The most serious complication of the vasculitic stage is heart disease, which is the cause of nearly one-half of all deaths in patients with EGPA. Among heart disease-related deaths, the most usual cause is inflammation of the heart muscle caused by the high level of eosinophils, although some are deaths due to inflammation of the arteries that supply blood to the heart or pericardial tamponade. Kidney complications have been reported as being less common. Complications in the kidneys can include glomerulonephritis, which prevents the kidneys' ability to filter the blood, ultimately causing wastes to build up in the bloodstream.