From the Guidelines
Dilated cardiomyopathy (DCM) is defined as a heart muscle disease characterized by left ventricular (LV) dilatation and global or regional systolic dysfunction, not attributable to abnormal loading conditions or coronary artery disease, as stated in a recent systematic review 1. The diagnostic criteria for DCM include:
- Left ventricular dilation with reduced systolic function, typically defined as a left ventricular ejection fraction (LVEF) less than 45% and increased left ventricular end-diastolic diameter
- Exclusion of other causes of ventricular dysfunction such as coronary artery disease, valvular heart disease, congenital heart defects, hypertension, or toxin exposure
- Clinical presentation often includes symptoms of heart failure like dyspnea, fatigue, and fluid retention, though some patients may be asymptomatic in early stages
- Family history is important as 30-50% of cases have genetic causes, with autosomal dominant inheritance being most common The diagnosis of DCM is ultimately made through a combination of clinical evaluation, imaging findings showing the characteristic ventricular enlargement with reduced contractility, and exclusion of alternative explanations for the cardiac dysfunction, as highlighted in the European Heart Journal 1. Key diagnostic tools include:
- Echocardiography
- Cardiac MRI
- Laboratory tests such as B-type natriuretic peptide (BNP) or NT-proBNP levels
- Electrocardiogram findings frequently include left bundle branch block, atrial fibrillation, or ventricular arrhythmias
- Endomyocardial biopsy may be performed to identify specific etiologies like inflammation or infiltrative diseases.
From the Research
Criteria for Dilated Cardiomyopathy
The criteria for dilated cardiomyopathy include:
- Left ventricular ejection fraction (LVEF) ≤35% 2
- Left ventricular dilatation, with an end-diastolic left ventricular volume ≥133.57±31.58 mL and an end-systolic left ventricular volume ≥99.9±26.03 mL 3
- Left atrial volume ≥61.63±27.13 mL 3
- Left ventricular end-diastolic diameter ≥66.11±7.3 mm and end-systolic diameter ≥57.7±8.02 mm 3
- Diastolic dysfunction, with grade II or III diastolic dysfunction being the most common 3
- Clinical symptoms such as dyspnea, with patients often being in New York Heart Association (NYHA) classes II-IV 4, 5, 6
Prognostic Factors
Prognostic factors for dilated cardiomyopathy include:
- LVEF ≤30% 4
- Left ventricular end-diastolic pressure ≥10 mm Hg 4
- Cardiothoracic ratio ≥54% 4
- Episodes of heart failure 4
- Left ventricular end-diastolic volume ≥200 ml/m2 4
- Dyspnea of NYHA class III or IV 4
- Absence of smoking 4
- Absence of moderate systemic hypertension 4
- Electrocardiographic evidence of left ventricular hypertrophy 4
- Mean systemic arterial pressure ≥95 mm Hg 4
- Late gadolinium enhancement ≥7.5% on cardiac magnetic resonance imaging 2
- Left atrial volume index ≥68.3 mL/m2 2
- NT-proBNP (N-terminal pro-B-type natriuretic peptide) 2
- Family history of sudden cardiac death 2