Nicorandil-Induced Hyperkalemia in a Uremic Patient

Nicorandil is an antianginal agent with nitrate-like and ATP-sensitive potassium channel activator properties. After activation of potassium channels, potassium ions are expelled out of the cells, which lead to membrane hyperpolarization, closure of voltage-gated calcium channels, and finally vasodilation. We present a uremic case suffering from repeated junctional bradycardia, especially before hemodialysis. After detailed evaluation, nicorandil was suspected to be the cause of hyperkalemia which induced bradycardia. This case reminds us that physicians should be aware of this potential complication in patients receiving ATP-sensitive potassium channel activator. 1. Introduction Nicorandil is an antianginal agent with nitrate-like and ATP-sensitive potassium (KATP) channel activator properties. After activation of KATP channels, they expel potassium out of the cells, which lead to membrane hyperpolarization, closure of voltage-gated calcium channels, and finally vasodilation [1]. However, excessive activation of KATP channels may logically cause overt potassium efflux, which results in hyperkalemia. To our best knowledge, rare hyperkalemic cases due to KATP channels activator use were reported in the literatures’ review. Mervyn Singer et al. had previously reported three cases of life-threatening hyperkalemia and hemodynamic disturbance due to KATP channels activation [2]. We present a uremic patient who developed hyperkalemia and junctional bradycardia after taking the nicorandil. 2. Case Presentation A 51-year-old man with a past medical history of hypertension and end-stage renal disease (ESRD) requiring regular hemodialysis (three times per week) presented to the cardiovascular clinic due to progressive dyspnea and chest tightness for 2-3 months. During the first hospitalization, coronary angiography showed right coronary artery stenosis, but the patient hesitated about further intervention. After discharge, we prescribed nicorandil (5？mg three times per day) and aspirin (100？mg per day) at return visits. However, he still felt chest discomfort especially before his regular hemodialysis. One month after the first angiography, he was admitted for percutaneous coronary intervention. However, chest tightness and dizziness were found in the next day after admission. Meanwhile, we found bradycardia (the heart rate between 30 and 40 beats per minutes) and relative hypotension (the blood pressure dropped from 188/79？mmHg to 102/79？mmHg). Electrocardiography (ECG) showed junctional bradycardia (Figure 1). Laboratory data revealed hyperkalemia (7.0？mmoL/L).