Bayés syndrome secondary to atrial lipoma.

This case describes a 74-year-old male who presented with rapid atrial flutter in association with large atrial lipoma along the interatrial septum. Conversion to sinus rhythm revealed the electrocardiographic criteria for advanced interatrial block. Interatrial block results from disruption of conduction through Bachmann's bundle, most commonly due to progressive atrial fibrosis. Bayés syndrome is recognized as the association of atrial arrhythmias with underlying interatrial block. This case supports the concept that localized disruption of atrial conduction via Bachmann's bundle from an atrial lipoma can produce the electrophysiologic substrate for atrial arrhythmias and the Bayés syndrome.

The relationship between myocardial fibrosis and myocardial microRNAs in dilated cardiomyopathy: A link between mir-133a and cardiovascular events.

It is unknown whether fibrosis-associated microRNAs: miR-21, miR-26, miR-29, miR-30 and miR-133a are linked to cardiovascular (CV) outcome. The study evaluated the levels of extracellular matrix (ECM) fibrosis and the prevalence of particular microRNAs in patients with dilated cardiomyopathy (DCM) to investigate any correlation with CV events. METHODS: Seventy DCM patients (48 ± 12 years, EF 24.4 ± 7.4%) underwent right ventricular biopsy. The control group was comprised of 7 patients with CAD who underwent CABG and intraoperative biopsy. MicroRNAs were measured in blood and myocardial tissue via qPCR. The end-point was a combination of CV death and urgent HF hospitalization at the end of 12 months. There were differential levels of circulating and myocardial miR-26 and miR-29 as well as myocardial miR-133a when the DCM and CABG groups were compared. Corresponding circulating and myocardial microRNAs did not correlate with one another. There was no correlation between microRNA and ECM fibrosis. By the end of the 12-month period of the study, CV death had occurred in 6 patients, and a further 19 patients required urgent HF hospitalization. None of the circulating microRNAs was a predictor of the combined end-point; however, myocardial miR-133a was an independent predictor in unadjusted models (HR 1.53; 95% CI 1.14-2.05; P < .004) and adjusted models (HR 1.57; 95% CI 1.14-2.17; P < .005). The best cut-off value for the miR-133a level for the prediction of the combined end-point was 0.74 ΔCq, with an AUC of 0.67. The absence of a correlation between the corresponding circulating and myocardial microRNAs calls into question their cellular source. This study sheds new light on the role of microRNAs in ECM fibrosis in DCM, which warrants further exploration.

Effectiveness of implantable cardioverter defibrillators for primary prevention of sudden cardiac death in subgroups a systematic review.

BACKGROUND: Previous systematic reviews of implantable cardioverter defibrillators (ICDs) used for primary prevention of sudden cardiac death (SCD) concluded that ICDs are less effective in women and the elderly. PURPOSE: To examine ICD effectiveness for primary prevention of SCD across subgroups by sex, age, New York Heart Association class, left ventricular ejection fraction, heart failure, left bundle branch block, QRS interval, time since myocardial infarction, blood urea nitrogen level, and diabetes. DATA SOURCES: MEDLINE and the Cochrane Central Register of Controlled Trials through 3 September 2013 with no language restriction. STUDY SELECTION: Researchers screened articles for studies comparing ICD versus no ICD for primary prevention. DATA EXTRACTION: Data were extracted about study design, patients, interventions, mortality and SCD outcomes, subgroup characteristics, and subgroup effects. Quality of subgroup analyses was determined by consensus. Relative odds ratios comparing subgroup effects were calculated, and random-effects model meta-analyses were conducted on these ratios. DATA SYNTHESIS: Meta-analysis of 14 studies showed a decrease in deaths and SCDs due to ICD treatment. Ten studies provided subgroup analyses. Nine studies compared ICD versus no ICD, whereas one compared cardiac resynchronization therapy plus a defibrillator versus no ICD. Within-study interaction tests and across-study meta-analyses yielded weak evidence that did not show differences for all-cause mortality in subgroups by sex, age, and QRS interval. The evidence was indeterminate for other evaluated subgroups because of a paucity of data. LIMITATION: Many subgroup analyses were underpowered, which may have resulted in false-negative findings. CONCLUSION: Weak evidence fails to show differences for all-cause mortality in subgroups of sex, age, and QRS interval. Evidence is indeterminate for all-cause mortality in the other subgroups and for SCD. PRIMARY FUNDING SOURCE: Agency for Healthcare Research and Quality.

Risk of Adverse Outcomes Associated With Cardiac Sarcoidosis Diagnostic Schemes.

