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.

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.

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.

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.