Stages of Chronic AR The most common causes of chronic severe AR in the United States and other high-income countries are BAV disease and primary diseases of the ascend- ing aorta or the sinuses of Valsalva. Rheumatic heart disease is the leading cause of AR in many low- to middle-income countries. With calcific valve disease, regurgitation often accompanies AS, but the degree of regurgitation usually is mild to moderate, not se- vere. In most patients with AR, the disease course is chronic and slowly progressive, with increasing LV volume overload and LV adaptation via chamber dila- tion and hypertrophy. Management of patients with AR depends on an accurate diagnosis of the cause and stage of the disease process. Table 15 shows the stages of AR, ranging from patients at risk of AR (Stage A) or with progressive mild to moderate AR (Stage B) to severe asymptomatic (Stage C) and symptomatic (Stage D) AR. Each of these stages is defined by valve anatomy, valve hemodynamics, se- verity of LV dilation, and LV systolic function, as well as by patient symptoms. CLINICAL STATEMENTS AND GUIDELINES Table 15. 