The study aims to see if a special system, called the **XVIVO Heart Preservation System (XHPS)**, can safely and effectively preserve and transport hearts that don't fully meet current standards for heart transplants. The hearts are kept in a non-ischemic state, meaning they get enough oxygen and nutrients during transport. This is a continuation of a previous trial called the **PRESERVE IDE trial**. **Here are some key points to consider:** - Participants must be at least 18 years old and waiting for a heart transplant. - The study seeks to help with the approval process of the **XVIVO Heart Assist Transport (XHAT) System**. - The study is open to those not involved in other trials or with specific medical conditions. Hearts used in this study are from donors who might not typically qualify, such as older donors or those with certain heart conditions. The study helps gather more information while awaiting official approval for the system, allowing it to be potentially used more widely in the future.