morphology mimicking complete left bundle branch block induced by right ventricular pacing is associated with pacing-induced cardiomyopathy.

Right ventricular (RV) pacing sometimes causes left ventricular (LV) systolic dysfunction, also known as pacing-induced cardiomyopathy (PICM). However, the association between specifically paced QRS morphology and PICM development has not been elucidated. This study aimed to investigate the association between paced QRS mimicking a complete left bundle branch block (CLBBB) and PICM development. We retrospectively screened 2009 patients who underwent pacemaker implantation from 2010 to 2020 in seven institutions. Patients who received pacemakers for an advanced atrioventricular block or bradycardia with atrial fibrillation, baseline LV ejection fraction (LVEF) ≥ 50%, and echocardiogram recorded at least 6 months postimplantation were included. The paced QRS recorded immediately after implantation was analyzed. A CLBBB-like paced QRS was defined as meeting the CLBBB criteria of the American Heart Association/American College of Cardiology Foundation/Heart Rhythm Society in 2009. PICM was defined as a ≥10% LVEF decrease, resulting in an LVEF of <50%. Among the 270 patients analyzed, PICM was observed in 38. Baseline LVEF was lower in patients with PICM, and CLBBB-like paced QRS was frequently observed in PICM. Multivariate analysis revealed that low baseline LVEF (odds ratio [OR]: 0.93 per 1% increase, 95% confidence interval [CI]: 0.89-0.98, p = 0.006) and CLBBB-like paced QRS (OR: 2.69, 95% CI: 1.25-5.76, p = 0.011) were significantly associated with PICM development. CLBBB-like paced QRS may be a novel risk factor for PICM. RV pacing, which causes CLBBB-like QRS morphology, may need to be avoided, and patients with CLBBB-like paced QRS should be followed-up carefully.

Applicability of the AHA/ACC/HRS Guideline for Implantable Cardioverter Defibrillator Implantation in Japanese Patients With Cardiac Sarcoidosis.

This study aimed to assess, among Japanese patients with cardiac sarcoidosis (CS), the implantable cardioverter-defibrillator (ICD) recommendations from the 2017 American Heart Association/American College of Cardiology/Heart Rhythm Society (AHA/ACC/HRS) guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death (SCD). Although ICDs are used to prevent SCD from ventricular tachycardia or ventricular fibrillation (VT/VF) in patients with CS, the generalizability of the AHA/ACC/HRS guidelines for Japanese patients with CS remains unclear. This study examined 188 consecutive patients with CS in 2 tertiary hospitals between 1979 and 2020. Patients were followed for a primary outcome of VT/VF or SCD. During a median follow-up of 5.68 years, the primary outcome occurred in 44 patients (23%). Patients with a Class I recommendation for ICD implantation showed the highest incidence of the primary outcome among patients in whom the guideline recommendations for ICD implantation were used (log-rank test; p=0.03). However, compared with patients with left ventricular ejection fractions (LVEFs)≤35%, there was no significant difference in the incidence of the primary outcome among patients with LVEFs >35% and those who required a permanent pacemaker (p=0.31); similar results were observed in those with LVEFs >35% and late gadolinium enhancement during cardiovascular magnetic resonance imaging (p=0.22). The American guideline recommendations for ICD implantation might be applicable to Japanese patients with CS. Implantation of an ICD may need to be considered in these patients if they require a permanentpacemaker or have late gadolinium enhancement, regardless of LVEF.

