Can just doing an ekg and blood test tell if you are at risk for getting a heart attack?

ECG : An ECG and a blood test can suggest the presence of risk factors for heart attack. As there are many risk factors and many aren't reflected in ECG or a single blood test, there is only partial information in the two test scenario.

Not really: Better at telling if one is having one! some blood tests can suggest risk- hyperlipidemia, diabetes, hyper triglycerides etc.