The natural history of primary first-degree atrioventricular heart block

PR prolongation as a predictor of atrial fibrillation onset: A state-of-the-art review

First-degree atrioventricular block (1-AVB), characterized by a PR interval exceeding 200 milliseconds, has traditionally been perceived as a benign cardiac condition. Recently, this perception has been challenged by investigations that indicate a potential association between PR prolongation and an elevated risk of atrial fibrillation (AF). To consolidate these findings, we performed a comprehensive review to assess the available evidence indicating a relationship between these two conditions. We searched MEDLINE and EMBASE databases as well as manually searched references of retrieved articles. We selected 18 cohort studies/meta-analyses involving general and special populations. Consistent findings across expansive cohort studies reveal that incremental increases in the PR interval may serve as an independent risk factor for AF. However, our analyses underscore the need for further research into the association between 1-AVB, defined by a specified PR interval cutoff, and the risk of AF.

Clinical and Non-Clinical Cardiovascular Disease Associated Pathologies in Parkinson's Disease

Despite considerable breakthroughs in Parkinson's disease (PD) research, understanding of non-motor symptoms (NMS) in PD remains limited. The lack of basic level models that can properly recapitulate PD NMS either in vivo or in vitro complicates matters. Even so, recent research advances have identified cardiovascular NMS as being underestimated in PD. Considering that a cardiovascular phenotype reflects sympathetic autonomic dysregulation, cardiovascular symptoms of PD can play a pivotal role in understanding the pathogenesis of PD. In this study, we have reviewed clinical and non-clinical published papers with four key parameters: cardiovascular disease risks, electrocardiograms (ECG), neurocardiac lesions in PD, and fundamental electrophysiological studies that can be linked to the heart. We have highlighted the points and limitations that the reviewed articles have in common. ECG and pathological reports suggested that PD patients may undergo alterations in neurocardiac regulation. The pathological evidence also suggested that the hearts of PD patients were involved in alpha-synucleinopathy. Finally, there is to date little research available that addresses the electrophysiology of in vitro Parkinson's disease models. For future reference, research that can integrate cardiac electrophysiology and pathological alterations is required.

Epidemiology and Outcomes Associated with PR Prolongation

PR prolongation is defined primarily as delayed conduction through the AV node, but can also signify delayed electrical impulse propagation through any part of the conduction system. The prevalence of PR prolongation ranges from 1% to 5% in patients younger than 50 years, with increasing prevalence, after the sixth decade of life and in patients with organic heart disease. Contemporary studies have documented increased risk of atrial arrhythmias, heart failure, and mortality in patients with PR prolongation. Future studies are needed to more accurately risk stratify elderly patients with PR prolongation who may be at increased risk of adverse outcomes.

The Aging Heart: A Molecular and Clinical Challenge

Aging is associated with an increasing burden of morbidity, especially for cardiovascular diseases (CVDs). General cardiovascular risk factors, ischemic heart diseases, heart failure, arrhythmias, and cardiomyopathies present a significant prevalence in older people, and are characterized by peculiar clinical manifestations that have distinct features compared with the same conditions in a younger population. Remarkably, the aging heart phenotype in both healthy individuals and patients with CVD reflects modifications at the cellular level. An improvement in the knowledge of the physiological and pathological molecular mechanisms underlying cardiac aging could improve clinical management of older patients and offer new therapeutic targets.

Prolonged PR Interval and Incidence of Atrial Fibrillation, Heart Failure Admissions and Mortality in Patients with Implanted Cardiac Devices: A Real-World Survey

Background

Prolongation of the PR interval has long been considered a benign condition, particularly in the setting of nonstructural heart disease.

Objective

The purpose of this study was to investigate the effect of PR interval on various well-adjudicated cardiovascular outcomes using a large real-world population data of patients with implanted dual-chamber permanent pacemakers or implantable cardioverter-defibrillators.

Methods

PR intervals were measured during remote transmissions in patients with implanted permanent pacemakers or implantable cardioverter-defibrillators. Study endpoints (time to the first occurrence of AF, heart failure hospitalization [HFH], or death) were obtained between January 2007 and June 2019 from the deidentified Optum de-identified Electronic Health Record dataset.

