Low serum potassium levels are associated with the risk of atrial fibrillation

Perioperative Care of Heart Failure, Arrhythmias, and Valvular Heart Disease

Frequently, the question of whether or not a patient is stable for surgery boils down to the question, "Does this patient need a preoperative stress test?" However, coronary artery disease and ischemic heart disease are only some of the many cardiac conditions that patients present with preoperatively-and that can negatively impact their intraoperative management and postoperative outcomes. This article will explore the evidence based, patient centered best practices surrounding the perioperative evaluation and management of heart failure, arrhythmias, and valvular heart disease.

Pseudohyperaldosteronism Due to Licorice: A Practice-Based Learning from a Case Series

Pseudohyperaldosteronism (PHA) is characterized by hypertension, hypokalemia, and a decrease in plasma renin and aldosterone levels. It can be caused by several causes, but the most frequent is due to excess intake of licorice. The effect is mediated by the active metabolite of licorice, glycyrrhetinic acid (GA), which acts by blocking the 11-hydroxysteroid dehydrogenase type 2 and binding to the mineralocorticoid receptor (MR) as an agonist. The management of licorice-induced PHA depends on several individual factors, such as age, gender, comorbidities, duration and amount of licorice intake, and metabolism. The clinical picture usually reverts upon licorice withdrawal, but sometimes mineralocorticoid-like effects can be critical and persist for several weeks, requiring treatment with MR blockers and potassium supplements. Through this case series of licorice-induced PHA, we aim to increase awareness about exogenous PHA, and the possible risk associated with excess intake of licorice. An accurate history is mandatory in patients with hypertension and hypokalemia to avoid unnecessary testing. GA is a component of several products, such as candies, breath fresheners, beverages, tobacco, cosmetics, and laxatives. In recent years, the mechanisms of action of licorice and its active compounds have been better elucidated, suggesting its benefits in several clinical settings. Nevertheless, licorice should still be consumed with caution, considering that licorice-induced PHA is still an underestimated condition, and its intake should be avoided in patients with increased risk of licorice toxicity due to concomitant comorbidities or interfering drugs.

Adrenal Mass and Hypokalaemia: The Zebra Among Horses

Pheochromocytoma rarely presents with unexplained hypokalaemia, although there are some case reports in the literature. The mechanism behind this could be the increased cellular potassium uptake promoted by beta-2-adrenoreceptor hyperactivation and insulin resistance. We present the case of a 68-year-old hypertensive female patient with a unilateral adrenal mass discovered on angio-CT and typical signs of adrenergic hyperstimulation (hypertensive crisis, headache, and sweating) associated with multiple arrhythmic episodes but with normal plasma and urinary catecholamine levels. During the work-up for hormonal hypersecretion and the cessation of anti-aldosterone medication, the patient presented resistant hypokalaemia. Due to uncorrectable hypokalaemia, we were unable to perform hormonal investigations for primary hyperaldosteronism and referred the patient for laparoscopic adrenalectomy. The histological diagnosis revealed left pheochromocytoma. Postoperatively, the patient experienced rebound hyperkalaemia. In a patient with a unilateral adrenal mass and hypokalaemia, besides primary hyperaldosteronism and adrenocorticotropic hormone-independent hypercortisolism, a possible pheochromocytoma should be ruled out as well by the clinician before surgery.

Diagnosis and Treatment of New-Onset Perioperative Atrial Fibrillation

This article reviews medical and surgical risk factors for developing atrial fibrillation (AF), the most common sustained dysrhythmia in the United States. Evidence for assessment and management of patients with AF, including AF newly identified in the preoperative clinic, immediately preoperatively, intraoperatively, and unstable AF, is presented. A stepwise approach to guide anesthetic decision-making in the assessment of newly identified preoperative AF is proposed. Anesthetic considerations, including the potential impacts of anesthetic and vasopressor selection, and current evidence related to rate control and rhythm control via pharmacologic or electrical cardioversion as well as anticoagulation strategies are discussed.

