Apolipoproteins as predictors of ischaemic stroke in patients with a previous transient ischaemic attack.

BACKGROUND: Weak associations between total and LDL cholesterol and ischaemic stroke compared with coronary heart disease (CHD) are at odds with the similar effectiveness of statin drugs in preventing ischaemic stroke and CHD, suggesting that other lipid sub-fractions that are affected by statins might be better predictors of ischaemic stroke. Apolipoprotein B levels are reduced by statins and are a stronger predictor of CHD than total and LDL cholesterol in patients both on and off statins. However, there are very few published data on apolipoproteins and stroke risk and no studies in patients with previous transient ischaemic attack (TIA). METHODS: We performed a prospective cohort study of the associations of baseline total cholesterol, LDL, HDL, apolipoproteins A1 and B (apo A1; apo B) and risk of ischaemic stroke in 261 patients with previous TIA. Cox proportional hazards models were used to determine crude and multivariate-adjusted hazard ratios (HR) above versus below median values at 10-years follow-up. RESULTS: The apo B/apo A1 ratio was the strongest independent predictor of ischaemic stroke (HR=2.94, 95% CI 1.43-5.88, p=0.003) followed by apo B (HR=2.26, 95% CI 1.16-4.38, p=0.02). The associations between total cholesterol, LDL, HDL, LDL/HDL ratio and apo A1 and ischaemic stroke risk did not reach statistical significance. CONCLUSIONS: Apo B and the apo B/apo A1 ratio are predictive of ischaemic stroke in patients with previous TIA. Further studies are required to determine whether the prognostic value of apolipoprotein levels is maintained in patients on statins.