Mean platelet volume in patients with slow coronary flow and its relationship with clinical presentation.

OBJECTIVES: We investigated mean platelet volume (MPV) in patients with slow coronary flow (SCF) and its possible relationship with clinical presentation.

STUDY DESIGN: The study included 50 patients with SCF and otherwise normal coronary arteries and 22 patients (control group) with normal coronary arteries. In the SCF group, there were 26 patients with stable angina pectoris (SAP), and 24 patients with unstable angina pectoris (USAP). Coronary blood flow was measured using the TIMI frame count. To determine MPV, blood samples with K3 EDTA were processed after one hour of venipuncture. The relationship between MPV and SCF was sought.

RESULTS: The mean TIMI frame count was markedly increased in patients with SCF compared to controls (p<0.0001). No significant differences existed between the groups with regard to white blood cell and platelet counts. Patients with SCF had significantly higher MPV values compared to controls (9.4+/-2.3 fl vs 8.1+/-2.0 fl, p=0.014). In subgroup analysis, MPV was significantly increased only in patients presenting with USAP, compared to patients with SAP (p=0.044) and controls (p=0.002). There was a positive correlation between the mean TIMI frame count and MPV in patients with SCF (r=0.32, p=0.01). In multivariate analysis, MPV was the only independent predictor of SCF (p=0.006, odds ratio=1.305, 95% CI=0.985-1.730).

CONCLUSION: Our findings show that MPV is increased in patients with SCF, and SCF patients presenting with USAP exhibit significantly increased MPV values, suggesting an altered platelet reactivity and aggregation which may require effective anti-platelet therapy in this patient subgroup.