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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 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.

BACKGROUND: Conflicting with clinical practice guidelines, recent studies demonstrated that serum potassium concentrations (SPC) of ≥4.5mEq/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 28-74years consecutively hospitalized between 1 January 2000 and 31 December 2008 and followed up until 31 December 2011. Patients were categorized into five SPC groups (

Background Paradoxically, beneficial effects of overweight and obesity on survival have been found in patients after cardiovascular events such as acute myocardial infarction (AMI). This obesity paradox has not been analyzed in AMI patients with diabetes even though their cardiovascular morbidity and mortality is increased compared to their counterparts without diabetes. Therefore, the objective of this long-term study was to analyze the association between body mass index (BMI) and all-cause mortality in AMI patients with and without diabetes mellitus. Methods Included in the study were 1190 patients with and 2864 patients without diabetes, aged 28-74 years, recruited from a German population-based AMI registry. Patients were consecutively hospitalized between 1 January 2000 and 31 December 2008 with a first ever AMI and followed up until December 2011. Data collection comprised standardized interviews and chart reviews. To assess the association between BMI and long-term mortality from all causes, Cox proportional hazards models were calculated adjusted for risk factors, co-morbidities, clinical characteristics, in-hospital complications as well as medical and drug treatment. Results AMI patients of normal weight (BMI 18.5-24.9 kg/m2) had the highest long-term mortality rate both in patients with and without diabetes with 50 deaths per 1000 person years and 26 deaths per 1000 person years, respectively. After adjusting for a selection of covariates, a significant, protective effect of overweight and obesity on all-cause mortality was found in AMI patients without diabetes (overweight: hazard ratio (HR) 0.73, 95% confidence interval (CI) 0.58-0.93; p=0.009; obesity: HR 0.64, 95% CI 0.47-0.87; p=0.004). In contrast, an obesity paradox was not found in AMI patients with diabetes. However, stratified analyses showed survival benefits in overweight AMI patients with diabetes who had been prescribed statins prior to AMI (HR 0.51, 95% CI 0.29-0.89, p=0.018) or four evidence-based medications at hospital-discharge (HR 0.52, 95% CI 0.34-0.80, p=0.003). Conclusion In contrast to AMI patients without diabetes, AMI patients with diabetes do not experience a survival benefit from an elevated BMI. To investigate the underlying reasons for these findings, further studies stratifying their samples by diabetes status are needed. Electronic supplementary material The online version of this article (doi:10.1186/s12933-015-0189-0) contains supplementary material, which is available to authorized users.