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(Stroke. 2007;38:1269.)
© 2007 American Heart Association, Inc.

Original Contributions

Magnesium for Treatment of Acute Lacunar Stroke Syndromes

Further Analysis of the IMAGES Trial

Stella Aslanyan, PhD; Christopher J. Weir, PhD; Keith W. Muir, MD, FRCP; Kennedy R. Lees, MD, FRCP for the IMAGES Study Investigators

From the Division of Cardiovascular and Medical Sciences (S.A., K.R.L.), the Robertson Centre for Biostatistics (C.J.W.), and the Division of Clinical Neurosciences (K.W.M.), University of Glasgow, Glasgow, Scotland.

Correspondence and reprint requests to Dr S. Aslanyan, Division of Cardiovascular and Medical Sciences, University of Glasgow, Gardiner Institute, Western Infirmary, Glasgow G11 6NT, UK. E-mail stella_s_aslanyan{at}hotmail.com

Background and Purpose— A prespecified interaction analysis of the neutral Intravenous Magnesium Efficacy in Stroke (IMAGES) trial revealed significant benefit from magnesium (Mg) in patients with noncortical stroke. Post hoc analysis indicated that this effect was seen in lacunar clinical syndromes (LACS), interaction P=0.005. We have now examined whether this interaction could be explained by confounding baseline factors.

Methods— LACS was defined on the basis of neurological signs and did not include imaging. We investigated the interaction between baseline variables and Mg treatment on global outcome. We used logistic-regression models to test whether the Mg-LACS interaction remained significant after adjusting for stratification variables, sex, a novel stroke severity score, and baseline variables that had an interaction with treatment (P<0.1).

Results— The Mg (n=383) and placebo (n=382) groups of LACS patients were well matched on baseline factors. In addition to LACS, we found an interaction between beneficial Mg treatment effect and younger age (P=0.003), higher baseline diastolic blood pressure (P=0.02), higher mean blood pressure (P=0.02), and absence of ischemic heart disease (P=0.07). Even so, the adjusted Mg-LACS interaction remained significant (odds ratio [OR] 0.57; 95% CI, 0.39 to 0.83; P=0.003). In the LACS subgroup, Mg improved Barthel Index <95 (OR 0.73; 95% CI, 0.55 to 0.98), modified Rankin Scale >1 (OR 0.67; 95% CI, 0.50 to 0.91), and global outcome (OR 0.70; 95% CI, 0.53 to 0.92) but not Barthel Index <60 or mortality.

Conclusions— The positive treatment effect of Mg in LACS cannot be ascribed to general issues of severity, time to treatment, blood pressure, or other baseline factors; equally, this finding may be due to chance. A large trial of Mg treatment in LACS appears justified.

Key Words: clinical trials • lacunar syndrome • magnesium

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