Heartburn is a common medical condition (which unfortunately for me I am familiar with). Therefore people will be seeking related information online, and the domain has traffic potential. "Anti heartburn" is understandable in the medical advice context, although the term isn't perhaps the most common. People would more often talk about "Heartburn treatments" rather than "Anti heartburn treatments". That said, the domain is descriptive and understandable.
The domain's main appeal will be to independent site developers.