Results

A total of 25,752 patients (age 69.3 ± 13.9 years; 58% male) were evaluated. The average intrinsic PR interval was 185 ± 55 ms. In the subset of 16,730 patients with available long-term device diagnostic data, a total of 2555 (15.3%) individuals developed AF during 2.59 ± 2.18 years of follow-up. The incidence of AF was significantly higher (up to 30%) in patients with a longer PR interval (ie, PR interval ≥270 ms; P < .05). Time-to-event survival analysis and multivariable analysis showed that PR interval ≥190 ms was significantly associated with higher incidence of AF, HFH, or HFH or death when compared with shorter PR intervals (P < .05 for all 3 parameters).

Conclusion

In a large real-world population of patients with implanted devices, PR interval prolongation was significantly associated with increased incidence of AF, HFH, or death.

Associação entre Bloqueio Atrioventricular e Mortalidade em Pacientes de Atenção Primária: O Estudo CODE

Fundamento

O bloqueio atrioventricular (BAV) descreve um comprometimento na condução dos átrios para os ventrículos. Embora o curso clínico do BAV tenha sido avaliado, os achados são de países de alta renda e, portanto, não podem ser extrapolados para a população latina.

Objetivo

Avaliar a associação entre BAV e mortalidade.

Métodos

Foram incluídos pacientes do estudo CODE (Clinical Outcomes in Digital Electrocardiology), maiores de 16 anos que realizaram eletrocardiograma (ECG) digital de 2010 a 2017. Os ECGs foram relatados por cardiologistas e por software automatizado. Para avaliar a relação entre BAV e mortalidade, foram utilizados o modelo log-normal e as curvas de Kaplan-Meier com valores de p bicaudais < 0,05 considerados estatisticamente significativos.

Resultados

O estudo incluiu 1.557.901 pacientes; 40,23% eram homens e a média de idade foi de 51,7 (DP ± 17,6) anos. Durante um seguimento médio de 3,7 anos, a mortalidade foi de 3,35%. A prevalência de BAV foi de 1,38% (21.538). Os pacientes com BAV de primeiro, segundo e terceiro graus foram associados a uma taxa de sobrevida 24% (taxa de sobrevida relativa [RS] = 0,76; intervalo de confiança [IC] de 95%: 0,71 a 0,81; p < 0,001), 55% (RS = 0,45; IC de 95%: 0,27 a 0,77; p = 0,01) e 64% (RS = 0,36; IC de 95%: 0,26 a 0,49; p < 0,001) menor quando comparados ao grupo controle, respectivamente. Os pacientes com BAV 2:1 tiveram 79% (RS = 0,21; IC de 95%: 0,08 a 0,52; p = 0,005) menor taxa de sobrevida do que o grupo controle. Apenas Mobitz tipo I não foi associado a maior mortalidade (p = 0,27).

Conclusão

BAV foi um fator de risco independente para mortalidade geral, com exceção do BAV Mobitz tipo I.

Prognostic significance of first-degree atrioventricular block in a large Asian population: a prospective cohort study

OBJECTIVE

To investigate the prognostic significance of first-degree atrioventricular block (AVB) in Asian populations.

DESIGN AND SETTING

Participants (N=9634) from the Northeast China Rural Cardiovascular Health Study were included. The first-degree AVB was defined as PR (from the beginning of the P wave to the beginning of the QRS complex on an electrocardiogram) interval >200 ms, and primary composite outcome (all events) included new onset cardiovascular disease (CVD) and mortality. Cox regression and restricted cubic spline were used to identify the associations of PR interval or first-degree AVB with end points. Furthermore, the relationship between new-onset CVD and mortality and first-degree AVB was separately evaluated. The value of first-degree AVB for predicting adverse events was evaluated by reclassification and discrimination analyses.

RESULTS

During a median of 4.65 years follow-up, 524 participants developed CVD and 371 died. Compared with participants with PR ≤200 ms, those with first-degree AVB had an increased risk of all events (HR: 1.84; 95% CI 1.18 to 2.88). Furthermore, first-degree AVB was predictive of incident CVD (1.96, 1.18 to 3.23) and stroke (2.22, 1.27 to 3.90) after adjusting for conventional risk. These statistically significant associations remained unchanged after further stratification by potential confounding factors. Discrimination and reclassification analyses suggested that first-degree AVB addition could improve the conventional model for predicting adverse outcomes within 4 years.

CONCLUSIONS

Our results indicated that first-degree AVB was an independent risk factor for adverse events, suggesting that it should not be considered as inconsequential factor in general population. These results have potential clinical value for identifying individuals at high risk for adverse outcomes.

