'American Pickers' Star Frank Fritz Official Cause of Death Revealed

Late "American Pickers" star Frank Fritz died from a stroke, TMZ has learned ... this according to officials.

According to Frank's death certificate, obtained by TMZ, the immediate cause of death is "late sequela of cerebral infarction" ... medical jargon for a stroke.

The document says Frank's fatal stroke was a result of cerebral vascular disease ... a condition that affects blood flow and blood vessels in the brain.

Frank also suffered from aortic stenosis -- a chronic condition that makes it difficult for blood to flow from the heart to the rest of the body -- and COPD ... according to the certificate, with both conditions playing a role in his death.

As we reported ... Frank died Sept. 30 in a hospice facility in the Midwest, surrounded by friends, including his longtime "American Pickers" costar Mike Wolfe.

Frank's rep previously told us he died from the effects of a stroke he had several years ago ... and that's confirmed in the death certificate.

The documents also say the official time of death was 8:50 PM, the manner of death was natural and his body has since been cremated.

Frank was 60.