New directions in cardiac arrhythmia management: present challenges and future solutions

A Comprehensive Analysis of Conventional Acupuncture and Pharmacological Approaches for Cardiac Arrhythmias: An Umbrella Review

With a global incidence of approximately 3.4% and an annual mortality rate of 3.7 million, cardiac arrhythmias (CAs) are a pressing global health issue. Their increasing prevalence, especially among older people, is intensifying the challenge for health care systems worldwide. This study aims to compare the safety and effectiveness of acupuncture and pharmacological treatments for CAs, addressing critical gaps in understanding optimal therapeutic approaches. A search of PubMed, EMBASE, and the Cochrane database of systematic reviews was performed to identify data compiled through September 2023 for this umbrella review. Randomized controlled trials (RCTs) as the foundation for meta-analyses and peer-reviewed systematic reviews were the primary focus of the literature search. The Grading of Recommendations Assessment, Development, and Evaluation method was used to assess the overall certainty of the evidence, whereas AMSTAR 2 and the Cochrane Collaboration tool were used to evaluate the quality of the included reviews. Following a comprehensive review, three systematic analyses of 27 RCTs were integrated. Acupuncture led to a slightly greater reduction in the recurrence rate of paroxysmal supraventricular tachycardia (SVT) compared to standard pharmaceutical therapy (risk ratio [RR], 1.06; 95% confidence interval [CI], 0.88-1.27; I2 = 56%; P = .55), although the difference was not statistically significant. In contrast, acupuncture significantly outperformed pharmacological treatment in the context of ventricular premature beats (VPBs) (RR, 1.16; 95 CI, 1.08-1.25; I2 = 0%; P < .0001). The reduction in paroxysmal atrial fibrillation (AF)/atrial flutter was increased with acupuncture, albeit without statistical significance (RR, 1.12; 95% CI, 0.88-1.42; I2 = 0%; P = .36). Acupuncture also led to a greater reduction in heart rate (HR) compared to pharmaceutical treatment despite notable heterogeneity and a lack of statistical significance (mean difference, -1.55; 95% CI, -41.37 to 38.28; I2 = 99%; P = .94). Adverse events were effectively managed, affirming the favorable safety profile of acupuncture. Our study suggests that acupuncture leads to a greater reduction in the recurrence rates of VPBs, AF, and atrial flutter but not significantly so in paroxysmal SVT or post-treatment HR. While promising for specific arrhythmias, the varying effectiveness of acupuncture underscores the need for further research and clinical assessment to determine its precise role and suitability in managing particular cardiac conditions.

Neurological Consequences of Cardiac Arrhythmias: Relationship Between Stroke, Cognitive Decline, and Heart Rhythm Disorders

Cardiac arrhythmias are one of the most common disorders with high morbidity and mortality. The effect of cardiac arrhythmias on the brain is very pronounced due to the high sensitivity of the brain to oxygen and blood supply. This mortality is preventable by early diagnosis and treatment which improves the patient's quality of life. Intervening at the right time, post arrhythmia is significant in preventing deaths and improving patient outcomes. Multiple pathophysiological mechanisms are studied for the brain-axis implications, that have the potential to be targeted by novel therapies. In this review, we describe the pathophysiological mechanisms and recent advances in detail to understand the functional aspects of the brain-heart axis and neurological implications post-stroke, caused by cardiac disorders.  This paper aims to discuss the current literature on the neurological consequences of cardiac arrhythmias and delve into a deeper understanding of the brain-heart axis, imbalances, and decline, with the aim of summarizing everything and all about the neurological consequences of cardiac arrhythmias.

Current Advancement in Diagnosing Atrial Fibrillation by Utilizing Wearable Devices and Artificial Intelligence: A Review Study

Atrial fibrillation (AF) is a common arrhythmia affecting 8–10% of the population older than 80 years old. The importance of early diagnosis of atrial fibrillation has been broadly recognized since arrhythmias significantly increase the risk of stroke, heart failure and tachycardia-induced cardiomyopathy with reduced cardiac function. However, the prevalence of atrial fibrillation is often underestimated due to the high frequency of clinically silent atrial fibrillation as well as paroxysmal atrial fibrillation, both of which are hard to catch by routine physical examination or 12-lead electrocardiogram (ECG). The development of wearable devices has provided a reliable way for healthcare providers to uncover undiagnosed atrial fibrillation in the population, especially those most at risk. Furthermore, with the advancement of artificial intelligence and machine learning, the technology is now able to utilize the database in assisting detection of arrhythmias from the data collected by the devices. In this review study, we compare the different wearable devices available on the market and review the current advancement in artificial intelligence in diagnosing atrial fibrillation. We believe that with the aid of the progressive development of technologies, the diagnosis of atrial fibrillation shall be made more effectively and accurately in the near future.

