Dilated cardiomyopathy

Disease Description (Causes and Symptoms)

• Definition summary: Cardiomyopathy characterized by dilation of the left ventricle or both ventricles and reduced contractile function, occurring in the absence of significant pressure/volume overload such as coronary artery disease, hypertension, or valvular disease.
• Causes: There are various acquired causes, including genetic factors (gene abnormalities observed in approximately 20–40% of familial cases; some gene abnormalities also reported in nonfamilial cases), infectious or autoimmune myocarditis, toxic substances (excessive alcohol, heavy metals), cardiotoxic anticancer agents or other medications, endocrine and metabolic diseases (diabetes, thyroid abnormalities), and peripartum (postpartum) cardiomyopathy.
• Pathophysiology: Damage to myocardial fibers causes the ventricles to dilate and contractile force to decrease, resulting in reduced cardiac output, left ventricular remodeling, and symptoms of heart failure.
• Main symptoms: Shortness of breath during activity (exertional dyspnea), breathlessness that worsens at rest or when lying down (orthopnea), paroxysmal nocturnal dyspnea, fatigue, weakness, palpitations (arrhythmia), and peripheral edema.

Treatment Methods and Precautions

• Standard pharmacological treatment (treatment recommended by heart failure guidelines)
  • ACE inhibitor or ARB or ARNI (angiotensin receptor–neprilysin inhibitor)
  • Beta-blocker (when tolerated)
  • Mineralocorticoid receptor antagonist (MRA)
  • SGLT2 inhibitor (depending on the heart failure indication)
  • Diuretics (to control fluid overload)
  • If necessary, symptom-relieving medications such as digoxin
• Device and procedural treatment
  • Implantable cardioverter-defibrillator (ICD): For prevention of sudden death when specific LVEF criteria are met
  • Cardiac resynchronization therapy (CRT): When there is dyssynchronous left ventricular contraction
  • Left ventricular assist device (LVAD) or heart transplantation: For end-stage heart failure that cannot be controlled with medications or devices
  • Anticoagulation therapy: When an intracardiac thrombus is present or the risk of thromboembolism is high
• Cause-specific treatment
  • Viral/autoimmune myocarditis: Antiviral or immunotherapy may be considered depending on the cause (at the specialist’s discretion)
  • Toxic causes: Stop alcohol or the causative medication and eliminate exposure to harmful substances
  • Correction of endocrine abnormalities (thyroid and diabetes control)
• Lifestyle management
  • Limit salt intake, monitor weight and symptoms (shortness of breath and edema), take medications regularly, and report immediately in the event of rapid weight gain
  • Limit alcohol and stop smoking; engage in appropriate exercise (caution: aerobic exercise tailored to symptoms is recommended, and strenuous exercise should be avoided)
  • Vaccination (such as seasonal influenza vaccination) is recommended
  • If pregnancy is planned, prior consultation is necessary (there is a risk of causing or worsening the condition, especially during pregnancy)
• Precautions and risk of complications
  • Risk of sudden death due to arrhythmias (ventricular tachycardia and ventricular fibrillation)
  • Risk of intracardiac thrombus and embolism
  • Worsening long-term prognosis due to progressive heart failure
  • Possibility of recurrence if medications are stopped even after improvement in contractile function (in patients with improved function, there is a risk of recurrence within approximately 6 months after stopping medication)

Checklist Before an Outpatient Visit (Including Preparation Items and Example Questions)

• Items to bring
  • List of currently used medications (prescriptions and medication bags), including dosage instructions and frequency
  • Previous test results (echocardiography, electrocardiography, blood tests, cardiac MRI, coronary artery tests, etc.) and imaging materials (CD/USB if possible)
  • Records of symptom changes: shortness of breath (during exercise or at rest), orthopnea or nocturnal dyspnea, weight changes (over the past several days or weeks), and whether edema is present
  • Past medical history (myocarditis, history of anticancer treatment, intoxication or alcohol use, thyroid disease, diabetes, etc.) and family history (cardiomyopathy or sudden death)
  • Lifestyle information (amount of exercise, alcohol consumption, smoking status, and pregnancy plans)
  • Cards or records related to currently used devices (pacemaker or ICD)
• Information to tell the healthcare provider in advance during the outpatient visit
  • Recent worsening of symptoms (breathlessness, fainting/dizziness, or rapid weight gain)
  • Newly started medications or supplements (which may interact with heart failure medications)

General Example Questions to Ask the Doctor

• What do you think is the cause of this condition? Are additional tests needed?
• What is my current cardiac contractile function (LVEF), and what does this value mean?
• Which medications are recommended, and what are the main side effects of each?
• In what situations is device therapy such as an ICD or CRT needed?
• What is the most important lifestyle change I should make first?

Examples of Condition-Specific Questions

• If a genetic cause is suspected, do you recommend family testing (genetic testing) and family screening (echocardiography and electrocardiography)? If so, which test should be started first?
• If contractile function improves, should medication treatment still be continued? What is the risk of recurrence if treatment is stopped?