Increased Risk Of Arrhythmias Research Articles

Clinical approach to palpitations in pregnancy.

Palpitations are common in pregnancy and warrant investigation. Palpitations may be caused by non-cardiac and cardiac causes. Patients with structural or functional abnormalities or inherited cardiovascular disease are more likely to develop arrhythmia, especially during pregnancy when the mother's body undergoes extensive physiological adaptations, which further contribute to an increased arrhythmia risk. While isolated ectopic beats do not require treatment, some heart rhythm disturbances can be life-threatening for mother and baby and mandate prompt intervention. Haemodynamically unstable patients should be electrically cardioverted. If the patient is stable, medical management is indicated, and early involvement of the pregnancy heart team can help facilitate appropriate treatment. In complex arrhythmia, consultation of an arrhythmia expert should be sought . Many antiarrhythmics are safe in pregnancy, and it is important to reassure the pregnant patient of this.

Temporal variability of electromechanical-window negativity in patients with inherited long-QT syndrome or drug-induced QT prolongation: relation to torsades de pointes

Abstract Background Electromechanical window (EMW) negativity is a novel parameter that identifies long-QT syndrome (LQTS) patients at increased arrhythmia risk. Whether the EMW remains stable or alters, especially close to arrhythmic events, is unknown. Purpose To study temporal variability of the EMW in controls and in patients with LQTS or drug-induced QT prolongation (di-QTprol), in relation to the timing of torsades de pointes (TdP) or ventricular fibrillation (VF). Methods In a retrospective cohort study with 5 participating centers, we assessed the EMW (ms) at 2 or 3 timepoints (if applicable, one of them close to TdP/VF) from cw-Doppler echocardiography in the apical long-axis view and concomitant ECG. EMW was calculated by subtracting the QT time from the aortic-valve closure time measured from QRS onset (surrogate of mechanical systole). Data are shown as mean±SD or median (25th to 75th percentile). Results Forty patients (75% female, 43±18 years old) were included: 8 controls, 27 LQTS (10 symptomatic: 9 TdP, 1 VF), and 5 di-QTprol (all TdP). LQTS genotypes were LQT1 (n=11), LQT2 (n=6), LQT3 (n=7), LQT7 (n=2), and genotype-negative (n=1). Overall, 67% of LQTS patients and 20% of di-QTprol were treated with β-blockers. Baseline QTc was 409±32 ms in controls, 444±32 ms in asymptomatic LQTS, 491±41 ms in symptomatic LQTS, and 498±49 ms in di-QTprol. Baseline EMW was 6±14 ms in controls, -12±29 ms in asymptomatic LQTS, -52±16 ms in symptomatic LQTS, and -5±69 ms in di-QTprol. Over years of follow-up, EMW remained stable in controls (8±10 ms; Fig. 1A) and the asymptomatic LQTS group (-17±20 ms; Fig. 1B). In LQTS patients with TdP/VF, EMW (baseline measured at -534 (-962 to -143) days before arrhythmia) had become profoundly more negative, -127±42 ms, (p=0.01 vs. baseline) at 1 (0 to 5) days after the arrhythmia and returned to basal values, -52±18 ms, (p=0.005) after 722 (155 to 3100) days (Fig. 1C). There was a significant correlation between time-to-event and EMW negativity (r=0.72, p<0.0001), indicating stronger EMW negativity when measured closer to TdP/VF. For the di-QTprol patients (n=2 amiodarone; n=2 escitalopram; n=1 sotalol) a trend towards more exaggerated EMW negativity was observed: from baseline (at -19 (-785 to -13) days before the event) to -125±33 ms (p=0.08 vs. baseline) at 1 (1 to 5) days after TdP (Fig. 1D). Again, significant correlation was found between time-to-event and EMW negativity (r=0.6, p=0.03). Conclusion Episodes of electrical instability in patients with LQTS or di-QTprol are associated with profound but reversible exaggeration of EMW negativity. If also present just prior to TdP/VF (as in experimental models of torsadogenic di-QTprol and anecdotal LQTS cases), imminent ventricular arrhythmias may be anticipated as electromechanical reciprocity may contribute to arrhythmogenesis.Figure 1Graphical Abstract

Endurance Training Provokes Arrhythmogenic Right Ventricular Cardiomyopathy Phenotype in Heterozygous Desmoglein-2 Mutants: Alleviation by Preload Reduction.

