Background and Purpose—Calcium (Ca²⁺) plays a role in the cellular and molecular pathways of ischemic neuronal death. We evaluated the impact of both early and delayed Ca²⁺ levels on clinical outcomes from acute ischemic stroke.

Methods—The relations between blood calcium level obtained early (<4.5 hours), and delayed (72 to 96 hours) after ischemic stroke onset versus clinical outcomes were analyzed in 826 subjects enrolled in an international trial in the Virtual International Stroke Trials Archive. Subjects were categorized into Ca²⁺ quartiles. Outcome measures analyzed included baseline and 72- to 96-hour stroke severity, as well as 3-month functional and global disability scales. The independent effect of calcium on outcome was evaluated by median and logistic regression analysis.

Results—Six hundred and fifty-nine (80%) of the trial subjects had complete baseline data including Ca²⁺ levels. Bivariately, the highest delayed Ca²⁺ quartile (versus lowest) was associated with lesser stroke severity and better 3-month functional and independence scale outcomes (all P<0.001), but no significant outcome differences were noted among early Ca²⁺ levels. In multivariable analysis, delayed Ca²⁺ in the highest quartile (versus lowest quartile) was associated with greater 3-month independence score on the Barthel Index scale (76.9 versus 55.4, P=0.006). No other significant outcome differences were noted between highest and lowest quartiles for both early and delayed Ca²⁺ quartiles.

Conclusions—Elevated 72- to 96-hour serum Ca²⁺ levels independently predict greater independence 3 months after ischemic stroke, but very early serum Ca²⁺ appear not to have any prognostic significance.