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

The Guidelines for use and promotion of low sodium salt in China

AIM

Both excessive intake of sodium and inadequate intake of potassium are associated with blood pressure elevation and subsequent increase in the risk of cardiovascular disease, which accounts for the largest number of deaths in China and worldwide. Low sodium salt, a mixture of mainly sodium chloride and potassium chloride, has shown its great potential as a promising population strategy for sodium intake reduction through multiple large-scale, multicenter, randomized controlled trials among populations including patients with cardiovascular disease, individuals with and without hypertension, older and younger adults, and men and women in China and other countries. This Guidelines aims to provide expert recommendations for promotion and use of low sodium salt in China, based on the current available scientific evidence regarding the effectiveness, safety, cost-effectiveness, and acceptability of low sodium salts in various population groups and different application scenarios. The suggestions to key stakeholders are also made.

METHODS

A working group, an expert review committee and an advisory committee were established to be responsible for formulating the guidelines' scope and key questions to be addressed, for searching, synthesizing, and evaluating research evidence, proposing and reviewing the recommendations. The consensus on the final recommendations was reached using the GRADE grid method.

RESULTS

The working group summarized current available evidence of salt substitution regarding its effectiveness, safety, cost-effectiveness, acceptability, availability, suitability, etc. The Guidelines provided six recommendations advising different populations how to use low sodium salt, four recommendations on the application of low sodium salts in different scenarios, and five suggestions for key stakeholders to promote salt substitution.

CONCLUSION

The first evidence-based guidelines on promotion and use of low sodium salts covers all key questions in relevance and would play a critical role in prevention and control of hypertension and cardiovascular disease in China and worldwide.

Effects of Serum Potassium on Mortality in Patients With ST-Elevation Myocardial Infarction

INTRODUCTION

Disturbances in potassium levels can induce ventricular arrhythmias and heighten mortality in patients with ST-elevation myocardial infarction (STEMI). This study evaluates the influence of sK levels on seven-day mortality and incidence of ventricular arrhythmias in STEMI patients to further improve clinical guidelines and outcomes.

METHODS

This retrospective, propensity-matched study analyzed approximately 250,000 acute STEMI patients from 55 major academic medical centers/healthcare organizations (HCOs) in the US Collaborative Network of the TriNetX database. The sK levels recorded on the day of STEMI diagnosis were categorized into four cohorts: sK ≤ 3.4 (hypokalemia), 3.5 ≤ sK ≤ 4.5 (normal-control), 4.6 ≤ sK ≤ 5.0 (high-normal), and sK ≥ 5.1 (hyperkalemia). Patient cohorts were propensity-matched using linear and logistic regression for demographics. Outcomes of seven-day mortality, ventricular tachycardia (VT), and ventricular fibrillation (VF) were compared between these cohorts and the control group.

RESULTS

The analysis showed hypokalemia was linked to significantly higher seven-day mortality (7.2% vs. 4.3%; RR 1.69; p<0.001), and increased rates of VT and VF. Similarly, hyperkalemia was associated with elevated mortality (12.7% vs. 4.6%; RR 2.76; p<0.001), VT, and VF rates. High-normal sK levels showed increased mortality (7.4% vs. 4.7%; RR 1.58; p<0.001), but unchanged VT or VF rates compared to the normal sK group.

CONCLUSION

This comprehensive study highlights the correlation of sK levels with death in STEMI patients, revealing a nearly doubled risk of mortality with hypokalemia and almost triples with hyperkalemia. More notably, the mortality for STEMIs is higher for high-normal vs normal sK values. Additionally, hypokalemia and hyperkalemia were found to significantly elevate VT and VF risks.

