Even though cardiologists consider themselves master of ischemic heart disease , their collective clinical acumen is put into acute stress test when they confront a patient with dilated LV and severe LV dysfunction.This is not a rare situation in clinical cardiology we stumble upon such instances often .Most of them are conferred a tag of DCM .
The differentiation from ischemic vs idiopathic or primary muscular is not a wasted academic exercise , since ischemic DCM may get reversed with revascularisation .We have various tests to differentiate ischemic from idiopathic like CAG,MRI, 3D RTE, etc . Still common sense would tell us 95 % of times we can differentiate ischemic DCM from non ischemic by asking two critical questions in the bed side echocardiogram
- Is there a regional wall motion defect ?
- Does all 4 chambers of the heart is enlarged ?
Idiopathic DCM is primary disease of muscle hence the cardiac muscle as a whole fails ( We know they are a single folded muscle sheet )
Since Ischemic DCM primarily affect left ventricle and left atrium RV,RA enlargement are terminal events.
* Please note the traditional dependence on CAG to diagnose ischemic DCM is fraught with a risk of missing small vessels induced DCM,
*** If atrial fibrillation is present longstanding it can dilate both atrium but still RV will be normal in sized in ischemic DCM until very late stages
Here is a 20 second flow chart to differentiate ischemic DCM from idiopathic