Understanding the Need for Better Post-PCI Risk Prediction
Dual antiplatelet therapy (DAPT), typically aspirin plus a P2Y12 receptor antagonist, is standard after percutaneous coronary intervention (PCI) with drug-eluting stents. While this approach reduces stent thrombosis and major adverse cardiac events (MACE), individual responses to antiplatelet drugs vary widely. High residual platelet reactivity (HRPR) after clopidogrel and aspirin intolerance can leave patients at elevated risk for adverse outcomes. This has driven efforts to monitor platelet function and tailor therapy to individual patients.
The VerifyNow P2Y12 Assay and Its Limitations
VerifyNow P2Y12 is a widely used whole-blood assay that measures platelet reactivity following P2Y12 inhibition. It reports P2Y12 reaction unit (PRU), baseline values (BASE), and the percentage of platelet inhibition (%INH). Clinicians interpret these values against thresholds to gauge clopidogrel responsiveness. However, results can be influenced by factors such as platelet or leukocyte counts, hemoglobin, and hematocrit, potentially affecting risk stratification after PCI.
Introducing the COP-INH Score
A recent study integrated PRU and %INH into a composite COP-INH score to predict long-term outcomes in ACS patients undergoing PCI. The score ranges from 0 to 2: a score of 2 indicates both high PRU and low %INH, suggesting poor drug response and higher thrombotic risk; a score of 0 or 1 reflects more favorable platelet reactivity and inhibition. The COPD-INH score thus captures both the magnitude of P2Y12 reactivity and the efficacy of platelet inhibition, offering a more nuanced risk profile than PRU or %INH alone.
Key Findings
- Among 337 ACS patients who completed 12-month follow-up, those with COP-INH score = 2 had a notably higher rate of MACE (23.08%) compared with those with COP-INH scores of 0 or 1 (5.88%).
- Multivariate analysis showed COP-INH score = 2 as a significant predictor of MACE after 1 year, independent of age and sex. In contrast, PRU ≥ 230 or %INH < 40% alone did not retain independent predictive value after adjustment.
- Kaplan–Meier analysis linked COP-INH score 2 to poorer long-term survival relative to lower scores.
Clinical Implications
The COP-INH score could help clinicians identify ACS patients at higher risk of adverse cardiovascular events after PCI, enabling earlier optimization of antithrombotic strategies. Rather than relying on a single biomarker, this composite score provides a broader view of a patient’s platelet reactivity and drug responsiveness, which may guide personalized therapy adjustments—such as intensification of antiplatelet regimens or closer follow-up in high-risk individuals.
Limitations and Future Directions
The study informing the COP-INH score was single-center with a relatively modest sample size. External validation in larger, multi-center cohorts is needed to confirm its generalizability. Further research should also explore how COP-INH-guided therapy affects clinical outcomes and whether interventions based on this score translate into reduced MACE across diverse patient populations.
Conclusion
The COP-INH score represents a promising step toward personalized antiplatelet therapy after PCI in ACS patients. By combining P2Y12 reactivity and platelet inhibition into a single metric, COP-INH may improve risk stratification and help reduce adverse cardiovascular events in the critical first year after PCI.
