Plasma tau protein in comatose patients after cardiac arrest treated with therapeutic hypothermia

Background: Neurological outcome after cardiac arrest (CA) is difficult to predict in the acute phase. In this pilot study, we assessed blood levels of tau protein as a prognostic marker for the neurological outcome after 6 months in patients treated with hypothermia after resuscitation from CA.

Methods: 22 unconscious patients resuscitated after CA were treated with mild hypothermia (32-34°C) for 26 h. Blood samples were collected at 2, 6, 12, 24, 48, and 96 h after CA, and the concentration of tau protein was analyzed. Neurological outcome was assessed with the Glasgow-Pittsburgh cerebral performance category (CPC) scale at intensive care unit (ICU) discharge and after 6 months. The higher of the two CPC scores was used.

Results: At ICU discharge, 21/22 patients were alive, of whom 10 had a good (CPC 1-2) outcome. After 6 months, 15/22 patients were alive, of whom 14 had a good outcome. Tau protein levels were higher among those with a poor outcome at 48 h and 96 h. At 96 h sampling, tau concentration predicted a poor outcome (CPC 3-5) with a sensitivity of 71% and a specificity of 93%.

Conclusions: Although in a pilot study, a late increase in plasma tau protein seems to be associated with a worse outcome after hypothermia treatment after CA, although more studies are needed.