Former President George W. Bush had a 95% coronary artery blockage, a condition that could have resulted in a "grave cardiac event" if it hadn't been identified during an August physical at the Cooper Clinic in Dallas, according to experts. Bush underwent a CT angiogram after his physicians noted changes in his electrocardiogram. The former president was subsequently treated with a stent, which some observers have questioned. "Every case is different," said interventional cardiologist Dr. Jonathan Reiner. "... But it's a very important vessel. If you occlude that particular artery, it can kill you."