Hyperkalemia often occurs in patients hospitalized with acute myocardial infarction (AMI), and it is associated with a greater risk of death, according to a new study.
“Our findings reveal that hyperkalemia is very common in patients hospitalized with acute myocardial infarction, and associated with marked increases in mortality, even with mild potassium elevations –both in patients with and without end-stage renal disease,” lead investigator Anna Grodzinsky, MD, of Saint Luke’s Mid American Heart Institute in Kansas City, MO, and colleagues revealed in The American Journal of Medicine.
Using the Cerner HealthFacts AMI database, the researchers evaluated serum potassium levels for 38,689 AMI patients hospitalized during 2000–2008 and rates of in-hospital mortality. They studied hyperkalemia at various degrees: potassium levels 5<5.5 mEq/L, 5.5<6.0 mEq/L, 6.0<6.5 mEq/L, and >6.5 mEq/L.
Among all patients, 886 (2.3%) were on dialysis. Hyperkalemia of 5 mEq/L and above occurred in 66.8% of dialysis patients and 22.6% of non-dialysis patients. Moderate to severe hyperkalemia (5.5 mEq/L and above) occurred in 9.8% of patients overall.
The investigators observed a steep increase in mortality during hospitalization with higher potassium levels and number of hyperkalemic events. In-hospital death rates surpassed 15% when maximum potassium levels rose to and above 5.5 mEq/L, regardless of patients’ dialysis status. Even patients with mild hyperkalemia were at risk for early death. The relationship between higher maximum potassium levels and mortality persisted even after researchers adjusted for factors such as comorbidities, in-hospital procedures, and medications. Patients with frequent and persistent hyperkalemia had higher in-hospital mortality than those with temporary rise of potassium.
“We feel that the poor prognosis associated with hyperkalemia should prompt clinicians to evaluate their patients for potentially modifiable factors that are associated with hyperkalemia following acute myocardial infarction,” Dr Grodzinsky and colleagues stated. They mentioned that several new hyperkalemia therapies are in development.
Among the limitations, the investigators noted that hemolysis can contribute to hyperkalemia. They also emphasized that it’s still unclear whether hyperkalemia is a marker or mediator of adverse outcomes.
Future studies should investigate whether aggressive management of hyperkalemia improves outcomes in AMI patients.