MRI safety wih abandoned or functional epicardial pacing leads

Abstract Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): HUS Medical Imaging Center research grant Background The Heart and Rhythm Society’s consensus statement 2017 approves magnetic resonance imaging (MRI) with cardiac implantable electronic devices (CIED), but excludes patients with epicardial and abandoned leads. Potential safety hazards of an MRI with epicardial pacing leads include heating of the tip of the lead and induction of current in the pacing lead resulting in inappropriate cardiac stimulation. Only a few small studies of MRI safety with epicardial pacing leads have been published and adverse events have been rare. The clinical dilemma remains, whether performing an MRI on a patient with CIED and epicardial pacing leads is safe. We have performed MRIs on patients with CIED and epicardial pacing leads when benefits have been considered to outweigh the risks after careful case-by-case evaluation following our institutional MRI with CIED safety protocol. Purpose The aim of this study was to evaluate the safety of performing an MRI scan on patients with CIED and abandoned or functional epicardial pacing leads. Methods All the clinically indicated MRI examinations conducted on adult patients with CIED and functional or abandoned epicardial leads (n = 24) performed in our hospital between November 2011 and October 2019 were included in this observational retrospective study. The data were retrospectively collected from electronic medical records. Results Altogether 24 MRIs were performed to 16 patients with functional or abandoned epicardial pacing leads (Table). 93.8% (15/16) patients had congenital heart disease. Cardiac MRI was the most frequent examination (21/24, 91.7%). 66.7% of the MRI scans (16/24) were conducted on patients with functional epicardial pacing leads. In 5/24 (20.8%) MRIs, the patient was pacemaker-dependent. A clinically significant event occurred in one MRI scan. This was transient elevation of the pacing lead threshold in a patient with functional epicardial ventricular pacing lead, that was implanted 29 years prior to the MRI. In another patient with 30-year-old functional epicardial pacing leads, clinically significant irreversible elevation in atrial pacing lead impedance was detected 6 months after the MRI and unlikely related to previous MRI examination. None of the patients experienced sensations leading to cessation of the MRI scans. No clinically significant pacing lead parameter changes were detected after MRIs performed on patients with modern (implanted year 2000 or later) functional epicardial pacing leads or functional endocardial leads and abandoned epicardial leads. Conclusions MRI examinations in patients with CIED and modern functional epicardial pacing leads were performed without detectable adverse events. Performing an MRI with old functional epicardial pacing leads may involve more risks.

Cryoablation may be superior to drug therapy for initial management of AFib

Results from two studies published in the New England Journal of Medicine support the use of catheter cryoballoon ablation over antiarrhythmic therapy as initial therapy for patients with symptomatic, paroxysmal atrial fibrillation (AFib). The research was based on two trials, known as EARLY-AF and STOP AF First, which both showed that initial use of cryoablation resulted in a significantly lower rate of AFib recurrence compared with drug therapy without increasing the risk for serious adverse events. “We can now offer pulmonary vein isolation–based ablation with greater confidence as first-line therapy for selected patients with paroxysmal atrial fibrillation, particularly those who are disinclined to take antiarrhythmic drugs,” said Joseph E. Marine, MD, from the division of cardiology at Johns Hopkins University School of Medicine, in an accompanying editorial. “The new data will inform shared decision-making discussions with all patients with paroxysmal atrial fibrillation.” The EARLY-AF (Early Aggressive Invasive Intervention for Atrial Fibrillation) trial included 303 adult patients with symptomatic, paroxysmal, untreated AFib who were randomized to catheter ablation with a cryothermy balloon (n = 154) or antiarrhythmic drug therapy (n = 149) as their initial rhythm control. Patients were followed for 12 months. The primary endpoint was the first documented recurrence of any atrial tachyarrhythmia (i.e., AFib, atrial flutter, or atrial tachycardia) lasting 30 seconds or longer between 91 and 365 days after catheter ablation or initiation of an antiarrhythmic drug. At 1 year, documented recurrence occurred in 42.9% of patients who underwent cryoablation compared with 67.8% in the antiarrhythmic group (hazard ratio 0.48 [95% CI 0.35–0.66]). The occurrence of serious adverse events was similar among the two groups: 3.2% of patients in the cryoablation group and 4.0% of patients in the antiarrhythmic group. The STOP AF First (Cryoballoon Catheter Ablation in Antiarrhythmic Drug Naive Paroxysmal Atrial Fibrillation) trial included 203 adult patients with paroxysmal AFib who had not previously received rhythm-control therapy. They were randomized to treatment with a class I or III antiarrhythmic (n = 99) or cryoballoon ablation (n = 104). The results were similar to those of the EARLY-AF trial. A higher percentage of patients in the cryoballoon ablation group had treatment success, defined as freedom from initial failure of the procedure or atrial arrhythmia recurrence after a 90-day period. The estimated percentage of treatment success at 12 months was 74.6% in the ablation group compared with 45.0% in the drug therapy group. Serious adverse events occurred in 14% of patients in both treatment groups. AFib is common, affecting approximately 0.4% to 1% of the general U.S. population, and recurrence rates are high, especially in individuals who are not receiving preventive treatments. Current guidelines by the American Heart Association/American College of Cardiology/Heart Rhythm Society and European Society of Cardiology have generally recommended the use of antiarrhythmic drugs as initial therapy for maintenance of sinus rhythm in patients with AFib. However, these medications tend to have limited efficacy and substantial adverse effects. Once an initial course of treatment fails, catheter ablation is superior to antiarrhythmic drug therapy for preventing further recurrences of atrial arrhythmias. Results of the EARLY-AF and STOP AF First trials could result in some modifications to these current recommendations, with catheter cryoballoon ablation used as initial management to prevent AFib recurrences in select patients. In his editorial, Marine noted that clinicians should consider the populations included in these trials when applying the data in clinical practice. As in the trials, most patients will need to have normal left ventricular function, normal left atrial size, and few coexisting conditions to be eligible for cryoablation. The results cannot be readily extrapolated to patients with persistent AFib, significant structural heart disease, or substantial coexisting conditions that may reduce the efficacy and safety of ablation. Clinicians will need to discuss with patients the benefits and risks of cryoablation compared with initial use of antiarrhythmic therapy. A shared clinical decision-making approach may be beneficial.