Desmoglein-2 mutations are detected in 5-10% of patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). Endurance training accelerates the development of the ARVC phenotype, leading to earlier arrhythmic events. Homozygous Dsg2 mutant mice develop a severe ARVC-like phenotype. The phenotype of heterozygous mutant (Dsg2mt/wt) or haploinsufficient (Dsg20/wt) mice is still not well understood. To assess the effects of age and endurance swim training, we studied cardiac morphology and function in sedentary one-year-old Dsg2mt/wt and Dsg20/wt mice and in young Dsg2mt/wt mice exposed to endurance swim training. Cardiac structure was only occasionally affected in aged Dsg20/wt and Dsg2mt/wt mice manifesting as small fibrotic foci and displacement of Connexin 43. Endurance swim training increased the right ventricular (RV) diameter and decreased RV function in Dsg2mt/wt mice but not in wild types. Dsg2mt/wt hearts showed increased ventricular activation times and pacing-induced ventricular arrhythmia without obvious fibrosis or inflammation. Preload-reducing therapy during training prevented RV enlargement and alleviated the electrophysiological phenotype. Taken together, endurance swim training induced features of ARVC in young adult Dsg2mt/wt mice. Prolonged ventricular activation times in the hearts of trained Dsg2mt/wt mice are therefore a potential mechanism for increased arrhythmia risk. Preload-reducing therapy prevented training-induced ARVC phenotype pointing to beneficial treatment options in human patients.

Effect of Selective 5-Hydroxytryptamine-3 Receptor and Neurokinin-1 Receptor Antagonists on Hemodynamic Changes and Arrhythmogenic Potential in Patients Receiving Chemotherapy: A Retrospective, Observational Study

Background: Prior speculation suggests that selective 5-hydroxytryptamine-3 receptors and neurokinin-1 receptor antagonists may increase arrhythmia risk and induce electrocardiographic changes. This study examined the effect of anti-emetic medications on arrhythmogenic potential and hemodynamic alterations. Methods: We considered patients aged 18 or above receiving chemotherapy between June 2013 and December 2013. Patients were grouped by anti-emetic medication: intravenous granisetron (Group G), oral aprepitant plus IV granisetron (Group AG), IV palonosetron (Group P), and oral aprepitant plus IV palonosetron (Group AP). We recorded blood pressure and electrocardiography initially and at the thirtieth minute post-medication, focusing on P dispersion, QTc dispersion, and systolic/diastolic blood pressure alterations. Results: The study included 80 patients (20 per group). Baseline systolic/diastolic blood pressure and P dispersion showed no significant variance. However, the baseline QTc dispersion was significantly lower in Groups P and AP than G and AG. The thirtieth-minute systolic/diastolic blood pressures were significantly lower than the baseline for Groups AG and AP, and the heart rates decreased in all groups. Group P showed significantly fewer blood pressure changes. Conclusions: We found no arrhythmogenic potential linked to granisetron, palonosetron, and aprepitant. Hypotension was more frequent at 30 min post-medication in granisetron or aprepitant recipients. Considering no hypotension occurred when using palonosetron alone, this treatment was deemed safer.

Redox imbalance in patients with heart failure and ICD/CRT-D intervention. Can it be an underappreciated and overlooked arrhythmogenic factor? A first preliminary clinical study.

Introduction: Redox imbalance and oxidative stress are involved in the pathogenesis of arrhythmias. They also play a significant role in pathogenesis of heart failure (HF). In patients with HFand implanted cardioverter-defibrillator (ICD) or cardiac resynchronization therapy defibrillator (CRT-D), the direct current shocks may be responsible for additional redox disturbances and additionally increase arrhythmia risk. However, the precise role of oxidative stress in potentially fatal arrhythmias and shock induction remains unclear. Methods: 36 patients with diagnosed HF and implanted ICD/CRT-D were included in this study. Patients were qualified to the study group in case of registered ventricular arrhythmia and adequate ICD/CRT-D intervention. The control group consisted of patients without arrhythmia with elective replacement indicator (ERI) status. Activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione (GSH) in erythrocyte (RBC), SOD, GPx activity and reactive oxygen/nitrogen species (ROS/RNS) concentration in plasma were determined. The values were correlated with glucose, TSH, uric acid, Mg and ion concentrations. Results: In the perishock period, we found a significant decrease in RBC and extracellular (EC) SOD and RBC CAT activity (p = 0.0110, p = 0.0055 and p = 0.0002, respectively). EC GPx activity was also lower (p = 0.0313). In all patients, a decrease in the concentration of all forms of glutathione was observed compared to the ERI group. Important association between ROS/RNS and GSH, Mg, TSH and uric acid was shown. A relationship between the activity of GSH and antioxidant enzymes was found. Furthermore, an association between oxidative stress and ionic imbalance has also been demonstrated. The patients had an unchanged de Haan antioxidant ratio and glutathione redox potential. Conclusion: Here we show significant redox disturbances in patients with HF and ICD/CRT-D interventions. Oxidative stress may be an additional risk factor for the development of arrhythmia in patients with HF. The detailed role of oxidative stress in ventricular arrhythmias requires further research already undertaken by our team.

