Heart failure as a substrate and trigger for ventricular tachycardia

Management of Ventricular Arrhythmias in Heart Failure: Can Less Be More?

PURPOSE OF REVIEW

Ventricular arrhythmias (VAs) affect many patients with heart failure and underlying structural heart disease and are associated with significant morbidity and mortality. Antiarrhythmic drugs are often the initial treatment, but medication alone often fails to sufficiently suppress VAs. While catheter ablation (CA) remains the gold standard for treatment of VAs, CA is an invasive procedure and can be associated with periprocedural complications including acute clinical decompensation. Thus, there is an important need for alternative therapies.

RECENT FINDINGS

Recent advances in risk stratification and the development of new ablation technologies may reduce some of the periprocedural complications and limitations of CA. In addition, less invasive therapies for VAs may provide an alternative treatment strategy for patients in both the acute and chronic setting. For patients acutely admitted with ventricular tachycardia electrical storm (VT-ES) or recurrent VT and cardiogenic shock, risk stratification tools have been developed to identify patients at high risk of acute hemodynamic decompensation during CA. These patients require a multidisciplinary approach and might need mechanical circulatory support (MCS) if CA is selected as the treatment strategy. Alternatively, less invasive therapies targeting the autonomic nervous system may be reasonable. In the chronic setting, developments in medical therapy have reduced the risk of sudden cardiac death in heart failure patients and stereotactic whole-body radiation (SBRT) has evolved as a potential, non-invasive therapy. Further research is needed to personalize VA therapy for individual patients.

Characteristics Associated with Ventricular Tachyarrhythmias and Their Prognostic Impact in Heart Failure with Mildly Reduced Ejection Fraction

Background: The occurrence of ventricular tachyarrhythmias represents an established risk factor of mortality in heart failure (HF). However, data concerning their prognostic impact in heart failure with mildly reduced ejection fraction (HFmrEF) is limited. Therefore, the present study aims to investigate patient characteristics associated with ventricular tachyarrhythmias and their prognostic impact in patients with HFmrEF. Methods: Consecutive patients hospitalized with HFmrEF (i.e., left ventricular ejection fraction 41-49% and signs and/or symptoms of HF) were retrospectively included at one institution from 2016 to 2022. The prognosis of patients with HFmrEF and different types of ventricular tachyarrhythmias (i.e., non-sustained ventricular tachycardia (nsVT), sustained VT (sVT), and ventricular fibrillation (VF) was investigated for the primary endpoint of long-term all-cause mortality at 30 months. Secondary endpoints included in-hospital all-cause mortality and long-term HF-related rehospitalization at 30 months. Results: From a total of 2184 patients with HFmrEF, 4.4% experienced ventricular tachyarrhythmias (i.e., 2.0% nsVT, 0.7% sVT, and 1.6% VF). The occurrence of nsVT was associated with higher New York Heart Association (NYHA) functional class, whereas the incidence of sVT/VF was associated with acute myocardial infarction and ischemic heart disease. However, nsVT (25.0%; HR = 0.760; 95% CI 0.419-1.380; p = 0.367) and sVT/VF (28.8%; HR = 0.928; 95% CI 0.556-1.549; p = 0.776) were not associated with a higher risk of long-term all-cause mortality compared to patients with HFmrEF without ventricular tachyarrhythmias (31.5%). In-hospital cardiovascular mortality was more frequently observed in patients with HFmrEF and sVT/VF compared to those with HFmrEF but without sustained ventricular tachyarrhythmias (7.7% vs. 1.5%; p = 0.004). Finally, the risk of rehospitalization for worsening HF was not affected by the presence of ventricular tachyarrhythmias. Conclusions: The occurrence of ventricular tachyarrhythmias in patients hospitalized with HFmrEF was low and not associated with long-term prognosis.

Gab1 Overexpression Attenuates Susceptibility to Ventricular Arrhythmias in Pressure Overloaded Heart Failure Mouse Hearts

PURPOSE

Grb2 associated binding protein 1 (Gab1) is an adaptor protein that is important for intracellular signal transduction which involved in several pathological process. However, the role of Gab1 in pressure overload-induced ventricular arrhythmias (VAs) remain poorly understood. In the current study, we aimed to test the role of Gab1 in VA susceptibility induced by pressure overload.

METHODS

We overexpressed Gab1 in the hearts using an adeno-associated virus 9 (AAV9) system through tail vein injection. Aortic banding (AB) surgery was performed in C57BL6/J mice to induce heart failure (HF). Four weeks following AB, histology, echocardiography, and biochemical analysis were conducted to investigate cardiac structural remodeling and electrophysiological studies were performed to check the electrical remodeling. Western blot analysis was used to explore the underlying mechanisms.

RESULTS

The mRNA and protein expression were downregulated in AB hearts compared to sham hearts. Gab1 overexpression significantly reversed AB-induced cardiac structural remodeling including ameliorated AB-induced cardiac dysfunction, cardiac fibrosis, and inflammatory response. Moreover, Gab1 overexpression also markedly alleviated AB-induced electrical remodeling including ion channel alterations and VA susceptibility. Mechanistically, we found that TLR4/MyD88/NF-κB contributes to the cardio protective effect of Gab1 overexpression on AB-induced VAs.

CONCLUSIONS

Our study manifested that Gab1 may serve as a promising anti-arrhythmic target via inhibiting TLR4/MyD88/NF-κB signaling pathway induced by AB.

Hospital Outcomes of Spontaneous Coronary Artery Dissection With Concurrent Ventricular Arrhythmias

Background

While patients with spontaneous coronary artery dissection (SCAD) occasionally present with concurrent ventricular arrhythmias (VA), the impact of VA on in-hospital outcomes in the United States (US) is not well-established. This study aims to analyze in-hospital outcomes of patients with SCAD and concurrent VA and to determine the factors associated with VA occurrence in this high-risk population in the US.

Methods

Using the Nationwide Readmissions Database, our study included patients age 18 years or older who had SCAD between 2017 and 2020. We categorized the cohort into 2 groups depending on the presence of VA during hospitalization. In-hospital outcomes were assessed between SCAD patients with VA and those without. Weighted analysis was performed. We analyzed the independent factors associated with VA occurring among SCAD patients through univariable and multivariable analyses.