Mild elevation of extracellular potassium greatly potentiates the effect of sodium channel block to cardiovert atrial fibrillation: The Lankenau approach

BACKGROUND

Cardioversion of atrial fibrillation (AF) is a common clinical necessity, and there is a need for more effective and safe options for acute cardioversion of AF.

OBJECTIVE

The purpose of this study was to test the hypothesis that the efficacy and time course of AF cardioversion by sodium channel current (INa) block can be improved by mild elevation of extracellular potassium ([K+]0).

METHODS

Using a canine acetylcholine (ACh)-mediated AF model (isolated coronary-perfused right atrial preparations with a rim of right ventricle), we evaluated the ability of flecainide to suppress AF in the presence of [K+]0 ranging from 3 to 8 mM.

RESULTS

At [K+]0 of 4 mM (baseline), persistent AF (>1 hour) was induced in 5 of 5 atria in the presence of 0.5 μM ACh. Flecainide alone (1.5 μM) cardioverted 3 of 6 atria at 4 mM [K+]0, 1 of 6 atria at 3 mM [K+]0, 5 of 5 atria at 5 mM and 6 mM [K+]0, and 4 of 4 atria at 8 mM [K+]0. In the absence of flecainide, an increase in [K+]0 from 4 mM to 5, 6, and 8 mM terminated AF in 0 of 5, 2 of 6, and 4 of 4 atria, respectively. The time to conversion was also abbreviated by elevation of [K+]0. After AF termination with flecainide plus elevated [K+]0, AF was either not inducible or brief (<100 seconds). Combined flecainide and elevated [K+]0 (6 mM) caused an atrial preferential depression of excitability.

CONCLUSION

Our findings suggest that a combination of INa block accompanied by mild elevation of serum potassium may be a novel approach to more effectively, rapidly, and safely cardiovert AF and prevent its recurrence in the short term.

Prognosis of Older Adult Patients Suffering from Atrial Fibrillation and Hypokalemia

Objective

To examine the effects of hypokalemia on the prognosis of older adult patients with atrial fibrillation (AF).

Methods

We enrolled 794 older adult patients ≥ 75 years suffering from AF, and divided them into two groups according to the inclusion and exclusion criteria: Group 1, (hypokalemia group), 246 cases, serum K+<3.5 mmol/L; Group 2, (normal blood potassium group), 548 cases, 3.5mmol/L≤serum K+<5.5 mmol/L. The two groups of patients were followed for 70 months to observe the occurrence of clinical events. The primary endpoint was cardiovascular death and the secondary endpoint was all-cause death.

Results

The median follow-up time was 15.00 months. In terms of baseline profile characteristics, serum creatinine levels were significantly lower in Group 1 than in Group 2 patients (P=0.002). In terms of the relationship between hypokalemia and clinical outcomes, Kaplan-Meier survival analysis revealed that the incidence of clinical primary endpoint in Group 1 was significantly higher than that in Group 2 (P < 0.001), and the incidence of the secondary endpoint did not differ significantly between the two groups (P> 005). Based on multivariate Cox regression risk model analysis, coronary heart disease, hemoglobin content, serum uric acid and usage of anticoagulant drugs were the independent variables related to the primary endpoint of cardiovascular death (all P< 0.01).

Conclusion

The incidence of hypokalemia in older adult patients with AF was 30.98%. Hypokalemia was closely related to the cardiovascular death, and coronary heart disease, hemoglobin content, serum uric acid level, and usage of anticoagulant drugs were the independent risk factors for the primary endpoint event.

Relationship between nutritional status and length of hospital stay among patients with atrial fibrillation - a result of the nutritional status heart study

Background

Nutritional status is related to the prognosis and length of hospital stay (LOHS) of patients with atrial fibrillation (AF). This study aimed to assess how nutritional status affects LOHS for patients with AF.

Methods

We performed retrospective analysis of the medical records of 1,813 patients admitted urgently with a diagnosis of AF to the Institute of Heart Diseases of the University Clinical Hospital in Wroclaw, Poland.