Abstract 15800: Evaluating the Correlation Between Right Ventricular Outflow Tract Dimensions and Arrhythmia Risk Following Self-Expanding Transcatheter Pulmonary Valve Replacement

Introduction: The introduction of self-expanding valves has allowed for an expanded range of patients who can be treated with transcutaneous pulmonary valve replacement (TPVR). Though major complications are rare, ventricular tachycardia has been reported following self-expanding valve placement prompting investigation of potential risk factors. Hypothesis: Significant variation in valve dimensions within the right ventricular outflow tract (RVOT) throughout the cardiac cycle is postulated as a cause for increased arrhythmia risk. We hypothesized that greater dynamic variation of the valve in the RVOT correlates to higher ventricular arrythmia risk. Methods: A single center review was performed of patients who underwent TPVR with either Harmony TPV or Alterra Pre-stent with subsequent placement of 29mm Sapien valve between 2019 and 2023. Using post-procedural 3D rotational angiography, minimum (systole) and maximum (diastole) diameters (mm), perimeter (mm) and cross-sectional area (mm 2 ) of the valve frame were measured in two locations: closest to the branch pulmonary artery bifurcation and the RV cavity. Results: Twenty-eight patients were included (14 Harmony TPV, 14 Alterra). Higher frequency of ventricular arrythmia was seen in patients with congenital pulmonary stenosis ( p =0.004). Higher ventricular arrythmia rate was associated with larger diastolic diameter (34.1 vs 33.2mm, p =0.04), mean perimeter (118.3 vs 108.6mm, p =0.03) and area (1124.5 vs 926.2mm 2 , p =0.03) of the valve frame closest to the RV cavity. Conclusions: Increased movement of the valve frame close to the RV cavity may correlate with a higher ventricular arrythmia risk due to increased contact with the native RVOT throughout the cardiac cycle. Future studies should focus on more accurate, mathematical methodology to better understand whether the complex interaction between self-expanding valves and the native RVOT is a determinant for post-procedural ventricular arrythmia.

Mental illness and cardiovascular health: observational and polygenic score analyses in a population-based cohort study.

Individuals with serious mental illness have a markedly shorter life expectancy. A major contributor to premature death is cardiovascular disease (CVD). We investigated associations of (genetic liability for) depressive disorder, bipolar disorder and schizophrenia with a range of CVD traits and examined to what degree these were driven by important confounders. We included participants of the Dutch Lifelines cohort (N = 147 337) with information on self-reported lifetime diagnosis of depressive disorder, bipolar disorder, or schizophrenia and CVD traits. Employing linear mixed-effects models, we examined associations between mental illness diagnoses and CVD, correcting for psychotropic medication, demographic and lifestyle factors. In a subsample (N = 73 965), we repeated these analyses using polygenic scores (PGSs) for the three mental illnesses. There was strong evidence that depressive disorder diagnosis is associated with increased arrhythmia and atherosclerosis risk and lower heart rate variability, even after confounder adjustment. Positive associations were also found for the depression PGSs with arrhythmia and atherosclerosis. Bipolar disorder was associated with a higher risk of nearly all CVD traits, though most diminished after adjustment. The bipolar disorder PGSs did not show any associations. While the schizophrenia PGSs was associated with increased arrhythmia risk and lower heart rate variability, schizophrenia diagnosis was not. All mental illness diagnoses were associated with lower blood pressure and a lower risk of hypertension. Our study shows widespread associations of (genetic liability to) mental illness (primarily depressive disorder) with CVD, even after confounder adjustment. Future research should focus on clarifying potential causal pathways between mental illness and CVD.

Evaluation of the relationship between speckle tracking echocardiography and arrhythmia markers Tp-e interval and Tp-e/QTc in patients with arterial hypertension.

