Risk Of Ventricular Arrhythmias Research Articles

Optical control of cardiac electrophysiology by the photochromic ligand azobupivacaine 2.

Patients suffering from ischaemic heart disease and heart failure are at high risk of recurrent ventricular arrhythmias (VAs), eventually leading to sudden cardiac death. While high-voltage shocks delivered by an implantable defibrillator may prevent sudden cardiac death, these interventions themselves impair quality of life and raise both morbidity and mortality, which accentuates the need for developing novel defibrillation techniques. Photopharmacology allows for reversible control of biological processes by light. When relying on synthetic and externally applied chromophores, it renders genetic modification of target cells dispensable and may hence be advantageous over optogenetic approaches. Here, the photochromic ligand azobupivacaine 2 (AB2) was probed as a modulator of cardiac electrophysiology in an ex vivo intact mouse heart model. By reversibly blocking voltage-gated Na+ and K+ channels, photoswitching of AB2 modulated both the ventricular effective refractory period and the conduction velocity in native heart tissue. Moreover, photoswitching of AB2 was able to convert VA into sinus rhythm. The present study provides the first proof of concept that AB2 enables gradual control of cardiac electrophysiology by light. AB2 may hence open the door to the development of an optical defibrillator based on photopharmacology.

Abstract 4115652: Effect of the sodium-glucose co-transporter 2 inhibitor, Dapagliflozin, on ventricular repolarization electrocardiographic parameters: DAPA-ECG study

Background: In patients with type 2 diabetes (T2D), hyperglycemia and glycemic variability lead to prolongation and greater heterogeneity of ventricular repolarization, manifested on the electrocardiogram through an increase in QT, QTc, TpeakTend (TpTe) intervals and the TpTe/QT ratio, increasing the risk of potentially malignant arrhythmias. Dapagliflozin has demonstrated efficacy in reducing cardiovascular events in T2D patients and in the risk of serious ventricular arrhythmias and sudden cardiac death. However, the exact mechanisms by which dapagliflozin confers this protection have not yet been fully elucidated. Goals/Aims: The main objective of the study was to evaluate the impact of dapagliflozin on the TpTe interval of patients with T2D, and secondarily, it examined its impact on various electrocardiographic parameters such as the QT and QTc intervals, the TpTf/QT ratio, QT dispersion, J-T peak interval, QRS-T angle and heart rate. Methods: This randomized, prospective, multicenter and open-label study involved 174 patients with T2D, divided into two groups: one treated with dapagliflozin and the other with optimized medical therapy without iSGLT2. Clinical, electrocardiographic, laboratory and echocardiographic evaluations were carried out at the beginning and after three months. The statistical analysis included means, standard deviations, quartiles, and frequencies, with 95% confidence intervals, using Chi-square (or Fisher) and t-test (or Mann-Whitney) for initial differences, and a linear mixed-effects model to evaluate the results, adopting a significance level of 0.05. Results: The TpTe interval was significantly reduced in the dapagliflozin group from 76.87 ± 12.47 to 67.80 ± 10.34 (p<0.001), and the QTc interval reduced from 424.07 ± 30.76 to 411.26 ± 25.31 (p=0.022). The TpTe/QT ratio in the dapagliflozin group was shortened from 0.20 ± 0.03 to 0.18 ± 0.02 (p<0.001). Both groups showed reductions in mean blood glucose and HbA1c, with a greater decrease observed in the control group. No significant changes were recorded in other variables analyzed. Conclusion: In patients with T2D, dapagliflozin significantly reduced the duration of the TpTe and QTc intervals, in addition to the TpTe/QT ratio. These findings indicate a decrease in ventricular electrical remodeling with a potential cardioprotective effect of dapagliflozin, which would partly explain its benefits in reducing potentially malignant ventricular arrhythmias and sudden cardiac death.

Abstract 4119187: Association of CMR derived Global Longitudinal Strain with adverse Outcomes in Arrhythmogenic Cardiomyopathy.

Background: Arrhythmogenic cardiomyopathy (ACM) is associated with high risk of ventricular arrhythmias (VA) and heart failure (HF). Different predictive models and diagnostic criteria include parameters related to myocardial structural abnormalities and right ventricular (RV) ejection fraction (EF). Nevertheless, the value of global longitudinal strain (GLS) ascertained from cardiac magnetic resonance (CMR) for risk-stratification in the context of ACM is unknown. Aim: We aim to study the association of low CMR-derived GLS with adverse outcomes in ACM patients. Methods: This was a retrospective cohort study of ACM patients seen at a single quaternary center. ACM diagnosis followed the modified 2010 ARVC modified task force criteria. Primary outcome was a composite of life-threatening VAs, heart transplant or HF hospitalization during follow up. We excluded patients who suffered events prior to diagnosis, and those with missing or inadequate CMR protocol. Imaging parameters were acquired by CMR including EF, GLS, and late gadolinium enhancement (LGE). Results: A total of 82 patients with suspected ACM were included, with a median age of 40 years, and 43 (52.4%) were females. Most common reason of initial visit was family history of genetic cardiomyopathy in 46 (56%), while 16 (20%) patients visited our clinic due to history of syncope. Out of 60 patients who had genetic testing, 21 (35%) had mutations of DSP gene. Left ventricular involvement (non-ischemic LV-LGE by CMR) was present in 42 (56.8%) out of 74 patients who had CMR with gadolinium. Median LVEF was 62% (56, 66), and RVEF of 53% (48, 59), both by CMR. Median LVGLS was -17.01% (-14.71, -18.43), while median RVGLS was -20.5% (-18.3, -24.4). A total of 15 (18%) patients suffered the composite endpoint during an average follow up period of 8 years. Patients who suffered the composite endpoint had significantly lower mean LVGLS (-15.04% vs -16.70%, p= 0.048), and lower average RVGLS (-18.45% vs -21.33%, p=0.035) compared to patients free from the adverse outcome. Meanwhile there was no significant difference in LVEF (60.13% vs 61.18%, p=0.67), nor in RVEF (49.13% vs 54.01%, p=0.065) between the two groups. Conclusion: Lower GLS was significantly associated with VAs and HF hospitalizations in our patient population. CMR derived GLS can be used as an important prognostic parameter of adverse outcomes in patients with suspected ACM. Especially in those with LV involvement and high genetic predisposition as our cohort.