2021 ISHNE/HRS/EHRA/APHRS Expert Collaborative Statement on mHealth in Arrhythmia Management

This collaborative statement from the International Society for Holter and Noninvasive Electrocardiology/Heart Rhythm Society (HRS)/European Heart Rhythm Association/Asia-Pacific HRS describes the current status of mobile health (mHealth) technologies in arrhythmia management. The range of digital medical tools and heart rhythm disorders that may be applied to and clinical decisions that may be enabled is discussed. The facilitation of comorbidity and lifestyle management (increasingly recognized to play a role in heart rhythm disorders) and patient self-management are novel aspects of mHealth. The promises of predictive analytics but also operational challenges in embedding mHealth into routine clinical care are explored.

Canadian Cardiovascular Society Clinical Practice Update on the Assessment and Management of Syncope

Syncope is a symptom that occurs in multiple settings and has a variety of underlying causes, ranging from benign to life threatening. Determining the underlying diagnosis and prognosis can be challenging and often results in an unstructured approach to evaluation, which is ineffective and costly. In this first ever document, the Canadian Cardiovascular Society (CCS) provides a clinical practice update on the assessment and management of syncope. It highlights similarities and differences between the 2017 American College of Cardiology/American Heart Association/Heart Rhythm Society and the 2018 European Society of Cardiology guidelines, draws on new data following a thorough review of medical literature, and takes the best available evidence and clinical experience to provide clinical practice tips. Where appropriate, a focus on a Canadian perspective is emphasized in order to illuminate larger international issues. This document represents the consensus of a Canadian panel comprised of multidisciplinary experts on this topic with a mandate to formulate disease-specific advice. The primary writing panel wrote the document, followed by peer review from the secondary writing panel. The CCS Guidelines Committee reviewed and approved the statement. The practice tips represent the consensus opinion of the primary writing panel authors, endorsed by the CCS. The CCS clinical practice update on the assessment and management of syncope focuses on epidemiology, the initial evaluation including risk stratification and disposition from the emergency department, initial diagnostic work-up, management of vasovagal syncope and orthostatic hypotension, and syncope and driving.

Management of Asymptomatic Wolff-Parkinson-White Pattern in Young Patients: Has Anything Changed?