The prolongation of the Tp-e interval, which is defined as the interval from the peak to the end of the T wave on electrocardiography (ECG), is considered a non-invasive predictor of malignant ventricular arrhythmia development. In our study, we aimed to compare the Tp-e interval and Tp-e/QTc ratios on ECG and subclinical myocardial dysfunction evaluated by left ventricular global longitudinal strain (LV-GLS) imaging in patients receiving treatment for hypertension.Two-dimensional speckle tracking echocardiography was performed in 102 consecutive hypertensive patients with blood pressure values regulated by treatment. The normal left ventricular global longitudinal strain (LV-GLS) limit was accepted as < -18%. The patients were divided into two groups: those with normal (≥ -18%) LV-GLS and those with impaired LV-GLS (< -18%). Comparisons between the groups were made by measuring ventricular repolarization parameters, such as QT, QTc, and Tp-e intervals, and Tp-e/QT and Tp-e/QTc ratios.While the mean age of the patients with impaired LV-GLS was 55±6 years, the mean age of the normal LV-GLS group was 58±9 years (p=0.101). The Tp-e interval, Tp-e/QT, and Tp-e/QTc ratios were significantly higher in the impaired LV-GLS group than in the normal LV-GLS group (p<0.05 for all). A positive correlation was observed between the ventricular repolarization parameters and LV-GLS values. This positive correlation was statistically significant in terms of the Tp-e interval, Tp-e/QT, and Tp-e/QTc ratios.The Tp-e interval, Tp-e/QT, and Tp-e/QTc ratios were increased in hypertensive patients with impaired LV-GLS, and therefore a close follow-up in terms of increased arrhythmia risk is required in this patient group.

BS-454195-1 ADRENERGIC MODULATION OF CONDUCTION DURING CARDIAC STRESS IS MEDIATED BY CALCIUM CHANNEL AUTOREGULATION OF INTERCALATED DISC NANODOMAINS

During stress, adrenergic signaling enhances cardiac conduction, although the mechanisms are not fully understood. Reducing extracellular calcium in the heart widens an intercalated disc (ID) nanodomain adjacent to gap junctions known as the perinexus. Under acute cardiac stress, the perinexus adaptively remodels; preventing this response by experimentally changing calcium levels slows conduction and increases arrhythmia risk. This raises the question of whether myocytes autoregulate calcium-mediated ID adhesion to stabilize conduction during cardiac stress. The cardiac voltage gated calcium channel (Cav1.2) is a primary source of calcium influx and a key target during adrenergic signaling. Expression of Cav1.2 within the ID has not been described. To test the hypothesis that Cav1.2 is expressed in the ID and autoregulates myocyte adhesion and conduction in the adrenergic response to cardiac stress. Ex vivo guinea pig hearts were Langendorff-perfused and ventricular tissue harvested for microscopy. Cav1.2 cellular localization was quantified by spinning disk confocal microscopy (n=5), conduction velocity (CV) was measured by optical mapping (n=9), and ID ultrastructure was quantified from transmission electron micrographs (n=17). Cav1.2 function was modulated by perfusion with the β-adrenergic agonist isoproterenol (Iso, 0.6μM), the Cav1.2 agonist BayK8644 (BayK, 0.5μM), or the Cav1.2 antagonist verapamil (Ver, 2μM). Super resolution confocal microscopy demonstrated that 2.5% of total Cav1.2 signal co-occurred with connexin43 and N-cadherin. At baseline, CV slowed at shorter CLs (150 vs 300ms = 4% slower), consistent with CV restitution. Treatment with Iso increased both Wp (20.2 vs 17.0 nm at baseline) and CV (300ms: 113% of baseline). Iso reversed CV restitution such that CV increased by 4%. Activation of Cav1.2 by BayK widened Wp to the same degree as Iso (20.1 vs 20.2 nm). Verapamil prevented both the Iso-induced increase in Wp (17.0 nm) and CV (93.9% of baseline), and exacerbated CV restitution. A subpopulation of Cav1.2 was identified within the ID. Adrenergic stimulation widened perinexal width, increased conduction, and reversed CV restitution. Blocking Cav1.2 prevented the adrenergic-mediated change in perinexal structure and conduction. Thus, Cav1.2 function regulates ID ultrastructure and may serve as an adaptive response to enhance conduction during conditions of acute cardiac stress.

Caveolin-3 and Caveolae regulate ventricular repolarization

RationaleFlask-shaped invaginations of the cardiomyocyte sarcolemma called caveolae require the structural protein caveolin-3 (Cav-3) and host a variety of ion channels, transporters, and signaling molecules. Reduced Cav-3 expression has been reported in models of heart failure, and variants in CAV3 have been associated with the inherited long-QT arrhythmia syndrome. Yet, it remains unclear whether alterations in Cav-3 levels alone are sufficient to drive aberrant repolarization and increased arrhythmia risk. ObjectiveTo determine the impact of cardiac-specific Cav-3 ablation on the electrophysiological properties of the adult mouse heart. Methods and resultsCardiac-specific, inducible Cav3 homozygous knockout (Cav-3KO) mice demonstrated a marked reduction in Cav-3 expression by Western blot and loss of caveolae by electron microscopy. However, there was no change in macroscopic cardiac structure or contractile function. The QTc interval was increased in Cav-3KO mice, and there was an increased propensity for ventricular arrhythmias. Ventricular myocytes isolated from Cav-3KO mice exhibited a prolonged action potential duration (APD) that was due to reductions in outward potassium currents (Ito, Iss) and changes in inward currents including slowed inactivation of ICa,L and increased INa,L. Mathematical modeling demonstrated that the changes in the studied ionic currents were adequate to explain the prolongation of the mouse ventricular action potential. Results from human iPSC-derived cardiomyocytes showed that shRNA knockdown of Cav-3 similarly prolonged APD. ConclusionWe demonstrate that Cav-3 and caveolae regulate cardiac repolarization and arrhythmia risk via the integrated modulation of multiple ionic currents.

