Implantable defibrillators in primary prevention of genetic arrhythmias. A shocking choice?

Managing long QT syndrome patients, cooking, and common sense

This essay stems from a controversial recommendation present in the 2022 European Guidelines which indicated the appropriateness of considering an implantable cardioverter defibrillator (ICD) implant even for still asymptomatic long QT syndrome (LQTS) patients deemed to be at high risk by the 1-2-3 LQTS score based on QTc and genotype calculated prior to the institution of therapy. As 15 years ago, we also had proposed, but never used, a risk score called M-FACT to identify patients at high risk of an appropriate ICD shock, we felt the responsibility of assessing what would have happened to our patients if we had rigorously used that score. We performed a study recently published in the European Heart Journal which brought to general attention two concepts important for clinical management. One is that all LQTS patients should be seen at least once a year for a reassessment of arrhythmic risk based on standard electrocardiogram, 12-lead 24 h Holter recording and an exercise stress test. The other is that, based on these yearly visits, we perform 'therapy optimization' by adding to the standard β-blocker therapy either left cardiac sympathetic denervation or mexiletine or an ICD implant. On almost 1000 LQTS patients, all genotyped, this dynamic approach was accompanied by not a single death, few events, and out of 142 patients who should have received an ICD based on the score, only 22 did and only 3 had an ICD shock. These data and concepts call for a reconsideration of the recommendation made by the guidelines.

Risk stratification in arrhythmogenic cardiomyopathy: scoring or personalized medicine?

Almost 40 years after the description of arrhythmogenic cardiomyopathy (ACM), arrhythmic risk stratification remains central to patient management. Antiarrhythmic therapy may involve the use of antiarrhythmic drugs as well as invasive tools such as catheter ablation, with the implantation of an implantable cardioverter defibrillator being of utmost importance. Given the wide phenotypic variability of ACM, the first step in arrhythmic risk stratification requires a thorough assessment of clinical, morphological, and electrical parameters. Moreover, in the last years, genetic testing has become increasingly important, not only for family screening but also in determining prognosis. Finally, data from large series of ACM patients have led to the creation of risk calculators, which are now available online for the medical community. While newly available methods for stratifying arrhythmic risk can be useful, the thoughtful clinical decision-making by clinicians with specific expertise in cardiomyopathies remains of fundamental importance. Additionally, as ACM is a progressive disease, arrhythmic risk stratification should be periodically revised based on newly emerging clinical and instrumental parameters.

The "Padua classification" of cardiomyopathies: Combining pathobiological basis and morpho-functional remodeling

Over the last 20 years, the scientific progresses in molecular biology and genetics in combination with the increasing use in the clinical setting of contrast-enhanced cardiac magnetic resonance (CMR) for morpho-functional imaging and structural myocardial tissue characterization have provided important new insights into our understanding of the distinctive aspects of cardiomyopathy, regarding both the genetic and biologic background and the clinical phenotypic features. This has led to the need of an appropriate revision and upgrading of current nosographic framework and pathobiological categorization of heart muscle disorders. This article proposes a new definition and classification of cardiomyopathies that rely on the combination of the distinctive pathobiological basis (genetics, molecular biology and pathology) and the clinical phenotypic pattern (morpho-functional and structural features), leading to the proposal of three different disease categories, each of either genetic or non-genetic etiology and characterized by a combined designation based on both "anatomic" and "functional" features, i.e., hypertrophic/restrictive (H/RC), dilated/hypokinetic (D/HC) and scarring/arrhythmogenic cardiomyopathy (S/AC). The clinical application of the newly proposed classification approach in the real-world practice appears crucial to design a targeted clinical management and evaluation of outcomes of affected patients. Although current treatment of cardiomyopathies is largely palliative and based on drugs, catheter ablation, device or surgical interventions aimed to prevent and manage heart failure and malignant arrhythmias, better knowledge of basic mechanisms involved in the onset and progression of pathobiologically different heart muscle diseases may allow to the development of disease-specific curative therapy.

Frequency of and outcomes associated with nonadherence to guideline-based recommendations for an implantable cardioverter-defibrillator in patients with congenital long QT syndrome

BACKGROUND

Guideline-directed device therapy for long QT syndrome (LQTS) has evolved during the years, and indications for an implantable cardioverter-defibrillator (ICD) vary between professional cardiac societies.

OBJECTIVE

We aimed to identify the subset of patients with LQTS who satisfied a class I or class II 2022 European Society of Cardiology guideline-based recommendation for an ICD and to determine the outcomes of those patients who received an ICD compared with those treated without an ICD.