Clinical electrophysiology of the aging heart

INTRODUCTION

Advancements in medical and consumer-grade technologies have made it easier than ever to monitor a patient's heart rhythm and to diagnose arrhythmias. Octogenarians with symptomatic arrhythmias have unique management challenges due to their frailty, complex drug interactions, cognitive impairment, and competing comorbidities. The management decisions are further complicated by the lack of randomized evidence to guide treatment.

AREAS COVERED

A comprehensive literature review was undertaken to outline various tachyarrhythmias and bradyarrhythmias and their management, the role of cardiac implantable electronic devices, cardiac ablations, and specific geriatric arrhythmia considerations as recommended in international guidelines.

EXPERT OPINION

Atrial fibrillation (AF) is arguably the most important arrhythmia in the elderly and is associated with significant morbidity and mortality. Early diagnosis of AF, potentially with smart devices (wearables), has the potential to reduce the incidence of stroke, systemic emboli, and the risk of dementia. Bradyarrhythmias have a high incidence in the elderly as well, often requiring implantation of a permanent pacemaker. Leadless pacemakers implanted directly into the right ventricle are great options for gaining traction in elderly patients.

Epidemiology and Outcomes Associated with PR Prolongation

PR prolongation is defined primarily as delayed conduction through the AV node, but can also signify delayed electrical impulse propagation through any part of the conduction system. The prevalence of PR prolongation ranges from 1% to 5% in patients younger than 50 years, with increasing prevalence, after the sixth decade of life and in patients with organic heart disease. Contemporary studies have documented increased risk of atrial arrhythmias, heart failure, and mortality in patients with PR prolongation. Future studies are needed to more accurately risk stratify elderly patients with PR prolongation who may be at increased risk of adverse outcomes.

Unravelling Atrioventricular Block Risk in Inflammatory Diseases: Systemic Inflammation Acutely Delays Atrioventricular Conduction via a Cytokine-Mediated Inhibition of Connexin43 Expression

Background

Recent data suggest that systemic inflammation can negatively affect atrioventricular conduction, regardless of acute cardiac injury. Indeed, gap‐junctions containing connexin43 coupling cardiomyocytes and inflammation‐related cells (macrophages) are increasingly recognized as important factors regulating the conduction in the atrioventricular node. The aim of this study was to evaluate the acute impact of systemic inflammatory activation on atrioventricular conduction, and elucidate underlying mechanisms.

Methods and Results

We analyzed: (1) the PR‐interval in patients with inflammatory diseases of different origins during active phase and recovery, and its association with inflammatory markers; (2) the existing correlation between connexin43 expression in the cardiac tissue and peripheral blood mononuclear cells (PBMC), and the changes occurring in patients with inflammatory diseases over time; (3) the acute effects of interleukin(IL)‐6 on atrioventricular conduction in an in vivo animal model, and on connexin43 expression in vitro. In patients with elevated C‐reactive protein levels, atrioventricular conduction indices are increased, but promptly normalized in association with inflammatory markers reduction, particularly IL‐6. In these subjects, connexin43 expression in PBMC, which is correlative of that measured in the cardiac tissue, inversely associated with IL‐6 changes. Moreover, direct IL‐6 administration increased atrioventricular conduction indices in vivo in a guinea pig model, and IL‐6 incubation in both cardiomyocytes and macrophages in culture, significantly reduced connexin43 proteins expression.

Conclusions

The data evidence that systemic inflammation can acutely worsen atrioventricular conduction, and that IL‐6‐induced down‐regulation of cardiac connexin43 is a mechanistic pathway putatively involved in the process. Though reversible, these alterations could significantly increase the risk of severe atrioventricular blocks during active inflammatory processes.

First-degree atrioventricular block is significantly associated with incident atrial fibrillation in the population predominantly including participants aged ≥ 60 years