Abstract 4138546: From Nature’s Remedy to Cardiac Emergency: A Case of Takotsubo Cardiomyopathy Induced by High-Dose Berberine Supplementation

Introduction: Takotsubo cardiomyopathy (TCM) is a reversible cardiac condition often precipitated by emotional or physical stress. Certain medications have also been implicated. While prognosis is generally favorable, associated QTc prolongation and ventricular arrhythmias can be life threatening, necessitating identification of potential triggers. This report highlights TCM in a patient using high-dose berberine, a plant alkaloid known for its hypoglycemic properties. Case description: A 69-year-old female with a history of type 2 diabetes mellitus, and hyperlipidemia presented after a syncopal event. It was preceded by sudden onset of dizziness, nausea, and vomiting. She had been using berberine for a year to lower her blood sugar and had recently switched to a higher dose of a more potent formulation. Vitals were unremarkable. Initial evaluation revealed a prolonged QTc interval of 659 ms (Figure 1A) and elevated troponin-I levels. She was treated with intravenous magnesium, which improved her QTc to 540 ms and revealed new T-wave inversions in the precordial leads. Echocardiogram showed an ejection fraction (EF) of 35%, with LV apical akinesia and hypercontractile basal segments. Cardiac catheterization ruled out significant coronary artery disease, leading to a diagnosis of TCM. Berberine was discontinued, and guideline-directed medical therapy was initiated. Given the presentation with syncope and high suspicion of aborted sudden cardiac death (SCD), she was discharged with a wearable cardioverter-defibrillator (WCD) as a precaution due to the risk of ventricular arrhythmias during recovery. At her 8-week follow-up, QTc and EF had normalized (Figure 1B), prompting WCD removal. Conclusion: The pathophysiology of berberine-induced cardiomyopathy remains uncertain and requires further research. This case underscores the importance of recognizing the potential cardiotoxic effects of berberine, particularly when used in high doses. A thorough medication and supplement history is crucial in patients presenting with unexplained cardiac symptoms. The reversible nature of TCM, when promptly recognized and treated, highlights the need for comprehensive follow-up to ensure recovery of cardiac function.

Abstract 4136452: Acute Cardiac Function Change After Catheter Ablation of Ventricular Arrhythmias in Patients with Arrhythmogenic Right Ventricular Cardiomyopathy

Introduction: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetic disorder characterized by fibrofatty replacement of myocardial tissue, creating areas of electrical heterogeneity and increasing the risk of ventricular arrhythmias (VAs) and sudden cardiac death (SCD). Catheter ablation is commonly performed in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) for management of ventricular arrhythmias (VAs). Whether catheter ablation affects cardiac function post-procedurally is uncertain. Research Question: Does catheter ablation for ARVC result in acute change in cardiac function? Goals/Aims: To assess the impact of catheter ablation for VAs on cardiac function in the acute post-procedure setting. Methods: This retrospective study included patients with ARVC who underwent catheter ablation for VAs at Mayo Clinic. Cardiac function was assessed on pre- and post-procedure transthoracic echocardiograms (TTEs). Post-procedure TTEs were obtained within 4 weeks after the ablation procedure. Right ventricular (RV) enlargement and systolic dysfunction were evaluated as continuous variables (0=none, 1=mild, 2=mild-moderate, 3=moderate, 4=moderate-severe, 5=severe). Results: The study included 32 patients who underwent a total of 44 ablations. Mean age at the time of ablation was 49±16 years, and 24 (75%) were male. After a mean follow-up duration of 2.6±5.5 days, there was a significant worsening in mean RV dysfunction (1.6±1.5 to 2.0±1.4, P = 0.001). There were no significant changes in mean left ventricular ejection fraction (LVEF), left ventricular (LV) dimensions, and RV size. 6 (14%) patients had a >5% decline in LVEF, and 14 (32%) patients had worsening RV function. Transient inotropic support was required in 4 (9%) patients. Conclusion(s): This study is the first to assess the acute impact of catheter ablation for VAs on cardiac function in ARVC patients. These results underscore the importance of careful post-procedure monitoring and planning of the ablation target in these patients to avoid excessive ablation and therefore impairment in cardiac function.

ATrial arrhythmias in inhEriTed aRrhythmIa Syndromes: results from the TETRIS study.

