Valproic Acid Combined With Postcardiac Arrest Hypothermic-Targeted Temperature Management Prevents Delayed Seizures and Improves Survival in a Rat Cardiac Arrest Model.

OBJECTIVES: High-dose valproic acid in combination with hypothermic-targeted temperature management has been reported to synergistically improve neurologic outcomes after cardiac arrest. This study investigated the potential synergistic mechanisms.

DESIGN: Prospective, randomized, experimental study.

SETTING: University research institution.

SUBJECTS: Male Long Evans rats.

INTERVENTION: Rats resuscitated from asphyxial cardiac arrest were randomized to one of the three groups: normothermic-targeted temperature management (37°C ± 1°C), hypothermic-targeted temperature management (33° ± 1° × 24 hr + placebo infusion), hypothermic-targeted temperature management plus high-dose valproic acid (300 mg/kg IV × 1 initiated 5 min post return of spontaneous circulation and infused over 20 min) (hypothermic-targeted temperature management + valproic acid).

MEASUREMENTS AND MAIN RESULTS: Seventy-two-hour survival was significantly greater with hypothermic-targeted temperature management + valproic acid, compared to hypothermic-targeted temperature management and normothermic-targeted temperature management (p < 0.05). Survival with good neurologic function, neurodegeneration, expression of HSP70, phosphorylation of Akt and Erk1/2 were not significantly different between hypothermic-targeted temperature management and hypothermic-targeted temperature management + valproic acid. The prevalence of seizures during the first 72-hour postcardiac arrest was significantly lower with hypothermic-targeted temperature management + valproic acid compared to hypothermic-targeted temperature management and normothermic-targeted temperature management (p = 0.01).

CONCLUSIONS: High-dose valproic acid combined with hypothermic-targeted temperature management prevents postcardiac arrest seizures and improves survival. It remains to be determined if the mechanism of seizure prevention is through the antiepileptic effect of valproic acid or direct neuroprotection. Overall, the combination of high-dose valproic acid and hypothermic-targeted temperature management remains a promising strategy to improve cardiac arrest outcomes.