Results

Eight hundred seventy-seven SCAD patients were included in the study: 118 (13.5%) with VA and 759 (86.6%) without. SCAD patients with concurrent VA were associated with higher rates of early mortality (10.2% vs 2.0%; P < .01), prolonged index hospital stay (≥7 days) (33.1% vs 11.7%; P < .01), and non-home discharge (21.2% vs 5.9%; P < .01). The length of hospital stay was longer in the SCAD with concurrent VA group (7.39 days vs 3.58 days; P < .01), and the median cumulative cost of hospitalization was also higher in this group ($31,451 vs $13,802; P < .01). SCAD patients with concurrent VA had increased in-hospital adverse events: acute heart failure, cardiac arrest, cardiogenic shock, cerebral infarction, pulmonary edema, and acute kidney injury. In multivariable analysis, the independent factors associated with VA occurrence among SCAD patients were chronic liver disease (aOR, 3.42; 95% CI, 1.43-8.20; P < .01) and heart failure (aOR, 5.63; 95% CI, 3.36-9.42; P < .01).

Conclusions

Concurrence of VA among SCAD patients was associated with poorer in-hospital outcomes. Heart failure and chronic liver disease were the independent factors associated with VA occurrence in SCAD patients.

Ventricular tachycardia and in-hospital mortality in the intensive care unit

Background

Continuous electrocardiographic (ECG) monitoring is used to identify ventricular tachycardia (VT), but false alarms occur frequently.

Objective

The purpose of this study was to assess the rate of 30-day in-hospital mortality associated with VT alerts generated from bedside ECG monitors to those from a new algorithm among intensive care unit (ICU) patients.

Methods

We conducted a retrospective cohort study in consecutive adult ICU patients at an urban academic medical center and compared current bedside monitor VT alerts, VT alerts from a new-unannotated algorithm, and true-annotated VT. We used survival analysis to explore the association between VT alerts and mortality.

Results

We included 5679 ICU admissions (mean age 58 ± 17 years; 48% women), 503 (8.9%) experienced 30-day in-hospital mortality. A total of 30.1% had at least 1 current bedside monitor VT alert, 14.3% had a new-unannotated algorithm VT alert, and 11.6% had true-annotated VT. Bedside monitor VT alert was not associated with increased rate of 30-day mortality (adjusted hazard ratio [aHR] 1.06; 95% confidence interval [CI] 0.88-1.27), but there was an association for VT alerts from our new-unannotated algorithm (aHR 1.38; 95% CI 1.12-1.69) and true-annotated VT(aHR 1.39; 95% CI 1.12-1.73).

Conclusion

Unannotated and annotated-true VT were associated with increased rate of 30-day in-hospital mortality, whereas current bedside monitor VT was not. Our new algorithm may accurately identify high-risk VT; however, prospective validation is needed.

Impact of Cardiac Magnetic Resonance to Arrhythmic Risk Stratification in Nonischemic Cardiomyopathy

Left ventricular ejection fraction-based arrhythmic risk stratification in nonischemic cardiomyopathy (NICM) is insufficient and has led to the failure of primary prevention implantable cardioverter defibrillator trials, mainly due to the inability of selecting patients at high risk for sudden cardiac death (SCD). Cardiac magnetic resonance offers unique opportunities for tissue characterization and has gained a central role in arrhythmic risk stratification in NICM. The presence of myocardial scar, denoted by late gadolinium enhancement, is a significant, independent, and strong predictor of ventricular arrhythmias and SCD with high negative predictive value. T1 maps and extracellular volume fraction, which are able to quantify diffuse fibrosis, hold promise as complementary tools but need confirmatory results from large studies.

Autonomic control of ventricular function in health and disease: current state of the art

PURPOSE

Cardiac autonomic dysfunction is one of the main pillars of cardiovascular pathophysiology. The purpose of this review is to provide an overview of the current state of the art on the pathological remodeling that occurs within the autonomic nervous system with cardiac injury and available neuromodulatory therapies for autonomic dysfunction in heart failure.

METHODS

Data from peer-reviewed publications on autonomic function in health and after cardiac injury are reviewed. The role of and evidence behind various neuromodulatory therapies both in preclinical investigation and in-use in clinical practice are summarized.

RESULTS

A harmonic interplay between the heart and the autonomic nervous system exists at multiple levels of the neuraxis. This interplay becomes disrupted in the setting of cardiovascular disease, resulting in pathological changes at multiple levels, from subcellular cardiac signaling of neurotransmitters to extra-cardiac, extra-thoracic remodeling. The subsequent detrimental cycle of sympathovagal imbalance, characterized by sympathoexcitation and parasympathetic withdrawal, predisposes to ventricular arrhythmias, progression of heart failure, and cardiac mortality. Knowledge on the etiology and pathophysiology of this condition has increased exponentially over the past few decades, resulting in a number of different neuromodulatory approaches. However, significant knowledge gaps in both sympathetic and parasympathetic interactions and causal factors that mediate progressive sympathoexcitation and parasympathetic dysfunction remain.

CONCLUSIONS

Although our understanding of autonomic imbalance in cardiovascular diseases has significantly increased, specific, pivotal mediators of this imbalance and the recognition and implementation of available autonomic parameters and neuromodulatory therapies are still lagging.

Predictors of in-hospital heart failure in patients with acute anterior wall ST-segment elevation myocardial infarction

BACKGROUND

Heart failure (HF) is a severe complication of acute ST-segment elevation myocardial infarction (STEMI). Its incidence is associated with myocardial infarction location, and it occurs frequently after acute anterior wall STEMI due to the larger infarct size. However, predictors of in-hospital HF in patients with acute anterior wall STEMI are inadequately defined. We aimed to determine potential predictors of HF in patients with acute anterior wall STEMI during hospitalization.

METHODS

A total of 714 consecutive patients who were diagnosed with acute anterior wall STEMI and underwent primary percutaneous coronary intervention (pPCI) between January 2013 to August 2019 were enrolled retrospectively. We assigned the patients to HF and non-HF groups. The clinical parameters were subjected to univariate analysis and logistic regression analysis to obtain the independent predictors.

