Mean platelet volume and its relation to insulin resistance in non-diabetic patients with slow coronary flow

Background: Increased mean platelet volume is a central process in the pathophysiology of coronary heart disease. Insulin resistance contributes to increased platelet activation. Aim: To assess the mean platelet volume and its possible relationship with insulin resistance in non-diabetic patients with slow coronary flow. Methods and subjects: The study included 60 patients with slow coronary flow and 20 subjects (controls) with normal coronary arteries. Slow coronary flow patients were divided into 2 groups, insulin resistant (32 patients) and insulin sensitive (28 patients) according to the homeostasis model assessment of insulin resistance index (HOMA-IR). Results: Patients with slow coronary flow had significantly higher mean platelet volume values (7.9 +/- 0.47 vs. 7.1 +/- 0.5, p < 0.01), insulin level (10.8 +/- 3.2 vs. 8.2 +/- 1.4, p < 0.01), and HOMA-IR scores (2.72 +/- 0.85 vs. 1.84 +/- 0.19, p<0.01). These parameters were significantly higher in insulin-resistant patients than in insulin-sensitive ones. The mean platelet volume was correlated with HOMA-IR (r = 0.52, p<0.01) and insulin level (r=0.58, p < 0.01). In multivariate analysis, mean platelet volume and HOMA-IR were independent predictors of mean TIMI frame count \{(B +/- SE = 0.562 +/- 2.95, p < 0.01) and (B +/- SE = 0.538 +/- 2.46, p < 0.01), respectively\}. Conclusion: Patients with slow coronary flow have increased mean platelet volume which was associated with insulin resistance in non-diabetic slow coronary flow patients. TIMI frame counts correlated with mean platelet volume and increased insulin resistance. Thus, insulin resistance and platelet activity may have a role in the pathogenesis of slow coronary flow. Also, they may have a possible benefit as follow-up markers in non-diabetic patients with slow coronary flow. (C) 2011 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.