Acute coronary syndrome is a manifestation of coronary artery disease caused by decreased blood flow to the heart musculature resulting in ischaemia and infarction of the heart. The Lewis (Le) blood group system comprise mainly Lewis a & b antigens which are secreted in plasma and are expressed on red cells, platelets and endothelium. This study assesses the risk of multivessel disease in acute coronary patients with lewis negative (a− b−) phenotype.

The study included 183 patients diagnosed with acute coronary syndrome and who underwent coronary angiography to detect stenosis of the coronary vessels. The severity of the disease was classified based upon the number of vessels stenosed and their blood sample was phenotyped for Lewis antigens. The patients’ risk factors, GRACE score and management were included for the study and multivariate logistic regression was carried out for analysis.

The prevalence of Lewis (a− b−) was 27.4% and there was a significant association with multivessel disease (P<0.05). However, there was no association of lewis (a− b−) with any of the risk factors causing coronary disease. The adjusted odds ratio of triple vessel disease in lewis (a− b−) was 2.6, female gender was 0.6 and patients with diabetes mellitus was 3.1, respectively. The GRACE score showed a significant association with ABO blood group (P<0.05) but not with lewis (a− b−).

Lewis negative patients are more likely to develop triple vessel disease compared to other lewis blood groups. This warrants further studies to investigate the link between lewis system and atherothrombosis.