RESULTS

Among the 714 patients enrolled in the present study (mean age 61.0 ± 13.8 years, men 80.7%), 387 (54.2%) had in-hospital HF. According to a multivariate logistic regression analysis, ventricular fibrillation (VF, OR: 5.66, 95% CI: 2.25-14.23, P < 0.001) was the most striking independent predictor of in-hospital HF. Community-acquired pneumonia (CAP, OR: 4.72, 95% CI: 2.44-9.10, P < 0.001), age (OR: 1.03, 95% CI: 1.01-1.04, P < 0.001), left ventricular ejection fraction (LVEF, OR: 0.96, 95% CI: 0.93-0.97, P < 0.001), and peak N-terminal pro-brain natriuretic peptide (NT-pro-BNP, OR: 1.06, 95% CI: 1.02-1.11, P = 0.006) were also independently associated with in-hospital HF.

CONCLUSION

VF, CAP, age, LVEF, and peak NT-pro-BNP were independently associated with in-hospital HF in patients with acute anterior wall STEMI.

Sudden cardiac death prevention in the era of novel heart failure medications

Sudden cardiac death (SCD) occurs unexpectedly and is usually a result of ventricular arrhythmia in patients with structural heart disease. The implantable cardioverter-defibrillator (ICD), with or without biventricular pacing, has been proven to be protective for heart failure patients with reduced ejection fraction of <35 % (HFrEF). This device therapy prevents SCD, with additional optimal medications, namely angiotensin-converting enzyme-inhibitors, angiotensin-II receptor-blockers, beta-blockers and mineralocorticoid receptor-antagonists. HFrEF patients present the majority of SCD incidents, as they are characterized by cardiac fibrosis, the main arrhythmogenic element. The introduction of angiotensin-receptor-neprilysin inhibitors, sodium-glucose co-transporter-2 inhibitors and guanylate-cyclase stimulators was associated with reduction of SCD. Additionally, clinical trials have evaluated the improved outcome of these new medications on left ventricular ejection fraction, arrhythmias and HFrEF. These beneficial effects could possibly lead to important changes in decision-making on ICD implantation for primary prevention in patients with HFrEF and reduce the need for device therapy. In this review, we highlight the pathophysiological mechanisms of the new drug agents, and evaluate the possible effect they could have on the role of device therapy as a primary prevention of SCD.

Hypokalemia-Induced Life-Threatening Arrhythmia in a Patient With Congestive Heart Failure

Ventricular tachyarrhythmias are common in patients with heart failure. It is one of the important preventable causes of death in these patient populations. Hypokalemia is prevalent in patients with heart failure due to various reasons. Hypokalemia can trigger ventricular arrhythmias through different mechanisms. In this case report, we present a middle-aged man with congestive heart failure (CHF) and an automated intracardiac defibrillator (AICD) on multiple diuretic medications (unintended) who presented with acute chest pain. He was found to have severe hypokalemia, hyponatremia, and an acute kidney injury. Interrogation of the AICD revealed multiple episodes of ventricular fibrillation. The patient was managed by holding his diuretic medications, cautious volume repletion, and potassium replacement. Fortunately, the patient showed rapid clinical improvement and his plasma potassium level improved. On discharge, we reconciled the patient's medications to avoid the recurrence of hypokalemia from over-diuresis and arranged a close follow-up outpatient visit with his cardiologist.

Prolonged QT Interval in Cirrhosis: Twisting Time?

Approximately 30% to 70% of patients with cirrhosis have QT interval prolongation. In patients without cirrhosis, QT prolongation is associated with an increased risk of ventricular arrhythmias, such as torsade de pointes (TdP). In cirrhotic patients, there is likely a significant association between the corrected QT (QTc) interval and the severity of liver disease, and possibly with increased mortality. We present a stepwise overview of the pathophysiology and management of acquired long QT syndrome in cirrhosis. The QT interval is mainly determined by ventricular repolarization. To compare the QT interval in time it should be corrected for heart rate (QTc), preferably by the Fridericia method. A QTc interval >450 ms in males and >470 ms in females is considered prolonged. The pathophysiological mechanism remains incompletely understood, but may include metabolic, autonomic or hormonal imbalances, cirrhotic heart failure and/or genetic predisposition. Additional external risk factors for QTc prolongation include medication (IKr blockade and altered cytochrome P450 activity), bradycardia, electrolyte abnormalities, underlying cardiomyopathy and acute illness. In patients with cirrhosis, multiple hits and cardiac-hepatic interactions are often required to sufficiently erode the repolarization reserve before long QT syndrome and TdP can occur. While some risk factors are unavoidable, overall risk can be mitigated by electrocardiogram monitoring and avoiding drug interactions and electrolyte and acidbase disturbances. In cirrhotic patients with prolonged QTc interval, a joint effort by cardiologists and hepatologists may be useful and significantly improve the clinical course and outcome.

Efficacy and safety profile of angiotensin receptor neprilysin inhibitors in the management of heart failure: a systematic review and meta-analysis of randomized controlled trials

Several guidelines have recommended the use of angiotensin receptor neprilysin inhibitors (ARNIs) as replacement for angiotensin-converting enzyme inhibitors in the management of heart failure. Till date, there are no reviews done that comprehensively cover different aspects of efficacy and safety parameters. Hence, we have performed a comprehensive systematic review and meta-analysis on role of ARNIs for the management of heart failure patients. Searches were done in Embase, Scopus, China National Knowledge Infrastructure, Chinese Biomedical Literature Database, PubMed Central, Cochrane Library, MEDLINE, Google Scholar, ScienceDirect and Clinicaltrials.gov until June 2022. Risk of bias assessment was done with Cochrane's risk of bias tool. Meta-analysis was carried out using random-effects model. Pooled standardized mean difference (SMD)/mean difference (MD) and/or risk ratio (RR) with 95% confidence intervals (CIs) was reported. In total, we analysed 34 studies, with almost all of them had a high risk of bias. Pooled RR was 0.88 (95% CI: 0.82-0.95) for all-cause mortality, 0.84 (95% CI: 0.77-0.92) for cardiovascular mortality and 0.78 (95% CI: 0.70-0.87) for hospitalization. Pooled MD was 3.74 (95% CI: 1.93-5.55) for left ventricular ejection fraction, -2.16 (95% CI: -3.58 to -0.74) for left atrial volume index, -3.80 (95% CI: -6.60 to -1.00) for left ventricular end-diastolic dimension and -1.16 (95% CI: -1.98 to -0.35) for E/E' ratio. Regarding adverse events, pooled RR was 1.55 (95% CI: 1.31-1.85) for symptomatic hypotension, 0.93 (95% CI: 0.78-1.11) for worsening renal function, 1.09 (95% CI: 0.94-1.26) for hyperkalaemia and 1.29 (95% CI: 0.67-2.50) for angioedema. ARNIs had beneficial efficacy and safety profile on the management of heart failure especially patients with reduced ejection fraction.

