Prognostic impact of high residual platelet reactivity after chronic total occlusion percutaneous coronary intervention in patients with diabetes mellitus.

Background: The study sought to determine the impact of high residual platelet reactivity (HRPR) on long-term cardiac mortality in diabetic patients treated with PCI for CTO. No data exist about the impact of HRPR after 600 mg clopidogrel loading on long-term clinical outcome in patients with diabetes mellitus and treated with percutaneous coronary angioplasty (PCI) for chronic total occlusion (CTO).

Methods: From the Florence CTO-PCI registry, we identified consecutive diabetic patients with available in vitro platelet reactivity assessment by light transmittance aggregometry after a loading dose of 600 mg of clopidogrel. HRPR was defined as residual platelet aggregation by 10 μmol/L ADP test ≥70%. The primary end point of the study was long-term cardiac mortality.

Results: Two-hundred and three diabetic patients underwent CTO-PCI. The incidence of HRPR was 23%. The 3-year cardiac survival was lower in the HRPR group than the low residual platelet reactivity (LRPR) group (70 ± 7% and 92 ± 3%, respectively; p=0.001). Within the oral antidiabetic patients there were no significant differences in long-term survival between HRPR and LRPR groups. Conversely, the association of insulin therapy and HRPR was related to a dramatic decrease in survival compared to the LRPR group (34 ± 14% vs. 89 ± 4%; p<0.001). At multivariable analysis insulin therapy (HR 4.31; p=0.001) and HRPR (HR 3.26; p=0.004) were significantly related to long-term mortality, while completeness of revascularization was inversely related to cardiac mortality (HR 0.40; p=0.029).

Conclusion: HRPR is a strong marker of increased risk of cardiac death in patients with DM who underwent PCI for CTO.