Relation of serum potassium level to long-term outcomes in patients with acute myocardial infarction

A Machine Learning Model for Predicting In-Hospital Mortality in Chinese Patients With ST-Segment Elevation Myocardial Infarction: Findings From the China Myocardial Infarction Registry

BACKGROUND

Machine learning (ML) risk prediction models, although much more accurate than traditional statistical methods, are inconvenient to use in clinical practice due to their nontransparency and requirement of a large number of input variables.

OBJECTIVE

We aimed to develop a precise, explainable, and flexible ML model to predict the risk of in-hospital mortality in patients with ST-segment elevation myocardial infarction (STEMI).

METHODS

This study recruited 18,744 patients enrolled in the 2013 China Acute Myocardial Infarction (CAMI) registry and 12,018 patients from the China Patient-Centered Evaluative Assessment of Cardiac Events (PEACE)-Retrospective Acute Myocardial Infarction Study. The Extreme Gradient Boosting (XGBoost) model was derived from 9616 patients in the CAMI registry (2014, 89 variables) with 5-fold cross-validation and validated on both the 9125 patients in the CAMI registry (89 variables) and the independent China PEACE cohort (10 variables). The Shapley Additive Explanations (SHAP) approach was employed to interpret the complex relationships embedded in the proposed model.

RESULTS

In the XGBoost model for predicting all-cause in-hospital mortality, the variables with the top 8 most important scores were age, left ventricular ejection fraction, Killip class, heart rate, creatinine, blood glucose, white blood cell count, and use of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs). The area under the curve (AUC) on the CAMI validation set was 0.896 (95% CI 0.884-0.909), significantly higher than the previous models. The AUC for the Global Registry of Acute Coronary Events (GRACE) model was 0.809 (95% CI 0.790-0.828), and for the TIMI model, it was 0.782 (95% CI 0.763-0.800). Despite the China PEACE validation set only having 10 available variables, the AUC reached 0.840 (0.829-0.852), showing a substantial improvement to the GRACE (0.762, 95% CI 0.748-0.776) and TIMI (0.789, 95% CI 0.776-0.803) scores. Several novel and nonlinear relationships were discovered between patients' characteristics and in-hospital mortality, including a U-shape pattern of high-density lipoprotein cholesterol (HDL-C).

CONCLUSIONS

The proposed ML risk prediction model was highly accurate in predicting in-hospital mortality. Its flexible and explainable characteristics make the model convenient to use in clinical practice and could help guide patient management.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01874691; https://clinicaltrials.gov/study/NCT01874691.

Potassium levels and the risk of all-cause and cardiovascular mortality among patients with cardiovascular diseases: a meta-analysis of cohort studies

BACKGROUND

Abnormal blood potassium levels are associated with an increased risk of cardiometabolic diseases and mortality in the general population; however, evidence regarding the association between dyskalemia and mortality among patients with cardiovascular disease (CVD) remains inconclusive. This study aimed to evaluate the association of potassium levels with all-cause and cardiovascular mortality among patients with CVD.

METHODS

PubMed, Embase, Web of Science, and Cochrane Library databases were searched up to August 2023 to identify relevant cohort studies among patients with CVD, such as myocardial infarction, stroke, and heart failure. Abnormal potassium levels were considered as hypokalemia or hyperkalemia. The primary outcomes were all-cause mortality based on follow-up length (including in-hospital, short-term and long-term mortality) and cardiovascular mortality. The methodological quality of included studies was assessed by using the Newcastle-Ottawa Scale. The pooled relative risks (RRs) and 95% confidence intervals (CIs) were calculated using random-effects models. Restricted cubic splines were applied to explore the dose-response relationship.

RESULTS

Thirty-one cohort studies involving 227,645 participants with an average age of 68.3 years were included in the meta-analysis, all of which achieved moderate to high quality. Hyperkalemia was significantly associated with an approximately 3.0-fold increased risk of all-cause in-hospital mortality (RR:2.78,95CI%:1.92,4.03), 1.8-fold of all-cause short-term mortality (RR:1.80, 95CI%:1.44,2.27), 1.3-fold of all-cause long-term mortality (RR:1.33, 95CI%:1.19,1.48) and 1.2-fold of cardiovascular mortality (RR:1.19, 95CI%:1.04,1.36). Similar positive associations were also observed between hypokalemia and risk of all-cause mortality and cardiovascular mortality. The RRs of all-cause in-hospital, short-term, long-term mortality and cardiovascular mortality with hyperkalemia were attenuated to 2.21 (95CI%:1.60,3.06), 1.46(95CI%:1.25,1.71), 1.23 (95CI%:1.09,1.39) and 1.13 (95CI%:1.00,1.27) when treating hypokalemia together with normokalemia as the reference group. A U-shaped association was observed between potassium levels and mortality, with the lowest risk at around 4.2 mmol/L.

CONCLUSIONS

Both hypokalemia and hyperkalemia were positively associated with the risk of mortality in patients with CVD. Our results support the importance of potassium homeostasis for improving the CVD management.

REGISTRATION

PROSPERO, CRD42022324337.

Disorders of Potassium

Abnormalities in serum potassium are commonly encountered in patients presenting to the emergency department. A variety of acute and chronic causes can lead to life-threatening illness in both hyperkalemia and hypokalemia. Here we summarize the relevant causes, risks, and treatment options for these frequently encountered disorders.

Clinical outcomes of serum potassium in patients with percutaneous coronary intervention: insights from a large single-center registry

Background

Serum potassium homeostasis plays an important role in myocardial electrical stability, but the impact of altered serum potassium levels on the major adverse cardiovascular and cerebral events (MACCE) in patients with percutaneous coronary intervention (PCI) has not been evaluated.

Aim

To evaluate the association between serum potassium level and the risk of MACCE in PCI patients.

Materials and methods

This retrospective study involved 8,263 in-patients from a single-center registry who were successfully treated with PCI between January 2003 and December 2020. Clinical data were collected for 24 h after admission. Data were analyzed from June 2003 to December 2021. The primary outcome was MACCE, defined as a composite of all-cause death, myocardial infarction, revascularization, stroke, and heart failure-related hospitalization.