Formation of a border ischemic zone depends on plasma potassium concentration

Extracellular potassium concentration might modify electrophysiological properties in the border zone of ischemic myocardium. We evaluated the depolarization and repolarization characteristics across the ischemic-normal border under [K+] variation. Sixty-four-lead epicardial mapping was performed in 26 rats ([K+] 2.3-6.4 mM) in a model of acute ischemia/reperfusion. The animals with [K+] < 4.7 mM (low-normal potassium) had an ischemic zone with ST-segment elevation and activation delay, a border zone with ST-segment elevation and no activation delay, and a normal zone without electrophysiological abnormalities. The animals with [K+] >4.7 mM (normal-high potassium) had only the ischemic and normal zones and no transitional area. Activation-repolarization intervals and local conduction velocities were inversely associated with [K+] in linear regression analysis with adjustment for the zone of myocardium. The reperfusion extrasystolic burden (ESB) was greater in the low-normal as compared to normal-high potassium animals. Ventricular tachycardia/fibrillation incidence did not differ between the groups. In patch-clamp experiments, hypoxia shortened action potential duration at 5.4 mM but not at 1.3 mM of [K+]. IK(ATP) current was lower at 1.3 mM than at 5.4 mM of [K+]. We conclude that the border zone formation in low-normal [K+] was associated with attenuation of IK(ATP) response to hypoxia and increased reperfusion ESB.

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.

Potassium status and the risk of type 2 diabetes, cardiovascular diseases, and mortality: a meta-analysis of prospective observational studies

Epidemiological evidence on the association between potassium and cardiometabolic outcomes remains controversial. This study aimed to examine associations of dietary intake and blood and urinary levels of potassium with risk of type 2 diabetes, cardiovascular disease (CVD), and mortality. Relevant prospective studies were retrieved through a comprehensive search of four electronic databases up to July 1, 2023. Random-effects models were used to pool the study-specific relative risks (RRs) and 95% confidence intervals (CIs). Fifty-six studies were included in this meta-analysis. A higher intake of potassium was significantly associated with a 16% lower risk of CVD (RR: 0.84, 95% CI: 0.78-0.90). Similar inverse associations were also observed between potassium intake and mortality. Each 1.0 g/d increment in potassium intake was associated with a decreased risk of CVD (RR: 0.85, 95% CI: 0.80-0.91) and all-cause mortality (RR: 0.93, 95% CI: 0.88-0.99). For blood and urinary potassium levels, higher level of blood potassium increased the risk of all-cause mortality by 23% (RR: 1.23, 95% CI: 1.11-1.36). The association of blood potassium levels with mortality was nonlinear (Pnon-linearit<0.001). However, urinary potassium levels were inversely associated with the risk of all-cause mortality (RR: 0.84, 95% CI: 0.76-0.93). Our findings support the benefits of moderate potassium consumption for primary prevention of chronic diseases and premature death.

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.

Electrolyte Imbalance Among Patients With and With No ST-Elevation Myocardial Infarction: A Cohort Study

Electrolytes imbalances are highly prevalent and have shown a high impact on mortality in patients with acute myocardial infarction. These electrolytes imbalance have prognostic value in predicting mortality in patients with acute myocardial infarction. The purpose of this study was to assess the prognostic value of electrolyte imbalances in predicting 1-month mortality among patients with myocardial infarction with and with no ST-elevation. This cohort study was conducted in a referral hospital in the West Bank, Palestine. All patients with confirmed medical diagnosis of acute myocardial infarction and admitted to the medical coronary care unit in the hospital were eligible participants. A convenience sample of 186 participants was obtained. These participants were followed up for 1 month to assess their survival (alive or dead). Demographic and clinical data were recorded by reviewing their health records. The derived data were analyzed using SPSS version 19. About 36% of all patients were found to be hyponatremic, 15% of them have hypokalemia, and 9% of patients had hypocalcemia. There was a significant difference between STEMI and non-STEMI in sodium (t = 4.7, P < .001). A multivariate logistic regression analysis was performed to predict 1-month mortality for patients with myocardial infarction with and with no ST-elevation. The predictors that were found to be significant are sodium (odds ratio [OR] = 0.789, P = .010), calcium (OR = 0.221, P = .014), diastolic blood pressure (OR = 0.933, P = .047), and blood urea nitrogen (OR = 0.821, P = .005). Electrolyte imbalance was highly prevalent among patients with acute myocardial infarction. Hyponatremia and hypocalcemia were present and associated significantly with predicting 1-month mortality. Health care providers should take into consideration the electrolytes of patients with acute myocardial infarction from the first moment of admission and correct them early to maximize the clinical outcomes and survival for patients.

