Kris Jenner Sister Karen Houghton's Cause of Death Revealed

Kris Jenner's sister, Karen Houghton, passed away due to heart issues ... according to her death certificate. TMZ obtained a copy of the document which lists Karen's official cause of death as cardiac arrest and sudden cardiac arrhythmia. It also notes Type 2 diabetes as a secondary underlying cause. The docs also say Karen had bipolar disorder, and was cremated following her death on March 19. She was 65. TMZ…