another thing to consider are the comorbid conditions that patients may have...being overweight places extra strain on the heart, thus one good reason for having the ekg done...it looks at the electrical function of the heart and can provide evidence of past injury to heart muscle or current injury that the patient may not even be aware of.
the chest xray is used as an indicator of whether or not pneumonia may be present but if a patient has other active disease processes, like COPD, asthma, etc, it can give a quick snapshot of their current state.
bloodwork wise, a quick very basic breakdown would look something like: a CBC would show whether a patient is anemic or has any current infection; a CMP (complete metabolic panel) is a broad screening tool used to evaluate organ function and check for conditions like diabetes, liver disease, and kidney disease. It may also be ordered to monitor known conditions, like hypertension, and to monitor people who are taking specific medications for any kidney or liver related side effects.
i hope some of this helps...
best of luck,
d-