What organ is most affected by stroke? the heart/circulatory or brain and spinal cord?

BRAIN: The term "stroke" refers to an apoplectic event causing brain injury due to acute decrease in blood flow due to a variety of causes. Although, vascular problems can occur in spinal cord, many neurologists prefer term, "cord infarction", instead of spinal cord stroke. If it involves heart, we term it a "heart attack" or myocardial infarction. (some docs like "brain attack" label for stroke).

The brain: In the classic sense, stroke affects the brain. The far majority are ischemic (due to lack of blood flow) with a much smaller percent hemorrhagic (ususally from ruptured cerebral aneurysm) .Spinal cord "strokes" are much less common.

Brain: Stroke is a condition that primarily affects the brain.There are ischemic strokes where a particular blood vessel is blocked and the part of the brain that is perfused is deprived of blood/oxygen and then dies.There are hemorrhagic strokes where there is the accumulation of blood in the brain (intracerebral hemorrhage)or aneuysmal bleed where the blood spills out into the outer layers of the brain.