Results

The median [interquartile range (IQR)] follow-up for all patients was 4.0 (2.1, 5.8) years, and 1,632 patients (19.7%) were diagnosed with MACCE. High serum potassium levels were associated with a 20% increased risk of MACCE (hazard ratio [HR]: 1.20, 95% confidence interval [CI]: 1.05-1.38, P = 0.008) and 72% increased risk of all-cause death (HR: 1.72, 95% CI: 1.39-2.14, P < 0.001). Multivariate Cox analysis showed that the risk of MACCE was higher in patients at the highest quartile of serum potassium (Q4 vs. Q1: adjusted HR: 1.18, 95% CI: 1.02-1.35, P = 0.026). Moreover, a higher serum potassium level was always associated with a higher risk of all-cause death (Q4 vs. Q1: adjusted HR: 1.50, 95% CI: 1.17-1.91, P = 0.001). A U-shaped relationship between serum potassium levels, MACCE, and all-cause death was derived in patients undergoing PCI. Serum potassium levels, maintained within the range of 3.8-4.0 mmol/L before PCI, exhibited the lowest risk of associated MACCE and all-cause death.

Conclusion

Our results demonstrate that the serum potassium level could be associated with higher risks of MACCE and all-cause death in PCI patients. In particular, serum potassium levels maintained at 3.8-4.0 mmol/L before PCI could lower the risk of MACCE and all-cause death.

Real-world clinical burden and economic assessment associated with hyperkalaemia in a large integrated healthcare system: a retrospective analysis

Background

Hyperkalaemia (HK) is a serious and potentially life-threatening condition. Both acute and chronic conditions may alter potassium homeostasis. Our aim is to describe HK incidence, clinical outcomes, and associated resource use within a large, integrated healthcare system.

Methods

Adult patients seen at Intermountain Healthcare facilities with a serum potassium (sK) result between January 1, 2003 and December 31, 2018 were retrospectively studied. Descriptive assessment of a population with detected HK, defined by any sK > 5.0 mmol/L and HK frequency and severity to associated resource use and characteristics of HK predictors were made. Multivariable Cox hazard regression was used to evaluate HK to outcomes.

Results

Of 1,208,815 patients included, 13% had HK. Compared to no-HK, HK patients were older (60 ± 18 vs 43 ± 18 years, P < 0.001), male (51% vs 41%, P < 0.001), and had greater disease burden (Charlson Comorbidity Index 3.5 ± 2.8 vs 1.7 ± 1.4, P < 0.001). At 3 years, more HK patients experienced major adverse cardiovascular events (MACEs) (19 vs 3%, P < 0.001), persisting post-adjustment (multivariable hazard ratio = 1.60, P < 0.001). They incurred higher costs for emergency department services ($552 ± 7,574 vs $207 ± 1,930, P < 0.001) and inpatient stays ($10,956 ± 93,026 vs $1,477 ± 21,423, P < 0.001). HyperK Risk Scores for the derivation and validation cohorts were: 44% low-risk, 45% moderate-risk, 11% high-risk. Strongest HK predictors were renal failure, dialysis, aldosterone blockers, diabetes, and smoking.

Conclusion

Within this large system, HK was associated with a large clinical burden, affecting over 1 in 10 patients; HK was also associated with increased 3-year MACE risk and higher medical costs. Although risk worsened with more severe or persistently recurring HK, even mild or intermittent HK episodes were associated with significantly greater adverse clinical outcomes and medical costs. The HyperK Score predicted patients who may benefit from closer management to reduce HK risk and associated costs. It should be remembered that our assumptions are valid only for detected HK and not HK per se.

Serum potassium level, variability and in-hospital mortality in acute myocardial infarction

OBJECTIVE

Clinical guidelines recommend an optimal serum potassium concentration between 4.0 and 5.0 mmol/L in patients with acute myocardial infarction (AMI), which was based on lower-quality evidence from more than 20 years ago. Therefore, it is essential to re-evaluate the range of optimal potassium levels in patients with AMI in intensive care unit (ICU).

METHODS

This was a retrospective study based on Philips eICU Collaborative Research Database, which covered 9776 patients with AMI between 2014 and 2015. All patients had more than or equal to 2 serum potassium measurements and were categorized by the mean serum potassium level (<3.5, 3.5-4.5, 4.5-5.5, ≥5.5 mmol/L) and potassium variability (1st, 2nd, and ≥3rd standard deviation (SD)). Binary logistic regression was used to determine the association between mean potassium levels, variability and in-hospital mortality in AMI.

RESULTS

Of all 9776 AMI patients in ICU, 8731 (89.3%) patients were included. A total of 69847 potassium measurements were performed in these patients. There was a J-shaped relationship between mean serum potassium level and in-hospital mortality. The lowest mortality (mortality rate, 7.2%; 95% CI, 6.57%-7.76%) was observed in patients with mean potassium level between 3.5 and 4.5 mmol/L and a low potassium variability within the 1st SD. Logistic regression showed that the risk of in-hospital mortality is highest when the mean potassium level ≥5.5 mmol/L (57.6%; 95% Cl, 45.02%-70.24%; multivariable adjusted OR, 14.8; 95% CI, 8.4-26.2) compared to the reference group of 3.5-4.5 mmol/L and potassium variability within the 3rd SD (16.5%; 95% Cl, 15.19%-17.88%; multivariable adjusted OR, 3.3; 95% CI, 2.7-4.1) compared to 1st SD. Several sensitivity analyses confirmed these results.

CONCLUSION

Among AMI patients in ICU, the minimum risk of in-hospital mortality was observed in those with mean potassium levels between 3.5 and 4.5 mmol/L or a minimal potassium variability compared to those who had higher or lower values.

Evaluation of the Relationship Between Changes in Potassium Concentration and Arrhythmia During Coronary Artery Bypass Grafting Surgery

Background

Coronary artery bypass grafting (CABG) surgery is a treatment option for coronary artery diseases. Cardiac arrhythmias during CABG surgery can lead to serious complications. Potassium ion concentration is a factor involved in such arrhythmias.