Acupuncture as an adjunctive therapy for arrhythmia: a Delphi expert consensus survey

Background

Current evidence suggests that acupuncture is an effective adjunctive therapy that can bring potential benefits to patients with cardiac arrhythmias. However, there are relevant gaps in the optimal therapeutic strategy, which may cause uncertainties on the best practice of acupuncture treatment for arrhythmia. We aim to develop consensus-based recommendations for clinical guidance on acupuncture treatment of cardiac arrhythmias.

Methods

A multidisciplinary panel of specialists was invited to participate in a two-round semi-open clinical issue investigation. Meanwhile, relevant literature reviews were searched in 3 databases to provide evidence. Subsequently, an initial consensus voting list on acupuncture as an adjunctive therapy for cardiac arrhythmias was derived from the clinical investigation and literature review. Finally, 30 authoritative experts reached a consensus on the key issues of the voting list by a three-round modified Delphi survey. Consensus was defined when >80% agreement was achieved.

Results

Following the three-round Delphi survey, there were 32 items (91.43%) finally reaching consensus, including the following 5 domains: (I) the benefits of acupuncture for the appropriate population; (II) the general therapeutic principle; (III) the acupuncture strategy; (IV) the relevant adverse events; (V) others.

Conclusions

Consensus was achieved on some key elements. Given the lack of guidelines and the substantial heterogeneity of previous studies, these recommendations are of value in providing guidance for clinical practice of acupuncturists and in assisting patients with arrhythmia to obtain standardized acupuncture treatment. It also pointed out some problems that need to be carefully explored in future studies.

Mathematical Modeling of Ion Quantum Tunneling Reveals Novel Properties of Voltage-Gated Channels and Quantum Aspects of Their Pathophysiology in Excitability-Related Disorders

Voltage-gated channels are crucial in action potential initiation and propagation and there are many diseases and disorders related to them. Additionally, the classical mechanics are the main mechanics used to describe the function of the voltage-gated channels and their related abnormalities. However, the quantum mechanics should be considered to unravel new aspects in the voltage-gated channels and resolve the problems and challenges that classical mechanics cannot solve. In the present study, the aim is to mathematically show that quantum mechanics can exhibit a powerful tendency to unveil novel electrical features in voltage-gated channels and be used as a promising tool to solve the problems and challenges in the pathophysiology of excitability-related diseases. The model of quantum tunneling of ions through the intracellular hydrophobic gate is used to evaluate the influence of membrane potential and gating free energy on the tunneling probability, single channel conductance, and quantum membrane conductance. This evaluation is mainly based on graphing the mathematical relationships between these variables. The obtained mathematical graphs showed that ions can achieve significant quantum membrane conductance, which can affect the resting membrane potential and the excitability of cells. In the present work, quantum mechanics reveals original electrical properties associated with voltage-gated channels and introduces new insights and implications into the pathophysiology of excitability- related disorders. In addition, the present work sets a mathematical and theoretical framework that can be utilized to conduct experimental studies in order to explore the quantum aspects of voltage-gated channels and the quantum bioelectrical property of biological membranes.

Self-restoration of cardiac excitation rhythm by anti-arrhythmic ion channel gating

Homeostatic regulation protects organisms against hazardous physiological changes. However, such regulation is limited in certain organs and associated biological processes. For example, the heart fails to self-restore its normal electrical activity once disturbed, as with sustained arrhythmias. Here we present proof-of-concept of a biological self-restoring system that allows automatic detection and correction of such abnormal excitation rhythms. For the heart, its realization involves the integration of ion channels with newly designed gating properties into cardiomyocytes. This allows cardiac tissue to i) discriminate between normal rhythm and arrhythmia based on frequency-dependent gating and ii) generate an ionic current for termination of the detected arrhythmia. We show in silico, that for both human atrial and ventricular arrhythmias, activation of these channels leads to rapid and repeated restoration of normal excitation rhythm. Experimental validation is provided by injecting the designed channel current for arrhythmia termination in human atrial myocytes using dynamic clamp.

