A 55-year-old man presents for a second opinion regarding treatment of long-standing hypertension diagnosed in his early 20s. He is compliant with chlorthalidone 25 mg daily, amlodipine 10 mg daily, lisinopril 40 mg daily, and spironolactone 50 mg daily. His BMI is 18 kg/m2. He exercises daily and adheres to a low sodium diet. Secondary causes of hypertension have been ruled out. His ambulatory blood pressures are routinely >140/90 mmHg.