Malpractice or Negligence

My husband had a heart attack 6 weeks ago. After an emergency cath procedure, they found that he needed a quadruple bypass. He was scheduled immediately for the bypass and everything went seemingly like clockwork. He is only 45 years old and no former health problems or symptoms. He was released 5 days later in congestive heart failure and on oxygen. Thirteen hours later, he had a significant heart attack and his right coronary graft was failing. The surgeon said it was because the radial artery was used which is muscular, the cardiologist reported that he removed a blod clot, which caused the failure. This lead to 5 stents being placed in the graft. Four days later and one day after returning home, he had a stroke. My husband wasn't on blood thinners when he was sent home. The neurologist states that the stroke was caused by the second heart attack. The ER doc's first question was ''is he on thinners'' when I replied ''no'' he immediately left the room.

Do we have a case for Malpractice or negligence?