METHODS

Retrospective analysis was conducted of 2861 patients with LQT1, LQT2, or LQT3 to identify patients meeting contemporary recommendations for guideline-directed device therapy. Basic demographics, clinical characteristics, and frequency/type of breakthrough cardiac events (BCEs) were extracted, and outcomes/complications were compared between patients treated with an ICD and those treated without one.

RESULTS

Of the 290 patients (approximately 10%) who met a guideline-based recommendation, 53 (18%) satisfied a class I/level B indication for an ICD; 56 (19%), a class I/level C indication; 19 (7%), a class IIa/level C indication; and 162 (56%), a class IIb/level B indication. However, most patients (156/290 [54%]) did not receive an ICD. Of those who received an ICD, 55 of 134 (41%) experienced ≥1 appropriate ventricular fibrillation-terminating ICD therapy, whereas ICD-related complications occurred in 13 patients (10%). Of those who were treated without an ICD, only 6 of 156 patients (4%) had nonlethal BCEs, which was significantly lower compared with the ICD group (P < .001).

CONCLUSION

With >1200 years of combined follow-up, the experience and evidence from our 2 LQTS specialty centers suggest that many patients who satisfy a recommendation for an ICD based on the latest 2022 European Society of Cardiology guidelines may not need one. This is particularly true when the indication stemmed from a BCE while receiving beta blocker therapy or in asymptomatic patients with an increased 1-2-3-LQTS-Risk score.

Cardiomegaly: Navigating the uncharted territories of heart failure - A multimodal radiological journey through advanced imaging, pathophysiological landscapes, and innovative therapeutic frontiers

Cardiomegaly is among the disorders categorized by a structural enlargement of the heart by any of the situations including pregnancy, resulting in damage to heart muscles and causing trouble in normal heart functioning. Cardiomegaly can be defined in terms of dilatation with an enlarged heart and decreased left or biventricular contraction. The genetic origin of cardiomegaly is becoming more evident due to extensive genomic research opening up new avenues to ensure the use of precision medicine. Cardiomegaly is usually assessed by using an array of radiological modalities, including computed tomography (CT) scans, chest X-rays, and MRIs. These imaging techniques have provided an important opportunity for the physiology and anatomy of the heart. This review aims to highlight the complexity of cardiomegaly, highlighting the contribution of both ecological and genetic variables to its progression. Moreover, we further highlight the worth of precise clinical diagnosis, which comprises blood biomarkers and electrocardiograms (EKG ECG), demonstrating the significance of distinguishing between numerous basic causes. Finally, the analysis highlights the extensive variation of treatment lines, such as lifestyle modifications, prescription drugs, surgery, and implantable devices, although highlighting the critical need for individualized and personalized care.

Long QT syndrome: importance of reassessing arrhythmic risk after treatment initiation

BACKGROUND AND AIMS

Risk scores are proposed for genetic arrhythmias. Having proposed in 2010 one such score (M-FACT) for the long QT syndrome (LQTS), this study aims to test whether adherence to its suggestions would be appropriate.

METHODS

LQT1/2/3 and genotype-negative patients without aborted cardiac arrest (ACA) before diagnosis or cardiac events (CEs) below age 1 were included in the study, focusing on an M-FACT score ≥2 (intermediate/high risk), either at presentation (static) or during follow-up (dynamic), previously associated with 40% risk of implantable cardioverter defibrillator (ICD) shocks within 4 years.

RESULTS

Overall, 946 patients (26 ± 19 years at diagnosis, 51% female) were included. Beta-blocker (βB) therapy in 94% of them reduced the rate of those with a QTc ≥500 ms from 18% to 12% (P < .001). During 7 ± 6 years of follow-up, none died; 4% had CEs, including 0.4% with ACA. A static M-FACT ≥2 was present in 110 patients, of whom 106 received βBs. In 49/106 patients with persistent dynamic M-FACT ≥2, further therapeutic optimization (left cardiac sympathetic denervation in 55%, mexiletine in 31%, and ICD at 27%) resulted in just 7 (14%) patients with CEs (no ACA), with no CEs in the remaining 57. Additionally, 32 patients developed a dynamic M-FACT ≥2 but, after therapeutic optimization, only 3 (9%) had CEs. According to an M-FACT score ≥2, a total of 142 patients should have received an ICD, but only 22/142 (15%) were implanted, with shocks reported in 3.

