Table 1.
Main gross and histologic features of primary inherited cardiomyopathies
| HCM | ACM | DCM | RCM | |
|---|---|---|---|---|
| Gross features | ||||
| Heart size/weight | Increased/normal | Normal/increased | Increased/normal | Normal |
| Wall thickness | Increased/normal/decreased | Normal/decreased/increased | Decreased/normal | Normal |
| RV dilatation | No | No/yes | Yes | No |
| LV dilatation | No/yes | No/yes | Yes | No |
| Atria | Normal/dilated LA | Normal/dilated RA | Normal/dilated LA | Very dilated RA-LA |
| Valve abnormalities | No/MV anterior leaflet thickening | No/TV anulus dilatation | MV anulus dilatation and PM displacement | No |
| Coronary arteries | Possible myocardial bridge | No disease-related abnormalities | No disease-related abnormalities | No disease-related abnormalities |
| Myocardial hypertrophy | Usually concentric, various patterns | No | Usually eccentric | No |
| Myocardial scarring LV | No/yes, multifocal | No/yes, subepicardium-midmural-transmural | No/yes, midmural confluent | No |
| Myocardial scarring RV | No | Yes | No | No |
| Myocardial fat in LV | No | No/yes | No | No |
| Myocardial fat in RV | No | Yes/no | No | No |
| Aneurysms |
No/yes LV apical |
No/yes, usually RV multiple locations | No | No |
| Hypertrabeculation |
No/yes LV |
No/Yes LV RV |
No/Yes, LV RV | No |
| Endocardium | Normal/impact lesion LVOT | Normal/mural thrombosis | Mural thrombosis/organized/fibroelastosis | Normal |
| Pericardium | Normal | Normal | Normal | Normal |
| Phenocopies/differential diagnosis | Hypertension, storage, metabolic, amyloidosis, aortic stenosis, aortic coarctation, elderly basal septal hypertrophy, anabolic drug abuse, idiopathic LVH, chronic IHD | Fatty heart, chronic myocarditis, sarcoidosis, muscular dystrophy, Chagas disease, chronic IHD, DCM | Muscular dystrophy, acute myocarditis, chronic myocarditis, sarcoidosis, end-stage HCM, ACM L, chronic IHD, toxic, alcohol, drugs | Loeffler endocarditis EMF, amyloidosis, sarcoidosis hemochromatosis |
| Histologic features | ||||
| Myocyte hypertrophy | Yes | No/yes | Yes | No |
| Myocyte disarray | Yes | No | No | Yes |
| Myocyte degeneration | Yes | Yes | Yes | No |
| Interstitial fibrosis | Yes | Yes | Yes | Yes |
| Replacement fibrosis | No/Yes (midmural, multifocal subendocardial) | Yes (subepicardium-midmural-transmural) | No/Yes (midmural confluent) | No |
| Endocardial fibrosis | No/yes | No/yes | Yes | No |
| Inflammation | No | Yes/no | Yes/no | No |
| Fibro-fatty tissue RV/LV | No | Yes (subepicardium- midmural-transmural) | No | No |
| Obstructive SVD | Yes/no | No | No | No |
ACM, arrhythmogenic cardiomyopathy; ACM-L, arrhythmogenic cardiomyopathy left variant; DCM; dilated cardiomyopathy; EMF; endomyocardial fibrosis; HCM, hypertrophic cardiomyopathy; IHD, ischemic heart disease; LA, left atrium; LV, left ventricle; LVH, left ventricular hypertrophy; LVOT; left ventricular outflow tract; MV, mitral valve; PM, papillary muscles; RCM, restrictive cardiomyopathy; RA, right atrium; RV, right ventricle; SVD; small vessel disease; TV, tricuspid valve