Spontaneous Coronary Artery Dissection (SCAD) is a tear and/or intramural hematoma formation, which leads to partial or complete occlusion of the coronary artery. It causes blood to build up in the space between the layers of your artery wall causing a decrease in the blood flow or a complete blockage of blood flow to your heart – damaging your heart muscle and heart rhythm. This reduced blood flow could cause a heart attack or cardiac arrest.