The etiology of combined mitral regurgitation and aortic regurgitation is commonly rheumatic, but it may occur with connective tissue disorders, and infective endocarditis.

The typical murmur of mitral regurgitation is holosystolic and best heard at the apex, while that of aortic regurgitation is diastolic, decrescendo and best heard at the mid left sternal edge. Both the apical diastolic flow murmur of severe mitral regurgitation and the Austin-Flint murmur of severe aortic regurgitation can mimic mitral stenosis.