Little is known about the distribution and clinical course of patients with inherited arrhythmia syndrome (IAS) and concomitant atrial arrhythmias (AAs). 1) to characterize the distribution of AAs in patients with IAS and 2) evaluate the long-term clinical course of these patients. An international multicenter study was performed and involved 28 centers in 16 countries. Inclusion criteria were: 1) IAS and 2) ECG documentation of AAs. The primary endpoint was a composite of sudden cardiac death, sustained VAs or appropriate ICD interventions. Strokes, inappropriate ICD shocks due to AAs, and the occurrence of sinus node dysfunction were assessed. A total of 522 patients with IAS and AAs were included. Most patients were diagnosed with Brugada syndrome (n=355, 68%) and long-QT syndrome (n=93, 18%). The remaining patients (n=71, 14%) presented with short-QT syndrome, early repolarization syndrome (ERS), catecholaminergic polymorphic ventricular tachycardia (CPVT), progressive cardiac conduction diseases, or idiopathic ventricular fibrillation. Atrial fibrillation (AF) was the most prevalent AA (82%), followed by atrial flutter (9%) and atrial tachycardia (9%). AA was the first clinical manifestation of IAS in 52% of patients. More than one type of AAs was documented in 23% of patients. Nine patients (3%) experienced VA before the diagnosis of IAS, due the use of anti-arrhythmic medications taken for the AA. The incidence of the primary endpoint was 1.4% per year, with a twofold increase observed in patients who experienced their first AA before the age of 20 (OR 2.2, p=0.043). This was consistent across the different forms of IAS. Inappropriate ICD shock due to AAs were reported in 2.8% of patients, strokes in 4.4% and sinus node dysfunction in 9.6%. Among patients with IAS and AAs, AA is the first clinical manifestation in about half of the cases, with more than one form of AAs present in one-fourth of the patients. The occurrence of AA earlier in life may be associated with a higher risk of ventricular arrhythmias. The occurrence of stroke and sinus node dysfunction is not-infrequently in this cohort.

Incidence of ventricular arrhythmias after implantable cardioverter-defibrillator implantation or replacement, and driving restriction consequences

BackgroundFollowing implantation/replacement of an implantable cardioverter-defibrillator, patients are legally subjected to variable lengths of driving restrictions based on the indication (1 and 3 months after primary and secondary prevention, respectively; 1 week after device replacement). AimTo assess the incidence of ventricular arrhythmia during the theoretical driving restriction period in a large cohort of patients. MethodsPatients who underwent implantable cardioverter-defibrillator implantation for primary or secondary prevention or device replacement between 2015 and 2021 were included retrospectively. The primary endpoint was the occurrence of ventricular arrhythmia during the theoretical driving restriction period, as defined by guidelines. ResultsA total of 914 patients were analysed, including 654 first implantations (438 and 216 for primary and secondary prevention, respectively) and 260 device replacements. The primary outcome occurred in 2/438 patients (0.004%) during the 1-month period following device implantation for primary prevention and in 25/216 patients (11.5%) during the 3-month period following device implantation for secondary prevention; it did not occur in the 1-week period following device replacement. The monthly calculated risk of harm remained below the accepted threshold of 0.005% for each group. ConclusionsPrimary prevention patients, such as those who have undergone device replacement, have a low risk of ventricular arrhythmia, which could lead to a reduction in their driving restriction period. Secondary prevention patients experienced a higher risk of recurrent ventricular arrhythmia, supporting the 3-month driving restriction period.

Concealed cardiomyopathy as an emerging cause of sudden cardiac arrest and sudden cardiac death.

The inherited cardiomyopathies exhibit a broad spectrum of disease, with some patients remaining asymptomatic throughout life, while, for others, the first symptom of disease is sudden cardiac death at a young age. The risk of malignant ventricular arrhythmia in these conditions has traditionally been linked to the degree of structural myocardial abnormalities and functional impairment. However, recent advances in genetic testing and knowledge of the genetic basis of the diseases have led to the identification of concealed cardiomyopathy, in which sudden cardiac arrest or sudden cardiac death occurs in the absence of observable clinical features of cardiomyopathy, with a diagnosis being made only after the identification of a causative genetic variant. Increased awareness of concealed cardiomyopathy, a better understanding of mechanisms of arrhythmia and identification of risk modulators will be vital to improve care for families with concealed cardiomyopathy.

PUFA stabilizes a conductive state of the selectivity filter in IKs channels.

In cardiomyocytes, the KCNQ1/KCNE1 channel complex mediates the slow delayed-rectifier current (IKs), pivotal during the repolarization phase of the ventricular action potential. Mutations in IKs cause long QT syndrome (LQTS), a syndrome with a prolonged QT interval on the ECG, which increases the risk of ventricular arrhythmia and sudden cardiac death. One potential therapeutical intervention for LQTS is based on targeting IKs channels to restore channel function and/or the physiological QT interval. Polyunsaturated fatty acids (PUFAs) are potent activators of KCNQ1 channels and activate IKs channels by binding to two different sites, one in the voltage sensor domain - which shifts the voltage dependence to more negative voltages - and the other in the pore domain - which increases the maximal conductance of the channels (Gmax). However, the mechanism by which PUFAs increase the Gmax of the IKs channels is still poorly understood. In addition, it is unclear why IKs channels have a very small single-channel conductance and a low open probability or whether PUFAs affect any of these properties of IKs channels. Our results suggest that the selectivity filter in KCNQ1 is normally unstable, contributing to the low open probability, and that the PUFA-induced increase in Gmax is caused by a stabilization of the selectivity filter in an open-conductive state.