CONCLUSIONS

Beta-blockers often shorten QTc, thus changing risk scores and ICD indications for primary prevention. Yearly risk reassessment with therapy optimization leads to fewer ICD implants (3%) without increasing life-threatening events.

A narrative review of inherited arrhythmogenic syndromes in young population: role of genetic diagnosis in exercise recommendations

Sudden cardiac death is a rare but socially devastating event, especially if occurs in young people. Usually, this unexpected lethal event occurs during or just after exercise. One of the leading causes of sudden cardiac death is inherited arrhythmogenic syndromes, a group of genetic entities characterised by incomplete penetrance and variable expressivity. Exercise can be the trigger for malignant arrhythmias and even syncope in population with a genetic predisposition, being sudden cardiac death as the first symptom. Due to genetic origin, family members must be clinically assessed and genetically analysed after diagnosis or suspected diagnosis of a cardiac channelopathy. Early identification and adoption of personalised preventive measures is crucial to reduce risk of arrhythmias and avoid new lethal episodes. Despite exercise being recommended by the global population due to its beneficial effects on health, particular recommendations for these patients should be adopted considering the sport practised, level of demand, age, gender, arrhythmogenic syndrome diagnosed but also genetic diagnosis. Our review focuses on the role of genetic background in sudden cardiac death during exercise in child and young population.

Back to the basics: The need for an etiological classification of chronic heart failure

The left ventricular (LV) ejection fraction (LVEF), despite its severe limitations, has had an epicentral role in heart failure (HF) classification, management, and risk stratification for decades. The major argument favoring the LVEF based HF classification has been that it defines groups of patients in which treatment is effective. However, this reasoning has recently collapsed, since medical treatment with neurohormonal inhibitors, has proved beneficial in most HF patients regardless of the LVEF. In addition, there has been compelling evidence, that the LVEF provides poor guidance for device treatment of chronic HF (implantation of cardioverter defibrillator, cardiac resynchronization therapy) since sudden cardiac death may occur and cardiac dyssynchronization may be disastrous in all HF patients. The same holds true for LV assist device implantation, in which the LVEF has been used as a surrogate for LV size. In this review article we update the evidence questioning the use of LVEF-based HF classification and argue that guidance of chronic HF treatment should transition to more contemporary concepts. Specifically, we propose an etiologic chronic HF classification predominantly based on epidemiological data, which will be foundational for further higher resolution phenotyping in the emerging era of precision medicine.

Navigating the path of TOF- A Literature review unveiling maternal-fetal dynamics, treatment strategies and psychological dimensions

Tetralogy of Fallot (TOF) is a complex congenital heart defect that poses unique challenges for both mothers and their unborn children. This comprehensive review, aims to provide a holistic exploration of the maternal-fetal dynamics, treatment strategies, and psychological dimensions involved in navigating the path of TOF during pregnancy. It delves into the physiological changes that occur during pregnancy in TOF patients, including pulmonary regurgitation, right ventricular hypertrophy, and the overriding aorta. By understanding these dynamics, healthcare professionals can tailor treatment strategies to optimize maternal and fetal outcomes. The review further investigates the treatment strategies employed in managing TOF during pregnancy, encompassing medical interventions, cardiac monitoring, and multidisciplinary care. It explores the role of advanced imaging techniques, such as echocardiography and cardiac magnetic resonance imaging, in assessing TOF severity and guiding treatment decisions. The psychological factors influencing maternal adaptation, coping strategies, and the long-term implications on the child's psychological development are also examined. The integration of multidisciplinary approaches, including cardiac care, psychosocial support, and mental health interventions, can orchestrate a harmonious symphony of maternal-fetal well-being in the challenging journey of TOF pregnancies. Future research endeavours should continue to explore these dimensions, further refining treatment strategies and enhancing the understanding of TOF pregnancies for improved outcomes.

Proposed diagnostic criteria for arrhythmogenic cardiomyopathy: European Task Force consensus report