The Impact of Angiotensin Receptor-Neprilysin Inhibitors on Arrhythmias in Patients with Heart Failure: A Systematic Review and Meta-analysis

Angiotensin receptor-neprilysin inhibitor (ARNI) use has become increasingly popular. Current guidelines recommend using ARNI therapy for heart failure with reduced (HFrEF) and preserved ejection fraction (HFpEF). As therapies become more widely available, heart failure-associated burdens such as ventricular arrhythmias and sudden cardiac death (SCD) will become increasingly prevalent. We conducted a systematic review and meta-analysis to assess the impact of ARNI therapy on HFrEF and HFpEF pertaining to arrhythmogenesis and SCD. We performed a search of MEDLINE (PubMed), the Cochrane Library, and ClinicalTrials.gov for relevant studies. The odds ratios (ORs) of SCD, ventricular tachycardia (VT), ventricular fibrillation (VF), atrial fibrillation/flutter (AF), supraventricular tachycardia (SVT), and implantable cardioverter-defibrillator (ICD) shocks were calculated. A total of 10 studies, including 6 randomized controlled trials and 4 observational studies, were included in the analysis. A total of 18,548 patients from all studies were included, with 9,328 patients in the ARNI arm and 9,220 patients in the angiotensin-converting enzyme inhibitor (ACEI)/angiotensin II receptor blocker (ARB) arm, with a median follow-up time of 15 months. There was a significant reduction in the composite outcomes of SCD and ventricular arrhythmias in patients treated with ARNIs compared to those treated with ACEIs/ARBs (OR, 0.71; 95% confidence interval, 0.54-0.93; P = .01; I² = 17%; P = .29). ARNI therapy was also associated with a significant reduction in ICD shocks. There was no significant reduction in the VT, VF, AF, or SVT incidence rate in the ARNI group compared to the ACEI/ARB group. In conclusion, the use of ARNIs confers a reduction in composite outcomes of SCD and ventricular arrhythmias among patients with heart failure. These outcomes were mainly driven by SCD reduction in patients treated with ARNIs.

Role of Trientine in Hypertrophic Cardiomyopathy: A Review of Mechanistic Aspects

Abnormality in myocardial copper homeostasis is believed to contribute to the development of cardiomyopathy. Trientine, a copper-chelating drug used in the management of patients with Wilson's disease, demonstrates beneficial effects in patients with hypertrophic cardiomyopathy. This review aims to present the updated development of the roles of trientine in hypertrophic cardiomyopathy. The drug has been demonstrated in animal studies to restore myocardial intracellular copper content. However, its mechanisms for improving the medical condition remain unclear. Thus, comprehending its mechanistic aspects in cardiomyopathy is crucial and could help to expedite future research.

From evidence-based medicine to digital twin technology for predicting ventricular tachycardia in ischaemic cardiomyopathy

Survivors of myocardial infarction are at risk of life-threatening ventricular tachycardias (VTs) later in their lives. Current guidelines for implantable cardioverter defibrillators (ICDs) implantation to prevent VT-related sudden cardiac death is solely based on symptoms and left ventricular ejection fraction. Catheter ablation of scar-related VTs is performed following ICD therapy, reducing VTs, painful shocks, anxiety, depression and worsening heart failure. We postulate that better prediction of the occurrence and circuit of VT, will improve identification of patients at risk for VT and boost preventive ablation, reducing mortality and morbidity. For this purpose, multiple time-evolving aspects of the underlying pathophysiology, including the anatomical substrate, triggers and modulators, should be part of VT prediction models. We envision digital twins as a solution combining clinical expertise with three prediction approaches: evidence-based medicine (clinical practice), data-driven models (data science) and mechanistic models (biomedical engineering). This paper aims to create a mutual understanding between experts in the different fields by providing a comprehensive description of the clinical problem and the three approaches in an understandable manner, leveraging future collaborations and technological innovations for clinical decision support. Moreover, it defines open challenges and gains for digital twin solutions and discusses the potential of hybrid modelling.

Peak Oxygen Uptake on Cardiopulmonary Exercise Test Is a Predictor for Severe Arrhythmic Events during Three-Year Follow-Up in Patients with Complex Congenital Heart Disease

Patients with congenital heart disease (CHD) are at increased risk for severe arrhythmia and sudden cardiac death (SCD). Although implantable cardioverter defibrillators (ICD) effectively prevent SCD, risk stratification for primary prophylaxis in patients with CHD remains challenging. Patients with complex CHD undergoing CPET were included in this single-center study. Univariable and backwards stepwise multivariable logistic regression models were used to identify variables associated with the endpoint of severe arrhythmic event during three years of follow-up. Cut-off values were established with receiver operating characteristic (ROC) curve analysis. Survival analysis was conducted via Kaplan–Meier plots. Severe Arrhythmia was documented in 97 of 1194 patients (8.1%/3 years). Independent risk factors for severe arrhythmia during follow-up were old age and a low peak oxygen uptake (V.O2peak) on multivariable analysis. Patients with more advanced age and with V.O2peak values of less than 24.9 mL/min/kg were at significantly increased risk for the occurrence of severe arrhythmias during follow-up. The combined analysis of both risk factors yielded an additional benefit for risk assessment. Age at CPET and V.O2peak predict the risk for severe arrhythmic events and should be considered for risk stratification of SCD in patients with complex CHD.

