Stroke generally occurs when blood supply to the brain is reduced or interrupted which results in the deprivation of oxygen and nutrients to the brain tissues. In this case the blood vessel clogs or bursts. Heart failure is phenomenon in which the heart is unable to pump blood efficiently around the body. Heart failure might lead to an erratic heart rate due to which the heart forms blood clots which travel to the brain blocking the blood supply to the heart. Cholesterol, high blood pressure, smoking and diabetes may increase the risk of stroke and it also causes heart failure. Heart failure is also diagnosed in people who have already had a heart attack.