A review of alternative measurements in strain imaging for ventricular arrhythmia prediction.

Global longitudinal strain has been established as a reliable tool to assess global left ventricular function and a marker of subclinical left ventricular dysfunction unrecognized by the ejection fraction. On the other hand, ventricular arrhythmias are the most common cause of sudden cardiac death. Their early detection is a challenge. Possible prognostic markers for the risk of ventricular arrhythmias are discussed in the literature - electrocardiographic, cardiac magnetic resonance, computed tomography, radionuclide imaging, and markers from new echocardiographic techniques. Of the latter, at this stage of knowledge, several markers have been discussed as informative for predicting ventricular arrhythmias - global longitudinal strain, radial strain and mechanical dispersion, and most recently, myocardial work. As far as we are informed, global longitudinal strain is particularly useful in patients with normal echocardiographic parameters such as left ventricular ejection fraction, left atrial diameter, left ventricular wall thickness, and aortic root. The relationship between mechanical dispersion and ventricular arrhythmias has been widely studied. The relationship has been studied more in some patient populations - heart failure, ischemic heart disease, long QT syndrome and arrhythmogenic cardiomyopathy, congenital heart disease. The role of mechanical dispersion as a predictor of ventricular arrhythmias in metabolic syndrome is scarce.

PUFA stabilizes a conductive state of the selectivity filter in IKs channels

In cardiomyocytes, the KCNQ1/KCNE1 channel complex mediates the slow delayed-rectifier current (IKs), pivotal during the repolarization phase of the ventricular action potential. Mutations in IKs cause long QT syndrome (LQTS), a syndrome with a prolonged QT interval on the ECG, which increases the risk of ventricular arrhythmia and sudden cardiac death. One potential therapeutical intervention for LQTS is based on targeting IKs channels to restore channel function and/or the physiological QT interval. Polyunsaturated fatty acids (PUFAs) are potent activators of KCNQ1 channels and activate IKs channels by binding to two different sites, one in the voltage sensor domain – which shifts the voltage dependence to more negative voltages – and the other in the pore domain – which increases the maximal conductance of the channels (Gmax). However, the mechanism by which PUFAs increase the Gmax of the IKs channels is still poorly understood. In addition, it is unclear why IKs channels have a very small single-channel conductance and a low open probability or whether PUFAs affect any of these properties of IKs channels. Our results suggest that the selectivity filter in KCNQ1 is normally unstable, contributing to the low open probability, and that the PUFA-induced increase in Gmax is caused by a stabilization of the selectivity filter in an open-conductive state.

Time-varying cox model for heart failure prediction in phospholamban p.(Arg14del)-positive individuals

Abstract Background Phospholamban (PLN) p.(Arg14del)-positive individuals are at risk for developing severe heart failure (HF), yet a comprehensive risk model for this outcome is missing. Our PLN registry contains longitudinal data which enables us to capture dynamic changes in covariables over time, while prior prediction models rely on baseline clinical information which may change over time. Using this longitudinal clinical information will enhance the accuracy of HF prediction and may aid patients selection for future (gene)therapy. Purpose The aim of this study is to develop a dynamic HF risk prediction model for PLN p.(Arg14del)-positive individuals. Method Data were collected of 594 PLN p.(Arg14del)-positive individuals who had no documented history of HF or myocardial infarction at time of the first echocardiography. We incorporated two time-dependent covariates in our time-varying Cox regression model: longitudinal individual predicted left ventricular ejection fraction (LVEF) and longitudinal individual predicted relative risk for major ventricular arrhythmia (VA). Predicted LVEF values were derived using observed LVEF values in a linear mixed-effect model, while the relative risk for major VA was predicted using a Cox regression model with major VA as the outcome. These time-dependent covariates were included in the time-varying Cox regression along with baseline covariables age at inclusion and previous major VA. The results were validated using 5-fold cross-validation. Results Over a median follow-up period of 3.6 years (interquartile range 1.4-6.8), 77 (13%) individuals developed HF, defined as a composite endpoint of HF hospitalisation, implantation of left ventricular assist device, heart transplantation and HF-related mortality. Our time-varying Cox regression model demonstrated a robust 5-year mean C-statistic of 0.904 (95% CI 0.901-0.908). The hazard ratio for time-dependent LVEF predictions was 0.89 per % LVEF increase (95% CI 0.87-0.91, p <0.001) and for time-dependent relative major VA risk predictions 3.59 (95% CI 1.49-8.69, p = 0.005). Regarding baseline covariates, age at inclusion had a hazard ratio of 1.01 (95% CI 0.99-1.03, p = 0.47) and previous major VA 0.48 (95% CI 0.21-1.1, p = 0.08). Combining the hazard ratios of time-dependent predicted relative risk for major VA and major VA in history results in a hazard ratio of 1.73. Conclusion Our study introduces a novel time-varying Cox regression model for the individual prediction of heart failure events in PLN p.(Arg14del)-positive individuals which may aid patient selection for future (gene)therapy. Results demonstrate robust predictive performance (C-statistic of 0.904, 95% CI 0.901-0.908), highlighting the significance of incorporating longitudinal data for enhanced prediction accuracy.