Amiodarone and acupuncture for cardiac arrhythmia: Study protocol for a systematic review

BACKGROUND

Amiodarone and acupuncture (AA) are commonly used to treat cardiac arrhythmia (CA). The objective of this systematic review is to assess the efficacy and safety of AA for patients with CA.

METHODS

Randomized controlled trials (RCTs) of AA for CC will be searched from 9 databases including PubMed, EMBASE, Cochrane Library, Web of Science, Scopus, Chinese Biomedical Literature Database, China National Knowledge Infrastructure, VIP Information, and Wanfang Data from inception to February 1, 2019 without any limitations. Two reviewers will independently screen the relevant papers, extract data, and evaluate the risk of bias for each included study. RevMan 5.3 software will be used for meta-analysis. The primary outcome includes arrhythmic episodes (including time and frequency domain parameters). The secondary outcomes consist of health-related quality of life, oxygen saturation, and safety.

RESULTS

The protocol of this proposed study will provide evidence to judge whether AA is an effective treatment for patients with CA.

CONCLUSION

The findings of this proposed study will summarize the up-to-date evidence of AA for CA.

PROSPERO REGISTRATION NUMBER

PROSPERO CRD42019120962.

Therapeutic Effects of Wenxin Keli in Cardiovascular Diseases: An Experimental and Mechanism Overview

Cardiovascular diseases (CVDs) are the major public health problem and a leading cause of morbidity and mortality on a global basis. Wenxin Keli (WXKL), a formally classical Chinese patent medicine with obvious efficacy and favorable safety, plays a great role in the management of patients with CVDs. Accumulating evidence from various animal and cell studies has showed that WXKL could protect myocardium and anti-arrhythmia against CVDs. WXKL exhibited its cardioprotective roles by inhibiting inflammatory reaction, decreasing oxidative stress, regulating vasomotor disorders, lowering cell apoptosis, and protection against endothelial injure, myocardial ischemia, cardiac fibrosis, and cardiac hypertrophy. Besides, WXKL could effectively shorten the QRS and Q-T intervals, decrease the incidence of atrial/ventricular fibrillation and the number of ventricular tachycardia episodes, improve the severity of arrhythmias by regulating various ion channels with different potencies, mainly comprising peak sodium current (INa), late sodium current (INaL), transient outward potassium current (Ito), L-type calcium current (ICaL), and pacemaker current (If).

CaMKII-dependent late Na+ current increases electrical dispersion and arrhythmia in ischemia-reperfusion

The mechanisms underlying Ca²⁺/calmodulin-dependent protein kinase II (CaMKII)-induced arrhythmias in ischemia-reperfusion (I/R) are not fully understood. We tested the hypothesis that CaMKII increases late Na⁺ current ( I_Na,L) via phosphorylation of Na_v1.5 at Ser⁵⁷¹ during I/R, thereby increasing arrhythmia susceptibility. To test our hypothesis, we studied isolated, Langendorff-perfused hearts from wild-type (WT) mice and mice expressing Na_v channel variants Na_v1.5-Ser571E (S571E) and Na_v1.5-Ser571A (S571A). WT hearts showed a significant increase in the levels of phosphorylated CaMKII and Na_v1.5 at Ser⁵⁷¹ [p-Na_v1.5(S571)] after 15 min of global ischemia (just before the onset of reperfusion). Optical mapping experiments revealed an increase in action potential duration (APD) and APD dispersion without changes in conduction velocity during I/R in WT and S571E compared with S571A hearts. At the same time, WT and S571E hearts showed an increase in spontaneous arrhythmia events (e.g., premature ventricular contractions) and an increase in the inducibility of reentrant arrhythmias during reperfusion. Pretreatment of WT hearts with the Na⁺ channel blocker mexiletine (10 μM) normalized APD dispersion and reduced arrhythmia susceptibility during I/R. We conclude that CaMKII-dependent phosphorylation of Na_v1.5 is a crucial driver for increased I_Na,L, arrhythmia triggers, and substrate during I/R. Selective targeting of this CaMKII-dependent pathway may have therapeutic potential for reducing arrhythmias in the setting of I/R. NEW & NOTEWORTHY Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) phosphorylation of Na_v1.5 at Ser⁵⁷¹ leads to a prolongation of action potential duration (APD), increased APD dispersion, and increased arrhythmia susceptibility after ischemia-reperfusion in isolated mouse hearts. Genetic ablation of the CaMKII-dependent phosphorylation site Ser⁵⁷¹ on Na_v1.5 or low-dose mexiletine (to inhibit late Na⁺ current) reduced APD dispersion, arrhythmia triggers, and ventricular tachycardia inducibility.

