Dilated cardiomyopathy

Disease of the heart muscle characterized by dilated ventricular chambers and systolic dysfunction (reduced contractility with LVEF <40%). Leads to heart failure with reduced ejection fraction and can progress to arrhythmias or death without intervention.

• Most common cardiomyopathy and a major cause of systolic heart failure (often requiring transplant). High morbidity/mortality due to pump failure and risk of sudden cardiac death from ventricular arrhythmias. Frequently tested with scenarios of reversible causes (alcohol, postpartum, myocarditis) and management of heart failure.

• Presents with heart failure symptoms: exertional dyspnea, fatigue, orthopnea, leg edema. Exam: displaced PMI, S3 gallop, often mitral/tricuspid regurgitation (holosystolic murmurs) from annular dilation.
• Common causes: ischemic cardiomyopathy (prior MI/CAD) is most common overall. Nonischemic etiologies include familial/genetic (~30%, often titin mutations), viral myocarditis (e.g., Coxsackie B), chronic alcohol abuse, anthracycline chemotherapy (doxorubicin), peripartum cardiomyopathy, prolonged tachyarrhythmias, and infiltrative or metabolic disorders (hemochromatosis, thyroid disease, wet beriberi, Chagas disease).
• Workup: Echocardiogram shows dilated ventricles with diffuse hypokinesis and low EF. ECG may show sinus tachycardia, conduction delays (LBBB) or arrhythmias. BNP is typically elevated. Chest X-ray reveals cardiomegaly. Coronary angiography is often performed to exclude ischemic disease.

1. Always evaluate for reversible causes: review medications, alcohol use, illicit drugs, recent viral illness, pregnancy, thyroid function (TSH), and check hemochromatosis screen, etc. Treat any identified cause (e.g., abstain from alcohol, control tachyarrhythmias, fix endocrine issues).
2. Exclude ischemic heart disease in new-onset DCM: perform stress testing or invasive coronary angiography to differentiate ischemic vs idiopathic cardiomyopathy (critical for management).
3. Genetic counseling/testing for familial DCM if young patient or family history of cardiomyopathy (mutations in titin, LMNA, etc., are common). Screen first-degree relatives with echocardiography.
4. Monitor for arrhythmias (e.g., atrial fibrillation or ventricular tachycardia); consider Holter monitoring. If LVEF remains <35% after 3+ months of optimal therapy, plan for ICD placement for primary prevention of sudden death; add CRT if QRS is prolonged (LBBB) and patient symptomatic.
5. Refer advanced cases for heart transplant evaluation or LVAD (bridge or destination therapy) if severe refractory heart failure.

1. Implement HFrEF therapy: ACE inhibitor (or ARNI) + beta blocker + mineralocorticoid antagonist + SGLT2 inhibitor to improve mortality; add diuretics for symptom relief. Tight control of blood pressure and avoid cardiotoxins.
2. Address specific causes: e.g., abstain from alcohol, revascularize if ischemic CAD, immunosuppressive therapy for giant-cell myocarditis, rate/rhythm control for tachycardia-induced DCM, etc.
3. Device therapy for advanced disease: if EF <35% persistently, place an ICD to prevent sudden death; consider biventricular pacemaker (CRT) if LBBB and low EF to improve synchronization. Severe refractory cases may require LVAD or heart transplant.

• Mnemonic: ABCCCD for dilated cardiomyopathy causes – Alcohol abuse, Beriberi (wet), Coxsackie B myocarditis, Cocaine, Chagas disease, Doxorubicin.
• S3 = Dilated (volume-overloaded ventricle); S4 = Hypertrophic/Restrictive (stiff ventricle).

• Unexplained syncope or sustained VT in DCM → high risk of sudden cardiac death (consider urgent ICD).
• Signs of systemic embolism (stroke, limb ischemia) in DCM → suspect LV mural thrombus; evaluate with imaging and anticoagulate if thrombus is present.

1. Suspect DCM in a patient with new-onset systolic heart failure (reduced EF) and enlarged heart on imaging.
2. Obtain echocardiography to confirm dilated chambers and reduced LVEF; concurrently, evaluate for ischemia (stress test or cath) to distinguish from ischemic HF.
3. Identify etiology: review history for alcohol, chemotherapy, recent viral infection, pregnancy, etc.; send labs (TSH, iron studies, viral titers as needed) and consider genetic testing if familial.
4. Start guideline-directed HF therapy (ACEi/ARB or ARNI, beta-blocker, MRA, SGLT2i) and remove/treat any offending causes. Ensure good blood pressure and volume control.
5. Follow up on EF and symptoms after a trial of therapy; if EF remains low, implement device therapy (ICD, CRT) as indicated. Refer to advanced heart failure center for transplant/LVAD evaluation if progressive despite treatment.

• Chronic alcoholic with progressive dyspnea, S3 gallop, and dilated heart on echo → alcoholic dilated cardiomyopathy.
• Woman in late pregnancy or early postpartum with acute heart failure (no valvular or coronary disease) → peripartum cardiomyopathy (DCM).
• Immigrant from rural Latin America with biventricular heart failure and megaesophagus/megacolon → Chagas disease causing DCM.