VESS26 - Viscoelastic Assays Identify Significant Variability of Antiplatelet Response in Patients with Peripheral Artery Disease

Objectives: Antiplatelet therapy is a pillar of management in peripheral artery disease (PAD) and the only antithrombotic medications with level 1A evidence. Nearly all PAD patients are prescribed antiplatelet therapy to render their platelets non-functional and decrease thrombotic risk. However, there is a significant subset of PAD patients who are resistant to certain antiplatelet medications and therefore have an increased risk of graft/stent thrombosis unbeknownst to the surgeon.
Currently, no data has been published regarding the variability of antiplatelet medication response in revascularized patients and no point-of-care testing to determine platelet function is presently incorporated into treatment guidelines to identity which patients are gleaning benefit from these medications. Viscoelastic testing such as thromboelastography with platelet mapping (TEG-PM) affords an opportunity to evaluate real-time coagulation dynamics and platelet function but has not been studied in the PAD population. This prospective, observational study aimed to delineate variation in response to anti-platelet therapy in PAD patients undergoing revascularization, and correlate patient outcomes associated with thrombosis.

Methods: All patients prescribed antiplatelet therapy who underwent named lower extremity vessel revascularization during December 2020–November 2021 at a large tertiary institution were prospectively included. TEG-PM assays were sampled pre-operatively and at serial intervals postoperatively up to six months. The distribution of platelet aggregation was assed using a Kolmogorov-Smirnov test of normality, and tests of variance, skewness, and interquartile range (IQR). The outcomes of thrombosis, infection and amputation were correlated with platelet mapping distribution.

Results: 211 blood samples from 91 individual patients were collected. Platelet aggregation was not normally distributed. The median platelet aggregation in patients on mono-antiplatelet therapy (MAPT) was 80.5% [range 0-100, IQR 23.5]. The median platelet aggregation in patients on dual antiplatelet therapy (DAPT) was 61.5% [range 3.7-100, IQR 43.6] (Table I). Histogram analysis confirmed a widely varied distribution in patients on either MAPT or DAPT. In the 28 patients who developed postoperative infection (53.6%) or thrombosis (46.4%), samples just prior to the event clustered in the third and fourth quartiles platelet aggregation (Figure 1).

Conclusions: There is significant variability in platelet mapping in revascularized PAD patients on antiplatelet therapy. Postoperative complications including infection and thrombosis clustered towards the higher quartiles of this range, indicating a propensity for macrovascular and microvascular thrombotic events as compared to patients with reduced aggregation. Thromboelastography with platelet mapping may provide integral insight to an individual’s platelet response to treatment and an opportunity to augment management with a patient-specific approach.