Mutations in voltage-gated L-type calcium channel: implications in cardiac arrhythmia

The voltage-gated L-type calcium channel (LTCC) is essential for multiple cellular processes. In the heart, calcium influx through LTCC plays an important role in cardiac electrical excitation. Mutations in LTCC genes, including CACNA1C, CACNA1D, CACNB2 and CACNA2D, will induce the dysfunctions of calcium channels, which result in the abnormal excitations of cardiomyocytes, and finally lead to cardiac arrhythmias. Nevertheless, the newly found mutations in LTCC and their functions are continuously being elucidated. This review summarizes recent findings on the mutations of LTCC, which are associated with long QT syndromes, Timothy syndromes, Brugada syndromes, short QT syndromes, and some other cardiac arrhythmias. Indeed, we describe the gain/loss-of-functions of these mutations in LTCC, which can give an explanation for the phenotypes of cardiac arrhythmias. Moreover, we present several challenges in the field at present, and propose some diagnostic or therapeutic approaches to these mutation-associated cardiac diseases in the future.

Predicting Short-term Risk of Arrhythmia among Patients With Syncope: The Canadian Syncope Arrhythmia Risk Score

BACKGROUND

Syncope can be caused by serious occult arrhythmias not evident during initial emergency department (ED) evaluation. We sought to develop a risk tool for predicting 30-day arrhythmia or death after ED disposition.

METHODS

We conducted a multicenter prospective cohort study at six tertiary care EDs and included adults (≥16 years) with syncope. We collected standardized variables from clinical evaluation and investigations including electrocardiogram and troponin at index presentation. Adjudicated outcomes included death or arrhythmias including procedural interventions for arrhythmia within 30 days. We used multivariable logistic regression to derive the prediction model and bootstrapping for interval validation to estimate shrinkage and optimism.

RESULTS

A total of 5,010 patients (mean ± SD age = 53.4 ± 23.0 years, 54.8% females, and 9.5% hospitalized) were enrolled with 106 (2.1%) patients suffering 30-day arrhythmia/death after ED disposition. We examined 39 variables and eight were included in the final model: lack of vasovagal predisposition, heart disease, any ED systolic blood pressure < 90 or > 180 mm Hg, troponin (>99th percentile), QRS duration > 130 msec, QTc interval > 480 msec, and ED diagnosis of cardiac/vasovagal syncope (optimism corrected C-statistic 0.90 [95% CI = 0.87-0.93]; Hosmer-Lemeshow p = 0.08). The Canadian Syncope Arrhythmia Risk Score had a risk ranging from 0.2% to 74.5% for scores of -2 to 8. At a threshold score of ≥0, the sensitivity was 97.1% (95% CI = 91.6%-99.4%) and specificity was 53.4% (95% CI = 52.0%-54.9%).

CONCLUSIONS

The Canadian Syncope Arrhythmia Risk Score can improve patient safety by identification of those at risk for arrhythmias and aid in acute management decisions. Once validated, the score can identify low-risk patients who will require no further investigations.

The cardioprotective and antiarrhythmic effects of Nardostachys chinensis in animal and cell experiments

Background

Cardiovascular disease (CVD) is the leading cause of premature death throughout the world. An estimated 17.5 million people died from CVD in 2012, representing 31% of all global deaths. Nardostachys chinensis (NC), a typical traditional Chinese medicine (TCM), plays a crucial role in the management of patients with CVD, especially for those with cardiac arrhythmia. The purpose of this study was to evaluate the cardioprotective and antiarrhythmic effects of NC in animal and cell experiments.