Some previous studies demonstrated that first-degree atrioventricular block (f-AVB) was associated with incident atrial fibrillation (AF), while evidence is scarce regarding the association between f-AVB and incident AF in older populations. Therefore, we sought to investigate the association of f-AVB with incident AF in the population predominantly including participants aged ≥ 60 years. Eligible participants were residents in Kanazawa City, Japan aged ≥ 40 years who underwent 12-lead ECG at the National Japanese Health Check-up in 2013. Participants with AF detected at the baseline exam and those without adequate follow-up were excluded. f-AVB was defined as PR interval ≥ 220 ms based on the Minnesota code (6-3). The cumulative incidence of AF was estimated by the Kaplan-Meier curve analysis, and statistical significance was evaluated by the Log-rank test. Unadjusted and adjusted hazard ratios (HRs) were computed by Cox proportional hazard models. HRs were adjusted for conventional risk factors for AF. 37,730 participants (mean age, 72.3 ± 9.6 years; male, 37%) were included. Baseline f-AVB was observed in 667 (1.8%) participants. During the median follow-up period of 5 years (interquartile range, 4.0-5.0 years), 691 cases of incident AF were observed. A 5-year cumulative incidence of AF was significantly higher in f-AVB (+) group compared with f-AVB (-) group (6.8% vs 2.1%, p < 0.01). In the fully adjusted model, f-AVB was significantly associated with incident AF (HR, 1.75; 95% confidence interval 1.25-2.45; p value < 0.01). f-AVB was independently associated with incident AF in the population predominantly including participants aged ≥ 60 years.

First-degree atrioventricular block in acute anterior myocardial infarction

BACKGROUND

There is paucity of data regarding the prognostic implications of first-degree atrioventricular block in patients with acute anterior myocardial infarction as a distinct group. The aim of this study was to elucidate the association of prolonged PR interval with hospital clinical outcomes in patients with treated with thrombolysis.

METHODS

Three hundred consecutive patients with a first acute anterior ST-segment elevation myocardial infarction undergoing thrombolysis between October 2017 and March 2018, were retrospectively enrolled in this study. They were divided into two groups based on PR interval on admission: PR interval ≤200 ms, and PR interval > 200 ms. Hospital mortality and complications were compared between the 2 groups.

RESULTS

Of the 300 patients, 26 (8.66%) had first-degree atrioventricular block on initial presentation. Overall, hospital death occurred in 20 (6.66%) patients. Patients with PR interval > 200 ms had a higher hospital mortality rate (26.9%) than those without (4.7%, p < 0.001). In multivariate Cox regression analysis, only left ventricular systolic function and PR interval were independent predictors of hospital mortality (odds ratio = 1.031; 95% confidence interval: 1.008-1.056, p = 0.009 for PR interval).

CONCLUSION

In patients with a first acute anterior ST-segment elevation myocardial infarction treated with thrombolysis, first-degree atrioventricular block was associated with increased hospital mortality and a worse prognosis.

Prognostic Implication of First-Degree Atrioventricular Block in Patients With Hypertrophic Cardiomyopathy

Background

The association between first‐degree atrioventricular block (AVB) and life‐threatening cardiac events in patients with hypertrophic cardiomyopathy (HCM) remains unclear. This study sought to investigate whether presence of first‐degree AVB was associated with HCM‐related death in patients with HCM.

Methods and Results

We included 414 patients with HCM (mean age, 51±16 years; 64.5% men). The P‐R interval was measured at the time of the initial evaluation and patients were classified into those with and without first‐degree AVB, which was defined as a P‐R interval ≥200 ms. HCM‐related death was defined as a combined end point of sudden death or potentially lethal arrhythmic events, heart failure–related death, and stroke‐related death. First‐degree AVB was noted in 96 patients (23.2%) at time of enrollment. Over a median (interquartile range) follow‐up period of 8.8 (4.9–12.9) years, a total of 56 patients (13.5%) experienced HCM‐related deaths, including 47 (11.4%) with a combined end point of sudden death or potentially lethal arrhythmic events. In a multivariable analysis that included first‐degree AVB and risk factors for life‐threatening events, first‐degree AVB was independently associated with an HCM‐related death (adjusted hazard ratio, 2.41; 95% CI, 1.27–4.58; P=0.007), and this trend also persisted for the combined end point of sudden death or potentially lethal arrhythmic events (adjusted hazard ratio, 2.60; 95% CI, 1.28–5.27; P=0.008).

Conclusions

In this cohort of patients with HCM, first‐degree AVB may be associated with HCM‐related death, including the combined end point of sudden death or potentially lethal arrhythmic events.

