Hydrochlorothiazide should be discontinued in this patient. She has mild symptoms of obstructive hypertrophic cardiomyopathy (HCM). Dynamic left ventricular outflow tract (LVOT) obstruction affects 70% of patients with HCM and is exacerbated by decreases in preload (for example, from diuretic use or squat-to-stand maneuvers) and afterload (for example, from expiration or vasodilator therapy) and by increases in myocardial contractility (for example, from digoxin therapy). For patients with symptoms of HCM, the initial treatment is medical therapy that addresses the factors that predispose toward LVOT obstruction. Use of hydrochlorothiazide and other diuretics, particularly in high doses, will exacerbate the propensity towards dynamic LVOT obstruction and, therefore, should be avoided in patients with HCM. Similarly, vasodilator therapy also should not be used. Negative inotropic agents, such as β-receptor antagonists, calcium channel blockers, and disopyramide, are the cornerstone of medical therapy in these patients. This patient was previously stable on hydrochlorothiazide; however, HCM and its associated pathophysiology can manifest at any age and result in symptoms of heart failure.

Dual-chamber pacemaker implantation previously was considered to be a therapeutic option but was found to be relatively ineffective in randomized clinical trials of patients with HCM. These trials showed a significant placebo effect (40%-50%) from dual-chamber pacing without clear clinical benefit.

ACE inhibitors, such as lisinopril, reduce afterload and can exacerbate LVOT obstruction, and therefore they should be avoided in patients with HCM.

For patients with drug-refractory, severely symptomatic obstructive HCM, septal reduction therapy with surgical myectomy or alcohol septal ablation may be considered. Neither myectomy nor alcohol ablation is recommended for patients with the minimal symptoms that this patient has or for those without an adequate trial of appropriate pharmacotherapy.