Obstructive Sleep Apnoea and Cardiac Arrhythmias (OSCA) trial: a nested cohort study using injectable loop recorders and Holter monitoring in patients with obstructive sleep apnoea

IntroductionObstructive sleep apnoea (OSA) is associated with increased cardiovascular mortality despite continuous positive airways pressure (CPAP) therapy. This excess risk may be related to increased arrhythmia risk, especially atrial fibrillation...

Transcriptional Dysregulation Underlies Both Monogenic Arrhythmia Syndrome and Common Modifiers of Cardiac Repolarization.

Brugada syndrome (BrS) is an inherited arrhythmia syndrome caused by loss-of-function variants in the cardiac sodium channel gene SCN5A (sodium voltage-gated channel alpha subunit 5) in ≈20% of subjects. We identified a family with 4 individuals diagnosed with BrS harboring the rare G145R missense variant in the cardiac transcription factor TBX5 (T-box transcription factor 5) and no SCN5A variant. We generated induced pluripotent stem cells (iPSCs) from 2 members of a family carrying TBX5-G145R and diagnosed with Brugada syndrome. After differentiation to iPSC-derived cardiomyocytes (iPSC-CMs), electrophysiologic characteristics were assessed by voltage- and current-clamp experiments (n=9 to 21 cells per group) and transcriptional differences by RNA sequencing (n=3 samples per group), and compared with iPSC-CMs in which G145R was corrected by CRISPR/Cas9 approaches. The role of platelet-derived growth factor (PDGF)/phosphoinositide 3-kinase (PI3K) pathway was elucidated by small molecule perturbation. The rate-corrected QT (QTc) interval association with serum PDGF was tested in the Framingham Heart Study cohort (n=1893 individuals). TBX5-G145R reduced transcriptional activity and caused multiple electrophysiologic abnormalities, including decreased peak and enhanced "late" cardiac sodium current (INa), which were entirely corrected by editing G145R to wild-type. Transcriptional profiling and functional assays in genome-unedited and -edited iPSC-CMs showed direct SCN5A down-regulation caused decreased peak INa, and that reduced PDGF receptor (PDGFRA [platelet-derived growth factor receptor α]) expression and blunted signal transduction to PI3K was implicated in enhanced late INa. Tbx5 regulation of the PDGF axis increased arrhythmia risk due to disruption of PDGF signaling and was conserved in murine model systems. PDGF receptor blockade markedly prolonged normal iPSC-CM action potentials and plasma levels of PDGF in the Framingham Heart Study were inversely correlated with the QTc interval (P<0.001). These results not only establish decreased SCN5A transcription by the TBX5 variant as a cause of BrS, but also reveal a new general transcriptional mechanism of arrhythmogenesis of enhanced late sodium current caused by reduced PDGF receptor-mediated PI3K signaling.

Diabetes and Excess Aldosterone Promote Heart Failure With Preserved Ejection Fraction.

Background The pathobiology of heart failure with preserved ejection fraction (HFpEF) is still poorly understood, and effective therapies remain limited. Diabetes and mineralocorticoid excess are common and important pathophysiological factors that may synergistically promote HFpEF. The authors aimed to develop a novel animal model of HFpEF that recapitulates key aspects of the complex human phenotype with multiorgan impairments. Methods and Results The authors created a novel HFpEF model combining leptin receptor-deficient db/db mice with a 4-week period of aldosterone infusion. The HFpEF phenotype was assessed using morphometry, echocardiography, Ca2+ handling, and electrophysiology. The sodium-glucose cotransporter-2 inhibitor empagliflozin was then tested for reversing the arrhythmogenic cardiomyocyte phenotype. Continuous aldosterone infusion for 4 weeks in db/db mice induced marked diastolic dysfunction with preserved ejection fraction, cardiac hypertrophy, high levels of B-type natriuretic peptide, and significant extracardiac comorbidities (including severe obesity, diabetes with marked hyperglycemia, pulmonary edema, and vascular dysfunction). Aldosterone or db/db alone induced only a mild diastolic dysfunction without congestion. At the cellular level, cardiomyocyte hypertrophy, prolonged Ca2+ transient decay, and arrhythmogenic action potential remodeling (prolongation, increased short-term variability, delayed afterdepolarizations), and enhanced late Na+ current were observed in aldosterone-treated db/db mice. All of these arrhythmogenic changes were reversed by empagliflozin pretreatment of HFpEF cardiomyocytes. Conclusions The authors conclude that the db/db+aldosterone model may represent a distinct clinical subgroup of HFpEF that has marked hyperglycemia, obesity, and increased arrhythmia risk. This novel HFpEF model can be useful in future therapeutic testing and should provide unique opportunities to better understand disease pathobiology.