Objectives

This study aimed to investigate the relationship between potassium concentration and cardiac arrhythmias in CABG surgery.

Methods

This descriptive cross-sectional study was performed on 60 patients with the American Society of Anesthesiologists class I, II, and III undergoing CABG surgery at Golestan Hospital, Ahvaz, Iran. All patients underwent general anesthesia, and ventilator control was achieved by mechanical ventilation. The on-pump method was used for CABG. Potassium levels were measured at several time points during surgery. All cardiac arrhythmias were recorded. Mean arterial pressure (MAP), serum level of potassium, blood sugar, blood urea nitrogen (BUN), creatinine, calcium, magnesium, hemoglobin (Hb), and sodium were also recorded.

Results

The mean age of the patients was 60.87 ± 7.35 years, and 45% of the subjects were female. Moreover, there was no statistically significant difference between the patients. There was a significant relationship between the changes in MAP, potassium, blood sugar, BUN, creatinine, calcium, and magnesium with the incidence of cardiac arrhythmias (P < 0.05). However, no significant relationship was noted between Hb and sodium levels with the incidence of cardiac arrhythmias (P < 0.05).

Conclusions

The changes in potassium levels increase the risk of cardiac arrhythmias and their complications.

Potassium variability during hospitalization and outcomes after discharge in patients with acute myocardial infarction

BACKGROUND

The variability of metabolic biomarkers has been determined to provide incremental prognosis information, but the implications of electrolyte variability remained unclear.

METHODS

We investigate the relationships between electrolyte fluctuation and outcomes in survivors of acute myocardial infarction (n = 4386). Ion variability was calculated as the coefficient of variation, standard deviation, variability independent of the mean (VIM) and range. Hazard ratios (HR) were estimated using the multivariable-adjusted Cox proportional regression method.

RESULTS

During a median follow-up of 12 months, 161 (3.7%) patients died, and heart failure occurred in 550 (12.5%) participants after discharge, respectively. Compared with the bottom quartile, the highest quartile potassium VIM was associated with increased risks of all-cause mortality (HR = 2.35, 95% CI: 1.36-4.06) and heart failure (HR = 1.32, 95% CI: 1.01-1.72) independent of cardiac troponin I (cTnI), N terminal pro B type natriuretic peptide (NT-proBNP), infarction site, mean potassium and other traditional factors, while those associations across sodium VIM quartiles were insignificant. Similar trend remains across the strata of variability by other three indices. These associations were consistent after excluding patients with any extreme electrolyte value and diuretic use.

CONCLUSIONS

Higher potassium variability but not sodium variability was associated with adverse outcomes post-infarction. Our findings highlight that potassium variability remains a robust risk factor for mortality regardless of clinical dysnatraemia and dyskalaemia.

Serum electrolyte/metabolite abnormalities among patients with acute myocardial infarction: comparison between patients with and without diabetes mellitus

Background: Diabetes mellitus (DM) in a setting of acute myocardial infarction (AMI) is associated with significant metabolic changes and worse outcomes.Objective: To evaluate the prevalence and the prognostic significance of electrolyte/metabolite disturbances among AMI patients with vs. without DM.Methods: Patients admitted to a tertiary medical center with AMI throughout 2002-2012 were screened. Exclusion criteria were: dialysis, mechanical ventilation, and in-hospital coronary artery bypass graft (CABG) surgery. All the results of the following analyses were obtained: Glucose, Uric Acid, (UA) Calcium, Magnesium, Albumin, Potassium, and Sodium. The primary outcome was in-hospital all-cause mortality.Results: A total of 14,364 AMI patient admissions was evaluated, mean age 68.1 ± 14.4 years, 65.5% males, and 41.2% with DM. Following an adjustment to potential confounders, DM patients had increased risk for significant hyperglycemia, hyperuricemia, hypercalcemia, hypomagnesemia, hyperkalemia, and hyponatremia as well as significantly decreased risk for hypoglycemia, hypermagnesemia, and hypokalemia compared with nondiabetics. Overall, 681 (4.7%) patients died throughout the index admission. Deceased had an increased incidence of electrolyte/metabolite abnormalities versus hospital survivors. The prognostic significance of the different categories of the investigated variables is very similar among diabetics and nondiabetics, except increased and decreased uric acid levels [<4.5 (men); <4.0 (women) and ≥9.0 (men); ≥9.4 (women)] which are associated with worse outcomes among diabetics while hyperglycemia (Glucose ≥213 mg/dL) and increased Potassium levels (Potassium ≥4.4mEq/L) which comprise significantly worse prognosis among nondiabetics.Conclusions: Patients with DM admitted with AMI are at greater risk for electrolyte/metabolite abnormalities which are associated with increased risk for in-hospital mortality. The latter association is similar among patients with and without DM except for hyperglycemia and increased potassium levels (stronger among nondiabetics).

Serum potassium levels and mortality of patients with acute myocardial infarction: A systematic review and meta-analysis of cohort studies

BACKGROUND

The evidence of current epidemiological studies investigating the association between serum potassium levels and mortality of acute myocardial infarction (AMI) patients is controversial and inadequate.

DESIGN

Systematic review and meta-analysis.

METHODS

Two researchers independently searched the PubMed, EMBASE and Web of Science databases to identify observational studies published prior to 31 October 2017. Similarly, two researchers separately extracted data and any differences were resolved by discussion. Pooled relative risks and 95% confidence intervals (CIs) were computed with an inverse variance-weighted random-effects model. Heterogeneity among studies was assessed with the I² statistic.