BACKGROUND: Multiple cardiac sarcoidosis (CS) diagnostic schemes have been published. OBJECTIVES: This study aims to evaluate the association of different CS diagnostic schemes with adverse outcomes. The diagnostic schemes evaluated were 1993, 2006, and 2017 Japanese criteria and the 2014 Heart Rhythm Society criteria. METHODS: Data were collected from the Cardiac Sarcoidosis Consortium, an international registry of CS patients. Outcome events were any of the following: all-cause mortality, left ventricular assist device placement, heart transplantation, and appropriate implantable cardioverter-defibrillator therapy. Logistic regression analysis evaluated the association of outcomes with each CS diagnostic scheme. RESULTS: A total of 587 subjects met the following criteria: 1993 Japanese (n = 310, 52.8%), 2006 Japanese (n = 312, 53.2%), 2014 Heart Rhythm Society (n = 480, 81.8%), and 2017 Japanese (n = 112, 19.1%). Patients who met the 1993 criteria were more likely to experience an event than patients who did not (n = 109 of 310, 35.2% vs n = 59 of 277, 21.3%; OR: 2.00; 95% CI: 1.38-2.90; P < 0.001). Similarly, patients who met the 2006 criteria were more likely to have an event than patients who did not (n = 116 of 312, 37.2% vs n = 52 of 275, 18.9%; OR: 2.54; 95% CI: 1.74-3.71; P < 0.001). There was no statistically significant association between the occurrence of an event and whether a patient met the 2014 or the 2017 criteria (OR: 1.39; 95% CI: 0.85-2.27; P = 0.18 or OR: 1.51; 95% CI: 0.97-2.33; P = 0.067, respectively). CONCLUSIONS: CS patients who met the 1993 and the 2006 criteria had higher odds of adverse clinical outcomes. Future research is needed to prospectively evaluate existing diagnostic schemes and develop new risk models for this complex disease.

Extracellular volume is an independent predictor of arrhythmic burden in dilated cardiomyopathy.

The current stratification of arrhythmic risk in dilated cardiomyopathy (DCM) is sub-optimal. Cardiac fibrosis is involved in the pathology of arrhythmias; however, the relationship between cardiovascular magnetic resonance (CMR) derived extracellular volume (ECV) and arrhythmic burden (AB) in DCM is unknown. This study sought to evaluate the presence and extent of replacement and interstitial fibrosis in DCM and to compare the degree of fibrosis between DCM patients with and without AB. This is a prospective, single-center, observational study. Between May 2019 and September 2020, 102 DCM patients underwent CMR T1 mapping. 99 DCM patients (88 male, mean age 45.2 ± 11.8 years, mean EF 29.7 ± 10%) composed study population. AB was defined as the presence of VT or a high burden of PVCs. There were 41 (41.4%) patients with AB and 58 (58.6%) without AB. Replacement fibrosis was assessed with late gadolinium enhancement (LGE), whereas interstitial fibrosis with ECV. Overall, LGE was identified in 41% of patients. There was a similar distribution of LGE (without AB 50% vs. with AB 53.7%; p = 0.8) and LGE extent (without AB 4.36 ± 5.77% vs. with AB 4.68 ± 3.98%; p = 0.27) in both groups. ECV at nearly all myocardial segments and a global ECV were higher in patients with AB (global ECV: 27.9 ± 4.9 vs. 30.3 ± 4.2; p < 0.02). Only indexed left ventricular end-diastolic diameter (HR 1.1, 95%CI 1.0-1.2; p < 0.02) and global ECV (HR 1.12, 95%CI 1.0-1.25; p < 0.02) were independently associated with AB. The global ECV cut-off value of 31.05% differentiated both groups (AUC 0.713; 95%CI 0.598-0.827; p < 0.001). Neither qualitative nor quantitative LGE-based assessment of replacement fibrosis allowed for the stratification of DCM patients into low or high AB. Interstitial fibrosis, expressed as ECV, was an independent predictor of AB in DCM. Incorporation of CMR parametric indices into decision-making processes may improve arrhythmic risk stratification in DCM.

Predictors of atrial fibrillation recurrence after radiofrequency catheter ablation: a systematic review.

UNLABELLED: AF Recurrence After RFA: Systematic Review. INTRODUCTION: The relationship between success of radiofrequency ablation for atrial fibrillation (AF) and patient characteristics has not been systematically evaluated. METHODS AND RESULTS: We searched MEDLINE and Cochrane Central Trials Registry databases from 2000 through 2008 for studies reporting preprocedure predictors and AF recurrence after radiofrequency ablation. We extracted multivariable analyses and univariable data on predictors and AF recurrence. Eligible studies were highly heterogeneous, particularly regarding ablation technique and definition of AF recurrence. Among 25 studies with multivariable analyses, two-thirds to 90% of studies found that AF type, ejection fraction, left atrial diameter, structural heart disease, hypertension, and AF symptom duration did not predict AF recurrence (among patients with ejection fraction above 40% and left atrial diameter below about 55 mm). Studies found that gender and age were not predictors (in patients between 40 and 70 years old). Meta-analyses of univariable AF recurrence rates by AF type in 31 studies found that studies were statistically heterogeneous, but that nonparoxysmal AF predicted AF recurrence compared to paroxysmal AF (relative risk 1.59; 95% confidence interval 1.38-1.82; P < 0.001); meta-analyses of persistent or permanent versus paroxysmal AF yielded similar findings. CONCLUSION: Nonparoxysmal AF may be a clinically useful proxy for a combination of confounded variables, none of which alone is an independent predictor of AF recurrence. Evaluation of predictors was limited by exclusion of patients with severe heart disease or at the age extremes; thus, the evidence may not be as applicable to these populations.