The Risk of Fatal Arrhythmias in Post-Myocardial Infarction Depression in Association With Venlafaxine.

Venlafaxine is a second line anti-depressant and the most commonly used in the treatment of selective serotonin reuptake inhibitor nonresponders in major depression; due to its effects on the noradrenergic and serotonergic systems as a serotonin and norepinephrine reuptake inhibitor, there has been considerable apprehension regarding its use in patients with cardiovascular diseases, particularly post-myocardial infarction depression, some of the feared adverse effects include QT prolongation, arrhythmias including torsades de pointes and sudden cardiac death. We tried to resolve the facts regarding the risks associated with venlafaxine use in cardiac patients. We have reviewed all the relevant information up to May 2022 regarding the risks of venlafaxine use in cardiovascular disease, particularly with a focus on post-myocardial infarction depression, and gathered around 350 articles in our research and narrowed it down to 49 articles. The database used was PubMed and the keywords used were venlafaxine, arrhythmia, major depression, post-myocardial infarction, and ventricular tachycardia. We carefully screened all relevant articles and found articles supporting and refuting the effects of venlafaxine in increasing cardiovascular morbidity and mortality. We have concluded that there is a significant variability due to confounding factors affecting individual cases. Overall there is no increased arrhythmia risk in comparison with other anti-depressants except in high-risk cases such as with pre-existing cardiovascular disease, certain genotypes, and other co-morbidities. Any patient with a high risk of arrhythmias due to any etiology should receive a screening electrocardiogram before venlafaxine prescription for baseline QT interval and periodically while on therapy to check for changes. We encourage further research, including randomized clinical trials and post-marketing surveillance regarding the use of venlafaxine in high-risk cases such as patients with multiple co-morbidities, elderly patients, or patients with certain genotypes.

Assessment of the Diagnostic Yield of Combined Cardiomyopathy and Arrhythmia Genetic Testing

Genetic testing can guide management of both cardiomyopathies and arrhythmias, but cost, yield, and uncertain results can be barriers to its use. It is unknown whether combined disease testing can improve diagnostic yield and clinical utility for patients with a suspected genetic cardiomyopathy or arrhythmia. To evaluate the diagnostic yield and clinical management implications of combined cardiomyopathy and arrhythmia genetic testing through a no-charge, sponsored program for patients with a suspected genetic cardiomyopathy or arrhythmia. This cohort study involved a retrospective review of DNA sequencing results for cardiomyopathy- and arrhythmia-associated genes. The study included 4782 patients with a suspected genetic cardiomyopathy or arrhythmia who were referred for genetic testing by 1203 clinicians; all patients participated in a no-charge, sponsored genetic testing program for cases of suspected genetic cardiomyopathy and arrhythmia at a single testing site from July 12, 2019, through July 9, 2020. Positive gene findings from combined cardiomyopathy and arrhythmia testing were compared with findings from smaller subtype-specific gene panels and clinician-provided diagnoses. Among 4782 patients (mean [SD] age, 40.5 [21.3] years; 2551 male [53.3%]) who received genetic testing, 39 patients (0.8%) were Ashkenazi Jewish, 113 (2.4%) were Asian, 571 (11.9%) were Black or African American, 375 (7.8%) were Hispanic, 2866 (59.9%) were White, 240 (5.0%) were of multiple races and/or ethnicities, 138 (2.9%) were of other races and/or ethnicities, and 440 (9.2%) were of unknown race and/or ethnicity. A positive result (molecular diagnosis) was confirmed in 954 of 4782 patients (19.9%). Of those, 630 patients with positive results (66.0%) had the potential to inform clinical management associated with adverse clinical outcomes, increased arrhythmia risk, or targeted therapies. Combined cardiomyopathy and arrhythmia gene panel testing identified clinically relevant variants for 1 in 5 patients suspected of having a genetic cardiomyopathy or arrhythmia. If only patients with a high suspicion of genetic cardiomyopathy or arrhythmia had been tested, at least 137 positive results (14.4%) would have been missed. If testing had been restricted to panels associated with the clinician-provided diagnostic indications, 75 of 689 positive results (10.9%) would have been missed; 27 of 75 findings (36.0%) gained through combined testing involved a cardiomyopathy indication with an arrhythmia genetic finding or vice versa. Cascade testing of family members yielded 402 of 958 positive results (42.0%). Overall, 2446 of 4782 patients (51.2%) had only variants of uncertain significance. Patients referred for arrhythmogenic cardiomyopathy had the lowest rate of variants of uncertain significance (81 of 176 patients [46.0%]), and patients referred for catecholaminergic polymorphic ventricular tachycardia had the highest rate (48 of 76 patients [63.2%]). In this study, comprehensive genetic testing for cardiomyopathies and arrhythmias revealed diagnoses that would have been missed by disease-specific testing. In addition, comprehensive testing provided diagnostic and prognostic information that could have potentially changed management and monitoring strategies for patients and their family members. These results suggest that this improved diagnostic yield may outweigh the burden of uncertain results.

