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.