RESULTS

Seven cohort studies were included for analysis. Compared with the reference group (3.5 to <4.0 mEq/L), the pooled relative risks of mortality were 1.15 (95% CI = 1.00-1.32), 1.09 (95% CI = 0.97-1.24), 1.42 (95% CI = 1.19-1.70) and 1.85 (95% CI = 1.39-2.47) for AMI patients with a potassium level of<3.5, 4.0 to <4.5, 4.5 to <5.0, and ≥5.0 mEq/L, respectively. For admission and post-admission potassium, although J-shaped associations were also indicated, non-significant results were observed for AMI patients with potassium levels of <3.5 mEq/L when compared with the reference group. Notably, in subgroup analyses of study characteristics, stratified by study quality, geographic location, type of outcome, number of cases, type of AMI, and adjustment for potential confounders, the findings were broadly consistent across strata.

CONCLUSIONS

These findings indicate that both lower (<3.5 mEq/L) and higher (≥4.5 mEq/L) serum potassium levels are associated with an increased risk of mortality of patients with AMI.

Retrospective evaluation of the severity of and prognosis associated with potassium abnormalities in dogs and cats presenting to an emergency room (January 2014-August 2015): 2441 cases

OBJECTIVE

To determine the severity, concurrent clinical signs, and disease processes associated with potassium abnormalities in dogs and cats presenting to a veterinary emergency department and associated mortality.

DESIGN

Retrospective and descriptive study over 20 months.

SETTING

University teaching hospital.

ANIMALS

1916 dog and 525 cat visits.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Medical records from patients with a potassium concentration measured within 24 hours of admission were identified. Hypokalemia and hyperkalemia were defined as a potassium concentration <3.5 mmol/L [3.5 mEq/L] and >5 mmol/L [5 mEq/L], respectively. Associated disease processes and pathophysiologic risk factors for potassium abnormalities were reviewed for moderate to severe potassium abnormalities (<3 mmol/L or ≥6 mmol/L) [<3 mEq/L or ≥6 mEq/L]. Mortality associated with normokalemia, mild, and moderate to severe dyskalemia were evaluated. Overall prevalence of abnormal potassium concentration was 27% in dogs and 40% in cats. Moderate to severe hypokalemia and hyperkalemia were present in 3% of dogs and 8% of cats, and 2% of dogs and 7% of cats, respectively. Moderate to severe hypokalemia was most commonly associated with gastrointestinal disease (48% of dogs and 44% of cats) while moderate to severe hyperkalemia was most commonly associated with urinary tract disease (60% of dogs and 97% of cats). Dogs with hypokalemia and dogs and cats with hyperkalemia (P < 0.001) had significantly greater mortality than those with normokalemia. Dogs with mild hypokalemia and mild hyperkalemia (P < 0.0001) had higher mortality than dogs with normokalemia, but this was not found in cats.

CONCLUSIONS

Dyskalemia was common in this population and was associated with greater mortality. Moderate to severe potassium abnormalities were uncommon in this population and occurred most frequently in animals with gastrointestinal and urinary tract disease.

The association of concomitant serum potassium and glucose levels and in-hospital mortality in patients with acute myocardial infarction (AMI). Soroka acute myocardial infarction II (SAMI-II) project

BACKGROUND

Acute myocardial infarction (AMI) is associated with significant systemic metabolic changes. These changes include increased plasma concentrations of counter-regulatory hormones and changes in potassium (K, mEq/L) and glucose (mg/dL) levels. The latter are associated with outcomes and investigated as potential focus for intervention; glucose-insulin‑potassium (GIK) solution.

OBJECTIVES

To evaluate the associations of concomitant K and glucose (K/glucose) levels with in-hospital mortality in AMI patients.

METHODS

AMI patients hospitalized in a tertiary Medical Center through 2002-2012 were studied. K/glucose levels were divided into equally sized categories. The intermediate category (glucose 124-143 mg/dL, K 4-4.9 mEq/L) was the reference group. The associations of these tests with the outcome were assessed using Generalized Estimating Equations model which included the interaction of K and glucose levels, adjusted for the patient's baseline characteristics and other laboratory results.

RESULTS

17,670 AMI admissions (mean age 67.8 ± 4.0 years, 66.6% males, mortality rate 7.7%) were included; 112,531 results of K/glucose tests were recorded. Univariate and multivariate analyses showed that K/glucose levels were significantly associated with in-hospital mortality, with highest risk being in patients with concomitant low K (<3.7 mEq/L) and high glucose (≥217 mg/dL), adjOR = 2.53. It seems that low-normal glucose levels attenuate the increased risk associated with low K.

CONCLUSIONS

The highest independent risk for mortality is found with low K and concomitant high glucose levels. Additional studies evaluating mechanisms and therapeutic interventions in K/glucose levels in this setting are warranted.

Association of hypokalemia with an increased risk for medically treated arrhythmias

Background

Potassium replenishment protocols are often employed across broad patient populations to prevent cardiac arrhythmias. Tailoring potassium thresholds to specific patient populations would reduce unnecessary tasks and cost. The objective of this retrospective cohort study was to determine the threshold at which hypokalemia increases the risk for medically treated arrhythmias in cardiac versus medical and surgical intensive care units.

Methods

Patients captured in the publicly available Philips eICU database were assessed for initiation of either intravenous amiodarone, adenosine, ibutilide, isoproterenol, or lidocaine as a surrogate for a clinically significant arrhythmia. A landmark time-to-event analysis was conducted to investigate the association of serum potassium values and time-marked administration of an antiarrhythmic drug. Analysis was adjusted for comorbidities, the use of vasopressor agents, diuretics, as well as age, gender and severity of illness.

Results

Among 20,665 admissions to cardiac intensive care units, 1,371 (6.6%) were treated with either amiodarone, adenosine, ibutilide, isoproterenol, or lidocaine. For potassium values of ≥3.0<3.5mEq/L, antiarrhythmic treatment occurred at an increased rate compared to a baseline of ≥4.0≤5.0mEq/L (HR 1.23, 95% CI 1.01–1.51; P = 0.04). For admissions to medical and surgical intensive care units, 2,100 of 69,714 patients (3.0%) were treated with either amiodarone, adenosine, ibutilide, isoproterenol, or lidocaine. Potassium values of ≥3.0<3.5mEq/L were also associated with an increased hazard of treatment (HR 1.26, 95% CI 1.09–1.45; P = 0.002). In both cohorts, worsening hypokalemia was associated with an increased risk of antiarrhythmic drug treatment. In neither cohort were there statistically significant differences for serum potassium values of ≥3.5<4.0 and a baseline of ≥4.0≤5.0mEq/L. The proportion of patients initiated on vasopressors or inotropes was over four-fold higher in those treated with one of the antiarrhythmic drugs in both cohorts.