The approach to pediatric asymptomatic Wolff-Parkinson-White (WPW) patients is controversial. The objective of this review is to update the last consensus of specialists of the Pediatric and Congenital Electrophysiology Society/Heart Rhythm Society on this subject in order to summarize the most recent evidence on the management of young patients with asymptomatic WPW pattern. A systematic review of the literature published between 2008 and 2018 was performed taking into account the protocol of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) in PubMed (including Cochrane), Embase, and Web of Science. Observational, experimental, and multicentric studies were included. Out of a total of 37 articles selected, 4 were considered eligible. Most studies considered a cutoff age of 8 or greater as recommended in the 2012 consensus. The identification of a shortest pre-excitatory RR interval (SPERRI) ≤ 250ms seems to be the best predictor for risk stratification. The importance of routine isoprenaline use to improve the sensitivity of the electrophysiological study to identify patients at high risk of sudden death was consensual. Prophylactic ablative therapy has been indicated in asymptomatic children with an accessory pathway (AP) who have a low SPERRI and/or a low effective anterograde period of the AP and/or multiple APs. Despite the evidence found in the most recent studies, more studies are warranted in this setting.

Safety and outcomes of catheter ablation for atrial fibrillation in adults with congenital heart disease: A multicenter registry study

An increasing number of adults with congenital heart disease (CHD) are undergoing catheter ablation for atrial fibrillation (AF). Data on ablation strategy and outcomes in CHD are limited. Rhythm control is often believed to be of greater importance among patients with complex CHD. The purpose of this study was to examine the safety and efficacy of AF ablation in adult patients with CHD. A multicenter retrospective analysis was performed of CHD patients undergoing AF ablation. Clinical data were collected, including AF and CHD type, procedural data, and outcomes. Patients were divided into 3 groups (simple, moderate, and severe) based on CHD complexity, as defined by the 2014 PACES/HRS (Pediatric and Congenital Electrophysiology Society/Heart Rhythm Society) consensus statement. One-year procedural success was defined as freedom from recurrent AF, off antiarrhythmic drugs (complete) or off/on previously failed antiarrhythmic drugs (partial). Overall, 84 CHD patients (mean age 51.5 ± 12.1 years; 65.5% male; 45.2% with paroxysmal AF) undergoing AF ablation (51 simple, 22 moderate, 11 severe complexity) were included. Pulmonary vein isolation was performed in 80 (95.2%), of whom 30 (35.7%) underwent pulmonary vein isolation alone. Overall, complete and complete/partial freedom was achieved at 1 year in 53.1% and 71.6%, respectively, with no significant differences between those with simple, moderate, or severe complexity. There were no major complications and 7 minor complications, and 2 patients died during follow-up. There are dramatic differences in the degree of CHD complexity among patients referred for AF ablation. When performed at experienced centers, AF ablation is safe and effective even among patients with the most complex forms of CHD.

Evaluation and Management of Syncope: Comparing the Guidelines of the American College of Cardiology/American Heart Association/Heart Rhythm Society and the European Society of Cardiology

Evaluation and Management of Syncope: Comparing the Guidelines of the American College of Cardiology/American Heart Association/Heart Rhythm Society and the European Society of Cardiology

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.

AN EVALUATION OF PRACTITIONERS' PREFERENCE OF STROKE RISK TOOLS IN NONVALVULAR ATRIAL FIBRILLATION: CHA2DS2VASC VERSUS CHADS2

Several stroke risk assessment tools exist. However, current nonvalvular atrial fibrillation (NVAF) guidelines differ in utilization of these tools. For instance, the American Heart Association/American College of Cardiology/Heart Rhythm Society (AHA/ACC/HRS) guidelines recommend use of the