Systematic review: comparative effectiveness of radiofrequency catheter ablation for atrial fibrillation.

BACKGROUND: Atrial fibrillation is the most common sustained arrhythmia. Medical treatment often fails to control symptoms. PURPOSE: To compare the benefits and harms of radiofrequency catheter ablation and medical therapy in adults with atrial fibrillation. DATA SOURCES: MEDLINE and the Cochrane Central Register of Controlled Trials (2000 to December 2008) were searched for English-language reports of studies in adults. STUDY SELECTION: 6 independent reviewers screened abstracts to identify longitudinal studies of adults with atrial fibrillation who underwent radiofrequency catheter ablation. Studies reported arrhythmia or other cardiovascular outcomes at least 6 months after ablation or any adverse events. DATA EXTRACTION: Data were extracted by 1 of 4 reviewers and were verified by a cardiac electrophysiologist. Study quality and overall strength of evidence for each question were rated by 2 independent reviewers; disagreements were resolved by consensus. DATA SYNTHESIS: 108 studies met eligibility criteria. Moderate strength of evidence (3 trials; n = 30 to 198) showed that radiofrequency ablation after a failed drug course was more likely than continuation of drug therapy alone to lead to maintained sinus rhythm. Low strength of evidence (4 trials [n = 30 to 137] and 1 retrospective study [n = 1171]) suggested that radiofrequency ablation improved quality of life, promoted avoidance of anticoagulation, and decreased readmission rates compared with medical treatment. Major adverse events occurred in fewer than 5% of patients in most of 84 studies. LIMITATIONS: Study follow-up was generally 12 months or less. Large heterogeneity of applied techniques and reporting of outcomes precluded many definitive conclusions. Reporting of adverse events was poor. Publication and selective reporting biases could not be ruled out. Studies with small samples and studies reported in a language other than English were excluded. CONCLUSION: Radiofrequency catheter ablation is effective for up to 12 months of rhythm control when used as a second-line therapy for atrial fibrillation in relatively young patients with near-intact cardiac function. Longer studies that use primary end points of stroke and mortality are needed.

Advances in mechanisms of atrial fibrillation: structural remodeling, high-frequency fractionated electrograms, and reentrant AF drivers.

The mechanisms to explain atrial fibrillation (AF) have been widely debated. Although contemporary experimental techniques have provided more insight, hypotheses regarding AF propagation conceived in the early half of the century remain minimally altered and relevant today. Modern mapping technologies have implicated multiwavelet reentry as the electrophysiologic basis to explain AF propagation within the atrial myocardium; however, reentry has also been observed within pulmonary veins and may behave as a focal trigger. The ability to terminate AF by catheter ablation has provided additional clues to explain AF induction and sustenance. The presence of complex fractionated electrograms (CFAE) and subsequent successful CFAE-directed ablation suggest that diseased atrial myocardium is a necessary substrate for AF maintenance. Atrial remodeling creates differential areas of refractory periods and conduction velocity, which, in turn, creates a suitable environment for AF. This review addresses the complex relationship between remodeled atrial myocardium and reentry and explores the role of CFAEs in AF maintenance.

His bundle pacing.

His bundle pacing (HBP) has recently emerged as a technique to avoid the negative effects of long-term right ventricular apical pacing. In addition to providing physiologic ventricular activation, HBP has been shown to correct underlying conduction abnormalities in certain patients. Although large prospective, randomized clinical trials have not yet been completed, the available observational clinical data support the safety and efficacy of this technique. Here, we review the physiology of the his bundle (HB) as it relates to HBP, describe the current clinical experience, and discuss future directions of this emerging therapy.

Percutaneous treatment of the superior vena cava syndrome via an excimer laser sheath in a patient with a single chamber atrial pacemaker.

A 21-year-old woman presented with a pacemaker-associated superior vena cava (SVC) syndrome refractory to medical therapy. In the past, treatment of this condition has involved surgical exploration which is invasive. With the evolution of percutaneous techniques, treatment has included venoplasty and stenting over the pacemaker lead. There is limited experience with a more advanced percutaneous technique in which the lead is extracted by an excimer laser sheath. The extraction is immediately followed by venoplasty and stenting at the site of stenosis with subsequent implantation of a new permanent pacemaker at the previously occluded access site. The patient underwent this procedure which proved to be safe, minimally invasive, and an efficient method of treating SVC syndrome secondary to a single chamber atrial pacemaker.