Impact of synchronized left ventricular pacing rate on risk for ventricular tachyarrhythmias after cardiac resynchronization therapy in patients with heart failure

BACKGROUND

The adaptive cardiac resynchronization therapy (aCRT) algorithm automatically produces synchronized left ventricular pacing (sLVP) with intrinsic atrioventricular conduction to improve clinical outcomes. However, relationship between sLVP percentage and risk for ventricular tachyarrhythmia (VT/VF) remains unclear. This study aimed to evaluate the clinical impact of sLVP rate on VT/VF occurrence.

METHODS

In total, 1,419 device interrogation data from 42 consecutive patients who underwent new aCRT device implantation were retrospectively analyzed. The primary endpoint was the first time VT/VF episode after aCRT device implantation.

RESULTS

During a median follow-up of 34 months, 15 patients had VT/VF episodes. Patients were divided into a high sLVP (the average sLVP percentage of ≥ 51.5%, n = 27) or low sLVP group (< 51.5%, n = 15). The high sLVP group had a significantly lower VT/VF incidence (22% vs. 60%; p = 0.014) and an independent predictor for VT/VF occurrence on multivariate analysis (hazard ratio 0.21; p = 0.007). LV ejection fraction improvements after 6 months (12.3 ± 8.7% vs. 2.8 ± 10.3%; p = 0.004) and 12 months (13.8 ± 9.3% vs. 6.2 ± 11.1%; p = 0.030) were significantly greater in the high sLVP group than in the low sLVP group. Age, PR interval, and left atrial diameter were significantly associated with the sLVP rate after aCRT.

CONCLUSIONS

Patients with high sLVP percentage after aCRT had lower long-term risk of VT/VF incidence with a favorable response to CRT. A synchronized pacing algorithm using intrinsic conduction may prevent malignant arrhythmias, as well as recover cardiac functions.

Exploration of Mechanisms of Sacubitril/Valsartan in the Treatment of Cardiac Arrhythmias Using a Network Pharmacology Approach

Significant reductions in the incidence of cardiac arrhythmia (CA) and sudden cardiac death (SCD), along with amelioration of heart failure, have been reported for treatment with Sacubitril/valsartan (SV). However, its anti-arrhythmic mechanism remains unclear. The current study aims to explore the anti-arrhythmic molecular mechanism of SV. The direct protein targets (DPT) of SV were extracted from DrugBank. The protein-protein interaction (PPI) network of SV DPTs was constructed using STRING, and the indirect protein targets (IPTs) were also identified. A search for arrhythmia-related genes was conducted using GeneCards and the Comparative Toxicogenomics Database (CTD). The DTPs, ITPs, and arrhythmia-related genes from the two datasets were combined in a Venn diagram, and the overlapping genes were identified as core target genes. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses identified the top 20 biological processes and signaling pathways related to disease and the therapeutic effects of SV. The renin-angiotensin system, adrenergic signaling in cardiomyocytes, and gap junction pathways are strongly implicated in the effects of SV on CA. In conclusion, our bioinformatics analyses provided evidence pertaining to the possible antiarrhythmic mechanisms of SV and may contribute to the development of novel drugs for CA.

Ageing Increases Cardiac Electrical Remodelling in Rats and Mice via NOX4/ROS/CaMKII-Mediated Calcium Signalling

Objective

Ageing is one of the risk factors associated with cardiovascular diseases including cardiac arrhythmias and heart failure. Ageing-related cardiac dysfunction involves a complicated pathophysiological progress. Abnormal membrane voltage and Ca²⁺ dynamics in aged cardiomyocytes contribute to ageing-related arrhythmias. However, its underlying mechanisms have not been well clarified.

Methods

Young and old rats or mice were included in this study. Cardiac electrophysiological properties and functions were assessed by ECG, echocardiography, and ex vivo heart voltage and Ca²⁺ optical mapping. Proteomics, phosphor-proteomics, Western blotting, Masson staining, and ROS measurement were used to investigate the underlying mechanisms.

Results

Ageing increased the incidence of cardiac hypertrophy and fibrosis in rats. Moreover, ageing increased the occurrence of ventricular tachycardia or ventricular fibrillation induced by rapid pacing and during isoprenaline (ISO) (1 mg/kg i.p.) challenge in mice in vivo. Optical mapping with dual dyes (membrane voltage (V_m) dye and intracellular Ca²⁺ dye) simultaneously recording revealed that ageing increased the action potential duration (APD) and Ca²⁺ transient duration (CaTD) and slowed the ventricular conduction with the Langendorff-perfused mouse heart. More importantly, ageing increased the ISO-induced (1 μM) changes of APD (ΔAPD80) and CaTD (ΔCaTD50). Ageing also delayed the decay of Ca²⁺ transient by extending the decay time constant from 30% to 90% (τ₃₀₋₉₀). In addition, ageing decreased the V_m/Ca²⁺ latency which represented the coupling of V_m/Ca²⁺ including between the midpoint of AP depolarization and Ca²⁺ upstroke, peak transmembrane voltage and peak cytosolic calcium, and time to 50% voltage repolarization and extrusion of cytosolic calcium. Optical mapping also revealed that ageing increased the ISO-induced arrhythmia incidence and occurrence of the excitation rotor. Proteomics and phosphor-proteomics assays from rat hearts demonstrated ageing-induced protein and phosphor-protein changes, suggesting that CaMKII was involved in ageing-induced change. Ageing increased the level of ROS and the expression of NOX4, oxidative CaMKII (ox-CaMKII), phosphorated CaMKII (p-CaMKII), and periostin.

Conclusion

Ageing accelerates cardiac remodelling and increases the susceptibility to ventricular arrhythmias through NOX4/ROS/CaMKII pathway-mediated abnormal membrane voltage and intracellular Ca²⁺ handling and V_m/Ca²⁺ coupling.