Low levels of apolipoprotein M are associated with increased risk of ventricular arrhythmias

Abstract Background Ventricular arrhythmia (VA) is a frequent cause of sudden cardiac death (SCD). Treatment to prevent SCD includes device therapy with implantable cardioverter defibrillator (ICD). Although the electrophysiology underlying VA have been described, the molecular understanding of VA risk remains unclear. Purpose To identify proteins that are associated with higher and lower risk of VA. Methods SMASH 1 Study was a prospective observational study of 490 patients treated with ICD. The plasma proteome was analyzed with the Olink Explore 384 Cardiometabolic platform at study inclusion, and patients were followed for mean 3.1± 0.7 years. VA events were defined as adjudicated ventricular fibrillation or sustained ventricular tachycardia registered from ICD recordings and clinical events were recorded from electronic health records. Protein concentrations were quantified relatively as normalized protein expression on a log2-transformed concentrations where a large number represents higher protein level in the sample. Results The mean age was 66±12 years, 83% were male and 51% had a primary prevention ICD-indication. Episode(s) of VA occurred in 137 patients (28%) during follow-up. In total, 353 distinct proteins were successfully analyzed in all patients. Among these, high B-type natriuretic peptide (BNP) and N-terminal pro-BNP (NT-proBNP) levels were associated with a higher risk of VA, while Apolipoprotein M (APOM) was the only protein significantly associated with a lower risk of VA after multiple testing using Benjamini-Hochberg correction (Figure, Panel A). After adjusting for age, sex, body mass index, coronary artery disease, heart failure, renal function, left ventricular ejection fraction and antiarrhythmic medication, only low APOM levels remained significantly associated with VA: HR 0.51 (95%CI 0.32-0.79] per log unit increase, p=0.003. Patients in the lowest quartile of APOM had a particularly high risk of incident VA: HR 2.26 (95%CI 1.60-3.19), p=3.61x10-6, compared to quartile 2-4 (Figure, Panel B). High APOM levels were also associated with a lower risk of HF hospitalizations (HR 0.25 [95%CI 0.16-0.40], p<0.001) and all-cause mortality (HR 0.36 [95%CI 0.22-0.60], p<0.001), and these associations remained significant in adjusted models. Conclusions Low levels of APOM are associated with a greater risk of incident VA, independently of established risk factors. Low APOM also predicted risk of HF hospitalizations and mortality in our cohort, which suggest protective cardiovascular effects of APOM. Figure: Association of individual proteomic measures with risk of ventricular arrhythmias (VA).A:Volcano plots of the associations of individual plasma proteins with incident VA. The dotted line represents the significance level at false discovery rate <0.05 and the red dots are significant proteins after multiple testing using Benjamini-Hochberg correction.B: Risk of VA by quartile of Apolipoprotein M.

Prediction of mortality, future arrhythmia and cardiovascular disease: an artificial intelligence-enhanced electrocardiography platform

Abstract Background Artificial intelligence-enhanced electrocardiography (AI-ECG) can be used to identify existing disease, but could additionally be used to predict occurrence of future disease and death. Purpose We developed an AI-ECG platform that predicts mortality and a wide spectrum of future arrhythmia and cardiovascular disease. Methods The AI-ECG risk estimation platform (AIRE) was developed in a dataset of 1,163,401 ECGs from 189,539 patients from a secondary care setting in the USA. Uniquely, AIRE uses deep learning with a residual convolutional neural network with a discrete-time survival loss function to output subject-specific survival curves (Fig 1A). AIRE was fine-tuned to additionally predict the endpoints described below. Results AIRE accurately predicts risk of all-cause mortality (C-index 0.775 (0.773-0.776) and can differentiate prognosis in high- and low-risk subjects, even when only cardiologist-defined normal ECGs are considered (Fig 2B). Additionally, in Cox regression analyses, AIRE was superior to conventional risk factors (Fig 1B). AIRE accurately predicted future ventricular arrhythmia (c-index 0.760 (0.756-0.763)), future complete heart block (CHB) (0.809 (0.805-0.814), future atrial fibrillation (0.753 (0.751-0.756), future atherosclerotic cardiovascular disease (0.696 (0.694-0.698)) and future heart failure (0.787 (0.785-0.789)) . AIRE was superior to left ventricular ejection fraction (LVEF) in predicting risk of future ventricular arrhythmias in subjects with LVEF <50% (C-index 0.649 (0.638 – 0.660) vs 0.615 (0.603 – 0.626) p < 0.0001 ). For CHB prediction, AIRE was able to further risk stratify subjects with bifascicular block and syncope into low (1.9% 5 year CHB), intermediate (8.8%), and high risk (20.7%) groups, and could guide treatment decisions. We externally validated our findings in four diverse, transnational cohorts from Brazil and the UK, including volunteers, primary care subjects and patients with Chagas disease, and found AIRE accurately predicted all-cause mortality in all four external cohorts (Fig 2). Non-mortality endpoints were successful externally validated in the UKB. In explainability analyses, we found features of QRS morphology, low QRS voltage, poor precordial R wave progression, inverted and biphasic T waves and ST segment changes were the most significant morphological features associated with high predicted mortality (Fig 1D). Through phenome- and genome-wide association studies (GWAS), we identified candidate biological pathways including changes in cardiac structure (LV mass, LV trabeculation and left atrial size). GWAS identified variants adjacent to VGLL2, KCNQ1, CCDC91 and TBX3 which have been described in association with QT interval, biological aging and metabolic syndrome (Fig 1E). Conclusion AIRE could be used worldwide across a range of clinical contexts for risk estimation of not only mortality but a wide spectrum of future arrhythmia and cardiovascular diseases.Figure 1Figure 2