Heart Disease and Stroke Statistics-2020 Update: A Report From the American Heart Association

BACKGROUND

The American Heart Association, in conjunction with the National Institutes of Health, annually reports on the most up-to-date statistics related to heart disease, stroke, and cardiovascular risk factors, including core health behaviors (smoking, physical activity, diet, and weight) and health factors (cholesterol, blood pressure, and glucose control) that contribute to cardiovascular health. The Statistical Update presents the latest data on a range of major clinical heart and circulatory disease conditions (including stroke, congenital heart disease, rhythm disorders, subclinical atherosclerosis, coronary heart disease, heart failure, valvular disease, venous disease, and peripheral artery disease) and the associated outcomes (including quality of care, procedures, and economic costs).

METHODS

The American Heart Association, through its Statistics Committee, continuously monitors and evaluates sources of data on heart disease and stroke in the United States to provide the most current information available in the annual Statistical Update. The 2020 Statistical Update is the product of a full year's worth of effort by dedicated volunteer clinicians and scientists, committed government professionals, and American Heart Association staff members. This year's edition includes data on the monitoring and benefits of cardiovascular health in the population, metrics to assess and monitor healthy diets, an enhanced focus on social determinants of health, a focus on the global burden of cardiovascular disease, and further evidence-based approaches to changing behaviors, implementation strategies, and implications of the American Heart Association's 2020 Impact Goals.

RESULTS

Each of the 26 chapters in the Statistical Update focuses on a different topic related to heart disease and stroke statistics.

CONCLUSIONS

The Statistical Update represents a critical resource for the lay public, policy makers, media professionals, clinicians, healthcare administrators, researchers, health advocates, and others seeking the best available data on these factors and conditions.

Prevalence of first-degree atrioventricular block and the associated risk factors: a cross-sectional study in rural Northeast China

Background

First-degree atrioventricular block (AVB) has traditionally been regarded as a benign condition but recent studies have challenged this conception. Prevalence of 1–2% have been reported in developed countries in Asia. However, no epidemiologic studies have established the prevalence of first-degree AVB in developing countries. The aim of the study was to investigate the prevalence of first-degree AVB in rural northeast China and identify the associated risk factors.

Methods

This cross-sectional study was undertaken from September 2017 to May 2018 in rural areas of Liaoning Province. It involved 10,926 participants aged ≥40 years (85.3% of those who were eligible). First-degree AVB was confirmed by at least two independent cardiologists. Risk factors were evaluated using stepwise logistic regression.

Results

The prevalence of first-degree AVB was 3.4% (95% confidence interval [CI]: 3.0–3.8%). Males had a higher prevalence than females (5.1% vs. 2.2%, p < 0.001). The regression model involving all participants showed that age (odds ratio [OR]: 1.32; p <0.001), male sex (OR: 1.72; p = 0.001), height (OR: 1.25; p = 0.008), systolic blood pressure (SBP) (OR: 1.15; p = 0.003), triglycerides (TG) (OR: 1.10; p < 0.001), high-density lipoprotein cholesterol (HDL-C) (OR: 0.73; p < 0.001), heart rate (OR: 0.78; p < 0.001), and exercising regularly (OR: 0.73; p = 0.030) were independent risk factors.

Conclusions

First-degree AVB is highly prevalent in rural areas of northeast China. The associated independent risk factors include being male, older, and taller, higher SBP and TG, lower HDL-C and heart rate, and lack of exercise.

Variants in NKX2-5 and FLNC Cause Dilated Cardiomyopathy and Sudden Cardiac Death

BACKGROUND

Dilated cardiomyopathy (DCM) is an important cause of heart failure. Variants in >50 genes have been reported to cause DCM, but causative variants have been found in less than half of familial cases. Variants causing DCM in Iceland have not been reported before.

METHODS

We performed a genome-wide association study on DCM based on whole genome sequencing. We tested the association of 32.5 million sequence variants in 424 cases and 337 689 population controls in Iceland.

RESULTS

We identified 2 DCM variants in established cardiomyopathy genes, a missense variant p.Phe145Leu in NKX2-5 carried by 1 in 7100 Icelanders ( P=7.0×10^-12) and a frameshift variant p.Phe1626Serfs*40 in FLNC carried by 1 in 3600 Icelanders ( P=2.1×10^-10). Both variants associate with heart failure and sudden cardiac death. Additionally, p.Phe145Leu in NKX2-5 associates with high degree atrioventricular block and atrial septal defect ( P<1.4×10^-4). The penetrance of serious heart disease among carriers of the NKX2-5 variant is high and higher than that of the FLNC variant.

