Diagnostic Approach to Cardiomegaly

Initial Evaluation

The American College of Cardiology recommends two-dimensional transthoracic echocardiography (TTE) as the primary imaging modality to rule out cardiomegaly, with key measurements including left ventricular wall thickness, left ventricular chamber dimensions, right ventricular size and function, ventricular mass calculation, systolic and diastolic function, and valvular abnormalities 1, 2
Left ventricular wall thickness is considered normal if less than 13 mm in adults, while a thickness of 15 mm or greater suggests hypertrophic cardiomyopathy (HCM) 1, 3
The European Heart Journal guidelines suggest assessing left ventricular chamber dimensions, right ventricular size and function, ventricular mass calculation, and systolic and diastolic function to evaluate cardiomegaly 4

Cardiovascular Magnetic Resonance (CMR) is superior to echocardiography for detecting subtle cardiac abnormalities and should be used when echocardiographic windows are inadequate, or to distinguish physiologic from pathologic hypertrophy, such as athlete's heart vs. HCM 2, 6, 3
CMR with late gadolinium enhancement (LGE) is useful for characterizing tissue and identifying fibrosis, and can quantify ventricular volumes and mass with high precision 8

The American College of Cardiology recommends obtaining a 12-lead Electrocardiogram (ECG) to assess for left ventricular hypertrophy (LVH) voltage criteria, conduction abnormalities, or arrhythmias 6, 9
Valvular heart disease, such as aortic stenosis or mitral regurgitation, can cause cardiac enlargement and should be excluded 5, 3
Infiltrative cardiomyopathies, such as amyloidosis or sarcoidosis, can also cause cardiac enlargement and should be considered 3, 8

In children, cardiomegaly on CXR has a low positive predictive value, and z-scores adjusted for body surface area should be used to evaluate left ventricular wall thickness, with a z-score greater than 2.5 suggesting early HCM 3
In adults, a maximal end-diastolic wall thickness of 15 mm or greater anywhere in the left ventricle indicates HCM, while a wall thickness of 13-14 mm can be diagnostic in family members of HCM patients or with positive genetic testing 3