Conclusions

Serum potassium levels <3.5mEq/L were associated with an increased hazard for treatment with specific antiarrhythmic drugs in a large cohort of patients admitted to both a cardiac as well as medical and surgical intensive care units. Potassium thresholds may be individualized further based on risk of relevant outcomes.

Association of Abnormal Serum Potassium Levels with Arrhythmias and Cardiovascular Mortality: a Systematic Review and Meta-Analysis of Observational Studies

PURPOSE

To provide the first systematic review and meta-analysis of observational studies on the association of abnormal serum potassium and cardiovascular outcomes.

METHODS

Medline and ISI Web of Knowledge were systematically searched from inception until November 24, 2017. Data synthesis of relevant studies was performed using random effects model meta-analyses.

RESULTS

Meta-analyses included 310,825 participants from 24 studies. In the older general population, low serum potassium was associated with a 1.6-fold increased risk of supraventricular arrhythmias (risk ratio [95% confidence interval] 1.62 [1.02-2.55]). Contrarily, high serum potassium was associated with increased cardiovascular mortality (CVM) (1.38 [1.14-1.66]). In patients with acute myocardial infarction, the risk of ventricular arrhythmias was increased for high serum potassium (2.33 [1.60-3.38]). A U-shaped association was observed with a composite cardiovascular outcome in hypertensive patients (2.6-fold increased risk with hypokalemia and 1.7-fold increased risk with hyperkalemia), with CVM in dialysis patients (1.1-fold increased risk with hypokalemia and 1.4-fold increased risk with hyperkalemia) and with CVM in heart failure patients (albeit not statistically significant). Further, only hyperkalemia was associated with an increased risk of a composite cardiovascular outcome in both dialysis (1.12 [1.03-1.23]) and chronic kidney disease (1.34 [1.06-1.71]) patients.

CONCLUSIONS

Controlled clinical trials are needed to determine which populations may profit from more frequent potassium-monitoring and subsequent interventions, e.g., change or withdrawal of potassium-influencing drugs, in order to restore normal values and prevent cardiovascular outcomes.

REGISTRATION DETAILS

Registration in PROSPERO (Centre for Reviews and Dissemination University of York, York, UK): CRD42016048897 ( https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=48897 ).

Dyskalemias and adverse events associated with discharge potassium in acute myocardial infarction

BACKGROUND

The incidence of dyskalemias and associated outcomes in acute myocardial infarction (AMI) are unknown in real-world settings and likely differ from the controlled environment of randomized controlled trials.

METHODS

We examined consecutive survivors of an AMI during 2006-2011 in SWEDEHEART registry and with plasma potassium at discharge (exposure). Study outcomes were 1-year risk of hyperkalemia (potassium >5.0 mmol/L), hypokalemia (potassium <3.5 mmol/L), and others (1-year risk of death, new myocardial infarction, heart failure, and de novo atrial fibrillation). Covariates included demographics, comorbidities, hospital procedures, and medications.

RESULTS

We included 4,861 patients (65% male, age 71.4 ± 12.6 years) with mean discharge potassium of 4.0 ± 0.4 mmol/L. Within 1 year, 784 (16.1%) new hyperkalemic and 991 (20.4%) new hypokalemic events occurred. Discharge potassium and kidney dysfunction were independent predictors of their occurrence. Compared with discharge potassium of 4.0 to <4.5 mmol/L, the adjusted risk of incident hyperkalemia was 1.71 (95% confidence interval 1.41-2.06) for potassium of 4.5-5.0 mmol/L and 2.38 (1.69-3.35) for potassium of >5.0 mmol/L; the adjusted risk of incident hypokalemia was 1.43 for potassium of 3.5 to <4.0 mmol/L (1.23-1.66) and 3.12 (2.58-3.77) for potassium of <3.5 mmol/L. A U-shaped association was observed between discharge potassium and the risk of death (n = 718), with increased hazards for potassium <3.5 and >4.5 mmol/L. No association was found between discharge potassium and the risk of new myocardial infarction, heart failure, or de novo atrial fibrillation.

CONCLUSIONS

Among real-world AMI survivors, both hyperkalemia and hypokalemia are frequent. Discharge potassium and kidney function strongly predicted their occurrence, as well as the 1-year risk of death.

Incidence, predictors and clinical management of hyperkalaemia in new users of mineralocorticoid receptor antagonists

BACKGROUND

Concerns for hyperkalaemia limit the use of mineralocorticoid receptor antagonists (MRAs). The frequency of MRA-associated hyperkalaemia in real-world settings and the extent of subsequent MRA discontinuation are poorly quantified.

METHODS AND RESULTS

Observational study including all Stockholm citizens initiating MRA therapy during 2007-2010. Hyperkalaemias were identified from all potassium (K+ ) measurements in healthcare. MRA treatment lengths and dosages were obtained from complete collection of pharmacy dispensations. We assessed the 1-year incidence and clinical hyperkalaemia predictors, and quantified drug prescription changes after an episode of hyperkalaemia. Overall, 13 726 new users of MRA were included, with median age of 73 years, 53% women and median plasma K+ of 3.9 mmol/L. Within a year, 18.5% experienced at least one detected hyperkalaemia (K+  > 5.0 mmol/L), the majority within the first 3 monthsnthsnthsnthsnths of therapy. As a comparison, hyperkalaemia was detected in 6.4% of propensity-matched new beta-blocker users. Chronic kidney disease (CKD), older age, male sex, heart failure, peripheral vascular disease, diabetes and concomitant use of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta-blockers and diuretics were associated with increased hyperkalaemia risk. After hyperkalaemia, 47% discontinued MRA and only 10% reduced the prescribed dose. Discontinuation rates were higher after moderate/severe (K+  > 5.5 mmol/L) and early in therapy (<3 months from initiation) hyperkalaemias. CKD participants carried the highest risk of MRA discontinuation in adjusted analyses. When MRA was discontinued, most patients (76%) were not reintroduced to therapy during the subsequent year.

