100 QUESTIONS IN CARDIOLOGY

52 What investigation protocol should a patient

with dilated cardiomyopathy undergo?

Niall G Mahon and W McKenna

A protocol for the investigation of dilated cardiomyopathy should

aim to confirm the diagnosis, rule out treatable causes, prevent

potential complications and determine prognosis. The following

investigations are routinely used:

11 Echocardiography.Two-dimensional echocardiography is the major

diagnostic test. Cardiac dimensions and systolic function are also

of prognostic value, with an approximately 2-fold increase in

relative risk of mortality for every 10% decline in ejection

fraction.^1 The presence of intracardiac thrombi, as well as poor

systolic function itself, may be indications for anticoagulation.

22 Electrocardiography. Twelve-lead electrocardiography and Holter

monitoring for arrhythmias should be performed. Occasionally

a diagnosis of incessant tachycardia as a cause of the cardio-

myopathy may be made. The signal averaged ECG may be a

useful predictor of risk of sudden death and progressive heart

failure and should be performed where available.2, 3

33 Metabolic exercise testingis of prognostic value, particularly in

advanced disease, and may guide referral for cardiac trans-

plantation.

44 Screens for metabolic causesshould routinely include liver function

tests for unsuspected alcohol excess, thyroid function tests and

iron studies including transferrin saturations. Further

investigation (such as for sarcoid or amyloid) should be guided

by history and examination.

Other tests may also be performed, but are not indicated in

every case:

11 Coronary angiographyshould be performed in patients over the

age of 40 years, or who have risk factors or symptoms or signs

suggestive of coronary disease.

22 Coxsackie and adenoviral titresshould be tested where there is a

history of recent suspected myocarditis or recent viral illness, but

the value of these in established cardiomyopathy is questionable.