Dilated Cardiomyopathy (DCM)

Risk factors

• Genetic mutations — TTN (titin) most common, also LMNA (lamin A/C — high risk of arrhythmia), MYH7, RBM20, DSP
• Alcohol (chronic heavy use)
• Cocaine, methamphetamine, anthracyclines (doxorubicin), trastuzumab, immune checkpoint inhibitors
• Viral myocarditis (coxsackie B, parvovirus B19, HHV-6, HIV, SARS-CoV-2)
• Peripartum cardiomyopathy (late pregnancy to 5 months postpartum)
• Tachycardia-mediated (chronic uncontrolled AF, frequent PVCs)
• Autoimmune disease, hemochromatosis, thyroid disease
• Stress (takotsubo — reversible apical ballooning)

Pathophysiology

Insult to the myocardium triggers maladaptive remodeling: chamber dilation, eccentric hypertrophy, increased wall stress, and neurohormonal activation (renin-angiotensin-aldosterone, sympathetic) that worsens fibrosis and dysfunction. Functional mitral regurgitation develops from annular dilation. The dilated, fibrosed LV is prone to ventricular arrhythmia.

Clinical presentation

Differential diagnosis

• Ischemic cardiomyopathy — CAD distribution of wall motion abnormalities, prior MI, obstructive disease on cath; treat with revascularization plus GDMT
• Hypertensive cardiomyopathy — History of poorly controlled HTN with concentric LVH that has progressed to dilation; treat BP
• Valvular cardiomyopathy — Significant primary valvular disease driving LV dysfunction; correct valve
• Takotsubo (stress) cardiomyopathy — Reversible apical ballooning after emotional/physical stress; normal coronaries; recovers in weeks
• Peripartum cardiomyopathy — DCM presenting in late pregnancy or up to 5 months postpartum
• Cardiac amyloidosis — Restrictive physiology with thick walls but reduced voltage on ECG; PYP scan, light chains, biopsy
• Arrhythmogenic right ventricular cardiomyopathy — RV-predominant disease with epsilon waves, T-wave inversion V1-V3, family history of SCD

Diagnostic workup

Diagnostic algorithm

flowchart TD
  A[New DCM<br/>LVEF <40%, dilated LV] --> B[Etiology workup]
  B --> C[CAD: angiography]
  B --> D[Toxic: alcohol, cocaine,<br/>anthracyclines]
  B --> E[Infiltrative: amyloid, sarcoid,<br/>hemochromatosis]
  B --> F[Familial: cascade<br/>genetic testing]
  B --> G[Other: viral, peripartum,<br/>tachy-mediated]
  A --> H[Start GDMT 4 pillars<br/>ARNI/ACEi/ARB + β-blocker +<br/>MRA + SGLT2i]
  H --> I[Reassess EF at 3 months]
  I --> J{LVEF still ≤35%?}
  J -->|Yes, NYHA II-III| K[ICD ± CRT<br/>if QRS ≥150 LBBB]
  J -->|Improved| L[Continue GDMT]

Treatment

Complications

• Heart failure decompensation requiring hospitalization
• Sudden cardiac death from ventricular arrhythmia
• Atrial fibrillation
• LV thrombus and systemic embolization (especially stroke)
• Hepatic and renal dysfunction (cardiorenal, congestive hepatopathy)
• Progressive functional MR

PANCE pearls

• Bromocriptine has been studied for peripartum cardiomyopathy (suppresses prolactin) — variable evidence; AVOID further pregnancy in patients with persistent LV dysfunction.
• LMNA mutations carry a particularly high risk of sudden cardiac death and warrant lower ICD thresholds.
• Tachycardia-mediated cardiomyopathy (chronic AF, frequent PVCs) is potentially reversible with rate/rhythm control or PVC ablation.
• Alcoholic cardiomyopathy may improve substantially with sustained abstinence.
• All four pillars of GDMT should be initiated rapidly (often before discharge) — outcome benefit is additive and shows up within weeks.

References

• ACC/AHA/HFSA 2022 HF — 2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure (Heidenreich et al., JACC 2022)
• PARADIGM-HF — Angiotensin-Neprilysin Inhibition versus Enalapril in Heart Failure (McMurray et al., NEJM 2014)
• DAPA-HF — Dapagliflozin in Patients with Heart Failure and Reduced Ejection Fraction (McMurray et al., NEJM 2019)
• EMPEROR-Reduced — Empagliflozin in Heart Failure with Reduced Ejection Fraction (Packer et al., NEJM 2020)
• ESC 2023 Cardiomyopathies — 2023 ESC Guidelines for the Management of Cardiomyopathies (Arbelo et al., Eur Heart J 2023)