Electrolyte Abnormalities in Patients Presenting With Ventricular Arrhythmia (from the LYTE-VT Study)

Comparison of bicarbonate Ringer's solution with lactated Ringer's solution among postoperative outcomes in patients with laparoscopic right hemihepatectomy: a single-centre randomised controlled trial

The study was aimed to investigate the positive impact of bicarbonate Ringer's solution on postoperative outcomes in patients who underwent laparoscopic right hemihepatectomy. Patients in the two groups were infused with lactated Ringer's solution (LRS, n = 38) and the bicarbonate Ringer's solution (BRS, n = 38) at a rate of 5 ml·kg-1·h-1. The stroke volume was monitored and 200 ml of hydroxyethyl starch with 130/0.4 sodium chloride injection (Hes) of a bolus was given in the first 5-10 min. The main outcome was to test lactic acid (LAC) concentration before and after surgery. The concentrations of LAC in the LRS group were higher than in the BRS group at 2 h after operation began, at the end of the operation and 2 h after the operation. Overall, the parameters including pH, base excess (BE), HCO3-, aspartate transaminase (AST) and alanine transaminase (ALT) were improved. The values of bilirubin in the LRS group were higher and albumin were lower than in the BRS group at post-operation 1st and 2nd day (P<0.05). The time of prothrombin time (PT) and activated partial thromboplastin time (APTT) in the LRS group were longer than that in the BRS group at post-operation 1st and 2nd day (P<0.05). Likewise, the concentrations of Mg2+, Na+ and K+ also varied significantly. The length of hospital was reduced, and the incidence of premature ventricular contractions (P = 0.042) and total complications (P = 0.016) were lower in group BRS. TRIAL REGISTRATION: The study was registered at clinicalTrials.gov with the number ChiCTR2000038077 on 09/09/2020.

Management of Arrhythmias in the Cardiovascular Intensive Care Unit

Arrhythmias in the cardiovascular intensive care unit (CVICU) can be difficult to manage because of the complex hemodynamic and respiratory states of critically ill patients. Treating physicians must be educated to prevent, diagnose, and treat a multitude of tachyarrhythmias and bradyarrhythmias. In this review article, the authors outline a pragmatic approach to patient assessment, arrhythmia diagnosis, and management of the most common arrhythmias seen in the CVICU.

Traditional Therapeutics and Potential Epidrugs for CVD: Why Not Both?

Cardiovascular disease (CVD) is the leading cause of death worldwide. In addition to the high mortality rate, people suffering from CVD often endure difficulties with physical activities and productivity that significantly affect their quality of life. The high prevalence of debilitating risk factors such as obesity, type 2 diabetes mellitus, smoking, hypertension, and hyperlipidemia only predicts a bleak future. Current traditional CVD interventions offer temporary respite; however, they compound the severe economic strain of health-related expenditures. Furthermore, these therapeutics can be prescribed indefinitely. Recent advances in the field of epigenetics have generated new treatment options by confronting CVD at an epigenetic level. This involves modulating gene expression by altering the organization of our genome rather than altering the DNA sequence itself. Epigenetic changes are heritable, reversible, and influenced by environmental factors such as medications. As CVD is physiologically and pathologically diverse in nature, epigenetic interventions can offer a ray of hope to replace or be combined with traditional therapeutics to provide the prospect of addressing more than just the symptoms of CVD. This review discusses various risk factors contributing to CVD, perspectives of current traditional medications in practice, and a focus on potential epigenetic therapeutics to be used as alternatives.

Defibrillation in the Cardiac Arrest Patient

Defibrillation is one of the few interventions known to favorably impact survival in cardiac arrest. In witnessed arrest, survival improves with defibrillation as early as possible, whereas it may improve outcomes to administer high-quality chest compressions for 90 seconds before defibrillation in unwitnessed arrest. Minimizing pre-, peri-, and post-shock pauses has been shown to have mortality benefits. Refractory ventricular fibrillation has high mortality rates, and there is ongoing research into promising adjunctive treatment modalities. There remains no consensus on optimal pad positioning and defibrillation energy level, however, recent data suggest anteroposterior pad placement may be superior to anterolateral placement.

