Discounting the security of the leads attached to the body, and ECG is not very reliable as a source for any anatomical irregularities caused by a prior myocardiopathy infarction, etc. Requires further testing, related symptoms and signs assessment.
Symptoms include shortness of breath, possibly chest pain, fatigue, etc. But it is possible to have had a mild heart attack and no symptoms. I had no symptoms or warning of having had a silent heart attack until congested heart failure and ICU for several days to stabilize oxygen levels, stent implant, etc..
It is proper protocol to follow up with further testing if the EKG is positive. An echocardiogram would be appropriate to determine if there is any heart wall movement impairment, size of heart chambers, the amount of blood pumped into circulation with each heartbeat, etc. If you had a silent heart attack, you may not have any symptoms until heart failure when the heart is to weak to adequately pump enough blood to meet the oxygen demand. My condition was 6 years ago, and with treatment my heart pumps normally, but an enlarged heart (now normal size) may have contributed to a mitral valve problem.
It is proper to rule out any silent MI.