Arrhythmogenic cardiomyopathy (ACM) is a heart muscle disease characterized by prominent "non-ischemic" myocardial scarring predisposing to ventricular electrical instability. Diagnostic criteria for the original phenotype, arrhythmogenic right ventricular cardiomyopathy (ARVC), were first proposed in 1994 and revised in 2010 by an international Task Force (TF). A 2019 International Expert report appraised these previous criteria, finding good accuracy for diagnosis of ARVC but a lack of sensitivity for identification of the expanding phenotypic disease spectrum, which includes left-sided variants, i.e., biventricular (ABVC) and arrhythmogenic left ventricular cardiomyopathy (ALVC). The ARVC phenotype together with these left-sided variants are now more appropriately named ACM. The lack of diagnostic criteria for the left ventricular (LV) phenotype has resulted in clinical under-recognition of ACM patients over the 4 decades since the disease discovery. In 2020, the "Padua criteria" were proposed for both right- and left-sided ACM phenotypes. The presently proposed criteria represent a refinement of the 2020 Padua criteria and have been developed by an expert European TF to improve the diagnosis of ACM with upgraded and internationally recognized criteria. The growing recognition of the diagnostic role of CMR has led to the incorporation of myocardial tissue characterization findings for detection of myocardial scar using the late‑gadolinium enhancement (LGE) technique to more fully characterize right, biventricular and left disease variants, whether genetic or acquired (phenocopies), and to exclude other "non-scarring" myocardial disease. The "ring-like' pattern of myocardial LGE/scar is now a recognized diagnostic hallmark of ALVC. Additional diagnostic criteria regarding LV depolarization and repolarization ECG abnormalities and ventricular arrhythmias of LV origin are also provided. These proposed upgrading of diagnostic criteria represents a working framework to improve management of ACM patients.

Arrhythmic risk stratification in arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a heritable cardiomyopathy characterized by a predominantly arrhythmic presentation. It represents the leading cause of sudden cardiac death (SCD) among athletes and poses a significant morbidity threat in the general population. As a causative treatment for ARVC is still not available, the placement of an implantable cardioverter defibrillator represents the current cornerstone for SCD prevention in this setting. Thanks to international ARVC-dedicated efforts, significant steps have been achieved in recent years towards an individualized, patient-centred risk stratification approach. A novel risk calculator algorithm estimating the 5-year risk of arrhythmias of patients with ARVC has been introduced in clinical practice and subsequently validated. The purpose of this article is to summarize the body of evidence that has allowed the development of this tool and to discuss the best way to implement its use in the care of an individual patient.

State-of-the-art document on optimal contemporary management of cardiomyopathies

Cardiomyopathies represent significant contributors to cardiovascular morbidity and mortality. Over the past decades, a progress has occurred in characterization of the genetic background and major pathophysiological mechanisms, which has been incorporated into a more nuanced diagnostic approach and risk stratification. Furthermore, medications targeting core disease processes and/or their downstream adverse effects have been introduced for several cardiomyopathies. Combined with standard care and prevention of sudden cardiac death, these novel and emerging targeted therapies offer a possibility of improving the outcomes in several cardiomyopathies. Therefore, the aim of this document is to summarize practical approaches to the treatment of cardiomyopathies, which includes the evidence-based novel therapeutic concepts and established principles of care, tailored to the individual patient aetiology and clinical presentation of the cardiomyopathy. The scope of the document encompasses contemporary treatment of dilated, hypertrophic, restrictive and arrhythmogenic cardiomyopathy. It was based on an expert consensus reached at the Heart Failure Association online Workshop, held on 18 March 2021.

The Lancet Commission to reduce the global burden of sudden cardiac death: a call for multidisciplinary action

Despite major advancements in cardiovascular medicine, sudden cardiac death (SCD) continues to be an enormous medical and societal challenge, claiming millions of lives every year. Efforts to prevent SCD are hampered by imperfect risk prediction and inadequate solutions to specifically address arrhythmogenesis. Although resuscitation strategies have witnessed substantial evolution, there is a need to strengthen the organisation of community interventions and emergency medical systems across varied locations and health-care structures. With all the technological and medical advances of the 21st century, the fact that survival from sudden cardiac arrest (SCA) remains lower than 10% in most parts of the world is unacceptable. Recognising this urgent need, the Lancet Commission on SCD was constituted, bringing together 30 international experts in varied disciplines. Consistent progress in tackling SCD will require a completely revamped approach to SCD prevention, with wide-sweeping policy changes that will empower the development of both governmental and community-based programmes to maximise survival from SCA, and to comprehensively attend to survivors and decedents' families after the event. International collaborative efforts that maximally leverage and connect the expertise of various research organisations will need to be prioritised to properly address identified gaps. The Commission places substantial emphasis on the need to develop a multidisciplinary strategy that encompasses all aspects of SCD prevention and treatment. The Commission provides a critical assessment of the current scientific efforts in the field, and puts forth key recommendations to challenge, activate, and intensify efforts by both the scientific and global community with new directions, research, and innovation to reduce the burden of SCD worldwide.

