| Background:Acute myocardial infarction remains one of the leading causes of morbidity and mortality worldwide despite improved and advanced clinical practices.Potassium derangement observed in these patients is a contributing factor for poor prognosis.Current guidelines recommend maintaining serum potassium concentration in patients with AMI between 4.0 and 5.0mmol/l or even higher at a range of 4.5-5.5mmol/1.In contrast,several recent studies have demonstrated the association of increase in mortality in patients with serum potassium greater than 4.5mmol/l.There is still controversy regarding the optimal level of serum potassium in patients with AMI.Objectives:1.To Investigate the relationship between admission SPC,cardiac arrhythmias,in-hospital mortality in patients with AMI2.To discern whether these relationships vary in different subgroups,including patients with and without diabetes,patients with and without heart failure and patients with or without renal failure during hospitalization for AMI.Method:We studied patients who were admitted with a recorded diagnosis of acute myocardial infarction(AMI)retrospectively.Analyzed data were of patients admitted at two hospitals(Qilu Hospital of Shandong University and Qianfoshan Hospital)with a diagnosis of AMI from January 1,2015 and June 30,2019.AMI clinically defined by chest pain,increased levels of cardiac troponin(cTn)with at least one value above the 99th percentile upper limit due to acute myocardial ischemia and abnormal ECG findings.Ethical clearance was requested and approved by the ethics committee of Shandong UniversityThe primary outcome considered was in-hospital mortality and the secondary outcomes were ventricular arrhythmia,atrial fibrillation,higher degree atrioventricular block(2nd/3rd degree AV block)and major adverse cardiovascular events(MACE).Inclusion criterion was all patients with a confirmed diagnosis of Acute Myocardial Infarction(AMI)at discharge.Patients with no recorded potassium values were excluded.Initial sample size was 2748 patients.Following exclusion of 50 records due to missing data on potassium concentration,we analyzed the data of 2698 patients.AMI patients were divided based on ECG features into STEMI and NSTEMI Taking into consideration underlying comorbidities,AMI was further divided into subgroups:1)patients with and without heart failure;2)patients with and without diabetes;3)patients with and without renal failureUsing multivariable logistic regression models,we assessed the relationship between admission serum potassium levels and the risk of in-hospital mortality and arrhythmias.Potassium levels were divided as follows:K+<3.5;K+=3.5-<4.0;K+=4.0-<4.5;K+=4.5-5.0;K+>5.0mmol/l;with K+=4.0-<4.5mmol/l as reference group.Continuous variables with normal distributions are expressed as mean±SD and compared using one-way analysis of variance.Categorical variables were expressed as number and percentages and Pearson’s chi-square test were used to assess the differences.Three models were generated sequentially to determine the influence of potential confounders on the relationship between serum potassium levels.The odds ratios indicate the relative risk of ventricular arrhythmia,atrial fibrillation and in-hospital mortality in each potassium level compared with those in the reference group(4.0-4.5mmol/L).Results:Of the 2698 patients included in this study,38.1%were diagnosed with ST-segment elevation myocardial infarction(STEMI)and 60.3%with non ST-segment elevation myocardial infarction(NSTEMI).Frequency of patients with diabetes,renal failure,atrial fibrillation and 2nd/3rd degree AV block were higher in the K+>5.0mmol/l group and those with Hypertension and ventricular arrhythmia in the K+<3.5mmol/l group.A U-shaped association between admission serum potassium and in-hospital mortality was observed.Compared with K+=4.0-<4.5mmol/l group,the risk of in-hospital mortality in K+>5.0mmol/l group and K+<3.5mmol/l group is 1.30 times higher(OR 1.30;95%CI:0.50,7.35)and 1.21 times higher(OR 1.21;95%CI:0.55,4.38)respectively.However patients with AMI and diabetes demonstrated a J shaped curve with the highest in-hospital mortality observed in the K+>5.0mmol/l group.The lowest risk for in-hospital mortality was observed in K+=3.5<4.0 group(OR 0.82;95%CI:0.53,2.19)followed by K+=4.0-<4.5mmol/l.Overall MACE(22.5%,p<0.001)with the lowest occurrence in in K+=3.5<4.0 group(OR 0.86;95%CI:0.13,2.51).Ventricular arrhythmia occurred in 147 patients(5.4%),atrial fibrillation in 180 patients(6.7%)and 2nd/3rd AV block in 23 patients(0.9%).K+<3.5mmol/l group has the highest occurrence of ventricular arrhythmia after adjustment for age and sex with OR 2.37;95%CI:1.35,5.93 and remains the highest with further adjustment in model 2 and 3.After controlling for all confounders,K+>5.0 group(OR 0.81;95%CI:0.80,1.09)has the lowest odd of ventricular arrhythmia occurring and K+<3.5mmol/l group(OR 1.12;95%CI:0.94,1.12)has the highest odd.Patients with NSTEMI and those with heart failure showed similar trend.The risk of atrial fibrillation was higher in patients with K+>5.0mmol/l(OR 2.25;95%CI:1.19,5.45)and K+<3.5mmol/l(OR 1.35;95%CI:0.88,2.24).The lowest risk was observed in patients with K+=3.5-4.0mmol/l(OR of 0.92;95%CI:0.83,1.18).Rate of occurrence of 2nd/3rd degree AV was lowest in K+<3.5mmol/l regardless of AMI subtype or underlying comorbidity and its incidence increases with increase in potassium levels in patients with STEMI,diabetes and renal failureConclusionBoth hyperkalemia and hypokalemia at admission in patients with AMI are associated with increase in-hospital mortality.It is possible that the U-shaped curve of in-hospital mortality is as a result of the arrhythmic complications observed in both hyper-and hypokalemia Potassium levels between 4.0 and 4.5mmol/l was found to be relatively safe but not superior to levels between 3.5 and 4.0mmol/l.It might be beneficial to target serum potassium levels between 3.5 and 4.0mmol/l as levels outside this range at admission were associated with increased risk of in-hospital mortality and arrhythmic complications. |
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