Perfusion stress test takes images of the blood flow through the vessels at rest and during exertion. There is some abnormal blood flow through the vessel(s) during the exertion phase usually indicating some blockage.
Normal LV function indicates the heart is pumping blood in the normal range of 55-75% of oxygenated blood received from the lungs.
Ischemia (lasck of blood flow) can cause chest pain (angina), etc.