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.

Relationship between Admission Electrolyte Level and Short-term Prognosis of Patients with Acute ST-segment Elevation Myocardial Infarction after Percutaneous Coronary Intervention

OBJECTIVE

The objective of this study is to analyze the relationship between the electrolyte level of patients with acute ST-segment elevation myocardial infarction (STEMI) and short-term prognosis after percutaneous coronary intervention (PCI).

METHODS

The clinical data of 142 patients with acute STEMI who underwent PCI in our hospital from September 2018 to September 2019 were retrospectively analyzed. According to the level of serum sodium, potassium, and chloride in patients admitted to the hospital, they were divided into the normal electrolyte group (n = 78), the mild decline group (n = 46), and the severe decline group (n = 16). Univariate and logistic regression multivariate analysis of the relationship between patient electrolyte levels and general clinical data is performed. Statistical analysis of patients' adverse events within 90 days was performed. The Kaplan-Meier survival curve analyzed the relationship between the survival period and electrolyte levels in patients with acute STEMI without major acute cardiovascular events (MACE) within 90 days.

RESULTS

The levels of creatine kinase-MB (CK-MB), cardiac troponin I (cTnI), myocardial infarction area, and Gensini score in patients with mild decline were significantly higher than those in the normal group, left ventricle ejection fractions (LVEF) value was significantly lower than the normal group, and patients with severe decline were significantly higher in creatine kinase (CK) level than the normal group (P < 0.05). The levels of CK-MB, CK, cTnI, and myocardial infarction area of the patients in the severe decline group were significantly higher than those in the mild decline group, and the LVEF values were significantly lower than those in the mild decline group (P < 0.05). The levels of CK-MB, CK, cTnI, the area of myocardial infarction, and Gensini score in patients with acute STEMI have an independent effect on their electrolyte levels. The patients in the mild decline group and severe decline group had significantly higher rates of cardiogenic shock, heart failure, ventricular aneurysm formation, ventricular septal perforation, or death within 90 days after PCI. The median without MACE survival time of patients with mildly and severely reduced electrolyte levels was significantly lower than that of patients with normal electrolyte levels.

CONCLUSION

Patients with acute STEMI are prone to electrolyte disturbances, and their CK-MB, CK, and cTnI levels; myocardial infarction area; and Gensini score have independent effects on electrolyte levels. Patients with electrolyte disturbances are prone to poor prognosis after PCI, and their survival period without MACE at 90 days is significantly lower than that of normal patients.

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.

The Preference, Effect, and Prognosis of Intra-Aortic Balloon Counterpulsation in Acute Myocardial Infarction Complicated by Cardiogenic Shock Patients: A Retrospective Cohort Study

BACKGROUNDS

Intra-aortic balloon counterpulsation is increasingly used in acute myocardial infarction complicated by cardiogenic shock. The aim of this study was to explore the preference, effect, and prognosis of intra-aortic balloon counterpulsation in acute myocardial infarction complicated by cardiogenic shock patients.

METHODS

Data of acute myocardial infarction complicated by cardiogenic shock patients at the Fourth Medical Center of PLA General Hospital were collected retrospectively. A propensity score was calculated with a logistic regression which contained clinically meaningful variables and variables selected by Lasso and then used to match the control group. The cumulative incidence curve and Gray's test were employed to analyse the effect and prognosis of intra-aortic balloon counterpulsation on mortality.

RESULTS

A total of 1962 acute myocardial infarction cases admitted between May 2015 and November 2018 were identified, and 223 cases with acute myocardial infarction complicated by cardiogenic shock were included as the study cohort, which contained 34 cases that received IABP and 189 cases that did not receive IABP. Patients with higher alanine aminotransferase (OR = 1.93, 95% CI 1.29-2.98), higher triglyceride (OR = 3.71, 95% CI 1.87-7.95), and higher blood glucose (OR = 1.08, 95% CI 0.99-1.18) had a higher probability of receiving intra-aortic balloon counterpulsation. In the propensity score matching analysis, 34 cases received intra-aortic balloon counterpulsation and 102 matched controls were included in the comparison. By comparing the cumulative incidence of in-hospital mortality, there was no statistically significant difference between the intra-aortic balloon counterpulsation group and matched control group (P = 0.454).