Managing atrial fibrillation after cardiac surgery

Open-heart surgery involves the opening of the thoracic cage followed by surgical intervention on the cardiac muscle, arteries, valves, or other structures. It is indicated for many cardiac diseases such as coronary artery blockage, valvular heart stenosis or calcification, aortic aneurysm or dissection ( National Heart, Lung, and Blood Institute, 2013 ). As with any surgery, it contains several complications, one of which is dysrhythmia, and atrial fibrillation (AF) is the most predominant of these ( Peretto et al, 2014 ). AF involves an abnormal elevated heart rate and irregular rhythm, resulting from abnormal electrical discharge from the atrium rather than the sinoatrial node (SA). AF post operation is common in surgeries of the heart and chest, as well as other non-cardiothoracic surgeries ( Mostafa et al, 2012 ). According to the American Heart Association/American College of Cardiology/Heart Rhythm Society (AHA/ACC/HRS), AF can be classified based on duration into: paroxysmal AF, which resolves by intervention or spontaneously within 7 days of onset; persistent AF, which continues for more than 7 days; longstanding AF, which continues for more than 12 months; permanent AF, which cannot be restored to sinus rhythm; and non-valvular AF, in which the occurrence of AF is unrelated to rheumatic mitral valve disease, a prosthetic heart valve, or mitral valve repair ( January et al, 2014 ).

Electrophysiology Updates in Adult Congenital Heart Disease.

Electrophysiology Updates in Adult Congenital Heart Disease.

Stroke prevention in atrial fibrillation patients with a single stroke risk factor: Clinical decision-making and guideline recommendations: A case report and comparative analysis of the European Society of Cardiology (ESC) and American Heart Association/American College of Cardiology/Heart Rhythm Society (AHA/ACC/HRS) guidelines on the management of atrial fibrillation

Stroke prevention in atrial fibrillation patients with a single stroke risk factor: Clinical decision-making and guideline recommendations: A case report and comparative analysis of the European Society of Cardiology (ESC) and American Heart Association/American College of Cardiology/Heart Rhythm Society (AHA/ACC/HRS) guidelines on the management of atrial fibrillation

Abstract 19336: Reported Stroke Rates in Patients With Nonvalvular Atrial Fibrillation in North America are Lower Than Those Cited in ESC and AHA Guidelines

Background: Anticoagulants (OAC) decrease ischemic stroke rates in patients with atrial fibrillation (AF) but increase the risk of bleeding. The risk of ischemic stroke where the absolute benefit of anticoagulation outweighs the bleeding risk has been shown to be 1-2% per year. The American Heart Association/American College of Cardiology/Heart Rhythm Society and the European Society of Cardiology (ESC) guidelines have adopted the CHA2DS2-VASc stroke risk score; their recommendations assume the scheme’s point scores correspond to fixed stroke rates. However, reported rates of stroke vary widely across cohorts, placing in question the generalizability of guideline recommendations. Objective: To contrast the reported rates of stroke in North American (NA) patients with AF who do not take OAC with the Danish AF cohort used to create the ESC guidelines. Methods: We conducted a systematic review to identify all cohort studies and randomized controlled trials including patients with non-valvular AF not treated with OAC. We excluded studies that enrolled only patients undergoing surgical procedures or cardioversion, or only patients with specific comorbidities such as prior stroke or kidney disease. Results: Of the 3,552 studies screened, we identified 13 eligible NA studies representing 137,652 patients. Larger and more contemporary cohorts generally had lower stroke rates (Table). When weighted by number of subjects, the NA cohorts’ ischemic stroke rate averaged 1.88% per year, whereas the Danish cohort had a rate of 4.66% per year. Conclusions: Large variation exists in stroke rates across putatively representative cohorts. This may reflect true differences in rates or methodologic differences among studies. These differences could change the point score threshold for recommending OAC in lower risk regions. Reexamining the net benefit of OAC in patients with a CHA2DS2-VASc score of 1 or 2 seems warranted, particularly for those with weak 1-point risk factors.

