Article continues below advertisementIn the ongoing investigation into the disappearance of 84-year-old Nancy Guthrie, mother of Today show co-anchor Savannah Guthrie, sleep expert Pat Byrne recently warned that she was at a "very high risk" of a heart attack during her suspected abduction.According to Byrne's analysis on former prosecutor Nancy Grace's "Crime Stories" podcast, the circumstances of her early-morning disappearance on February 1 created a dangerous medical scenario.Pat explained that being violently or abruptly woken at 2 a.m.