MCC950 ameliorates ventricular arrhythmia vulnerability induced by heart failure

MCC950, a specific NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inhibitor, has been reported to play a role in various cardiovascular diseases. However, its role in heart failure (HF)-induced ventricular arrhythmias (VAs) remains unclear. Hence, the present study aimed to clarify the role and underlying mechanisms of MCC950 in HF-induced VAs. Male C57BL/6 mice were induced with HF via transverse aortic constriction (TAC). Histological analysis, echocardiography, electrophysiological investigation, and western blot analysis were conducted to evaluate VA vulnerability induced by TAC and the potential mechanisms underlying the effects. MCC950 markedly improved cardiac function and decreased pulmonary edema induced by HF. Moreover, MCC950 also decreased VA vulnerability, as shown by the shortened QTc duration and action potential duration 90 (APD₉₀), reduced APD alternans threshold, and decreased VA induction rate. Furthermore, MCC950 treatment significantly reversed TAC-induced cardiac hypertrophy and fibrosis. In addition, MCC950 administration increased the protein levels of ion channels (Kv4.2, KChIP2, and Cav1.2). Mechanistically, the above changes induced by MCC950 were due to the inhibition of the NLRP3 inflammasome. As a specific NLRP3 inhibitor, MCC950 significantly decreased HF-induced VA vulnerability by reversing cardiac structural remodeling and electrical remodeling, and the mechanism through which MCC950 exhibited this effect was inhibition of NLRP3 inflammasome activation.

Ten-year follow-up of cardiac resynchronization therapy patients with non-ischemic dilated cardiomyopathy assessed by radionuclide angiography: a single-center cohort study

PURPOSE

Relatively few data are available on long-term survival and incidence of ventricular arrhythmias in cardiac resynchronization therapy (CRT) patients. We investigated long-term outcomes of CRT patients with non-ischemic dilated cardiomyopathy stratified as responders or non-responders according to radionuclide angiography.

METHODS

Fifty patients with non-ischemic dilated cardiomyopathy undergoing CRT were assessed by equilibrium Tc⁹⁹ radionuclide angiography with bicycle exercise at baseline and after 3 months. Intra- and interventricular dyssynchrony were derived by Fourier phase analysis. Patient clinical outcome was assessed after 10 years.

RESULTS

At 3 months, 50% of patients were identified as CRT responders according to an increase in LV ejection fraction ≥ 5%. During a follow-up of 109 ± 48 months, 30% of patients died and 6% underwent heart transplantation. Age and history of paroxysmal atrial fibrillation were found to be predictors of all-cause mortality. CRT responders showed lower risk of death from cardiac causes than non-responders. At follow-up, 38% of patients presented at least one episode of sustained ventricular tachycardia, with a similar percentage between responders and non-responders.

CONCLUSION

At long-term follow-up, non-ischemic CRT recipients identified as responders by radionuclide angiography were found to be at lower risk of worsening heart failure death than non-responders. Long-term risk for sustained ventricular arrhythmia was similar between CRT responders and non-responders.

Temporal Trends in Outcomes of ST-Elevation Myocardial Infarction Patients With Heart Failure and Diabetes

Aims

We aimed to assess temporal trends in outcomes of ST-elevation myocardial infarction (STEMI) patients with diabetes and heart failure with reduced ejection fraction (HFrEF) and heart failure with preserved ejection fraction (HFpEF) and compared both groups.

Methods

Data from the National Inpatient Sample was analyzed between 2005 and 2017. We assessed hospitalizations rate and in-hospital mortality, ventricular tachycardia (VT), ventricular fibrillation (VF), atrial fibrillation (AF), cardiogenic shock (CS), ischemic stroke, acute renal failure (ARF), and revascularization strategy. Socio-economic outcomes consisted of the length of stay (LoS) and total charges/stay.

Results

Hospitalization rate steadily decreased with time in STEMI patients with diabetes and HFrEF. Mean age (SD) decreased from 71 ± 12 to 67 ± 12 (p < 0.01), while the prevalence of comorbidities increased. Mortality was stable (around 9%). However, VT, VF, AF, CS, ischemic stroke, and ARF significantly increased with time. In STEMI patients with HFpEF and diabetes, the hospitalization rate significantly increased with time while mean age was stable. The prevalence of comorbidities increased, mortality remained stable (around 4%), but VF, ischemic stroke, and ARF increased with time. Compared to patients with HFrEF, HFpEF patients were 2 years older, more likely to be females, suffered from more cardio-metabolic risk factors, and had a higher prevalence of cardiovascular diseases. However, HFpEF patients were less likely to die [adjusted OR = 0.635 (0.601-0.670)] or develop VT [adjusted OR = 0.749 (0.703-0.797)], VF [adjusted OR = 0.866 (0.798-0.940)], ischemic stroke [adjusted OR = 0.871 [0.776-0.977)], and CS [adjusted OR = 0.549 (0.522-0.577)], but more likely to develop AF [adjusted OR = 1.121 (1.078-1.166)]. HFpEF patients were more likely to get PCI but less likely to get thrombolysis or CABG. Total charges per stay increased by at least 2-fold in both groups. There was a slight temporal reduction over the study period in the LoS of the HFpEF.

Conclusion

While hospitalizations for STEMI in patients with diabetes and HFpEF followed an upward trend, we observed a temporal decrease in those with HFrEF. Mortality was unchanged in both HF groups despite the temporal increase in risk factors. Nevertheless, HFpEF patients had lower in-hospital mortality and cardiovascular events, except for AF.

SGLT2 Inhibitors and Their Antiarrhythmic Properties

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are gaining ground as standard therapy for heart failure with a class-I recommendation in the recently updated heart failure guidelines from the European Society of Cardiology. Different gliflozins have shown impressive beneficial effects in patients with and without diabetes mellitus type 2, especially in reducing the rates for hospitalization for heart failure, yet little is known on their antiarrhythmic properties. Atrial and ventricular arrhythmias were reported by clinical outcome trials with SGLT2 inhibitors as adverse events, and SGLT2 inhibitors seemed to reduce the rate of arrhythmias compared to placebo treatment in those trials. Mechanistical links are mainly unrevealed, since hardly any experiments investigated their impact on arrhythmias. Prospective trials are currently ongoing, but no results have been published so far. Arrhythmias are common in the heart failure population, therefore the understanding of possible interactions with SGLT2 inhibitors is crucial. This review summarizes evidence from clinical data as well as the sparse experimental data of SGLT2 inhibitors and their effects on arrhythmias.