Candesartan Cilexetil Attenuates Arrhythmogenicity Following Pressure Overload in Rats via the Modulation of Cardiac Electrical and Structural Remodeling and Calcium Handling Dysfunction.

BackgroundCardiac hypertrophy is associated with abnormal electrophysiology and increased arrhythmia risk. This study assessed whether candesartan cilexetil, an angiotensin II type 1 receptor blocker, could suppress arrhythmogenecity by attenuating cardiac electrical remodeling and calcium mishandling in rats with pressure‐overload hypertrophy.Methods and ResultsMale Sprague‐Dawley rats were randomly subjected to abdominal aorta banding or sham procedure and received either candesartan cilexetil (3.0 mg/kg per day) or vehicle by gavage for 5 weeks. Pressure overload was characterized by compensated left ventricular (LV) hypertrophy and fibrosis, increased LV pressure and its decay time, and prolonged corrected QT interval, all of which were attenuated by candesartan cilexetil treatment. Candesartan cilexetil–treated banded rat hearts displayed shorter QT intervals and lower vulnerability to atrial and ventricular tachyarrhythmias than vehicle‐treated banded hearts. Candesartan cilexetil prevented banding‐induced prolonged action potential duration and reduced the occurrence of triggered activity in LV papillary muscles. In addition, the prolonged time to 50% cell relengthening and calcium transient decay time were normalized in LV myocytes from candesartan cilexetil–treated banded rats, along with a normalization of decreased SERCA2a (sarco[endo]plasmic reticulum calcium‐ATPase) expression in LV tissues. Furthermore, candesartan cilexetil normalized depressed transient outward potassium current densities and protein and mRNA levels of both voltage‐gated potassium 4.2 and 4.3 channel subunits (Kv4.2 and Kv4.3) in banded rats.ConclusionsCandesartan cilexetil protects the heart from pressure overload‐induced adverse electrical remodeling by preserving potassium channel densities. In addition, calcium handling and its molecular regulation also improved after treatment. These beneficial effects may contribute to a lower susceptibility to arrhythmias in hearts from candesartan cilexetil–treated pressure‐overloaded rats.

Admission hyperglycemia in acute myocardial infarction is associated with an increased risk of arrhythmias: A systematic review and meta-analysis.

BackgroundAdmission hyperglycemia (AH) has shown to be associated with higher mortality rates in acute myocardial infarction (AMI). Malignant arrhythmia is one of the causes of death in AMI; however, it is unclear whether AH is associated with an increased arrhythmia risk. We conducted this systematic review and meta‐analysis to assess the association between AH and arrhythmias in AMI.MethodsWe searched MEDLINE, and Embase databases from inception to September 2021 to identify studies that compared arrhythmia rates between AMI patients with AH and those without. Arrhythmias of interest included ventricular tachyarrhythmias (VA), atrial fibrillation (AF), and atrioventricular block.ResultsThirteen cohort studies with a total of 12,898 patients were included. AH was associated with a higher risk of overall arrhythmias (18% vs 10.3%, pooled odds ratio [OR] = 1.89, 95% confidence interval [CI]: 1.39–2.56, P < .001), VA (16.4% vs 11.1%, pooled OR = 1.56, 95% CI: 1.11–2.18, P = .01), and new onset AF (17.8% vs 6.4%, pooled OR = 2.13, 95% CI: 1.4–3.25, P < .0010. Subgroup analysis of diabetes status regarding overall arrhythmias showed that the increased risk of arrhythmias in the AH group was consistent in both patients with a history of diabetes (18% vs 12.5%, pooled OR = 2.33, 95%CI: 1.2–4.52, P = .004) and without (15.7%. vs 9% pooled OR = 1.35, 95% CI: 1.1–1.66, P = .013).ConclusionAdmission hyperglycemia in AMI was associated with the increased risk of arrhythmias, regardless of history of diabetes mellitus.