Methods

To review the cardioprotective and antiarrhythmic effects of NC, studies of NC on cardiovascular diseases in animal and cell experiments were identified from five databases through April 2016. Two investigators independently conducted the literature search, study selection, and data extraction.

Results

A total of 16 studies were identified, including five animal experiments and eleven cell experiments. Four studies showed significant effects of NC on myocardial protection by inhibiting myocardial apoptosis, inflammation and oxidative stress. Twelve studies indicated significant beneficial effects of NC in cardiac arrhythmia primarily through the modulation of ion channels (I_k, I_k1, I_Na, I_Ca-L, I_to).

Conclusion

The above findings showed the possible efficacy of NC via its cardioprotective and antiarrhythmic effects, but the results should be interpreted with caution due to the limitations and the deficiencies in the studies.

Reasons for Hospitalization Among Emergency Department Patients With Syncope

BACKGROUND

Variations in syncope management exist. Our objective was to identify the reasons for consultations and hospitalizations and outcomes among emergency department (ED) syncope patients.

METHODS

We conducted a prospective cohort study to enroll adult syncope patients at five EDs. We collected baseline characteristics, reasons for consultation and hospitalization, and hospital length of stay. Adjudicated 30-day serious adverse events (SAEs) including death, myocardial infarction, arrhythmia, structural heart disease, pulmonary embolism, significant hemorrhage, and procedural intervention. We used descriptive analysis.

RESULTS

From 4,064 enrolled patients (mean ± SD age = 53.1 ± 23.2 years; 55.9% female), 3,255 (80.1%) were discharged directly by the ED physician. Of those with no SAEs identified in the ED (n = 600), 42.8% of referrals and 46.5% of hospitalizations were for suspected arrhythmias, and 71.2% of patients hospitalized for arrhythmias had no cause identified. SAEs among groups were 9.7% in total, 2.5% discharged by ED physician, 3.4% discharged by consultant, 21.7% as inpatient, and 4.8% following discharge from hospital. The median hospital length of stay for suspected arrhythmias was 5 days (interquartile range = 3 to 8 days).

CONCLUSION

Cardiac syncope, particularly suspected arrhythmia, was the major reason for ED referrals and hospitalization. The majority of patients hospitalized for cardiac monitoring had no identified cause. An important number of patients suffered SAEs, particularly arrhythmias, outside the hospital. Development of a risk-stratification tool and out-of-hospital cardiac monitoring strategy should improve patient safety and save substantial resources.

A Simple, Non-Invasive Score to Predict Paroxysmal Atrial Fibrillation

Paroxysmal atrial fibrillation (pAF) is a major risk factor for stroke but remains often unobserved. To predict the presence of pAF, we developed model scores based on echocardiographic and other clinical parameters from routine cardiac assessment. The scores can be easily implemented to clinical practice and might improve the early detection of pAF. In total, 47 echocardiographic and other clinical parameters were collected from 1000 patients with sinus rhythm (SR; n = 728), pAF (n = 161) and cAF (n = 111). We developed logistic models for classifying between pAF and SR that were reduced to the most predictive parameters. To facilitate clinical implementation, linear scores were derived. To study the pathophysiological progression to cAF, we analogously developed models for cAF prediction. For classification between pAF and SR, amongst 12 selected model parameters, the most predictive variables were tissue Doppler imaging velocity during atrial contraction (TDI, A’), left atrial diameter, age and aortic root diameter. Models for classifying between pAF and SR or between cAF and SR showed areas under the ROC curves of 0.80 or 0.93, which resembles classifiers with high discriminative power. The novel risk scores were suitable to predict the presence of pAF based on variables readily available from routine cardiac assessment. Modelling helped to quantitatively characterize the pathophysiologic transition from SR via pAF to cAF. Applying the scores may improve the early detection of pAF and might be used as decision aid for initiating preventive interventions to reduce AF-associated complications.

