A 23-year-old man comes to the office due to chest discomfort that usually occurs during exercise, such as jogging or climbing stairs. The symptoms go away 5 to 10 minutes after he stops. The patient has not had syncope but mentions some shortness of breath that accompanies the chest pain. Family history includes an uncle who died suddenly at age 35. Blood pressure is 122/70 mm Hg and pulse is 70/min and regular. The apical impulse is strong and sustained. While supine, the patient has a soft crescendo-decrescendo systolic murmur at the apex and left sternal border; it becomes quite pronounced when he stands. Which of the following medications should be avoided while treating this patient's condition?

Question

A 23-year-old man comes to the office due to chest discomfort that usually occurs during exercise, such as jogging or climbing stairs.  The symptoms go away 5 to 10 minutes after he stops.  The patient has not had syncope but mentions some shortness of breath that accompanies the chest pain.  Family history includes an uncle who died suddenly at age 35.  Blood pressure is 122/70 mm Hg and pulse is 70/min and regular.  The apical impulse is strong and sustained.  While supine, the patient has a soft crescendo-decrescendo systolic murmur at the apex and left sternal border; it becomes quite pronounced when he stands.  Which of the following medications should be avoided while treating this patient's condition?

Quizplus · Accepted Answer

11ec160b_3b8e_5e91_9249_b9ad1fdf90f4_MD0001_00 This patient with exertional chest pain, family history of sudden cardiac death, and a crescendo-decrescendo systolic murmur that intensifies on standing most likely has hypertrophic cardiomyopathy (HCM), an autosomal dominant inherited condition involving mutations in cardiac sarcomere proteins. The clinical manifestations of HCM result mostly from enlargement of the intraventricular septum that leads to left ventricular outflow tract (LVOT) obstruction. Patients may be asymptomatic or can experience exertional dyspnea, fatigue, anginal pain, lightheadedness, or syncope; sudden cardiac arrest (or death) can occur due to reduced cardiac output and ventricular arrhythmia. The degree of LVOT obstruction in HCM varies with changes in left ventricular (LV) blood volume. Low LV blood volume collapses the LVOT and worsens the obstruction; therefore, medications that decrease LV blood volume should be avoided. These medications include the following: Preload reducers: Venous dilators (eg, nitrates) and diuretics (eg, furosemide) reduce venous return to the heart and decrease LV end-diastolic volume. Afterload reducers: Arterial dilators (eg, hydralazine) facilitate increased stroke volume, which decreases LV end-systolic volume. Balanced vasodilators: Combined venous and arterial dilators (eg, dihydropyridine calcium channel blockers, ACE inhibitors) can worsen LVOT obstruction via reductions in preload and afterload. In contrast, negative chronotropic agents (which reduce heart rate, increasing diastolic filling time) and negative inotropic agents (which reduce contractility, decreasing the systolic ejection fraction) help improve LVOT obstruction by increasing LV volumes. Beta blockers (eg, metoprolol) and nondihydropyridine calcium channel blockers (eg, verapamil) have negative chronotropic and ionotropic effects and are used for treating HCM (Choices D and E). Disopyramide, a class I antiarrhythmic (ie, sodium channel blocker) that has negative inotropic effects, is also effective via the same mechanism (Choice B). (Choice A) Amiodarone is a class III antiarrhythmic (potassium channel blocker) that may be used in patients with HCM who develop arrhythmia complications (eg, atrial fibrillation, ventricular tachycardia). Educational objective: Left ventricular outflow tract obstruction in hypertrophic cardiomyopathy worsens with decreased left ventricular blood volume. Therefore, medications that decrease preload (eg, nitrates), afterload (eg, hydralazine), or both (eg, dihydropyridine calcium channel blockers, ACE inhibitors) should be avoided.

A 23-Year-Old Man Comes to the Office Due to Chest