Hypertrophic cardiomyopathy medical treatment

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [mailto:mgibson@perfuse.org]; Cafer Zorkun, M.D. [mailto:zorkun@perfuse.org], Caitlin J. Harrigan [mailto:charrigan@perfuse.org]; Martin S. Maron, M.D.; Barry J. Maron, M.D.;

Overview
In all patients with hypertrophic cardiomyopathy risk stratification is essential to attempt to ascertain which patients are at risk for sudden cardiac death . In those patients deemed to be at high risk the benefits and infrequent complications of defibrillator therapy are discussed; devices have been implanted in as many as 15% of patients at HOCM centers. Treatment symptoms of obstructive HOCM is directed towards decreasing the left ventricular outflow tract gradient and symptoms of dyspnea, chest pain and syncope.

Avoid volume depletion

 * These patients should avoid volume depletion and dehydration which reduces Left ventricular volume and thereby exacerbates left ventricular outflow tract obstruction.

Avoid strenuous Activity

 * Strenuous activity has been associated with sudden cardiac death in these patients and for this reason these patients are counseled to avoid engaging in competitive sports.

Screening Relatives

 * This autosomal dominant disease has a high degree of penetrance and first degree relatives should be screened.

Pharmacotherapy
Medical therapy is successful in the majority of patients. The first medication that is routinely used is beta-blockade (metoprolol, atenolol, bisoprolol, propranolol). If symptoms and gradient persist disopyramide may be added to the beta-blocker . Alternately a calcium channel blocker such as verapamil may be substituted for beta-blockade. It should be stressed that most patient's symptoms may be managed medically without needing to resort to inteventions such as surgical septal myectomy, alcohol septal ablation or pacing. Severe symptoms in non-obstructive HCM may actually be more difficult to treat because there is no obvious target (obstruction) to treat. Medical therapy with verapamil, beta-blockade may improve symptoms. Diuretics should be avoided, as they reduce the intravascular volume of blood, decreasing the amount of blood available to distend the left ventricular outflow tract, leading to an increase in the obstruction to the outflow of blood in the left ventricle.

As a summary:

 * The asymptomatic patient without risk factors for SCD (sudden cardiac death[) does not require therapy, even in the presence of NSVT. The symptomatic patient can be treated with negative inotropes such as calcium channel blockers and/or beta-blockers. Atrial fibrillation should be treated aggressively. Some use Disopyramide to maintain NSR (normal sinus rhythm) because of its negative inotropic effects. Amiodarone is the best medicine to maintain NSR and has been associated with symptomatic improvement in patients with HCM.


 * These patients require endocarditis prophylaxis.

2011 ACCF/AHA Guideline Recommendations: Pharmacologic Management in Symptomatic Patients
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Class I
1. Beta-blocking drugs are recommended for the treatment of symptoms (angina or dyspnea) in adult patients with obstructive or non-obstructive HCM but should be used with caution in patients with sinus bradycardia or severe conduction disease.(3,9,10,134,137,229–236) (Level of Evidence: B)

2. If low doses of beta-blocking drugs are ineffective for controlling symptoms (angina or dyspnea) in patients with HCM, it is useful to titrate the dose to a resting heart rate of less than 60 to 65 bpm (up to generally accepted and recommended maximum doses of these drugs).(3,10,137, 229–236) (Level of Evidence: B)

3. Verapamil therapy (starting in low doses and titrating up to 480 mg/d) is recommended for the treatment of symptoms (angina or dyspnea) in patients with obstructive or non-obstructive HCM who do not respond to beta-blocking drugs or who have side effects or contraindications to beta-blocking drugs. However, verapamil should be used with caution in patients with high gradients, advanced heart failure, or sinus bradycardia.(10,134,137,237–241) (Level of Evidence: B)

4. Intravenous phenylephrine (or another pure vasoconstricting agent) is recommended for the treatment of acute hypotension in patients with obstructive HCM who do not respond to ﬂuid administration.(137,242–244) (Level of Evidence: B)

Class IIa
1. It is reasonable to combine disopyramide with a beta-blocking drug or verapamil in the treatment of symptoms (angina or dyspnea) in patients with obstructive HCM who do not respond to beta-blocking drugs or verapamil alone.(10,134,137,245–248) (Level of Evidence: B)

2. It is reasonable to add oral diuretics in patients with non-obstructive HCM when dyspnea persists despite the use of beta blockers or verapamil or their combination.(67,134) (Level of Evidence: C)

Class IIb
1. Beta-blocking drugs might be useful in the treatment of symptoms (angina or dyspnea) in children or adolescents with HCM, but patients treated with these drugs should be monitored for side effects, including depression, fatigue, or impaired scholastic performance. (Level of Evidence: C)

2. It may be reasonable to add oral diuretics with caution to patients with obstructive HCM when congestive symptoms persist despite the use of beta blockers or verapamil or their combination.(10,134,137) (Level of Evidence: C)

3. The usefulness of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers in the treatment of symptoms (angina or dyspnea) in patients with HCM with preserved systolic function is not well established, and these drugs should be used cautiously (if at all) in patients with resting or provocable LVOT obstruction. (Level of Evidence: C)

4. In patients with HCM who do not tolerate verapamil or in whom verapamil is contraindicated, diltiazem may be considered. (Level of Evidence: C)

Class III (Harm)
1. Nifedipine or other dihydropyridine calcium channel-blocking drugs are potentially harmful for treatment of symptoms (angina or dyspnea) in patients with HCM who have resting or provocable LVOT obstruction. (Level of Evidence: C)

2. Verapamil is potentially harmful in patients with obstructive HCM in the setting of systemic hypotension or severe dyspnea at rest. (Level of Evidence: C)

3. Digitalis is potentially harmful in the treatment of dyspnea in patients with HCM and in the absence of AF.(3,10,137,249–251) (Level of Evidence: C)

4. The use of disopyramide alone without beta blockers or verapamil is potentially harmful in the treatment of symptoms (angina or dyspnea) in patients with HCM with AF because disopyramide may enhance atrioventricular conduction and increase the ventricular rate during episodes of AF.(10,66,134,252–257) (Level of Evidence: B)

5. Dopamine, dobutamine, norepinephrine, and other intravenous positive inotropic drugs are potentially harmful for the treatment of acute hypotension in patients with obstructive HCM.(3,82,242–244,258–260) (Level of Evidence: B)}}

2011 AHA/ACC Guidelines Recommendations- Management of Atrial Fibrillation in HCM
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Class I
1. Oral anticoagulation (INR 2.0 to 3.0) is recommended in patients with hypertrophic cardiomyopathy who develop atrial fibrillation, as for other patients at high risk of thromboembolism. (Level of Evidence: B)

Class IIa
1. Antiarrhythmic medications can be useful to prevent recurrent atrial fibrillation in patients with hypertrophic cardiomyopathy. Available data are insufficient to recommend one agent over another in this situation, but (a) disopyramide combined with a beta blocker or nondihydropyridine calcium channel antagonist or (b) amiodarone alone is generally preferred. (Level of Evidence: C)}}

Guideline Resources

 * 2011 ACCF/AHA Guideline for the Diagnosis and Treatment of Hypertrophic Cardiomyopathy


 * 2011 ACCF/AHA/HRS Focused Updates Incorporated Into the ACC/AHA/ESC 2006 Guidelines for the Management of Patients With Atrial Fibrillation : A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines