Differentiating ischemic from nonischemic cardiomyopathy poses a particular
problem, but this is important prognostically and therapeutically. Patients with
ischemic cardiomyopathy have worse prognosis than the patients with idiopathic
dilated cardiomyopathy. Joseph et al, in 1983 have demonstrated that in patients with
severe chronic left ventricular failure, mortality rate in patients with coronary artery
was 46% and 69% at 1 and 2 years, respectively compared with 23% and 48% at 1
and 2 years in those with idiopathic dilated cardiomyopathy. In 1997, Bradley and
colleagues also have shown ischemic etiology is a significant independent predictor of
mortality in patients with cardiomyopahy.
Therapeutically also it is important to distinguish between ischemic and
nonischemic cardiomyopathy because the diagnosis influences the management.
Antiplatelets and lipid lowering therapy are important in management of patients
with cardiomyopathy of ischemic etiology. Revascularisation in patients with low
ejection fraction and significant coronary artery disease is strongly associated with
improved survival and should be considered in all patients with ischemic
cardiomyopathy and proven hibernation. Moreover ischemic cardiomyopathy may not
respond to medical therapy as favorably as patients with nonischemic
cardiomyopathy.
Differentiating ischemic from nonischemic cardiomyopathy clinically is not
always easy. Although ischemic cardiomyopthy is generally a late consequence of
clinically established coronary artery disease, sometimes the clinical course is really
occult and indistinguishable from idiopathic cardiomyopathy. An ischemic cause is
probable in patients with history of definite or documented prior myocardial
infarction or left ventricular aneurysm in echocardiogram. However, some patients
with ischemic cardiomyopathy have neither history nor electrocardiographic evidence of myocardial infarction, never complaint of chest pain and shows
diffuse rather than regional hypocontractility. Conversely many patients with
idiopathic dilated cardiomyopathy report frequent episodes of chestpain and
have electrocardiographic evidence of myocardial infarction.
CONCLUSIONS :
(1) Tissue Doppler Imaging during dobutamine stress is a simple,
and effective non-invasive modality in differentiating ischemic
from nonischemic dilated cardiomyopathy.
(2) Blunted response to dobutamine identifies ischemic cardiomyopathy.
(3) Tissue Doppler Imaging was especially useful in patients with
left bundle branch block and dilated cardiomyopathy.
(4) Tissue Doppler Imaging findings correlate well with coronary angiogram