CONCLUSIONS

Two rare variants in NKX2-5 and FLNC, carried by 1 in 2400 Icelanders, cause familial DCM in Iceland. These genes have recently been associated with DCM. Given the serious consequences of these variants, we suggest screening for them in individuals with DCM and their family members, with subsequent monitoring of carriers, offering early intervention.

Arrhythmias in Patients ≥80 Years of Age: Pathophysiology, Management, and Outcomes

Advances in medical care have led to an increase in the number of octogenarians and even older patients, forming an important and unique patient subgroup. It is clear that advancing age is an independent risk factor for the development of most arrhythmias, causing substantial morbidity and mortality. Patients ≥80 years of age have significant structural and electrical remodeling of cardiac tissue; accrue competing comorbidities; react differently to drug therapy; and may experience falls, frailty, and cognitive impairment, presenting significant therapeutic challenges. Unfortunately, very old patients are under-represented in clinical trials, leading to critical gaps in evidence to guide effective and safe treatment of arrhythmias. In this state-of-the-art review, we examine the pathophysiology of aging and arrhythmias and then present the available evidence on age-specific management of the most common arrhythmias, including drugs, catheter ablation, and cardiac implantable electronic devices.

Atrioventricular block can be used as a risk predictor of clinical atrial fibrillation

Background

Atrial fibrillation (AF) is the most common cardiac arrhythmia, with its incidence making up nearly one‐third of all hospital admissions. Atrioventricular block (AVB) is a conduction abnormality along the atrioventricular node or the His‐Purkinje system. The relationship between atrioventricular conduction block and AF is controversial.

Hypothesis

This study is designed to observe whether there is a correlation between AVB and AF, and which type of AVB has the most obvious correlation with AF.

Methods

This study retrospectively reviewed 1345 patients. We classified the AVB according to the AVB classification criteria. One hundred and two patients were excluded, and the final total sample size was 1243 patients, including 679 patients in the AF group (378, 55.7% males) and 564 patients in the non‐AF group (287, 50.8% males). AF group and non‐AF group were compared to observe the relationship between AVB and AF.

Results

The I AVB have a relative statistical risk of 1.927 (95% confidence interval [CI]: 1.160‐3.203, P < 0.05) with the occurrence of AF. II AVB occupied the largest proportion, accounting for 67 cases (9.87%), and the statistical risk of II AVB in AF is 16.845 (95% CI: 6.099‐46.524, P < 0.000). III AVB has a comparative statistical risk of 17.599 (95% CI: 4.212‐73.541, P < 0.000).

Conclusions

The three types of AVB in the AF group were significantly higher than that in the non‐AF group. II AVB has the highest incidence rate compared with other types of AVB in the AF group. AVB can be used as a risk factor for AF occurrence.

Prevalence of resting-ECG abnormalities in systemic lupus erythematosus: a single-center experience

Cardiovascular complications are a major cause of morbidity and even mortality among systemic lupus erythematosus (SLE) patients. Whether cardiac arrhythmias contribute to this burden among SLE patients, however, is not currently known. The goal of this study was to determine the prevalence of cardiac conduction abnormalities among SLE patients from a single center. We retrospectively reviewed the medical records of SLE patients who had 12-lead electrocardiograms (ECGs) available from various settings at a single academic center over the period of 10 years. In addition, ICD-9 codes for arrhythmias were obtained for the SLE patients whose ECGs were reviewed. The hospital setting (in-patient, out-patient, emergency department) and the indication for obtaining the ECG were evaluated. Two hundred thirty-five SLE patients had available ECGs. Sinus tachycardia was most common (18%). With direct ECG review, tachyarrhythmias were found in 6% of SLE patients, with the most common being atrial fibrillation (3%). Atrial fibrillation was seen even more frequently (9%) when ICD-9 codes were reviewed. No patients had brady-arrhythmias. QT prolongation was present in 17% of patients upon direct ECG review. More ECGs with tachyarrhythmias and QT prolongation were found among inpatients, with preoperative evaluation and gastrointestinal symptoms being the most common indications. Sinus tachycardia was the most common finding seen among our SLE patients with ECGs. Further study into the possible mechanisms behind this is warranted, including the possibility of autonomic nervous system involvement in SLE.