CONCLUSION

Among real-world adults initiating MRA therapy, hyperkalaemia was very common and frequently followed by therapy interruption, especially among participants with CKD.

Effect of Dynamic Potassium Change on In-Hospital Mortality, Ventricular Arrhythmias, and Long-Term Mortality in STEMI

We evaluated the effect of serum potassium (K) deviation on in-hospital and long-term clinical outcomes in patients with ST-segment elevation myocardial infarction who were normokalemic at admission. A total of 2773 patients with an admission serum K level of 3.5 to 4.5 mEq/L were retrospectively analyzed. The patients were categorized into 3 groups according to their K deviation: normokalemia-to-hypokalemia, normokalemia-to-normokalemia, and normokalemia-to-hyperkalemia. In-hospital mortality, long-term mortality, and ventricular arrhythmias rates were compared among the groups. In a hierarchical multivariable regression analysis, the in-hospital mortality risk was higher in normokalemia-to-hypokalemia (odds ratio [OR] 3.03; 95% confidence interval [CI], 1.72-6.82) and normokalemia-to-hyperkalemia groups (OR 2.81; 95% CI, 1.93-4.48) compared with the normokalemia-to-normokalemia group. In a Cox regression analysis, long-term mortality risk was also higher in normokalemia-to-hypokalemia (hazard ratio [HR] 3.78; 95% CI, 2.07-7.17) and normokalemia-to-hyperkalemia groups (HR, 2.97; 95% CI, 2.10-4.19) compared with the normokalemia-to-normokalemia group. Ventricular arrhythmia risk was also higher in normokalemia-to-hypokalemia group (OR 2.98; 95% CI, 1.41-5.75) compared with normokalemia-to-normokalemia group. The current study showed an increased in-hospital ventricular arrhythmia and mortality and long-term mortality rates with the deviation of serum K levels from normal ranges.

Association of serum potassium concentration with mortality and ventricular arrhythmias in patients with acute myocardial infarction: A systematic review and meta-analysis

Background

Challenging clinical practice guidelines that recommend serum potassium concentration between 4.0–5.0 mEq/L or ≥4.5 mEq/L in patients with acute myocardial infarction, recent studies found increased mortality risks in patients with a serum potassium concentration of ≥4.5 mEq/L. Studies investigating consequences of hypokalemia after acute myocardial infarction revealed conflicting results. Therefore, the aim of this systematic review and meta-analysis was to combine evidence from previous studies on the association of serum potassium concentration with both short and long-term mortality as well as the occurrence of ventricular arrhythmias.

Design

Systematic review and meta-analysis.

Methods

A structured search of MEDLINE and EMBASE databases yielded 23 articles published between 1990 and January 2017 that met the inclusion criteria. Study selection, data extraction and quality assessment were carried out by three reviewers. Random effects models were used to pool estimates across the included studies and sensitivity analyses were performed when possible.

Results

Twelve studies were included in the meta-analysis. Both pooled results from six studies investigating short-term mortality and from five studies examining long-term mortality revealed significantly increased risks in patients with serum potassium concentrations of <3.5 mEq/L, 4.5–<5.0 mEq/L and ≥5.0 mEq/L after acute myocardial infarction. In addition, a serum potassium concentration of <3.5 mEq/L was significantly associated with the occurrence of ventricular arrhythmias.

Conclusions

Mortality, both short and long term, and the occurrence of ventricular arrhythmias in patients with acute myocardial infarction seem to be negatively associated with hypokalemic serum potassium concentration. There is evidence for adverse consequences of serum potassium concentrations of ≥4.5 mEq/L. Due to the heterogeneity among existing studies, further research is necessary to confirm the need to change clinical practice guidelines.

Potassium Fluctuations Are Associated With Inhospital Mortality From Acute Myocardial Infarction. Soroka Acute Myocardial Infarction II (SAMI-II) Project

Potassium levels (K, mEq/L) fluctuate in patients with acute myocardial infarction (AMI). Potassium was reported to be associated with prognosis in patients with AMI; however, studies evaluating the prognostic value of K fluctuations in this setting are scarce. We retrospectively analyzed patients with AMI hospitalized in a tertiary medical center, through 2002 to 2012. Patients on chronic dialysis or mechanical ventilation were excluded. Based on all K values during hospitalization, minimal, maximal, and fluctuation (gap between 2 consecutive K) were recorded. Primary outcome was inhospital all-cause mortality. Overall, 10 032 patients were studied (age 68.1 ± 14.3 years, 65.4% males, 44.2% ST-segment elevation MI), of which 507 (3.7%) died in hospital. Potassium decreased during the first 2 to 3 days ( P for trend <.001), followed by stabilization ( P for trend = .807). Potassium in the extreme categories (<3.8 and ≥4.7) and absolute fluctuations >0.1 mEq/L were more common among nonsurvivors than survivors ( P < .001 each). In a multivariate analysis, combinations of minimal K <3.8 with maximal K ≥4.7 (odds ratio [OR] = 18.1), K ≥4.4 with fluctuation ≥0.1 (OR = 1.74), or <−0.1 (OR = 2.6) and minimal K after the first 2 admission days (OR = 2.07) were associated with increased risk of mortality ( P < .001 each). Potassium fluctuations, peak and nadir K, and its timing independently predict inhospital mortality in patients with AMI.

Admission serum potassium concentration and long-term mortality in patients with acute myocardial infarction: results from the MONICA/KORA myocardial infarction registry

BACKGROUND

Conflicting with clinical practice guidelines, recent studies demonstrated that serum potassium concentrations (SPC) of ≥4.5 mEq/l were associated with increased mortality in patients with acute myocardial infarction (AMI). This study examined the association between SPC and long-term mortality following AMI in patients recruited from a population-based registry.

