What are the causes of a dilated left ventricular (LV) cavity?

Causes of Dilated Left Ventricular Cavity

Dilated cardiomyopathy (DCM) is the most common cause of a dilated left ventricular cavity, characterized by LV or biventricular dilation with systolic dysfunction in the absence of abnormal loading conditions or significant coronary artery disease. 1

Primary (Genetic) Causes

• Inherited cardiomyopathies:
  • Familial dilated cardiomyopathy (various genetic mutations)
  • Left-dominant arrhythmogenic cardiomyopathy 2
  • Late-stage hypertrophic cardiomyopathy (end-stage evolution) 3
  • Left ventricular non-compaction cardiomyopathy 4

Secondary (Acquired) Causes

• Infectious/Inflammatory:

  • Viral myocarditis 4
  • Bacterial, fungal, or parasitic infections
  • Immune-mediated myocarditis 1

• Toxic/Drug-induced:

  • Alcohol cardiomyopathy
  • Chemotherapeutic agents (anthracyclines)
  • Cocaine and other recreational drugs
  • Anorectic drugs 4

• Metabolic/Endocrine:

  • Thyroid disorders
  • Pheochromocytoma
  • Diabetes mellitus
  • Nutritional deficiencies (thiamine, selenium, carnitine)

• Cardiovascular Conditions:

  • Chronic pressure overload (hypertension, aortic stenosis)
  • Chronic volume overload (aortic regurgitation, mitral regurgitation) 4
  • Tachycardia-induced cardiomyopathy 2
  • Ischemic cardiomyopathy (from coronary artery disease)
  • Right ventricular failure with ventricular interdependence 4

• Systemic Diseases:

  • Sarcoidosis 4
  • Amyloidosis (advanced stages)
  • Hemochromatosis
  • Connective tissue disorders (lupus, scleroderma)

• Other Causes:

  • Peripartum cardiomyopathy
  • Stress-induced cardiomyopathy (Takotsubo) 2
  • Idiopathic dilated cardiomyopathy 5

Physiologic Causes

• Athletic heart syndrome: Up to 15% of elite athletes demonstrate significant LV enlargement with end-diastolic dimensions up to 70 mm in men and 66 mm in women 4
  • Usually associated with normal or enhanced systolic function
  • Proportional wall thickening
  • Normal diastolic function

Diagnostic Considerations

Distinguishing Pathological from Physiological Dilation

• Pathological signs include:

  • Reduced ejection fraction (<50%) 4
  • Spherical remodeling of LV cavity 4
  • Regional wall motion abnormalities
  • Mitral regurgitation from annular dilation 4
  • Disproportionate chamber enlargement (LV vs RV) 4
  • Arrhythmias (present in ~30% of DCM patients) 4

• Athletic heart features:

  • Preserved systolic function (though EF may be low-normal, ~45-50%)
  • Proportional chamber enlargement
  • Normal diastolic function
  • Regression of changes with detraining 4

Emerging Concept

The European Society of Cardiology has recognized hypokinetic non-dilated cardiomyopathy (HNDC) as a distinct entity, characterized by LV systolic dysfunction without dilation 2, 6. This may represent an early stage of DCM, with similar mortality outcomes despite less severe heart failure symptoms 6.

Clinical Implications

Understanding the cause of LV dilation is crucial for appropriate management. While athletic remodeling is benign, pathological dilation requires specific treatment based on etiology. Early identification of DCM is important as it can lead to heart failure, arrhythmias, and sudden cardiac death if left untreated 4.

For athletes with suspected pathological dilation, comprehensive evaluation including ECG, echocardiography, CMR, exercise testing, and potentially genetic testing is recommended before clearing them for competitive sports 4.