Higher serum potassium levels are associated with an increased 30-day mortality risk in patients with ST-segment elevation myocardial infarction (STEMI) and no renal insufficiency, researchers concluded.
In a retrospective study, patients who had potassium levels of 4.5 mEq/L or higher were at higher risk of 30-day mortality compared with patients who had levels of at least 4.0 but less than 4.5 mEq/L (reference), researchers reported online ahead of print in Angiology. Patients with potassium levels of 5.0 or higher had a significant 80% increased risk.
Wenfang Ma, MD, and colleagues at Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, studied 6,613 patients with STEMI who presented with normal renal function. They categorized subjects into 5 groups based on mean serum potassium levels: less than 3.5, at least 3.5 but less than 4.0, at least 4.0 but less than 4.5, at least 4.5 but less than 5.0, and 5.0 mEq/L or higher The rates of 7-day malignant arrhythmia for patients with these potassium levels were 8.5%, 6.6%, 6.4%, 8.4%, and 10.1%, respectively. The rates of 7-day all-cause mortality were 3.7%, 3.8%, 3.7%, 5.9%, and 7.1%, respectively. The rates of 30-day all-cause mortality were 6.3%, 5.9%, 5.3%, 8.8%, and 12.0%, respectively.
In multivariate analysis, a potassium level of at least 4.5 but less than 5.0 mEq/L was associated with a significant 52% increased risk of 30-day mortality compared with the reference value. A level of 5.0 mEq/L or higher was associated with a significant 80% increased risk.
Current guidelines recommend maintaining serum potassium levels of 4.0–5.0 mEq/L in patients with acute myocardial infarction, but the guidelines are based on studies conducted before the beta-blocker and reperfusion era, the authors noted.