The genetic architecture of exercise-induced ventricular ectopy

Abstract Background Previously, we have shown that the frequency of exercise-induced premature ventricular contractions (PVCs) during and after exercise are associated with increased risk of major adverse cardiovascular events in asymptomatic individuals from the UK Biobank study1. The underlying mechanisms are, however, unclear. Several electrocardiographic markers associated with arrhythmogenesis have a known hereditary component, but the genetic underpinnings of exercise-induced ventricular ectopy have not been investigated. Purpose Our aim was to explore the genetic basis of premature ventricular ectopy during and after exercise and unveil plausible candidate genes and biological mechanisms. Methods We conducted a genome-wide association study (GWAS) for PVC frequency during exercise and recovery in >44,000 asymptomatic individuals of European ancestry without known cardiovascular disease from the UK Biobank study. As the distribution of PVC frequency is highly skewed (e.g. absence of negative values and excess of zero values), we first applied Gaussian transformation. Simulation studies were performed to justify that this approach would lead to valid inference. In the GWAS model, we included sex, age, UK Biobank genotyping array, and the first 10 genetic principal components as covariates. Statistical power was boosted by joint analysis of exercise and recovery PVC traits using multi-trait analysis of GWAS (MTAG)2. Genetic risk scores were constructed in independent samples from UK Biobank (N=341,948) and were tested for association with heart failure and life-threatening ventricular arrhythmias. Results We identified 4 loci for PVC frequency during exercise, and 1 locus for PVC frequency during recovery (Picture 1). Candidate genes included CRIM1, FLNC, and BAG3 for which mutations have been linked in the pathogenesis of (arrhythmogenic) cardiomyopathy. Subjects in the top 10% of the genetic risk scores had a significantly higher risk of heart failure and life-threatening ventricular arrhythmias compared to the bottom 90%, (odds ratio (OR) (95% confidence interval): 1.14 (1.08 – 1.20), p < 0.001; and 1.13 (1.02 – 1.24), p < 0.001, respectively). Conclusions Ventricular ectopic burdens during exercise and recovery have a significant heritable component. Candidate genes highlight a possible shared genetic background with inherited cardiomyopathy and a genetic risk score was associated with heart failure and ventricular arrhythmias. These findings substantial advance our understanding of the genetic basis of exercise-induced ventricular ectopy in a population-based cohort without cardiovascular disease.Miami plot of ventricular ectopic burden

Comparing outcomes in cardiogenic shock patients with ischemic versus nonischemic cardiomyopathy: A nationwide retrospective observational study

Abstract Introduction Ischemic and non-ischemic cardiomyopathy are common causes of heart failure. In our study, we compare the in-hospital outcomes between these two groups of patients with cardiogenic shock. Methods Data was obtained from the Nationwide Inpatient Sample database between January 2016 to December 2020. The study included all adult patients who were in cardiogenic shock and either ischemic cardiomyopathy (ICM) or non-ischemic cardiomyopathy (NICM). The primary outcome was inpatient mortality. Secondary outcomes were cardiac arrest, arrhythmias, acute respiratory failure, and acute renal failure, as well as the need for ventilators, dialysis, and ECMO. Results Among 168,591 adult patients who had cardiogenic shock during their hospitalization, 72,538 patients had either ischemic cardiomyopathy or nonischemic cardiomyopathy. Among them, 31,854 (43.9%) had ischemic cardiomyopathy (ICM) vs 40,684 (56.1%) who had nonischemic cardiomyopathy (NICM). Patients with NICM had higher in-patient mortality (24.6% vs 26.1, aOR: 1.12; 95% CI: 1.08-1.16, p<0.001); when adjusted for age, sex, race, and Charlson comorbidity index. Furthermore, patients with NICM also had a higher risk of respiratory failure (54.1% vs 53.8%, aOR:1.11, 95% CI: 1.07-1.14, p<0.001) and required more life-saving treatments like pressors (1.6% vs 0.7%, aOR: 1.14; 95% CI: 1.10-1.20, p< 0.001) and dialysis (12.7.1% vs 11.3%, aOR:1.20, 95% CI: 1.14-1.26, p<0.001). However, these patients with NICM had a lower risk of cardiac arrest (7.2% vs 7.8%, aOR: 0.88; 95% CI: 0.84-0.94, p< 0.001) and ventricular arrhythmias (29.5% vs 32.2%, aOR: 0.82; 95% CI: 0.80-0.86, p<0.001) as well as lower ECMO utilization (2.5 vs 2.1, aOR:0.82; 95% CI: 0.73-0.92, p <0.001) and blood transfusions (9.8% vs 11.7%, aOR:0.839; 95% CI: 0.80-0.88, p< 0.001). There was no significant difference in the ventilator use between the 2 groups (40.3% vs 39.7%, aOR:1.01, 95% CI: 0.97-1.04, p=0.714). Conclusion The findings of this study underscore the higher in-patient mortality among patients with non-ischemic cardiomyopathy (NICM) presenting with cardiogenic shock. These results emphasize the need for tailored treatment approaches targeting NICM-CS, warranting dedicated diagnostic and therapeutic strategies to improve prognosis in this vulnerable patient subset.Odd's ratios for NICM-CS vs ICM-CS

Long-term time-to-ventricular arrhythmic event prediction using a deep learning based model on the electrocardiogram signal