Modelling the interaction between stem cells derived cardiomyocytes patches and host myocardium to aid non-arrhythmic engineered heart tissue design.

Application of epicardial patches constructed from human-induced pluripotent stem cell- derived cardiomyocytes (hiPSC-CMs) has been proposed as a long-term therapy to treat scarred hearts post myocardial infarction (MI). Understanding electrical interaction between engineered heart tissue patches (EHT) and host myocardium represents a key step toward a successful patch engraftment. EHT retain different electrical properties with respect to the host heart tissue due to the hiPSC-CMs immature phenotype, which may lead to increased arrhythmia risk. We developed a modelling framework to examine the influence of patch design on electrical activation at the engraftment site. We performed an in silico investigation of different patch design approaches to restore pre-MI activation properties and evaluated the associated arrhythmic risk. We developed an in silico cardiac electrophysiology model of a transmural cross section of host myocardium. The model featured an infarct region, an epicardial patch spanning the infarct region and a bath region. The patch is modelled as a layer of hiPSC-CM, combined with a layer of conductive polymer (CP). Tissue and patch geometrical dimensions and conductivities were incorporated through 10 modifiable model parameters. We validated our model against 4 independent experimental studies and showed that it can qualitatively reproduce their findings. We performed a global sensitivity analysis (GSA) to isolate the most important parameters, showing that the stimulus propagation is mainly governed by the scar depth, radius and conductivity when the scar is not transmural, and by the EHT patch conductivity when the scar is transmural. We assessed the relevance of small animal studies to humans by comparing simulations of rat, rabbit and human myocardium. We found that stimulus propagation paths and GSA sensitivity indices are consistent across species. We explored which EHT design variables have the potential to restore physiological propagation. Simulations predict that increasing EHT conductivity from 0.28 to 1–1.1 S/m recovered physiological activation in rat, rabbit and human. Finally, we assessed arrhythmia risk related to increasing EHT conductivity and tested increasing the EHT Na+ channel density as an alternative strategy to match healthy activation. Our results revealed a greater arrhythmia risk linked to increased EHT conductivity compared to increased Na+ channel density. We demonstrated that our modeling framework could capture the interaction between host and EHT patches observed in in vitro experiments. We showed that large (patch and tissue dimensions) and small (cardiac myocyte electrophysiology) scale differences between small animals and humans do not alter EHT patch effect on infarcted tissue. Our model revealed that only when the scar is transmural do EHT properties impact activation times and isolated the EHT conductivity as the main parameter influencing propagation. We predicted that restoring physiological activation by tuning EHT conductivity is possible but may promote arrhythmic behavior. Finally, our model suggests that acting on hiPSC-CMs low action potential upstroke velocity and lack of IK1 may restore pre-MI activation while not promoting arrhythmia.

Vascular endothelial barrier protection prevents nanoscale cardiac remodeling: a novel strategy to prevent atrial fibrillation

Atrial fibrillation (AF) patients experience inflammation and vascular dysfunction and have elevated levels of cytokines that promote vascular leak and edema, such as vascular endothelial growth factor (VEGF). We previously identified edema-induced disruption of sodium channel (NaV1.5) -rich intercalated disk (ID) nanodomains as a novel arrhythmia mechanism. Therefore, we hypothesized that: (i) VEGF-induced vascular leak acutely slows action potential propagation in the atria and increases arrhythmia risk by disrupting ID nanodomains, and (ii) protection of the vascular barrier can prevent vascular leak-induced atrial arrhythmias.

Role of plakophilin-2 expression on exercise-related progression of arrhythmogenic right ventricular cardiomyopathy: a translational study.

Exercise increases arrhythmia risk and cardiomyopathy progression in arrhythmogenic right ventricular cardiomyopathy (ARVC) patients, but the mechanisms remain unknown. We investigated transcriptomic changes caused by endurance training in mice deficient in plakophilin-2 (PKP2cKO), a desmosomal protein important for intercalated disc formation, commonly mutated in ARVC and controls. Exercise alone caused transcriptional downregulation of genes coding intercalated disk proteins. The changes converged with those in sedentary and in exercised PKP2cKO mice. PKP2 loss caused cardiac contractile deficit, decreased muscle mass and increased functional/transcriptomic signatures of apoptosis, despite increased fractional shortening and calcium transient amplitude in single myocytes. Exercise accelerated cardiac dysfunction, an effect dampened by pre-training animals prior to PKP2-KO. Consistent with PKP2-dependent muscle mass deficit, cardiac dimensions in human athletes carrying PKP2 mutations were reduced, compared to matched controls. We speculate that exercise challenges a cardiomyocyte "desmosomal reserve" which, if impaired genetically (e.g., PKP2 loss), accelerates progression of cardiomyopathy.