LTE uses two different radio links for downlink and uplink, that is, from tower to device, and vice versa. For the downlink, LTE uses an OFDMA (orthogonal frequency division multiple access), which requires MIMO.
What you are referring to is called plaque, and it's a hallmark of atherosclerosis or arteriosclerosis (they both mean the same thing). Basically, cholesterol deposits end up lining the interior walls (lumen, intima) of the arteries narrowing the opening.
Plaque is the fatty substance that forms blockages in the arteries. Bits of plaque that break off can clog arteries or blood vessels elsewhere in the body and potentially cause a heart attack or stroke. Complications such as these are very rare. In the rare cases of a heart attack during angioplasty, the patient almost never experiences any significant medical issues or heart damage.