Has anyone ever survived a heart attack without medical attention

Of course. Heart attacks are not always severe. They're never good, and should ALWAYS be addressed, but they're not always massive life stopping events. Often times, small heart attacks are misdiagnosed as anxiety attacks. Symptomatically, they're very similar.

yes, there are many people have survived after heart attack without any medical attention. Actually it depends on the intensity of the heart attack. In most common cases of mild heart attack you do not need any medical attention. check out this site for more information on this subject
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When ur echocardiogram said, ''myocardial infarction''. The cardio knows that u have not had one heart attack. He/She will say, ''you have a silent heart attack before!''

So as an ECG, it also showed that u have a heart muscle damaged before. Emmm, the doctor will raise a question, ''when u have had a heart attack?'' If no documentary or as u know. ''You have a silent heart attack sometimes ago!''

It may be one silent attack, it could be a multiple silent heart attacks. You still survived.

25% of heart attacks detected on routine ECG in the Framingham Heart Study were silent. They never had any symptoms. Silent attacks are more common in diabetics. They have painless attacks due to diabetic involvement of the sensory nerves necessary to transmit the pain signals from the heart to the brain.

Sure. People have been told months and even years later that they've had heart attacks that they never knew.