Prolapsed MV happens when the heart is pumping blood into circulation the pressure billow (rather than tightily close) the valve leaflets back into the left atrium causing the blood to back flow. The decreased output of blood into circulation can cause the heart to beat faster (make up for the blood lost to the back flow) and if the there is a deficity of blood/opxygen in circulation will cause shortness of breath.
Yes, you should be concerned with a fast heart rate as that can cause irregular heartbeats which is a serious condition and can cause cardiac arrest. A resting heart rate is normal at 70 to 100, and the 162 is not very very high and may not cause a problem, but the underlying cause should be treated.