RYR2-ryanodinopathies: from calcium overload to calcium deficiency

The sarcoplasmatic reticulum (SR) cardiac ryanodine receptor/calcium release channel RyR2 is an essential regulator of cardiac excitation-contraction coupling and intracellular calcium homeostasis. Mutations of the RYR2 are the cause of rare, potentially lethal inherited arrhythmia disorders. Catecholaminergic polymorphic ventricular tachycardia (CPVT) was first described more than 20 years ago and is the most common and most extensively studied cardiac ryanodinopathy. Over time, other distinct inherited arrhythmia syndromes have been related to abnormal RyR2 function. In addition to CPVT, there are at least two other distinct RYR2-ryanodinopathies that differ mechanistically and phenotypically from CPVT: RYR2 exon-3 deletion syndrome and the recently identified calcium release deficiency syndrome (CRDS). The pathophysiology of the different cardiac ryanodinopathies is characterized by complex mechanisms resulting in excessive spontaneous SR calcium release or SR calcium release deficiency. While the vast majority of CPVT cases are related to gain-of-function variants of the RyR2 protein, the recently identified CRDS is linked to RyR2 loss-of-function variants. The increasing number of these cardiac 'ryanodinopathies' reflects the complexity of RYR2-related cardiogenetic disorders and represents an ongoing challenge for clinicians. This state-of-the-art review summarizes our contemporary understanding of RYR2-related inherited arrhythmia disorders and provides a systematic and comprehensive description of the distinct cardiac ryanodinopathies discussing clinical aspects and molecular insights. Accurate identification of the underlying type of cardiac ryanodinopathy is essential for the clinical management of affected patients and their families.

Scarring/arrhythmogenic cardiomyopathy

The designation of 'arrhythmogenic cardiomyopathy' reflects the evolving concept of a heart muscle disease affecting not only the right ventricle (ARVC) but also the left ventricle (LV), with phenotypic variants characterized by a biventricular (BIV) or predominant LV involvement (ALVC). Herein, we use the term 'scarring/arrhythmogenic cardiomyopathy (S/ACM)' to emphasize that the disease phenotype is distinctively characterized by loss of ventricular myocardium due to myocyte death with subsequent fibrous or fibro-fatty scar tissue replacement. The myocardial scarring predisposes to potentially lethal ventricular arrhythmias and underlies the impairment of systolic ventricular function. S/ACM is an 'umbrella term' which includes a variety of conditions, either genetic or acquired (mostly post-inflammatory), sharing the typical 'scarring' phenotypic features of the disease. Differential diagnoses include 'non-scarring' heart diseases leading to either RV dilatation from left-to-right shunt or LV dilatation/dysfunction from a dilated cardiomyopathy. The development of 2020 upgraded criteria ('Padua criteria') for diagnosis of S/ACM reflected the evolving clinical experience with the expanding spectrum of S/ACM phenotypes and the advances in cardiac magnetic resonance (CMR) imaging. The Padua criteria aimed to improve the diagnosis of S/ACM by incorporation of CMR myocardial tissue characterization findings. Risk stratification of S/ACM patients is mostly based on arrhythmic burden and ventricular dysfunction severity, although other ECG or imaging parameters may have a role. Medical therapy is crucial for treatment of ventricular arrhythmias and heart failure. Implantable cardioverter defibrillator (ICD) is the only proven life-saving treatment, despite its significant morbidity because of device-related complications and inappropriate shocks. Selection of patients who can benefit the most from ICD therapy is one of the most challenging issues in clinical practice.

Timing of cardioverter-defibrillator implantation in patients with cardiac laminopathies-External validation of the LMNA-risk ventricular tachyarrhythmia calculator

BACKGROUND

LMNA genotype-positive patients have high risk of experiencing life-threatening ventricular tachyarrhythmias (VTAs). The LMNA-risk VTA calculator published in 2019 has not been externally validated.

OBJECTIVE

The purpose of this study was to validate the LMNA-risk VTA calculator.

METHODS

We included LMNA genotype-positive patients without previous VTAs from 2 large Scandinavian centers. Patients underwent electrocardiography, 24-hour Holter monitoring, and echocardiographic examinations at baseline and repeatedly during follow-up. Validation of the LMNA-risk VTA calculator was performed using Harrell's C-statistic derived from multivariable Cox regression analysis.