Feasibility of cardiac-synchronized quantitative T1 and T2 mapping on a hybrid 1.5 Tesla magnetic resonance imaging and linear accelerator system

Background and Purpose

Materials and methods

Results

Conclusions

Sacubitril/valsartan versus angiotensin inhibitors and arrhythmia endpoints in heart failure with reduced ejection fraction

Background

Angiotensin receptor–neprilysin inhibitor (ARNI) therapy has been associated with improved survival for patients with symptomatic heart failure and reduced ejection fraction (HFrEF).

Objectives

We performed a meta-analysis of arrhythmia endpoints from studies comparing ARNI with angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) for patients with HFrEF to assess for incremental benefit.

Methods

We searched PubMed, Embase, and ClinicalTrials.gov. Baseline study characteristics were collected and outcomes were sustained ventricular arrhythmias, atrial arrhythmias, appropriate implantable cardioverter-defibrillator (ICD) therapy, sudden cardiac death (SCD), and biventricular (BiV) pacing rate.

Results

We included 9 studies, 4 randomized trials, and 5 observational studies (5589 patients on ARNI vs 5615 on ACEIs/ARBs). Follow-up ranged from 2 to 51 months. The mean age was 65.4 ± 9.8 years, with 77.3% male patients and a mean ejection fraction of 29.0% ± 7.6%. Ischemic cardiomyopathy was present in 62% of patients. In the ARNI group, there were less SCD (odds ratio [OR] 0.78, 95% confidence interval [CI] 0.63–0.96; P = .02), ventricular arrhythmias (OR 0.45, 95% CI 0.25–0.79; P = .005), and appropriate ICD therapy (OR 0.39, 95% CI 0.21–0.74; P = .004). Higher rates of BiV pacing were seen (mean difference 3.13, 95% CI 2.58–3.68; P < .00001) when compared with ACEIs/ARBs. No difference in atrial arrhythmias was seen.

Conclusion

ARNI therapy provides incremental benefit with respect to ventricular tachyarrhythmias/SCD, which may, in part, explain improved outcomes in patients with HFrEF compared to ACEIs/ARBs. There was increased BiV pacing and decreased ICD therapy in the ARNI group.

Ventricular tachycardia originating from the His bundle: A case report

BACKGROUND

Ventricular tachycardia (VT) commonly occurs among patients with heart failure and can even cause sudden cardiac death. VT originating from the His bundle branch has been rarely reported. We present the case of a patient with VT from the His bundle branch.

CASE SUMMARY

A 58-year-old female complained of paroxysmal palpitations and dizziness for approximately 6 mo. She had a history of fatty liver and cholecystitis, and carotid atherosclerosis could not be excluded from the ultrasound results. An evaluation of the electrocardiogram obtained after admission showed spontaneous conversion between two different morphologies. The possible electrophysiologic mechanism suggested that the dual-source VT originated from the same source, the His bundle branch. Finally, the His bundle branch was ablated, and a dual-chamber pacemaker was inserted into the patient’s heart. No further VT occurred during the 3-year follow-up after hospital discharge.

CONCLUSION

The diagnosis of VT originating from the His bundle is rare and difficult to establish. The results of this study showed VT originating from the His bundle based on a careful evaluation of the electrocardiogram, and the diagnosis was confirmed by an intracardiac electrophysiologic examination.

Cardiac stereotactic ablative radiotherapy for refractory ventricular arrhythmias: A radical alternative? A narrative review of rationale and cardiological aspects

Ventricular arrhythmias are serious life-threatening cardiac disorders. Despite many technological improvements, a non-negligible number of patients present refractory ventricular tachycardias, resistant to a catheter ablation procedure, placing these patients in a therapeutic impasse. Recently, a cardiac stereotactic radioablative technique has been developed to treat patients with refractory ventricular arrhythmias, as a bail out strategy. This new therapeutic option historically brings together two fields of expertise unknown to each other, pointing out the necessity of an optimal partnership between cardiologists and radiation oncologists. As described in this narrative review, the understanding of cardiological aspects of the technique for radiation oncologists and treatment technical aspects comprehension for cardiologists represent a major challenge for the application and the future development of this promising treatment.

Serine-threonine protein phosphatase regulation of Cx43 dephosphorylation in arrhythmogenic disorders

Regulation of cell-to-cell communication in the heart by the gap junction protein Connexin43 (Cx43) involves modulation of Cx43 phosphorylation state by protein kinases, and dephosphorylation by protein phosphatases. Dephosphorylation of Cx43 has been associated with impaired intercellular coupling and enhanced arrhythmogenesis in various pathologic states. While there has been extensive study of the protein kinases acting on Cx43, there has been limited studies of the protein phosphatases that may underlie Cx43 dephosphorylation. The focus of this review is to introduce serine-threonine protein phosphatase regulation of Cx43 phosphorylation state and cell-to-cell communication, and its impact on arrhythmogenesis in the setting of chronic heart failure and myocardial ischemia, as well as on atrial fibrillation. We also discuss the therapeutic potential of modulating protein phosphatases to treat arrhythmias in these clinical settings.

Phytosterol accumulation results in ventricular arrhythmia, impaired cardiac function and death in mice

Heart failure (HF) and cardiac arrhythmias share overlapping pathological mechanisms that act cooperatively to accelerate disease pathogenesis. Cardiac fibrosis is associated with both pathological conditions. Our previous work identified a link between phytosterol accumulation and cardiac injury in a mouse model of phytosterolemia, a rare disorder characterized by elevated circulating phytosterols and increased cardiovascular disease risk. Here, we uncover a previously unknown pathological link between phytosterols and cardiac arrhythmias in the same animal model. Phytosterolemia resulted in inflammatory pathway induction, premature ventricular contractions (PVC) and ventricular tachycardia (VT). Blockade of phytosterol absorption either by therapeutic inhibition or by genetic inactivation of NPC1L1 prevented the induction of inflammation and arrhythmogenesis. Inhibition of phytosterol absorption reduced inflammation and cardiac fibrosis, improved cardiac function, reduced the incidence of arrhythmias and increased survival in a mouse model of phytosterolemia. Collectively, this work identified a pathological mechanism whereby elevated phytosterols result in inflammation and cardiac fibrosis leading to impaired cardiac function, arrhythmias and sudden death. These comorbidities provide insight into the underlying pathophysiological mechanism for phytosterolemia-associated risk of sudden cardiac death.

