The best way to test if you have heart failure
is to get evaluated by a doctor. After evaluation, if there are features of heart failure or at least a clinical suspicion, investigations like ECG, Chest X-ray, echocardiogram
and the currently popular blood test
for BNP - brain type natriuertic peptide can be done. BNP is released from the heart muscle in response to stretch due to heart failure. But any test report has value only if analysed along with clinical details and not in isolation.