Electrolyte Disorders USMLE Step 1 Practice Question

A 45-year-old man with a history of autosomal dominant polycystic kidney disease presents to the emergency department with palpitations and muscle weakness. His wife reports he started a new antihypertensive medication 1 week ago. Vital signs: BP 168/102 mmHg, HR 98 bpm, RR 20/min, O2 saturation 98% on room air. Laboratory studies show serum potassium 7.2 mEq/L, creatinine 3.2 mg/dL, bicarbonate 16 mEq/L, and arterial pH 7.25. An ECG is obtained and demonstrates peaked T waves with a widened QRS complex. Which of the following is the most likely cause of this acute electrolyte derangement?