From the FDA Drug Label
Table 2. Hypokalemia (<3.5 mEq/L) or Hyperkalemia (>5.5 or ≥6.0 mEq/L) in EPHESUS Potassium (mEq/L) Eplerenone (N=3,251) n (%) Placebo (N=3,237) n (%) <3.5 273 (8.4) 424 (13.1)
5.5 508 (15.6) 363 (11.2) ≥6.0 180 (5.5) 126 (3. 9)
The answer to the question is yes, hypokalemia can occur after an MI.
- The frequency of hypokalemia (<3.5 mEq/L) in the eplerenone group was 8.4% compared to 13.1% in the placebo group 1.
- This suggests that while hypokalemia is possible after an MI, the use of eplerenone may actually decrease its frequency.
From the Research
Yes, hypokalemia can occur after a myocardial infarction (MI). Potassium levels often drop during the acute phase of an MI due to several mechanisms, including stress-induced catecholamine release, which drives potassium into cells, lowering serum levels 2. Additionally, common treatments for MI, such as beta-agonists, insulin-glucose infusions, and diuretics, especially loop diuretics like furosemide, can further deplete potassium. This is concerning because hypokalemia increases the risk of dangerous arrhythmias in post-MI patients, particularly ventricular fibrillation and torsades de pointes.
The most recent and highest quality study, published in 2022, highlights the importance of monitoring potassium levels in patients taking diuretics, as diuretic-induced hypokalaemia is a common and potentially life-threatening adverse drug reaction 3. The study emphasizes that reducing diuretic dose and potassium supplementation are the most direct and effective therapies for hypokalaemia.
Key points to consider:
- Hypokalemia is a common problem in patients with acute myocardial infarction, with a prevalence of 14% at admission 4.
- The presence of hypokalemia is associated with an increased frequency of ventricular tachycardia and ventricular fibrillation 4.
- 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 2.
- Clinicians should monitor potassium levels closely after MI and maintain them between 4.0-5.0 mEq/L, which is slightly higher than the normal range.
- Replacement is usually done with oral potassium chloride supplements for mild deficiency, while severe hypokalemia may require IV potassium at rates not exceeding 10-20 mEq/hour to prevent complications.
- Magnesium levels should also be checked and corrected if low, as magnesium deficiency can make potassium replacement less effective.