METHODS

Included in the study were 3347 patients with AMI aged 28-74 years consecutively hospitalized between 1 January 2000 and 31 December 2008 and followed up until 31 December 2011. Patients were categorized into five SPC groups (<3.5, 3.5 to <4.0, 4.0 to <4.5, 4.5 to <5.0, and ≥5.0 mEq/l). The outcome of the study was all-cause mortality. Cox regression models adjusted for risk factors, co-morbidities and in-hospital treatment were constructed.

RESULTS

In our study population, 249 patients (7.4%) had a low SPC (<3.5 mEq/l) and 134 (4.0%) patients had a high SPC (≥5.0 mEq/l). Patients with SPC of ≥5.0 mEq/l had the highest long-term mortality (29.9%) and in the adjusted model, their risk of dying was significantly increased (HR 1.46, 95% CI 1.03 to 2.07) compared to patients with SPC between 4.0 and <4.5 mEq/l. Analyses of increasing observation periods showed a trend towards a higher risk of dying in patients with SPC between 4.5 and <5.0 mEq/l.

CONCLUSION

An admission SPC of ≥5.0 mEq/l might be associated with an increased mortality risk in patients with AMI. Patients with an admission SPC between 4.5 and <5.0 mEq/l might have an increased mortality risk in the first few years following AMI.

Serum potassium concentrations: Importance of normokalaemia

Abnormalities in potassium concentrations are associated with morbidity and mortality. In recent years it has been considered that small variations in serum potassium concentrations within normal intervals may also be associated with mortality. Strategies for achieving normokalaemia include dietary measures, limiting the use of potassium retaining drugs, and use of conventional cation exchange resins (calcium/sodium polystyrene sulfonate) and/or the new non-absorbed cation exchange polymer (patiromer).

Serum potassium levels, cardiac arrhythmias, and mortality following non-ST-elevation myocardial infarction or unstable angina: insights from MERLIN-TIMI 36

BACKGROUND

In acute coronary syndrome (ACS), potassium levels <3.5 mEq/L are associated with ventricular arrhythmias. Current guidelines therefore recommend a potassium target >4.0 mEq/L in ACS. Our study evaluated the association between potassium levels, cardiac arrhythmias, and cardiovascular death in patients with non-ST-segment elevation myocardial infarction or unstable angina.

METHODS

Potassium levels were measured in 6515 patients prior to randomization to receive either ranolazine or a placebo in the MERLIN-TIMI 36 trial. A seven-day continuous electrocardiographic assessment was obtained to determine the incidence of non-sustained ventricular tachycardia (NSVT) and ventricular pauses. The association between potassium levels and cardiovascular death was evaluated using a Cox proportional hazards regression model with multivariable adjustment.

RESULTS

NSVT lasting for at least eight consecutive beats occurred more frequently at potassium levels <3.5 mEq/L than at potassium levels ⩾5 mEq/L (10.1 vs. 4.5%, p=0.03 for trend), whereas the inverse pattern was observed for ventricular pauses >3 s, which occurred more frequently at potassium levels ⩾5 mEq/L than at potassium levels <3.5 mEq/L (5.9 vs. 2.0%, p=0.03 for trend). There was a U-shaped relationship between the potassium level at admission and both early and late risk of cardiovascular death. Compared with patients with potassium levels of 3.5 to <4 mEq/L, a potassium level <3.5 mEq/L was associated with an increased risk of cardiovascular death at day 14 (2.4 vs. 0.8%, HR_adj 3.1, p=0.02) and at one year (6.4 vs. 3.0%, HR_adj 2.2, p=0.01). The risk of cardiovascular death at one year was also significantly increased at potassium levels ⩾4.5 mEq/L and a similar trend was noted at potassium levels ⩾5 mEq/L.

CONCLUSIONS

The lowest risk of cardiovascular death was observed in patients with admission potassium levels between 3.5 and 4.5 mEq/L. Both lower and higher levels of potassium were associated with tachyarrhythmias and bradyarrhythmias, suggesting a potential mechanistic explanation for the increased risk of cardiovascular death at the extremes of potassium homeostasis.

Lower mean corpuscular hemoglobin concentration is associated with poorer outcomes in intensive care unit admitted patients with acute myocardial infarction

BACKGROUND

Accumulated studies have shown that hematological parameters [e.g., red blood cell distribution width (RDW), hemoglobin, platelet count] and serum potassium level can impact the prognosis of patients with acute myocardial infarction (AMI). However, no previous study has evaluated the prognostic values of these laboratory tests simultaneously.

METHODS

This study is based on an intensive care unit (ICU) database named Multiparameter Intelligent Monitoring in Intensive Care II (MIMIC II). Adult patients with AMI were included, and their hematological parameters and serum ion levels on admission were extracted. The relationships between these laboratory tests and hospital mortality were evaluated using a logistic regression model and receiver operating characteristic (ROC) curve analysis. The effects of these laboratory tests on 1-year mortality were evaluated using a Cox hazard regression model and Kaplan-Meier curve analysis.

RESULTS

In univariable analysis, increased white blood cell (WBC), neutrophil percentage, mean corpuscular volume (MCV), RDW, potassium and decreased red blood cell (RBC), hemoglobin, mean corpuscular hemoglobin concentration (MCHC), hematocrit and percentage of lymphocyte, monocyte, basophil and eosinophil were significantly associated with hospital mortality. In multivariable analyses, basophil percentage, potassium, WBC and MCHC were independently associated with hospital morality, while WBC, RDW, MCHC, potassium and percentages of neutrophil and lymphocyte were associated with 1-year mortality.

CONCLUSIONS

Hematological parameters and serum potassium can provide prognostic information in AMI patients. MCHC is an independent prognostic factor for both short and long term outcomes of AMI.