Nonclinical Cardiovascular Assessment of the Soluble Guanylate Cyclase Stimulator Vericiguat

Vericiguat and its metabolite M-1 were assessed for proarrhythmic risk in nonclinical in vitro and in vivo studies. In vitro manual voltage-clamp recordings at room temperature determined the effect of vericiguat on human Ether-a-go-go Related Gene (hERG) K+ channels. Effects of vericiguat and M-1 on hERG K+, Nav1.5, hCav1.2, hKvLQT1/1minK, and hKv4.3 channels were investigated via automated voltage-clamp recordings at ambient temperature. Effects of vericiguat and M-1 on hERG K+ and Nav1.5 channels at pathophysiological conditions were explored via manual voltage-clamp recordings at physiologic temperature. Single oral doses of vericiguat (0.6, 2.0, and 6.0 mg/kg) were assessed for in vivo proarrhythmic risk via administration to conscious telemetered dogs; electrocardiogram (ECG) and hemodynamic parameters were monitored. ECG recordings were included in 4- and 39-week dog toxicity studies. In manual voltage-clamp recordings, vericiguat inhibited hERG K+-mediated tail currents in a concentration-dependent manner (20% threshold inhibitory concentration ∼1.9 µM). In automated voltage-clamp recordings, neither vericiguat nor M-1 were associated with biologically relevant inhibition (>20%) of hNav1.5, hCav1.2, hKvLQT1, and hKv4.3. No clinically relevant observations were made for hNav1.5 and hKvLQT1 under simulated pathophysiological conditions. Vericiguat was associated with expected mode-of-action-related dose-dependent changes in systolic arterial blood pressure (up to -20%) and heart rate (up to +53%). At maximum vericiguat dose, corrected QT (QTc) interval changes from baseline varied slightly (-6 to +1%) depending on correction formula. Toxicity studies confirmed absence of significant QTc interval changes. There was no evidence of an increased proarrhythmic risk from nonclinical studies with vericiguat or M-1. SIGNIFICANCE STATEMENT: There was no evidence of an increased proarrhythmic risk from in vitro and in vivo nonclinical studies with vericiguat or M-1. The integrated risk assessment of these nonclinical data combined with existing clinical data demonstrate administration of vericiguat 10 mg once daily in patients with heart failure with reduced ejection fraction is not associated with a proarrhythmic risk.

Targeted potassium levels to decrease arrhythmia burden in high risk patients with cardiovascular diseases (POTCAST): Study protocol for a randomized controlled trial

BACKGROUND

Low plasma potassium (p-K) is associated with increased risk of malignant arrhythmia and observational studies indicate protective effects of p-K in the upper reference level. However, randomized clinical studies are needed to document whether actively increasing p-K to high-normal levels is possible and safe and improves cardiovascular outcomes.

OBJECTIVE

To investigate if increased p-K reduces the risk of malignant arrhythmia and all-cause death in high-risk patients with a cardiovascular disease treated with an implantable cardioverter defibrillator (ICD) for primary or secondary preventive causes. Secondly, to investigate whether high-normal p-K levels can be safely reached and maintained using already available medications and potassium-rich dietary guidance.

METHODS

This is a prospective, randomized, and open-labelled study enrolling patient at high-risk of malignant arrhythmias. According to sample size calculations, 1,000 patients will be randomized 1:1 to either an investigational regiment that aims to increase and maintain p-K at high-normal levels (4.5-5.0 mmol/L) or to usual standard of care and followed for an expected four years. The trial will run until a total of 291 events have occurred providing an α = 0.05 and 1-β = 0.80. The composite primary endpoint includes ventricular tachycardia >125 bpm lasting >30 seconds, any appropriate ICD-therapy, and all-cause mortality. At present, 739 patients have been randomized.

CONCLUSIONS

We present the rationale for the design of the POTCAST trial. The inclusion was initiated 2019 and is expected to be finished 2022. The study will show if easily available treatments to increase p-K may be a new treatment modality to protect against malignant arrythmias.