Position paper for management of elderly patients with pacemakers and implantable cardiac defibrillators: Groupe de Rythmologie et Stimulation Cardiaque de la Société Française de Cardiologie and Société Française de Gériatrie et Gérontologie

Despite the increasingly high rate of implantation of pacemakers (PMs) and implantable cardioverter defibrillators (ICDs) in elderly patients, data supporting their clinical and cost-effectiveness in this age stratum are ambiguous and contradictory. We reviewed the data regarding the applicability, safety and effectiveness of conventional pacing, ICDs and cardiac resynchronization therapy (CRT) in elderly patients. Although periprocedural risk may be slightly higher in the elderly, the implantation procedure for PMs and ICDs is still relatively safe in this age group. In older patients with sinus node disease, the general consensus is that DDD pacing with the programming of an algorithm to minimize ventricular pacing is preferred. In very old patients presenting with intermittent or suspected atrioventricular block, VVI pacing may be appropriate. In terms of correcting potentially life-threatening arrhythmias, the effectiveness of ICD therapy is similar in older and younger individuals. However, the assumption of persistent ICD benefit in the elderly population is questionable, as any advantageous effect of the device on arrhythmic death may be attenuated by higher total non-arrhythmic mortality. While septuagenarians and octogenarians have higher annual all-cause mortality rates, ICD therapy may remain effective in selected patients at high risk of arrhythmic death and with minimum comorbidities despite advanced age. ICD implantation among the elderly, as a group, may not be cost-effective, but the procedure may reach cost-effectiveness in those expected to live more than 5-7years after implantation. Elderly patients usually experience significant functional improvement after CRT, similar to that observed in middle-aged patients. Management of CRT non-responders remains globally the same, while considering a less aggressive approach in terms of reinterventions (revision of left ventricular [LV] lead placement, addition of a right ventricular or LV lead, LV endocardial pacing configuration). Overall, physiological age, general status and comorbidities rather than chronological age per se should be the decisive factors in making a decision about device implantation selection for survival and well-being benefit in elderly patients.

Outcomes Related to First-Degree Atrioventricular Block and Therapeutic Implications in Patients With Heart Failure

The prevalence of first-degree atrioventricular block in the general population is approximately 4%, and it is associated with an increased risk of atrial fibrillation. Cardiac pacing for any indication in patients with first-degree heart block is associated with worse outcomes compared with patients with normal atrioventricular conduction. Among patients with heart failure, first-degree atrioventricular block is present in anywhere between 15% and 51%. Data from cardiac resynchronization therapy studies have shown that first-degree atrioventricular block is associated with an increased risk of mortality and heart failure hospitalization. Recent studies suggest that optimization of atrioventricular delay in patients with cardiac resynchronization therapy is an important target for therapy; however, the optimal method for atrioventricular resynchronization remains unknown. Understanding the role of first-degree atrioventricular block in the treatment of patients with heart failure will improve medical and device therapy.

The Association between the PR Interval and Left Ventricular Measurements in the Multiethnic Study of Atherosclerosis

Introduction. Few studies have examined the association between the PR interval (PRi) and subclinical cardiovascular disease measures. Methods and Results. The Multiethnic Study of Atherosclerosis (MESA) is a population-based study of 6814 men and women aged 45-84 years without clinical cardiovascular disease and 4962 had complete baseline data on cardiac magnetic resonance imaging measures of LV dimension and ejection fraction and surface electrocardiogram. Linear regression models were constructed to determine the adjusted association between the PRi and measures of LV stroke volume, LV mass, LV end-systolic and end-diastolic volumes, and ejection fraction. Overall, mean age was 61.5 years, and 47.6% were male and race/ethnicity was white in 39.1%, Chinese in 13.1%, African-American in 25.7%, and Hispanic in 22.2%. The PRi ranged from 88 to 308 ms with a median value of 162 ms. As a continuous variable, every standard deviation unit (25 ms) increment in PRi was associated with a 2.00 mL (95% CI 1.52, 2.48) higher stroke volume, a 3.08 g (95% CI 2.30, 3.86) higher LV mass, a 1.36 g/m(2) (95% CI 0.96, 1.76) higher LV mass index, and 1.31 mL (95% CI 0.88, 1.73) higher end-systolic and 3.31 mL (95% CI 2.58, 4.03) higher end-diastolic volumes after adjustment for all covariates. No significant association was noted between the PRi and LV ejection fraction. Conclusions. A prolonged PRi is associated with LV measures and may in part explain the link between a prolonged PRi and cardiovascular outcomes.

