This study is looking at the safety and effectiveness of a device called the **HeartMate 3 LVAS** for people with serious heart failure. Heart failure is when the heart can't pump blood well enough. In some cases, a device called a **Left Ventricular Assist Device (LVAD)** can help the heart pump better. This study compares using the HeartMate 3 device to regular heart medicine for patients who walk around but have a serious form of heart failure.
Participants will be monitored for elevated **pulmonary artery pressure (PAP)**, a sign that can show worsening heart failure. This is done using a small device called the **CardioMEMS PA Sensor** that measures PAP inside the body.
- Participants must have had a hospital stay for heart failure and agree to use the CardioMEMS sensor.
- The study will last across multiple locations with two types of participants: those getting the HeartMate 3 and those not.
- Participants must be 18 or older and cannot have used certain heart medicines recently.