L-Type Calcium Channels Do Not Play a Critical Role in Chest Blow Induced Ventricular Fibrillation: Commotio Cordis.

Background. In a commotio cordis swine model, ventricular fibrillation (VF) can be induced by a ball blow to the chest believed secondary to activation of mechanosensitive ion channels. The purpose of the current study is to evaluate whether stretch induced activation of the L-type calcium channel may cause intracellular calcium overload and underlie the VF in commotio cordis. Method and Results. Anesthetized juvenile swine received 6 chest wall strikes with a 17.9 m/s lacrosse ball timed to the vulnerable period for VF induction. Animals were randomized to IV verapamil (n = 6) or placebo (n = 6). There was no difference in the observed frequency of VF between verapamil (19/26: 73%) and placebo (20/36: 56%) treated animals (p = 0.16). There was also no significant difference in the combined endpoint of VF or nonsustained VF (21/26: 81% in verapamil versus 24/36: 67% in controls, p = 0.22). Conclusions. In this experimental model of commotio cordis, verapamil did not prevent VF induction. Thus, in commotio cordis it is unlikely that stretch activation of the L-type calcium channel with resultant intracellular calcium overload plays a prominent role.

Adverse events following implantable cardioverter defibrillator implantation: a systematic review.

PURPOSE: Implantable cardioverter defibrillators (ICDs) prevent sudden cardiac death, but patients need to be counseled about potential harms. We summarized the evidence on adverse events from ICDs with a focus on ICD use for primary prevention of sudden cardiac death. METHODS: We searched MEDLINE and Cochrane Central Register of Controlled Trials from 2002 through 2012 for reports of adverse events from ICDs implanted for primary prevention or mixed indications (primary and secondary prevention). Studies had to have ≥500 patients and specify patient numerators and denominators. RESULTS: Data from 35 independent cohorts reported in 53 articles were included. Reports from one registry provided high quality evidence on adverse events during hospitalization for ICD implantation. Adverse events ranged from 2.8 to 3.6%. Serious adverse events ranged from 1.2 to 1.4%. The most frequent serious adverse events were pneumothorax (0.4-0.5%) and cardiac arrest (0.3%). The quality of the evidence for long-term adverse events was low. Frequency of adverse events post-hospitalization was variable, as was follow-up: device-related complications <0.1-6.4% (2-49 months), lead-related complications <0.1-3.9% (1.5-40 months), infection 0.2-3.7% (1.5-49 months), and thrombosis 0.2-2.9% (1.5-49 months). Evidence for inappropriate shock was of moderate quality with 3-21% of patients experiencing at least one inappropriate shock during 1 to 5 years of follow-up. LIMITATIONS: The limitation of the evidence reviewed in this study is low quality evidence for adverse events post-hospitalization. Evidence is predominantly from mixed primary and secondary prevention populations. CONCLUSIONS: In-hospital adverse events after ICD implantation are infrequent. The estimates for long-term adverse events are uncertain. Up to one-fifth of patients receive inappropriate shocks.

The Relationship between Obstructive Sleep Apnea and Atrial Fibrillation: A Complex Interplay.

In recent years, growing evidence suggests an association between obstructive sleep apnea (OSA), a common sleep breathing disorder which is increasing in prevalence as the obesity epidemic surges, and atrial fibrillation (AF), the most common cardiac arrhythmia. AF is a costly public health problem increasing a patient's risk of stroke, heart failure, and all-cause mortality. It remains unclear whether the association is based on mutual risk factors, such as obesity and hypertension, or whether OSA is an independent risk factor and causative in nature. This paper explores the pathophysiology of OSA which may predispose to AF, clinical implications of stroke risk in this cohort who display overlapping disease processes, and targeted treatment strategies such as continuous positive airway pressure and AF ablation.

Prevention of sudden cardiac death in patients with chronic kidney disease: risk and benefits of the implantable cardioverter defibrillator.

Implantation of implantable cardioverter defibrillators (ICDs) for primary prevention has been shown to significantly reduce mortality in several randomized controlled trials. However, many of these trials have excluded patients on hemodialysis as well as patients with advanced chronic kidney disease (CKD). Whether the benefits of ICD therapy extend to patients with CKD is not clear. This review will examine the relationship between advancing stage of CKD and risk/benefit of ICD placement. Furthermore, we will review the recent evidence for the rates of complications as CKD advances. The intent is to assist the clinician who is considering the risks and benefits of ICD implantation in patients who have significant competing comorbidities and have not been specifically studied in randomized controlled trials.