Abstract Background Ventricular arrhythmias (VA) risk stratification tools in individuals without known cardiovascular disease are still insufficient. Previous studies have used convolutional neural networks (CNN) to classify VA by the end of an established follow-up period using the electrocardiogram (ECG), showing a moderate performance (area under the curve [AUC] of 0.610). We hypothesised that the appearance of the VA substrate on the ECG signal depends on the proximity of the ECG acquisition to the VA event. Thus, the performance could improve if the CNN was trained to predict time-to-VA event instead, and if the presence of censored data was considered. Purpose We developed and tested a CNN to predict time-to-VA event in middle-aged individuals without known cardiovascular disease, and we compared its performance with that from ECG indices, such as QRS duration, QT interval and T-wave morphology variations (TMV), as well as sex and age. Methods A total of 69,283 individuals without known cardiovascular disease from the UK Biobank were used as the training set. We applied 10-fold cross validation to train a CNN, where the input was a 15-second ECG at rest (lead I), and the output was ‘occurrence of VA’, ‘censored’, or ‘survival’, up to 1, 2, 3, 4, 6, 8, 10 and 12 years after the ECG acquisition. We used 15-second ECG (lead I) from an independent cohort of 17,320 individuals without cardiovascular disease also from UK Biobank as a test set, where we set a follow-up of 10 years. The above ECG indices were derived from the median heartbeat from the ECG using in-house algorithms. We derived optimal cut-off thresholds from the training test, and we evaluated the AUC, sensitivity, specificity and Cox regression hazard ratios (HR) in the test set. Results In the test set, 9,206 individuals (53%) reached the 10-year follow-up, during which 60 (0.7%) had a VA event. The AUC, sensitivity and specificity values of the CNN were 0.715, 0.881 and 0.400, respectively. These values were 0.592, 0.686 and 0.383 for the QRS duration, 0.569, 0.156 and 0.717 for the QT interval and 0.552, 0.712 and 0.350 for TMV. The combination of sex and age alone showed performance values of 0.760, 0.694 and 0.683, respectively. Survival analyses showed a HR of 3.883 (P = 3.0 x 10-7) for individuals with a CNN prediction greater than the threshold derived in the training set after adjusting for age and gender. Conclusions A CNN that is trained to predict time-to-VA event and accounts for censored data outperforms previous classification proposed models and the predictive value of individual ECG indices of risk. Although the predictive value of the CNN does not show a better long-term VA predictive value than sex and age alone, it provides a significant contribution independently from these two risk factors. Our findings support the use of the ECG to improve long-term VA risk stratification, which might be particularly useful in age- and sex-stratified analyses.

Smaller intrinsic QRS area and smaller reduction of QRS area during cardiac resynchronisation therapy are associated with higher risk of ventricular arrhythmias and appropriate ICD therapy

Abstract Background Cardiac resynchronisation therapy (CRT) patients are at high risk for ventricular arrhythmias (VAs), and little is known about which characteristics are associated with an increased risk for arrhythmic events. Purpose To investigate the association between QRS area parameters and the risk for VAs in patients with heart failure undergoing primary preventive CRT with defibrillator (CRT-D) implantation. Methods All patients receiving CRT-D between 2015 and 2020 at a large-volume tertiary care center were retrospectively evaluated. Digital 12-lead electrocardiograms (ECGs) were collected before and after CRT implantation. Patients were included if they had native LBBB and were implanted with a primary preventive CRT-D. Kors’ regression transformation was used to derive vectorcardiographic QRS area from the 12-lead ECGs. QRS area parameters were analysed in relation to a primary endpoint of first appropriate ICD therapy, i.e., ATP or shock therapy. Results 177 patients with LBBB (68.9 years [60.7–73.8]; 21.5% female; 52.9% New York Heart Association (NYHA) class III-IV; LVEF 25.9±6.3%) were followed over a median follow-up time of 2.5 years [1.6–3.0] after CRT-D implantation. 27 patients reached the primary endpoint. The median pre-CRT QRS area was 134.5 μVs [102.3–163.8]. Multivariable Cox regression identified a small pre-CRT QRS area (HR, per 10 μVs decrease, 1.30; [1.12–1.51]; p=<.001) and a small post-CRT reduction in QRS area (HR, per 10 μVs decrease, 1.30; [1.13–1.49]; p=<.001) as independent predictors of an increased risk of appropriate ICD therapy. In analyses with a scoring variable combining pre-CRT QRS area and QRS area reduction both above or below median, the combination of a small pre-CRT QRS area and a small QRS area reduction was strongly associated with an increased risk of reaching the endpoint (HR, per point increase, 2.47; [1.2–4.9]; p=0.01). Conclusion A small intrinsic QRS area, by itself or in combination with a small reduction of post-CRT QRS area, was strongly associated with a higher risk of ventricular arrhythmias in this cohort of CRT-D treated patients. In conjunction with other parameters, further risk stratification for arrhythmic events could be achieved by assessing QRS area data pre- and post-CRT.Figure 1.K-M pre-CRT QRS area quartilesFigure 2.K-M QRS area score

Comparison of ventricular tachyarrhythmias in HF patients on dapagliflozin versus empagliflozin