Results

In total, 1,813 patients were included in the analysis. The average LOHS in the entire group was 3.53 ± 3.41 days. The mean BMI was 28.7 kg/m² (SD: 5.02). Patients who were hospitalized longer were statistically more likely to have a Nutritional Risk Score (NRS) ≥3 (p = 0.028). A higher percentage of longer hospitalized patients with LDL levels below 70 mg/dl (p < 0.001) and those with HDL ≥40 mg/dl (p < 0.001) were observed. Study participants with NRS ≥3 were an older group (M = 76.3 years), with longer mean LOHS (M = 4.44 days). The predictors of LOHS in the univariate model were age (OR = 1.04), LDL (OR = 0.99), HDL (OR = 0.98), TC (OR = 0.996), CRP (OR = 1, 02, p < 0.001), lymphocytes (OR = 0.97, p = 0.008) and in the multivariate model were age, LDL (mg/dl), HDL (mg/dl), Na, and K.

Conclusion

For nutritional status, factors indicating the risk of prolonged hospitalization in patients with AF are malnutrition, lower serum LDL, HDL, potassium, and sodium levels identified at the time of admission to the cardiology department. Assessment of nutritional status in patients with AF is important both in the context of evaluating obesity and malnutrition status, as both conditions can alter the prognosis of patients. Further studies are needed to determine the exact impact of the above on the risk of prolonged hospitalization.

New-Onset Atrial Fibrillation in Acute Myocardial Infarction Is a Different Phenomenon than Other Pre-Existing Types of That Arrhythmia

(1) Background: Atrial fibrillation (AF) in acute myocardial infarction (AMI) could worsen the prognosis. Yet, there is no definitive answer to whether new-onset AF (NOAF) is a more aggravating diagnosis than other types of that arrhythmia. The purpose of our study was to compare in-hospital clinical course and outcomes of NOAF patients contrary to patients with other pre-existing types of AF. (2) Methods: AMI patients hospitalized in the high-volume cardiological center within 2017−2018 were included in the study. NOAF was noticed in 106 (11%) patients, 95 (10%) with an AF history and AF during AMI formed the AF group, 60 (6%) with an AF history but without AF during AMI constituted the Prior-AF group, and 693 (73%) patients were without an AF before and during AMI. Medical history, routinely monitored clinical parameters, and in-hospital outcomes were analyzed between the groups. (3) Results: NOAF patients, contrary to others, initially had the highest high-sensitivity troponin I (hsTnI), B-type natriuretic peptide (BNP), C-reactive protein (CRP), and glucose levels, and the lowest potassium concentration, with the worst profile of changes for that parameter within the first four days of hospitalization. NOAF patients had the highest rate of ST-elevated AMI (40%), the longest hospitalization (p < 0.001), and the highest in-hospital mortality (p < 0.001). Not NOAF, but other AF groups (AF and Prior-AF groups) were more burdened with the previous comorbidities. (4) Conclusions: NOAF could be a distinct phenomenon in AMI patients, identifying those with the worst clinical in-hospital course and outcomes as compared to other types of AF.

The Effect of Obesity, Hypertension, Diabetes Mellitus, Alcohol, and Sleep Apnea on the Risk of Atrial Fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia associated with a two-fold increase in mortality caused by a higher risk of stroke and heart failure. Currently, AF is present in ~ 2 % of the general population, and its incidence and prevalence are increasing. Obesity, hypertension, diabetes mellitus, obstructive sleep apnea, and alcohol consumption increase the risk of AF. Each unit of increase in BMI increases the risk of AF by 3 %, and intensive weight loss is also associated with reduced AF recurrence. Hypertension increases the risk of AF by 50 % in men and by 40 % in women, and explains ≈ 20 % of new AF cases. Patients with obstructive sleep apnea are at four times higher risk of developing AF than subjects without sleep apnea. Higher concentrations of pro-inflammatory cytokines, higher amounts of epicardial adipose tissue, and a higher degree of ventricular diffuse myocardial fibrosis are present in AF patients and patients with the aforementioned metabolic disorders. Several prospective cohort studies and randomized trials have been initiated to show whether weight loss and treatment of other risk factors will be associated with a reduction in AF recurrences.

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.