The pioneering work of George Mines on cardiac arrhythmias: groundbreaking ideas that remain influential in contemporary cardiac electrophysiology

George Mines was a pioneering physiologist who, despite an extremely short period of professional activity and only primitive experimental methodology, succeeded in formulating concepts that continue to be of great influence today. Here, we review some of his most important discoveries and their impact on contemporary concepts and clinical practice. Mines' greatest contribution was his conceptualization and characterization of circus movement reentry. His observations and ideas about the basis for cardiac reentrant activity underlie how we understand and manage a wide range of important clinical rhythm disturbances today. The notions he introduced regarding the influence of premature extrastimuli on reentry (termination, resetting and entrainment) are central to contemporary assessment of arrhythmia mechanisms in clinical electrophysiology laboratories and modern device therapy of cardiac tachyarrhythmias. Refinements of his model of reentry have led to sophisticated biophysical theories of the mechanisms underlying cardiac fibrillation. His seminal observations on the influence of electrolyte derangements and autonomic tone on the heart are relevant to our understanding of the physiology and pharmacology of arrhythmias caused by cardiac pathology. In this era of advanced technology, it is important to appreciate that ideas of lasting impact come from great minds and do not necessarily require great tools.

Atrial fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac rhythm disorder, and increases in prevalence with increasing age and the number of cardiovascular comorbidities. AF is characterized by a rapid and irregular heartbeat that can be asymptomatic or lead to symptoms such as palpitations, dyspnoea and dizziness. The condition can also be associated with serious complications, including an increased risk of stroke. Important recent developments in the clinical epidemiology and management of AF have informed our approach to this arrhythmia. This Primer provides a comprehensive overview of AF, including its epidemiology, mechanisms and pathophysiology, diagnosis, screening, prevention and management. Management strategies, including stroke prevention, rate control and rhythm control, are considered. We also address quality of life issues and provide an outlook on future developments and ongoing clinical trials in managing this common arrhythmia.

The crossroads of inflammation, fibrosis, and arrhythmia following myocardial infarction

Optimal healing of damaged tissue following myocardial infarction (MI) requires a coordinated cellular response that can be divided into three phases: inflammatory, proliferative/reparative, and maturation. The inflammatory phase, characterized by rapid influx of cytokines, chemokines, and immune cells, is critical to the removal of damaged tissue. The onset of the proliferative/reparative phase is marked by increased proliferation of myofibroblasts and secretion of collagen to replace dead tissue. Lastly, crosslinking of collagen fibers and apoptosis of immune cells marks the maturation phase. Excessive inflammation or fibrosis has been linked to increased incidence of arrhythmia and other MI-related pathologies. This review describes the roles of inflammation and fibrosis in arrhythmogenesis and prospective therapies for anti-arrhythmic treatment.

The value of basic research insights into atrial fibrillation mechanisms as a guide to therapeutic innovation: a critical analysis

Atrial fibrillation (AF) is an extremely common clinical problem associated with increased morbidity and mortality. Current antiarrhythmic options include pharmacological, ablation, and surgical therapies, and have significantly improved clinical outcomes. However, their efficacy remains suboptimal, and their use is limited by a variety of potentially serious adverse effects. There is a clear need for improved therapeutic options. Several decades of research have substantially expanded our understanding of the basic mechanisms of AF. Ectopic firing and re-entrant activity have been identified as the predominant mechanisms for arrhythmia initiation and maintenance. However, it has become clear that the clinical factors predisposing to AF and the cellular and molecular mechanisms involved are extremely complex. Moreover, all AF-promoting and maintaining mechanisms are dynamically regulated and subject to remodelling caused by both AF and cardiovascular disease. Accordingly, the initial presentation and clinical progression of AF patients are enormously heterogeneous. An understanding of arrhythmia mechanisms is widely assumed to be the basis of therapeutic innovation, but while this assumption seems self-evident, we are not aware of any papers that have critically examined the practical contributions of basic research into AF mechanisms to arrhythmia management. Here, we review recent insights into the basic mechanisms of AF, critically analyse the role of basic research insights in the development of presently used anti-AF therapeutic options and assess the potential value of contemporary experimental discoveries for future therapeutic innovation. Finally, we highlight some of the important challenges to the translation of basic science findings to clinical application.

Modeling the aging heart: from local respiratory defects to global rhythm disturbances

In this issue, Baris et al. (2015) describe cardiac rhythm abnormalities in a mouse model of mitochondrial dysfunction in widely distributed cells of the aging human heart. How do a few metabolically challenged cells disrupt cardiac rhythm? We suggest that these cells provide "crystallization centers" for latent dysfunctional zones to allow arrhythmia emergence.