CONCLUSION

The use of intra-aortic balloon counterpulsation may not improve the prognosis of the acute myocardial infarction complicated by cardiogenic shock patients.

Association Between Average Plasma Potassium Levels and 30-day Mortality During Hospitalization in Patients with COVID-19 in Wuhan, China

Background: Coronavirus disease 2019 (COVID-19) has resulted in more than 610,000 deaths worldwide since December 2019. Given the rapid deterioration of patients' condition before death, markers with efficient prognostic values are urgently required. During the treatment process, notable changes in plasma potassium levels have been observed among severely ill patients. We aimed to evaluate the association between average plasma potassium (K_a ⁺) levels during hospitalization and 30-day mortality in patients with COVID-19. Methods: Consecutive patients with COVID-19 hospitalized in the Zhongfaxincheng branch of Tongji Hospital in Wuhan, China from February 8 to 28, 2020 were enrolled in this study. We followed patients up to 30 days after admission. Results: A total of 136 patients were included in the study. The average age was 62.1±14.6 years and 51.5% of patients were male. The median baseline potassium level was 4.3 (3.9-4.6) mmol/L and K_a ⁺ level during hospitalization was 4.4 (4.2-4.7) mmol/L; the median number of times that we measured potassium was 4 (3-5). The 30-day mortality was 19.1%. A J-shaped association was observed between K_a ⁺ and 30-day mortality. Multivariate Cox regression showed that compared with the reference group (K_a ⁺ 4.0 to <4.5 mmol/L), 30-day mortality was 1.99 (95% confidence interval [CI]=0.54-7.35, P=0.300), 1.14 (95% CI=0.39-3.32, P=0.810), and 4.14 (95% CI=1.29-13.29, P=0.017) times higher in patients with COVID-19 who had K_a ⁺ <4.0, 4.5 to <5.0, and ≥5.0 mmol/L, respectively. Conclusion: Patients with COVID-19 who had a K_a ⁺ level ≥5.0 mmol/L had a significantly increased 30-day mortality compared with those who had a K_a ⁺ level 4.0 to <4.5 mmol/L. Plasma potassium levels should be monitored routinely and maintained within appropriate ranges in patients with COVID-19.

Serum calcium levels correlates with coronary artery disease outcomes

Background

Effect of serum calcium levels on prognosis of patients with coronary artery disease (CAD) is not well evaluated. We aimed to assess the associations of baseline serum calcium levels with both short-term and long-term outcomes in CAD patients.

Methods

This study included 3,109 consecutive patients with angiographically confirmed CAD. Patients were categorized into quartiles according to admission serum calcium. Multivariable regression analysis was used to determine the association of serum calcium with mortality.

Results

Compared to patients in the lowest quartile of serum calcium, patients in upper quartiles were presented with lower all-cause mortality (Hazard ratios [HRs] were -0.636 [95% CI: -0.424 to -0.954], -0.545 [95% CI: -0.351 to -0.846] and -0.641 [95% CI: -0.450 to -0.913] for three upper quartiles versus lowest quartile respectively), cardiovascular mortality (HRs 0.594 [0.368-0.961], 0.261 [0.124-0.551] and 0.407 [0.229-0.725]), and in-hospital mortality (Odd ratios [ORs] 0.391 [0.188-0.812], 0.231 [0.072-0.501] and 0.223 [0.093-0.534]). Consistent associations between serum calcium and long-term mortality were also obtained in subgroup analysis of ACS patients, stable CAD patients and discharged patients.

Conclusions

Serum calcium is inversely associated with CAD and can independently predict both in-hospital and long-term mortality among CAD patients.

Short-term prognosis of normalising serum potassium following an episode of hypokalaemia in patients with chronic heart failure

BACKGROUND/ AIM

It is well known that patients with chronic heart failure and hypokalaemia have increased mortality risk. We investigated the impact of normalising serum potassium following an episode of hypokalaemia on short-term mortality among patients with chronic heart failure.

