What are the treatment guidelines for cardiomyopathy?

Treatment Guidelines for Cardiomyopathy

Beta blockers are the cornerstone of pharmacological treatment for most forms of cardiomyopathy, with specific additional therapies tailored to the cardiomyopathy subtype and presence of complications.

Classification of Cardiomyopathies

Cardiomyopathies are a heterogeneous group of diseases affecting heart muscle that often lead to progressive heart failure. They are classified into several major types:

• Hypertrophic cardiomyopathy (HCM)
• Dilated cardiomyopathy (DCM)
• Restrictive cardiomyopathy
• Arrhythmogenic right ventricular cardiomyopathy

Treatment of Hypertrophic Cardiomyopathy (HCM)

Obstructive HCM

1. First-line therapy:

   • Nonvasodilating beta blockers (e.g., metoprolol, propranolol), titrated to maximally tolerated doses 1
   • Target resting heart rate <60-65 bpm

2. Second-line therapy (if beta blockers ineffective/not tolerated):

   • Non-dihydropyridine calcium channel blockers (verapamil or diltiazem) 2, 1
   • Verapamil starting dose: 40 mg TID (max 480 mg daily)
   • CAUTION: Verapamil is potentially harmful in patients with severe dyspnea at rest, hypotension, very high resting gradients (>100 mm Hg), and in children <6 weeks 2

3. Third-line therapy (for persistent symptoms):

   • Add disopyramide in combination with beta blockers or calcium channel blockers 2, 1
   • Monitor QTc interval when using disopyramide

4. Invasive treatment options (for severely symptomatic patients despite optimal medical therapy):

   • Septal reduction therapy (SRT) at experienced centers 2
   • Surgical myectomy (preferred in younger patients <50 years) 1
   • Alcohol septal ablation (alternative for older patients or those with comorbidities) 1

Non-obstructive HCM with Preserved EF

• Beta blockers or non-dihydropyridine calcium channel blockers for symptoms of exertional angina or dyspnea 2
• Consider adding oral diuretics when dyspnea persists despite beta blockers or calcium channel blockers 2
• Valsartan may benefit younger patients (≤45 years) with mild phenotype to slow adverse cardiac remodeling 1

Treatment of Dilated Cardiomyopathy (DCM)

1. Standard heart failure therapy:

   • ACE inhibitors (e.g., lisinopril) 2, 3
   • Beta blockers (e.g., metoprolol, carvedilol, bisoprolol) 2, 4
   • Mineralocorticoid receptor antagonists (e.g., spironolactone) 5
   • Diuretics for volume overload 2

2. Advanced therapies for refractory cases:

   • Cardiac resynchronization therapy (CRT) 2
   • Implantable cardioverter-defibrillator (ICD) for prevention of sudden cardiac death 2
   • Mechanical circulatory support 2
   • Heart transplantation 2

3. Specific etiologies:

   • Chemotherapy-induced cardiomyopathy: Early initiation of ACE inhibitors and beta blockers improves LVEF recovery 2
   • Peripartum cardiomyopathy: Standard heart failure therapy with special considerations for pregnancy/breastfeeding 2

Management of Complications

Atrial Fibrillation in Cardiomyopathy

1. Anticoagulation:

   • Direct-acting oral anticoagulants (first-line) or vitamin K antagonists (second-line) regardless of CHA₂DS₂-VASc score 2, 1
   • Required even for subclinical AF episodes >24 hours 2

2. Rate control:

   • Beta blockers, verapamil, or diltiazem based on patient preferences and comorbidities 2
   • Avoid digoxin in HCM as it can worsen outflow tract obstruction 2

3. Rhythm control:

   • Amiodarone or disopyramide for persistent symptoms 2
   • Consider radiofrequency ablation for refractory cases 2

Ventricular Arrhythmias

• Antiarrhythmic drugs for symptomatic ventricular arrhythmias 2
• ICD implantation for high-risk patients 2
• Heart transplantation assessment for recurrent life-threatening ventricular tachyarrhythmias refractory to maximal therapy 2

Special Considerations

Medications to Avoid

• In obstructive HCM:
  • Vasodilators (ACE inhibitors, ARBs, dihydropyridine calcium channel blockers)
  • Digoxin
  • High-dose diuretics (may exacerbate obstruction)

Monitoring

• Regular assessment of symptom status
• Periodic echocardiography to evaluate ventricular function
• ECG monitoring for arrhythmias
• Assessment of medication side effects and tolerance

Lifestyle Modifications

• Weight loss in obese patients
• Sodium restriction
• Regular moderate-intensity exercise (with appropriate precautions)
• Avoid dehydration and excess alcohol consumption
• Management of comorbidities (diabetes, obesity, sleep apnea)

Treatment Algorithm Based on Cardiomyopathy Type

1. Identify cardiomyopathy type through clinical evaluation, imaging, and possibly genetic testing
2. Assess for complications (heart failure, arrhythmias, thromboembolism)
3. Initiate type-specific therapy:
   • HCM: Beta blockers → calcium channel blockers → disopyramide → SRT
   • DCM: ACE inhibitors + beta blockers + MRAs + diuretics → advanced therapies
4. Manage complications as they arise
5. Monitor response and adjust therapy accordingly

This approach prioritizes mortality reduction, symptom improvement, and quality of life enhancement across the spectrum of cardiomyopathies.