Abstract Background Ventricular tachycardia (VT) and ventricular fibrillation (VF) are devastating tachyarrhythmias that can cause sudden cardiac death in patients with heart failure (HF) if not anticipated or treated promptly. Although post-hoc analysis in DAPA-HF showed promise in their benefit, Sodium-glucose transport protein 2 inhibitors (SGLT2i) have not yet been evaluated for their effect on these tachyarrhythmias. This retrospective analysis aims to compare the 2 most commonly used SGLT2i agents, dapagliflozin and empagliflozin, and the incidence of VT in patients with HF. Methods The TriNetX Research network was used for this study. The two initial patient cohorts were created using ICD-10 codes and medication codes from the TriNetX platform. Both cohorts consisted of patients over age 60 with a history of heart failure and either VF or VT. One cohort was on treatment with dapagliflozin and the other with empagliflozin. The cohorts were balanced by propensity score matching and the greedy nearest neighbor algorithm for age, gender, race, ethnicity, hyperkalemia, and the current use of spironolactone, amiodarone, metoprolol, and carvedilol, resulting in 9,841 patients in each arm. The cohorts were then evaluated for the development of VF or VT over the subsequent five years as well as all-cause mortality. Additional cohorts were created to evaluate dapagliflozin vs empagliflozin in diabetics, nondiabetics, and patients with ejection fractions less than 35% Results Dapagliflozin was associated with an increased risk of ventricular arrhythmia in heart failure patients compared to empagliflozin (46.0% vs. 40.8%, RR 1.13, 95% CI (1.09,1.16), P value < 0.0001). It was also associated with higher mortality at five years (RR 1.10, 95% CI (1.03,1.18), P value 0.0034). Conclusions In comparisons between dapagliflozin and empagliflozin in heart failure patients with previously documented ventricular arrhythmias, empagliflozin had 13% less risk of recurrence of ventricular arrhythmias. Secondarily, the empagliflozin cohort also exhibited lower all-cause mortality (14.8% vs 16.3%) at five years from starting the drug. Our analysis does not disprove findings in DAPA-HF, but rather may support the potential class effect of SGLT2 inhibitors in their ability to suppress VT.(1) Importantly, the overall incidence of ventricular tachyarrhythmias is high in both cohort, given we selected a high-risk population. Notably, our documented recurrence rate is similar to past reports of recurrence after VT ablation, the gold standard for treatment of VT. (2) SGLT2 inhibitors have shown clear benefit in multiple placebo-controlled studies in terms of heart failure outcomes like mortality and readmission, but their effect on arrhythmias is one more additional benefit this class may have. (3) Given these associations, empagliflozin may be a more favorable options for HF patients who have already had VT or VF.

The cardiac sympathetic co-transmitter neuropeptide-Y is pro-arrhythmic in human cardiomyocytes by lengthening activation-recovery interval

Abstract Background Myocardial infarction (MI) is associated with sympathetic overactivity, during which the co-release of neuropeptide-Y (NPY) is prominent. NPY is associated with arrhythmia risk and mortality following ST-elevation MI, although the exact mechanisms for this in human cardiomyocytes remains unclear. Purpose We therefore tested the hypothesis that NPY signalling would alter the electrophysiology of human induced-pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) in a way that would promote arrhythmia, and that in patients being treated for MI, high NPY concentrations previously associated with ventricular arrhythmia (>27.3 pg.mL-1) would be associated with comparable ECG changes. Methods Immunohistochemistry and western blot were performed on hiPSC-CMs and ventricular biopsies from human patients undergoing valve surgery. The FRET-based sensor Epac-SH187 was expressed in hiPSC-CMs to monitor the cyclic adenosine 3’,5’-monophosphate (cAMP) response to NPY. A micro-electrode array was used to investigate the effects of NPY on a confluent layer of iPSC-CMs, measuring changes in activation, recovery, conduction velocity and spontaneous automaticity. Additionally, patients presenting with ST-elevation MI had peripheral venous [NPY] measured and compared to 12-lead ECGs recorded following stenting. Results hiPSC-CMs expressed Y1 and Y5 receptor mRNA and protein, which are also expressed in ventricular biopsies from human patients. NPY (1-100 nM) significantly reduced intracellular cAMP levels (n=65), most effectively prevented by Y5 receptor inhibition (1µM CGP71683A, n=40). In a confluent layer of hiPSC-CM, NPY (100 nM) slowed late-repolarisation represented by T-wave peak-end duration (p=0.04), which could be prevented by Y1-receptor inhibition (1 μM BIBO 3304, n=6), and caused prolongation of rate corrected activation-recovery interval (ARIc) (p=0.009, n=6) which could be abolished by Y5-receptor inhibition (n=7). NPY significantly increased automaticity to more than one site of initiation in 4/6 (66.7%) compared to 2/14 (14.3%) control plates (p=0.037), despite no change in conduction velocity. Moreover, in 65 patients being treated for ST elevation MI, those with high peripheral venous NPY concentrations were well matched in terms of cardiovascular risk factors, medications on admission, and pain to balloon times, but had significantly longer corrected QT interval (QTc) on the 12 lead ECG (p=0.04) despite no differences in PR interval, heart rate or electrolyte concentrations. Conclusions NPY slowed late repolarisation and caused ARIc prolongation, which was associated with increased automaticity in human iPSC-CMs. NPY also correlated with QTc-prolongation in patients being treated for MI and may contribute to the increased incidence of ventricular arrhythmia observed in these patients. Antagonists of Y1 and Y5 receptors may therefore offer an adjunct to β-blockade therapy to reduce the risk of ventricular arrhythmia.