METHODS AND RESULTS

We identified 1673 patients diagnosed with chronic heart failure who had a serum potassium measurement under 3.5 mmol/l within 14 days and one year after initiated medical treatment with both loop diuretics and angiotensin-converting enzyme inhibitors or angiotensin-II receptor blockers. A second serum potassium measurement was required 8-30 days after the episode of hypokalaemia. All-cause mortality and cardiovascular mortality was examined within 90 days from the second serum potassium measurement. Mortality was examined according to six predefined potassium groups derived from the second measurement:<3.5 mmol/l (n = 302), 3.5-3.7 mmol/l (n = 271), 3.8-4.1 mmol/l (n = 464), 4.2-4.4 mmol/l (n = 270), 4.5-5.0 mmol/l (n = 272), and 5.1-8.0 mmol/l (n = 94). We used Cox regression to estimate both all-cause mortality risk and cardiovascular mortality, with serum potassium at 3.8-4.1 mmol/l as reference. After 90 days, the all-cause mortality in the six groups was 29.5%, 22.1%, 20.3%, 24.8%, 23.5% and 43.6%, respectively. In multivariable adjusted analysis, patients with serum potassium <3.5 mmol/l (hazard ratio: 1.51; 95% confidence interval: 1.13-2.02) and serum potassium 5.1-8.0 mmol/l (hazard ratio: 2.18; 95% confidence interval: 1.50-3.17) had an increased risk of all-cause mortality compared to the reference. After 90 days, the cardiovascular mortality in the six groups was 19.2%, 17.7%, 14.4%, 18.9%, 18.8% and 34.0%, respectively. In multivariable adjusted analysis, patients with serum potassium 5.1-8.0 mmol/l (hazard ratio: 2.32; 95% confidence interval: 1.51-3.56) had an increased risk of cardiovascular mortality compared to the reference, while serum potassium <3.5 mmol/l (hazard ratio: 1.37; 95% confidence interval: 0.97-1.95) had a trend toward increased risk of cardiovascular mortality compared to the reference.

CONCLUSION

Patients with chronic heart failure and hypokalaemia, who after 8-30 days remained hypokalaemic, had a significantly higher 90-day all-cause mortality risk compared to patients in the reference group (3.8-4.1 mmol/l). Patients with chronic heart failure and hypokalaemia, who after 8-30 days had the serum potassium level increased to a level within 5.1-8.0 mmol/l, had both a significantly higher 90-day all-cause mortality risk and cardiovascular mortality risk compared to patients in the reference group (3.8-4.1 mmol/l).

Admission Serum Potassium Levels in Hospitalized Patients and One-Year Mortality

Background: The aim of this study was to assess the relationship between admission serum potassium and one-year mortality in all adult hospitalized patients. Methods: All adult hospitalized patients who had an admission serum potassium level between the years 2011 and 2013 at a tertiary referral hospital were enrolled. End-stage kidney disease patients were excluded. Admission serum potassium was categorized into levels of ≤2.9, 3.0–3.4, 3.5–3.9, 4.0–4.4, 4.5–4.9, 5.0–5.4, and ≥5.5 mEq/L. Cox proportional hazard analysis was performed to assess the independent association between admission serum potassium and one-year mortality after hospital admission, using an admission potassium level of 4.0–4.4 mEq/L as the reference group. Results: A total of 73,983 patients with mean admission potassium of 4.2 ± 0.5 mEq/L were studied. Of these, 12.6% died within a year after hospital admission, with the lowest one-year mortality associated with an admission serum potassium of 4.0–4.4 mEq/L. After adjustment for age, sex, race, estimated glomerular filtration rate (eGFR), principal diagnosis, comorbidities, medications, acute kidney injury, mechanical ventilation, and other electrolytes at hospital admission, both a low admission serum potassium ≤3.9 mEq/L and elevated admission potassium ≥5.0 mEq/L were significantly associated with an increased risk of one-year mortality, when compared with an admission serum potassium of 4.0–4.4 mEq/L. Subgroup analysis of chronic kidney disease and cardiovascular disease patients showed similar results. Conclusion: This study demonstrated that hypokalemia ≤3.9 mEq/L and hyperkalemia ≥5.0 mEq/L at the time of hospital admission were associated with higher one-year mortality.