I cannot create a summary of the requested article because it is not found in the search results provided. The results include information about other cardiovascular studies and cases, but not about the March 2026 Science Volume 391 Issue 6789 article titled "Single intramuscular injection of self-amplifying RNA of Nppa to treat myocardial infarction." In order to create an accurate and factual summary as per your requirements, I would need access to the full text of this particular article.