Impact of the caFFR-Guided Functional SYNTAX Score on Ventricular Tachycardia/Fibrillation Development in Patients With Acute Myocardial Infarction

Aims

To explore the relationship between the severity of coronary artery disease (CAD) and the occurrence of ventricular tachycardia/ventricular fibrillation (VT/VF) in patients with acute myocardial infarction (AMI).

Methods

We retrospectively enrolled 705 patients with AMI, who were hospitalized and underwent percutaneous coronary intervention (PCI), in Nanfang Hospital from July 2017 to July 2020. Logistic regression analysis and backward stepwise approach were taken to select the correlation factors. The left and the receiver operating characteristic curves (ROC) analysis were plotted to observe the discriminative power of the SYNTAX score (SS)/caFFR-guided functional SS (FSS_caFFR) on the incident VT/VF.

Results

About 58 (8.2%) patients experienced life-threatening VT/VF. The FSS_caFFR (OR: 1.155; 95% CI: 1.047 to 1.273; p = 0.004) was an independent predictor of VT/VF after AMI. The ROC analysis showed that the discriminative power of FSS_caFFR on the incident VT/VF was significantly better than SS (0.759 vs.0.695, p < 0.0001). Patients with VT/VF were categorized into 2 groups according to the interval between the onset of AMI and the VT/VF. The logistic regression analysis revealed that FSS_caFFR was a significant independent correlation of early- and late-VT/VF.

Conclusion

The incident VT/VF in patients with AMI is closely associated with the severity of CAD evaluated by SS and FSS_caFFR. Compared to SS, FSS_caFFR has a higher correlation with VT/VF, and FSS_caFFR was demonstrated to be an independent correlation factor of incident VT/VF after AMI.

A Carvedilol Analogue, VK-II-86, Prevents Hypokalaemia-induced Ventricular Arrhythmia through Novel multi-Channel Effects

BACKGROUND AND PURPOSE

QT prolongation and intracellular Ca²⁺ loading with diastolic Ca²⁺ release via ryanodine receptors (RyR2) are the predominant mechanisms underlying hypokalaemia-induced ventricular arrhythmia. We investigated the antiarrhythmic actions of two RyR2 inhibitors: dantrolene and VK-II-86, a carvedilol analogue with no β-blocking activity, in hypokalaemia.

EXPERIMENTAL APPROACH

Surface ECG and ventricular action potentials (APs) were recorded from whole-heart murine Langendorff preparations. Ventricular arrhythmia incidence was compared in hearts perfused with low [K⁺ ], and those pre-treated with dantrolene or VK-II-86. Whole-cell patch clamping was used in murine and canine ventricular cardiomyocytes to study the effects of dantrolene and VK-II-86 on AP parameters in low [K⁺ ] and the effects of VK-II-86 on the inward rectifier current (I_K1 ), late sodium current (I_{Na_L} ) and the L-type Ca²⁺ current (I_Ca ). Effects of VK-II-86 on I_Kr were investigated in transfected HEK-293 cells. A fluorogenic probe quantified the effects of VK-II-86 on oxidative stress in hypokalaemia.

KEY RESULTS

Dantrolene reduced the incidence of ventricular arrhythmias induced by low [K⁺ ] in explanted murine hearts by 94%, whereas VK-II-86 prevented all arrhythmias. VK-II-86 prevented hypokalaemia-induced AP prolongation and depolarization, but did not alter AP parameters in normokalaemia. Hypokalaemia was associated with a significant reduction of I_K1 and I_Kr , and increase in I_Na-L , and I_Ca . VK-II-86 prevented all hypokalaemia-induced changes in ion channel activity and oxidative stress.

CONCLUSIONS AND IMPLICATIONS

VK-II-86 prevents hypokalaemia-induced arrhythmogenesis by normalising calcium homeostasis and repolarization reserve. VK-II-86 may provide an exciting treatment in hypokalaemia and other arrhythmias caused by delayed repolarization or Ca²⁺ overload.

Electrical storm after correction of an uncomplicated congenital atrial septal defect in an adult: a case report

BACKGROUND

There is a paucity of published literature describing electrical storm after the correction of uncomplicated atrial septal defect (ASD) in an adult.

