Background Acute coronary syndrome (ACS) patients are at increased risk of cardiovascular events, despite optimal antiplatelet medication. Thrombotic events depend on the propensity for thrombus formation and the efficacy of endogenous thrombolytic activity in preventing lasting arterial occlusion. Until recently, there has been no physiological test available to assess endogenous thrombolytic activity.
Methods We measured endogenous thrombolytic status (lysis time) in 214 ACS patients using the global thrombosis test, a novel near-patient test that measures spontaneous thrombolysis in native blood (lysis of a platelet-rich thrombus in the absence of added plasminogen activators). Patients receiving aspirin and clopidogrel for 48 h or more were tested during their index admission and were followed up for major adverse cardiac events (MACE; composite of recurrent ACS, stroke or cardiovascular death) over 253 ± 11 days.
Results Lysis time in ACS patients showed a bimodal distribution when compared with healthy volunteers (fig A). The majority of ACS patients had lysis times of less than 5000 s (group1, 84%), but a second peak was seen at lysis times greater than 5000 s (group 2, 16%). Using survival analysis (fig B), MACE occurred in 40% of patients with lysis times greater than 5000 s compared with 14.6% in those with lysis times less than 5000 s. Impaired lysis time was associated with increased MACE, with a relative risk of 2.7, and a hazard ratio of 2.33 (p = 0.006). The mean time to event was 125 ± 19 days.