Association between baseline lipoprotein (a) levels and restenosis after coronary stenting: Meta-analysis of 9 cohort studies

Background: Previous studies have shown inconsistent results on the association between baseline plasma Lipoprotein (a) [Lp(a)] levels and in-stent restenosis (ISR) after coronary stenting. Objective: We conducted a meta-analysis of observational studies to assess the association between baseline Lp(a) levels and the restenosis after successful coronary stenting. Methods: We searched for studies without language restriction in PubMed, Embase, Cochrane library, Ovid library database prior to October 2012. Random-effects method was applied to estimate the pooled standard mean difference (SMD). Heterogeneity, sensitivity and subgroup analysis were used to evaluate the results. Meta-regression analysis was employed to investigate sources of heterogeneity. Results: 9 cohort studies including 1834 patients (600 ISR and 1234 no-ISR patients) were eligible for our analysis. Overall, we found significantly elevated baseline Lp(a) levels in ISR (in-stent restenosis) patients (SMD = 0.42, 95% CI: 0.14-0.71, P = 0.003). High heterogeneity existed between the individual studies (P < 0.001, I-2 = 86.9%). The association was stronger in the Asian population than the overall association found. Further, similar observations were made in the subgroup with drug-eluting stent and the group in which Lp(a) was assayed by immunoturbidimetry. Multivariable regression analysis suggested that ethnicity was the major source of heterogeneity in the data (P = 0.036). Conclusions: Our meta-analysis suggests that significantly elevated baseline plasma Lp(a) level is associated with ISR. The Lp(a) level appears to be a good predictor of ISR, especially in the Asian population or patients who received drug-eluting stent implantation. Further research is warranted to evaluate the association by taking the ethnicity and type of stent into account. (C) 2013 Elsevier Ireland Ltd. All rights reserved.