CASE PRESENTATION

We present a 49-year-old woman with a congenital ASD combined with mild tricuspid regurgitation who denied any history of arrhythmia or other medical history. She suffered from electrical storm (≥ 3 episodes of ventricular tachycardias or ventricular fibrillations) in the early stage after ASD repair with combined tricuspid valvuloplasty. During electrical storm, her electrolytes were within normal ranges and no ischemic electrocardiographic changes were detected, which suggested that retained air embolism or acute coronary thrombosis were unlikely. Additionally, echocardiographic findings and her central venous pressure (5-8 mmHg during the interval between attacks) failed to support the diagnosis of pericardial tamponade. After a thorough discussion, the surgeons conducted an emergent re-exploration and repeated closure of the ASD with combined DeVega's annuloplasty. Eventually, the patient recovered uneventfully, without reoccurring arrhythmias during follow-up. Although we fail to determine the definite cause, we speculate that the causes probably are iatrogenic injury of the conduction system due to a rare anatomic variation, poor intraoperative protection, latent coronary distortion during tricuspid valvuloplasty, or idiopathic or secondary abnormalities of the conduction system.

CONCLUSIONS

For most surgeons, performing re-exploration without a known etiology is a difficult decision to make. This case illustrates that re-exploration could be an option when electrical storm occurs in the early stage postoperatively. Nevertheless, surgeons should assess the benefit-risk ratio when taking this unconventional measure.

Arrhythmogenic Mechanisms in Hypokalaemia: Insights From Pre-clinical Models

Potassium is the predominant intracellular cation, with its extracellular concentrations maintained between 3. 5 and 5 mM. Among the different potassium disorders, hypokalaemia is a common clinical condition that increases the risk of life-threatening ventricular arrhythmias. This review aims to consolidate pre-clinical findings on the electrophysiological mechanisms underlying hypokalaemia-induced arrhythmogenicity. Both triggers and substrates are required for the induction and maintenance of ventricular arrhythmias. Triggered activity can arise from either early afterdepolarizations (EADs) or delayed afterdepolarizations (DADs). Action potential duration (APD) prolongation can predispose to EADs, whereas intracellular Ca²⁺ overload can cause both EADs and DADs. Substrates on the other hand can either be static or dynamic. Static substrates include action potential triangulation, non-uniform APD prolongation, abnormal transmural repolarization gradients, reduced conduction velocity (CV), shortened effective refractory period (ERP), reduced excitation wavelength (CV × ERP) and increased critical intervals for re-excitation (APD-ERP). In contrast, dynamic substrates comprise increased amplitude of APD alternans, steeper APD restitution gradients, transient reversal of transmural repolarization gradients and impaired depolarization-repolarization coupling. The following review article will summarize the molecular mechanisms that generate these electrophysiological abnormalities and subsequent arrhythmogenesis.

The Hidden Fragility in the Heart of the Athletes: A Review of Genetic Biomarkers

Sudden cardiac death (SCD) is a devastating event which can also affect people in apparent good health, such as young athletes. It is known that intense and continuous exercise along with a genetic background that predisposes a person to the risk of fatal arrhythmias is a trigger for SCD. Therefore, knowledge of the athlete’s genetic conditions underlying the onset of SCD must be extended, in order to develop new effective prevention and/or therapeutic strategies. Arrhythmic features occur across a broad spectrum of cardiac diseases, sometimes presenting with overlapping phenotypes. The genetic basis of arrhythmogenic disorders has been greatly highlighted in the last 30 years, and has shown marked heterogeneity. The advent of next-generation sequencing has constantly updated our understanding of the genetic basis of arrhythmogenic diseases and is laying the foundation for precision medicine. With the exception of a few clinical cases involving a single athlete showing a highly suspected phenotype for the presence of a heart disease, there are few studies to date that analysed the applicability of genetic testing on cohorts of athletes. This evidence shows that genetic testing can contribute to the diagnosis of up to 13% of athletes; however, the presence of clinical markers is essential. This review aims to provide a reference collection on current knowledge of the genetic basis of sudden cardiac death in athletes and to review updated evidence on the effectiveness of genetic testing in early identification of athletes at risk for SCD.