Open Access Open Badges Research article

Coronary collaterals and risk for restenosis after percutaneous coronary interventions: a meta-analysis

Pascal Meier1*, Andreas Indermuehle2, Bertram Pitt3, Tobias Traupe4, Stefano F de Marchi5, Tom Crake1, Guido Knapp6, Alexandra J Lansky7 and Christian Seiler4

Author Affiliations

1 The Heart Hospital London, University College London Hospital Trust, London, UK

2 St Thomas' Hospital, Department of Cardiology, King's College London, UK

3 University of Michigan Medical Center, Department of Cardiology, Ann Arbor, MI, USA

4 University Hospital Bern, Department of Cardiology, Bern, Switzerland

5 University of Oslo, Department of Cardiology, Oslo, Norway

6 TU University Dortmund, Department of Statistics, Dortmund, Germany

7 Yale University Medical Center, Department of Cardiology, New Haven, CT, USA

For all author emails, please log on.

BMC Medicine 2012, 10:62  doi:10.1186/1741-7015-10-62

Published: 21 June 2012



The benefit of the coronary collateral circulation (natural bypass network) on survival is well established. However, data derived from smaller studies indicates that coronary collaterals may increase the risk for restenosis after percutaneous coronary interventions. The purpose of this systematic review and meta-analysis of observational studies was to explore the impact of the collateral circulation on the risk for restenosis.


We searched the MEDLINE, EMBASE and ISI Web of Science databases (2001 to 15 July 2011). Random effects models were used to calculate summary risk ratios (RR) for restenosis. The primary endpoint was angiographic restenosis > 50%.


A total of 7 studies enrolling 1,425 subjects were integrated in this analysis. On average across studies, the presence of a good collateralization was predictive for restenosis (risk ratio (RR) 1.40 (95% CI 1.09 to 1.80); P = 0.009). This risk ratio was consistent in the subgroup analyses where collateralization was assessed with intracoronary pressure measurements (RR 1.37 (95% CI 1.03 to 1.83); P = 0.038) versus visual assessment (RR 1.41 (95% CI 1.00 to 1.99); P = 0.049). For the subgroup of patients with stable coronary artery disease (CAD), the RR for restenosis with 'good collaterals' was 1.64 (95% CI 1.14 to 2.35) compared to 'poor collaterals' (P = 0.008). For patients with acute myocardial infarction, however, the RR for restenosis with 'good collateralization' was only 1.23 (95% CI 0.89 to 1.69); P = 0.212.


The risk of restenosis after percutaneous coronary intervention (PCI) is increased in patients with good coronary collateralization. Assessment of the coronary collateral circulation before PCI may be useful for risk stratification and for the choice of antiproliferative measures (drug-eluting stent instead bare-metal stent, cilostazol).

coronary collateral circulation; meta-analysis; restenosis; therapy failure