High Grade Atrioventricular Block Presenting with Cardiac Arrest

Introduction: Atrioventricular block usually does not cause cardiac arrest because of the development of an escape rhythm which maintains cardiac output. We report a case of high grade AV block presenting with cardiac arrest. Case Description: A 74-year-old man with past medical history of hypertension, dyslipidemia and a recent stroke was brought to the emergency room after a cardiac arrest, with pulseless electrical activity as the initial rhythm. Cardiopulmonary resuscitation was performed with return of spontaneous circulation after five minutes. On examination, he was unresponsive, with heart rate of 33 beats per minute, blood pressure of 108/51mmHg, normal heart sounds and clear lungs. He was given a total of 2mg of atropine, following which he was started on dopamine infusion, with no significant increase in heart rate. His electrocardiogram showed high grade AV block with ventricular rate of 30 beats per minute. An assessment of cardiac arrest due to severe conduction disease, with no evidence of acute coronary syndrome was made. A trans-venous pacemaker was inserted with improvement in the patient’s blood pressure and mental status. EKG revealed demand ventricular pacing with 100% ventricular capture. By the third day of admission, he was fully awake and following simple commands, but he remained pacemaker-dependent with no subsidiary rhythm. He had a dual chamber permanent pacemaker inserted without complication. Discussion: In advanced (high grade) second degree AV block, there is failure of conduction of two or more consecutive P waves. High grade AV block may be asymptomatic, or it may present with symptoms of hypoperfusion due to reduced cardiac output. Conclusion: This case describes a not previously reported presentation of high grade AV block with cardiac arrest and is in agreement with the 2008 American College of Cardiology/American Heart Association/Heart Rhythm Society (ACC/AHA/HRS) device guidelines recommendations for permanent pacemaker insertion.

QRS Duration Criteria to Select Patients for Cardiac Resynchronization Therapy

Current American College of Cardiology/American Heart Association/Heart Rhythm Society as well as European Society of Cardiology guidelines recommend the use of cardiac resynchronization therapy (CRT) in patients with symptomatic heart failure (HF) and QRS durations >120 ms1,2 (Table 1). However, 2 recent meta-analyses by Sipahi et al6 and Stavrakis et al7 challenged these recommendations. Both studies found that patients with QRS durations between 120 and 150 ms do not benefit from CRT. View this table: Table 1. Indications for Cardiac Resynchronization Therapy Response by Sipahi and Fang on p 435 This is a very important conclusion, from both the clinical and financial standpoints. If the conclusions of these meta-analyses are correct, the guidelines should be revised, and the cutoff for QRS duration indicating the need for CRT should be changed from 120 to 150 ms. From the reimbursement standpoint, these analyses would suggest that the cost of CRT devices implanted in patients with QRS durations shorter than 150 ms should not be covered by insurers. Indeed, the authors of the second meta-analysis state that “the decision to routinely recommend CRT for patients with QRS <150 ms may not be justified.”7 Although not in such categorical terms, some societies are already embracing this idea. In fact, in their recently published update, the Heart Failure Society of America, citing one of the abovementioned meta-analyses,6 definitely recommends CRT only for patients with QRS durations >150 ms (and not because of right bundle-branch block), with severe left ventricular (LV) systolic dysfunction and persistent New York Heart Association (NYHA) functional class II-III symptoms, despite optimal medical therapy. According to the same update, CRT may still be considered for patients with QRS intervals between 120 and 150 ms and severe left ventricular dysfunction who have persistent symptoms on medical treatment.5 However, the wording …

Recent Atrial Fibrillation Guidelines – Looking at Both Sides of the Atlantic

The American College of Cardiology (ACC), the American Heart Association (AHA) and the European Society of Cardiology (ESC) reported joint guidelines on atrial fibrillation (AF) in 2001 and a revised version in 2006. In 2010 new guidelines on AF were published by the ESC, and in 2011 by the American College of Cardiology Foundation (ACCF)/AHA/Heart Rhythm Society (HRS) and by the Canadian Cardiac Society (CCS). Focused updates have also appeared more recently. We reviewed these three sets of AF guidelines and compared their rating systems and their recommendations regarding four major AF management aspects (i.e. long-term rate control strategy, long-term rhythm control strategy, oral anticoagulation and AF catheter ablation). Significant differences were found between guidelines in the quality of evidence or level of evidence and on the strength of recommendations. Use of new anticoagulants and of new antiarrhythmic drug therapy is also discussed in the light of recent trial results. Whether multiplication of guidelines and differences in recommendation impact their implementation in clinical practice, remains to be assessed.