A client with heart failure (HF) returns to the clinic two weeks after adjustments were made to the prescribed cardiac glycoside, diuretic, and potassium supplement. The client's lungs are clear, heart rate is 58 beats/minute, and serum potassium level is 2.9 mEq/L (2.9 mmol/L). Which action is most important for the nurse to implement? Reference Range: Potassium (K+) [3.5 to 5 mEq/L (3.5 to 5 mmol/L)

Rationale: A. Check the pretibial areas and ankles for edema: Assessing for peripheral edema is important in heart failure management, but it does not address the immediate risk posed by severe hypokalemia. B. Report serum potassium to healthcare provider (HCP): A potassium level of 2.9 mEq/L is critically low and increases the risk of life-threatening cardiac dysrhythmias, especially in a client taking a cardiac glycoside. Prompt reporting allows the provider to initiate urgent potassium replacement or adjust medications. C. Compare the weight with what it was at last visit: Weight monitoring helps assess fluid status in heart failure, but it does not address the immediate threat from hypokalemia. D. Review the dietary history from the past week: Dietary review can help identify potential causes of hypokalemia, but it does not provide immediate correction or protection from cardiac complications.