Clinical Research Directory

Hypertrophic cardiomyopathy (HCM) is defined as the presence of increased LV wall thickness (with or without RV hypertrophy) or mass that is not solely explained by abnormal loading conditions.

Dilated cardiomyopathy (DCM) is defined as the presence of LV dilatation and global or regional systolic dysfunction unexplained solely by abnormal loading conditions (e.g. hypertension, valve disease, CHD) or CAD.Very rarely, LV dilatation can occur with normal ejection fraction (EF) in the absence of athletic remodelling or other environmental factors; this is not in itself a cardiomyopathy, but may represent an early manifestation of DCM. The preferred term for this is isolated left ventricular dilatation. Right ventricular dilatation and dysfunction may be present but are not necessary for the diagnosis.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is defined as the presence of predominantly RV dilatation and/or dysfunction in the presence of histological involvement and/or electrocardiographic abnormalities in accordance with published criteria.

The NDLVC phenotype is defined as the presence of non-ischaemic LV scarring or fatty replacement regardless of the presence of global or regional wall motion abnormalities (RWMAs), or isolated global LV hypokinesia without scarring.

Restrictive cardiomyopathy (RCM) is defined as restrictive left and/or RV pathophysiology in the presence of normal or reduced diastolic volumes (of one or both ventricles), normal or reduced systolic volumes, and normal ventricular wall thickness.Restrictive cardiomyopathy commonly presents as biatrial enlargement. Left ventricular systolic function can be preserved, but it is rare for contractility to be completely normal. Restrictive pathophysiology may not be present throughout the natural history, but only at an initial stage (with an evolution towards a hypokinetic-dilated phase). Restrictive physiology can also occur in patients with end-stage hypertrophic and dilated cardiomyopathy; the preferred terms are 'hypertrophic' or 'dilated cardiomyopathy with restrictive physiology'. Restrictive ventricular physiology can also be caused by endocardial pathology (fibrosis, fibroelastosis, and thrombosis) that impairs diastolic function

The term 'left ventricular non-compaction' (LVNC) has been used to describe a ventricular phenotype characterized by prominent LV trabeculae and deep intertrabecular recesses. The myocardial wall is often thickened with a thin,compacted epicardial layer and a thickerendocardial layer. Left ventricular non-compaction is frequently a familial trait and is associated with variants in a range of genes, including those encoding proteins of the sarcomere, Z-disc, cytoskeleton, and nuclear envelope. Left ventricular non-compaction has also been used to describe an acquired and sometimes transient phenomenon of excessive LV trabeculation (e.g. in athletes, during pregnancy, or following vigorous activity)that must reflect increased prominence of an otherwise normal myocardial architecture, given that cardiomyocytes are terminally differentiated and the formation of new cardiac structures is impossible.The Task Force does not consider LVNC to be a cardiomyopathy in the general sense.