Does the mitral valve prolapse increase, decrease, or not change stroke volume (the amount of blood exiting the ventricle with each ventricular contraction) ?

Answer: this depends on the direction of flow of blood

Explanation:

The mirror valve prolapse also known as mirror regurgitation occurs when part of the mitral valve slips backwards loosely into the left atrium and this can be as a result of damage or the abnormal size of the mitral valve tissues.

This thing physiological aftermaths of mirror valve prolapse includes

1. reduced forward stroke volume (reduced stroke volume of blood exiting the ventricles to flow to other parts of the body

2. Increased left atrial volume and pressure. Due to the backwards flip of the valve, and instead of being closed each ventricular contraction, blood flows into the left atrium increasing the volume and its pressure producing pulmonary oedema.