Final answer:
The likely cause of acute onset of abdominal pain in this patient is acute diverticulitis.
Step-by-step explanation:
The likely cause of acute onset of abdominal pain in a patient with CAD (coronary artery disease) and XR revealing "thumbprinting" in the bowel is acute diverticulitis. Diverticulitis is a digestive disease characterized by the infection and inflammation of the pouches (diverticula) in the large intestine. It can cause sudden lower abdominal pain, fever, nausea, constipation or diarrhea, and blood in the stool.