Vagomimetic effects of fingolimod: physiology and clinical implications

Fingolimod is a sphingosine 1-phosphate (S1P) receptor modulator approved to treat relapsing-remitting multiple sclerosis (MS). Initiation of treatment with fingolimod has been found to produce transient bradycardia and/or slowing of atrioventricular impulse conduction in a small proportion of patients. This effect is thought to be due to the interaction of fingolimod with S1P receptors on the surface membrane of atrial myocytes causing a vagomimetic effect, similar to the action of acetylcholine on muscarinic receptors. As a precaution, patients are under electrocardiogram (ECG) monitoring for 6 h after receiving their first dose. Fingolimod is contraindicated in patients with overt or concealed cardiac diseases. However, the Fingolimod Initiation and caRdiac Safety Trial (FIRST), which was designed specifically to investigate the cardiac profile of fingolimod, did not show an increased risk of clinically relevant cardiac events with fingolimod. This review examines the electrophysiology and pathophysiology of cardiac impulse formation in the context of fingolimod. It concludes that these vagomimetic effects should be considered benign and should not prevent the effective use of fingolimod in the treatment of patients with MS.

Cohort Profile: The Manitoba Follow-up Study (MFUS)

The Manitoba Follow-up Study (MFUS) is Canada's longest running study of cardiovascular disease and ageing. The MFUS cohort consists of 3983 men recruited from the Royal Canadian Air Force at the end of World War II. At entry to the study, 1 July 1948, their mean age was 31 years, with 90% between ages 20 and 39 years. All study members were free of clinical evidence of ischaemic heart disease. The protocol of MFUS was to obtain routine medical examinations from these men at regular intervals over time. The research goal of the study was to examine the role that any abnormalities detected on routine electrocardiograms from apparently healthy men might play in the prediction of subsequent diagnoses of cardiovascular disease. Over the course of 65 years, about 35% of the cohort has documented evidence of ischaemic heart disease. The research focus was expanded in 1996 to explore the roles of physical, mental and social functioning in support of healthy and successful ageing. On 1 July 2013, 429 original cohort members were alive with a mean age of 92 years. Collaborative research with others outside the in-house team is welcomed.

First-degree AV block-an entirely benign finding or a potentially curable cause of cardiac disease?

First-degree atrioventricular (AV) block is a delay within the AV conduction system and is defined as a prolongation of the PR interval beyond the upper limit of what is considered normal (generally 0.20 s). Up until recently, first-degree AV block was considered an entirely benign condition. In fact, some complain that it is a misnomer since there is only delay and no actual block in the AV conduction system (usually within the AV node). However, it has long been acknowledged that extreme forms of first-degree AV block (typically a PR interval exceeding 0.30 s) can cause symptoms due to inadequate timing of atrial and ventricular contractions, similar to the so-called pacemaker syndrome. Consequently, the current guidelines state that permanent pacemaker implantation is reasonable for first-degree AV block with symptoms similar to those of pacemaker syndrome or with hemodynamic compromise, but also stresses that there is little evidence to suggest that pacemakers improve survival in patients with isolated first-degree AV block. Recent reports suggest that it may be time to revisit the impact of first-degree AV block. Also, several findings in post hoc analyses of randomized device trials give important insights in possible treatment options. The present review aims to provide an update on the current knowledge concerning the impact of first-degree AV block and also to address the issue of pacing in patients with this condition.

The evaluation and management of drug effects on cardiac conduction (PR and QRS intervals) in clinical development

Recent advances in electrocardiographic monitoring and waveform analysis have significantly improved the ability to detect drug-induced changes in cardiac repolarization manifested as changes in the QT/corrected QT interval. These advances have also improved the ability to detect drug-induced changes in cardiac conduction. This White Paper summarizes current opinion, reached by consensus among experts at the Cardiac Safety Research Consortium, on the assessment of electrocardiogram-based safety measurements of the PR and QRS intervals, representing atrioventricular and ventricular conduction, respectively, during drug development.

Epidemiology of arrhythmias and conduction disorders in older adults

Normal aging is associated with a multitude of changes in the cardiovascular system, including decreased compliance of blood vessels, mild concentric left ventricular hypertrophy, an increased contribution of atrial contraction to left ventricular filling, and a higher incidence of many cardiac arrhythmias, both bradyarrhythmias and tachyarrhythmias. Conduction disorders also become more common with age, and may either be asymptomatic, or cause hemodynamic changes requiring treatment. The epidemiology of common arrhythmias and conduction disorders in the elderly is reviewed.