7th March 2024

Investigations

The diagnosis of DCM requires imaging demonstrating cardiac dilation, typically with a left ventricular ejection fraction <45% and an LV end-diastolic diameter >117% of the predicted value, with other causes of myocardial disease excluded.

This is most commonly diagnosed on echocardiography, given the greater availability of the modality, but it can be seen or confirmed via other modalities such as cardiac MRI. Cardiac MRI can also provide useful information regarding the quality of the myocardial tissue including myocardial fibrosis, a greater extent of which is a poor prognostic marker. Both will often show an element of functional valvular regurgitation i.e., valvular disease due to dilation of the valve annulus not due to an intrinsic defect in the valve itself.

Reductions in global longitudinal strain and strain rate can also be seen prior to dilation and reductions in ejection fraction.

ECG can be relatively nonspecific, showing ST or T wave changes, sinus tachycardia or a bundle branch block due to the increased distance that the electrical impulses have to travel in the enlarged heart.

Given that genetic links are not uncommon, it is standard to perform a detailed family tree and offer genetic counselling if a link is suggested. This can involve inviting other family members in for genetic testing to identify the nature of the putative mutation.