RESULTS

We included 118 patients (age 37 years [IQR 27-49 years]; 39 [33%] probands; 65 [55%] women; 100 [85%] with non-missense LMNA variants). Twenty-three patients (19%) experienced VTA during 6.1 years (interquartile range 3.0-9.1 years) follow-up, resulting in 3.0% (95% confidence interval 2.0%-4.5%) yearly incidence rate. Atrioventricular block and reduced left ventricular ejection fraction were independent predictors of VTAs, while nonsustained ventricular tachycardia, male sex, and non-missense LMNA variants were not. The LMNA-risk VTA calculator showed 83% sensitivity and 26% specificity for identifying patients with VTAs during the coming 5 years, and a Harrell's C-statistic of 0.85, when applying ≥7% predicted 5-year VTA risk as threshold. The sensitivity increased to 100% when reevaluating risk at the time of last consultation before VTA. The calculator overestimated arrhythmic risk in patients with mild and moderate phenotype, particularly in men.

CONCLUSION

Validation of the LMNA-risk VTA calculator showed high sensitivity for subsequent VTAs, but overestimated arrhythmic risk when using ≥7% predicted 5-year risk as threshold. Frequent reevaluation of risk was necessary to maintain the sensitivity of the model.

Highly malignant disease in childhood-onset arrhythmogenic right ventricular cardiomyopathy

AIMS

This study aimed to explore the incidence of severe cardiac events in paediatric arrhythmogenic right ventricular cardiomyopathy (ARVC) patients and ARVC penetrance in paediatric relatives. Furthermore, the phenotype in childhood-onset ARVC was described.

METHODS

Consecutive ARVC paediatric patients and genotype positive relatives ≤18 years of age were followed with electrocardiographic, structural, and arrhythmic characteristics according to the 2010 revised Task Force Criteria. Penetrance of ARVC disease was defined as fulfilling definite ARVC criteria and severe cardiac events were defined as cardiac death, heart transplantation (HTx) or severe ventricular arrhythmias. Childhood-onset disease was defined as meeting definite ARVC criteria ≤12 years of age.

RESULTS

Among 62 individuals [age 9.8 (5.0-14.0) years, 11 probands], 20 (32%) fulfilled definite ARVC diagnosis, of which 8 (40%) had childhood-onset disease. The incidence of severe cardiac events was 23% (n = 14) by last follow-up and half of them occurred in patients ≤12 years of age. Among the eight patients with childhood-onset disease, five had biventricular involvement needing HTx and three had severe arrhythmic events. Among the 51 relatives, 6% (n = 3) met definite ARVC criteria at time of genetic diagnosis, increasing to 18% (n = 9) at end of follow-up.

CONCLUSIONS

In a paediatric ARVC cohort, there was a high incidence of severe cardiac events and half of them occurred in children ≤12 years of age. The ARVC penetrance in genotype positive paediatric relatives was 18%. These findings of a high-malignant phenotype in childhood-onset ARVC indicate a need for ARVC family screening at younger age than currently recommended.

Metabolism regulator adiponectin prevents cardiac remodeling and ventricular arrhythmias via sympathetic modulation in a myocardial infarction model

The stellate ganglia play an important role in cardiac remodeling after myocardial infarction (MI). This study aimed to investigate whether adiponectin (APN), an adipokine mainly secreted by adipose tissue, could modulate the left stellate ganglion (LSG) and exert cardioprotective effects through the sympathetic nervous system (SNS) in a canine model of MI. APN microinjection and APN overexpression with recombinant adeno-associated virus vector in the LSG were performed in acute and chronic MI models, respectively. The results showed that acute APN microinjection decreased LSG function and neural activity, and suppressed ischemia-induced ventricular arrhythmia. Chronic MI led to a decrease in the effective refractory period and action potential duration at 90% and deterioration in echocardiography performance, all of which was blunted by APN overexpression. Moreover, APN gene transfer resulted in favorable heart rate variability alteration, and decreased cardiac SNS activity, serum noradrenaline and neuropeptide Y, which were augmented after MI. APN overexpression also decreased the expression of nerve growth factor and growth associated protein 43 in the LSG and peri-infarct myocardium, respectively. Furthermore, RNA sequencing of LSG indicated that 4-week MI up-regulated the mRNA levels of macrophage/microglia activation marker Iba1, chemokine ligands (CXCL10, CCL20), chemokine receptor CCR5 and pro-inflammatory cytokine IL6, and downregulated IL1RN and IL10 mRNA, which were reversed by APN overexpression. Our results reveal that APN inhibits cardiac sympathetic remodeling and mitigates cardiac remodeling after MI. APN-mediated gene therapy may provide a potential therapeutic strategy for the treatment of MI.