Decreased platelet reactivity and faster endogenous fibrinolysis in patients with STEMI were found to predict spontaneous reperfusion, which was associated with smaller infarcts and improved survival, according to a study published May 8 in JACC.

In this prospective, observational, single-center study, Rahim Kanji, BSc (Med), MBBS, et al., analyzed biomarkers in blood taken before their PCI from 801 patients presenting with a STEMI. They examined in vitro, point-of-care, occlusion times (OT) and endogenous lysis times (LT), as well as major cardiovascular events including death, myocardial infarction or stroke over four years.

Spontaneous reperfusion, defined as Thrombolysis in Myocardial Infarction grade 3 flow in the infarct-related artery (IRA) before PCI, was identified in 148 of the 801 patients (18%), during emergency coronary angiography, similar with the known approximately 20% rate of spontaneous reperfusion seen in STEMI.

Results showed spontaneous reperfusion vs. no spontaneous reperfusion, respectively, was associated with a longer OT (435 seconds vs. 366 seconds; p<0.001) and shorter LT (1,257 seconds vs. 1,616 seconds; p<0.001) along with lower troponin levels and better left ventricular function. When comparing the two measures, LT was superior for predicting spontaneous reperfusion (area under the curve for LT, 0.707; 95% CI, 0.661-0.753 vs. area under the curve for OT, 0.629; 95% CI, 0.581-0.677).

Researchers also found that in patients with spontaneous reperfusion, those with complete, as opposed to partial ST-segment resolution, had a longer OT (p=0.002) and shorter LT (p<0.001). They noted that "spontaneous reperfusion was unrelated to clinical characteristics or pain-to-angiography times."

Over the four-year follow-up, the rate of major adverse cardiovascular events was lower in patients with spontaneous reperfusion than those without (4.1% vs. 10.6%; p=0.013). Furthermore, in patients with both spontaneous reperfusion and complete ST-segment resolution vs. no spontaneous reperfusion, the rate was 1.5% vs. 10.1%; p=0.029.

The authors write, "Patients with spontaneous reperfusion have a more favorable thrombotic profile in vitro, with reduced platelet reactivity and more efficient endogenous fibrinolysis, compared with those without spontaneous reperfusion." They add, "This finding indicates a possible role for modulating global thrombotic status early following the onset of STEMI, to facilitate spontaneous reperfusion and a decrease in infarct size and mortality, which will need to be assessed in future trials."

In an accompanying editorial comment, Robert F. Storey, MD, DM, and William A.E. Parker, MD, PhD, MBBCH, add "the observations provided by Kanji, et al., provide a foundation for the further exploration of pharmacological interventions that increase endogenous fibrinolysis in patients presenting with STEMI or, alternatively, treat impaired endogenous fibrinolysis in patients at high risk of coronary atherothrombosis."

Clinical Topics: Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Stable Ischemic Heart Disease, Vascular Medicine, Interventions and Imaging, Interventions and Vascular Medicine, Angiography, Nuclear Imaging, Chronic Angina

Keywords: ST Elevation Myocardial Infarction, Fibrinolysis, Troponin, Percutaneous Coronary Intervention, Ketamine, Follow-Up Studies, Myocardial Infarction, Coronary Angiography, Reperfusion, Biomarkers, Thrombolytic Therapy

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