Hematologic Parameters, Atherosclerotic Progression, and Prognosis in Patients With Previous Coronary Artery Bypass Grafting (from the Post CABG Trial)

Although inflammatory markers and anemia have both been associated with prognosis in patients with cardiovascular disease, their relation with atherosclerotic progression in patients with previous coronary artery bypass grafting (CABG) is unknown. A total of 1,273 patients enrolled in the Post CABG Trial who had undergone CABG 1 to 11 years before entry were studied. Subjects were randomly assigned to lovastatin in low or high doses and low-dose warfarin or placebo in a factorial design. Subjects underwent coronary angiography at baseline and after a mean follow-up of 4.3 years. White blood cells (WBCs), hemoglobin, and platelets were measured at baseline in all subjects. Graft progression was defined as a decrease ≥0.6 mm in lumen diameter at the site of greatest change at follow-up. During follow-up, 195 subjects sustained a clinical event and 857 grafts developed significant worsening. Risk of clinical events tended to be greater with higher WBC counts, with hazard ratios for ascending quartiles of 1.4 (95% confidence interval [CI] 0.9 to 2.2), 1.6 (95% CI 1.0 to 2.6), and 1.6 (95% CI 1.0 to 2.7). WBC count also tended to be associated with significant atherosclerotic progression, particularly in subjects assigned to placebo rather than warfarin (p interaction = 0.04). There was no association of hemoglobin or platelet count with risk of clinical events or graft progression, but few trial subjects were anemic. In conclusion, WBC count is associated with a graded increase in cardiovascular events in patients with coronary artery bypass grafts.