The association between normal-range admission potassium levels in Israeli patients with acute coronary syndrome and early and late outcomes

Abnormal serum potassium levels are associated with an increased risk of ventricular arrhythmias and mortality in patients with acute myocardial infarction (AMI). The aim of the present study was to evaluate whether different levels of serum potassium, within the normal range, are associated with worse outcomes. The present study comprised 1277 patients with AMI and normal-range admission potassium levels (3.5-5.2 mEq/L), who were enrolled and prospectively followed up in the Acute Coronary Syndrome Israeli Survey between 2010 and 2013. Patients were divided into 4 quartiles based on admission potassium levels; "normal-low" (K ≥ 3.5 and K ≤ 3.9), "normal-moderate" (K > 3.9 and K ≤ 4.18), "normal-high" (K > 4.18 and K ≤ 4.45), and "normal-very high" (K > 4.45 and K ≤ 5.2). We analyzed the association between admission serum potassium levels and 7 days in-hospital complication rates, and 30-day and 1-year all-cause mortality rates. Patients with "normal-very high" potassium displayed increased frequency of baseline clinical risk factors and experienced a higher rate of acute kidney injury during hospitalization compared with the "normal-low" group (7.7% vs 2.4%; P = 0.002). However, the rate of in-hospital ventricular arrhythmias was similar across the range of admission potassium levels (overall P = 0.26), Multivariate analysis showed that compared with "low-normal" potassium values, patients with "normal-very high" potassium levels experienced increased risk for 30-days (adjusted hazard ratio 2.88, 95% confidence interval 1.05-7.87, P = 0.039) and 1-year all-cause mortality (adjusted hazard ratio 1.98, 95% confidence interval 1.05-3.75, P = 0.034). In patients admitted with AMI, admission serum potassium levels of 4.45 to 5.2 mEq/L are not associated with in-hospital ventricular arrhythmias, but are associated with increased short and long-term mortality.

Admission serum potassium level is associated with in-hospital and long-term mortality in ST-elevation myocardial infarction

OBJECTIVE

Current guidelines recommend a serum potassium (sK) level of 4.0-5.0 mmol/L in acute myocardial infarction patients. Recent trials have demonstrated an increased mortality rate with an sK level of>4.5 mmol/L. The aim of this study was to figure out the relation between admission sK level and in-hospital and long-term mortality and ventricular arrhythmias.

METHODS

Retrospectively, 611 patients with ST-elevation myocardial infarction (STEMI) who underwent primary percutaneous coronary intervention were recruited. Admission sK levels were categorized accordingly: <3.5, 3.5-<4, 4-<4.5, 4.5-<5, and ≥5 mmol/L.

RESULTS

The lowest in-hospital and long-term mortality occurred in patients with sK levels of 3.5 to <4 mmol/L. The long-term mortality risk increased for admission sK levels of >4.5 mmol/L [odds ratio (OR), 1.58; 95% confidence interval (CI) 0.42-5.9 and OR, 2.27; 95% CI 0.44-11.5 for sK levels of 4.5-<5 mmol/L and ≥5 mmol/L, respectively]. At sK levels <3 mmol/L and ≥5 mmol/L, the incidence of ventricular arrhythmias was higher (p=0.019).

CONCLUSION

Admission sK level of >4.5 mmol/L was associated with increased long-term mortality in STEMI. A significant relation was found between sK level of <3 mmol/L and ≥5 mmol/L and ventricular arrhythmias.

Serum Potassium Levels and Short-Term Outcomes in Patients With ST-Segment Elevation Myocardial Infarction

Current guidelines recommend maintaining serum potassium levels between 4.0 and 5.0 mEq/L (1 mEq/L = mmol/L) in patients with acute myocardial infarction. However, these guidelines are based on studies conducted before the β blocker and reperfusion era. We retrospectively analyzed 6613 patients diagnosed with ST-segment elevation myocardial infarction (STEMI) who presented without renal insufficiency. Patients were categorized into 5 groups according to mean serum potassium levels: <3.5, 3.5 to <4.0, 4.0 to <4.5, 4.5 to <5.0, and ≥5.0 mEq/L. Patients with potassium levels of 4.0 to <4.5 mEq/L had the lowest predefined event rates, which were 6.4% for 7-day malignant arrhythmia, 3.7% for 7-day mortality, and 5.3% for 30-day mortality. Compared with the reference group (4.0 to <4.5 mEq/L), multivariate regression analysis revealed significantly higher 30-day mortality risk in patients with potassium level of 4.5 to <5.0 (hazard ratio [HR]: 1.52, 95% confidence interval [CI]: 1.17-1.98; P = .002) and even higher risk in patients with potassium level of ≥5.0 mEq/L (HR: 1.80, 95% CI: 1.22-2.66; P = .002). The lowest 30-day mortality was observed in patients with STEMI having potassium levels between 4.0 and 4.5 mEq/L, and a level >4.5 mEq/L significantly increased mortality risk.

Serum potassium levels as an outcome determinant in acute medical admissions

The relationship between serum potassium levels and mortality in acute medical admissions is uncertain. In particular, the relevance of minor abnormalities in potassium level or variations within the normal range remains to be determined. We performed a retrospective cohort study of all emergency medical admissions to St James's Hospital (Dublin, Ireland) between 2002 and 2012. We used a stepwise logistic regression model to predict in-hospital mortality, adjusting risk estimates for major predictor variables. There were 67,585 admissions in 37,828 patients over 11 years. After removing long-stay patients, 60,864 admissions in 35,168 patients were included in the study. Hypokalaemia was present in 14.5% and hyperkalaemia in 4.9%. In-hospital mortality was 3.9, 5.0, and 18.1% in the normokalaemic, hypokalaemic and hyperkalaemic groups respectively. Hypokalaemic patients had a univariate odds ratio (OR) of 1.29 for in-hospital mortality (95% confidence interval (CI) 1.16-1.43; p<0.001). Hyperkalaemic patients had a univariate OR for in-hospital mortality of 5.2 (95% CI 4.7-5.7; p<0.001). The ORs for an in-hospital death for potassium between 4.3 and 4.7 mmol/l, and 4.7 and 5.2 mmol/l, were 1.73 (95% CI 1.51-1.99) and 2.97 (95% CI 2.53-3.50) respectively. Hyperkalaemia and hypokalaemia are associated with increased mortality.