Angiotensin receptor blocker neprilysin inhibitors

Heart failure (HF) is a clinical syndrome that results from a structural or functional cardiac disorder that reduces the ability of the ventricle of the heart to fill with, or eject, blood. It is a multifaceted clinical condition that affects up to 2% of the population in the developed world, and is linked to significant morbidity and mortality; it is therefore considered a major concern for public health. Regarding the mechanism of HF, three neurohumoral factors - the renin-angiotensin-aldosterone system, the sympathetic nervous system, and natriuretic peptides - are related to the pathology of chronic HF (CHF), and the targets of treatment. Angiotensin receptor blocker and neprilysin inhibitor (angiotensin-receptor neprilysin inhibitor), namely sacubitril/valsartan (SAC/VAL), has been introduced as a treatment for CHF. SAC/VAL is an efficacious, safe, and cost-effective therapy that improves quality of life and longevity in patients with HF with reduced ejection fraction (HFrEF), and reduces hospital admissions. An in-hospital initiation strategy offers a potential new avenue to improve the clinical uptake of SAC/VAL. In the last five years, SAC/VAL has been established as a cornerstone component of comprehensive disease-modifying medical therapy in the management of chronic HFrEF. On the other hand, further work, with carefully designed and controlled preclinical studies, is necessary for understanding the molecular mechanisms, effects, and confirmation of issues such as long-term safety in both human and animal models.

Hospitalization for Heart Failure and Subsequent Ventricular Tachyarrhythmias in Patients With Left Ventricular Dysfunction

OBJECTIVES

This study aimed to evaluate the risk of sustained life-threatening ventricular tachyarrhythmias (VTAs) after hospitalization for heart failure (HHF).

BACKGROUND

HHF is common among patients with an implantable cardioverter-defibrillator (ICD).

METHODS

We analyzed all 5,511 ICD patients enrolled in the landmark MADIT and RAID trials. Multivariate Cox regression was used to evaluate the association of in-trial HHF occurrence with the risk of subsequent VTA and the composite end point of VTA or cardiac death.

RESULTS

Mean age was 64 ± 11 years, 23% were women, 62% were ischemic, and 40% had cardiac resynchronization therapy with defibrillators. The 3-year cumulative rate of VTA subsequent to HHF was significantly higher than the corresponding rate without HHF (44% vs. 24%, respectively; p < 0.001). After multivariable adjustment, time-dependent HHF was shown to be associated with a 79% increased risk for VTA and a 2.9-fold increased risk for VTA/cardiac death (p < 0.001 for both). In-trial development of atrial tachyarrhythmia (ATA) was also identified as an independent risk factor for the VTA and VTA/cardiac death end points (hazard ratios [HRs]: 1.59 and 1.43, respectively; p ≤ 0.001 for both) but did not affect the association of HHF with VTA. Subgroup analysis demonstrated that the association of HHF with the risk of subsequent VTA was maintained among risk subsets categorized by age, sex, history of ATA, and implantation indication, but was significantly more pronounced among patients with nonischemic versus ischemic cardiomyopathy (HRs: 2.54 and 1.43, respectively; p value for interaction: 0.017).

CONCLUSIONS

HHF is a powerful risk factor for subsequent VTA in patients implanted with an ICD. These data may be used for improved risk stratification in this population.

Ventricular arrhythmias and ARNI: is it time to reappraise their management in the light of new evidence?

The remarkable scientific progress in the treatment of patients with heart failure (HF) and reduced ejection fraction (HFrEF) has more than halved the risk of sudden cardiac death (SCD) in this setting. However, SCD remains one of the major causes of death in this patient population. Beyond the acknowledged role of beta blockers and inhibitors of the renin-angiotensin-aldosterone system (RAAS), a new class of drugs, the angiotensin receptor neprilysin inhibitors (ARNI), proved to reduce the overall cardiovascular mortality and, more specifically, the risk of SCD in HFrEF patients. The mechanism by which ARNI may reduce the mortality connected with harmful ventricular arrhythmias is not utterly clear. A variety of direct and indirect mechanisms have been suggested, but a favorable left ventricular reverse remodeling seems to play a key role in this setting. Furthermore, the well-known protective effect of implantable cardioverter-defibrillator (ICD) has been debated in HFrEF patients with non-ischemic cardiomyopathy (NICM) arguing against the role of primary prevention ICD in this setting, particularly when ARNI therapy is considered. The purpose of this review was to provide insights into the SCD mechanisms involved in HFrEF patients together with the current role of electrical therapies and new drug agents in this setting. Graphical abstract.

ArrhythmoGenoPharmacoTherapy

This review is focusing on the understanding of various factors and components governing and controlling the occurrence of ventricular arrhythmias including (i) the role of various ion channel-related changes in the action potential (AP), (ii) electrocardiograms (ECGs), (iii) some important arrhythmogenic mediators of reperfusion, and pharmacological approaches to their attenuation. The transmembrane potential in myocardial cells is depending on the cellular concentrations of several ions including sodium, calcium, and potassium on both sides of the cell membrane and active or inactive stages of ion channels. The movements of Na+, K+, and Ca2+ via cell membranes produce various currents that provoke AP, determining the cardiac cycle and heart function. A specific channel has its own type of gate, and it is opening and closing under specific transmembrane voltage, ionic, or metabolic conditions. APs of sinoatrial (SA) node, atrioventricular (AV) node, and Purkinje cells determine the pacemaker activity (depolarization phase 4) of the heart, leading to the surface manifestation, registration, and evaluation of ECG waves in both animal models and humans. AP and ECG changes are key factors in arrhythmogenesis, and the analysis of these changes serve for the clarification of the mechanisms of antiarrhythmic drugs. The classification of antiarrhythmic drugs may be based on their electrophysiological properties emphasizing the connection between basic electrophysiological activities and antiarrhythmic properties. The review also summarizes some important mechanisms of ventricular arrhythmias in the ischemic/reperfused myocardium and permits an assessment of antiarrhythmic potential of drugs used for pharmacotherapy under experimental and clinical conditions.