Summary
About 30% of patients with acute ST-segment elevation myocardial infarction (STEMI)
undergoing recanalisation of the infarct-related coronary artery do not achieve valid
myocardial reperfusion (no-reflow phenomenon or coronary microvascular obstruction
[MVO]). The mechanisms of MVO are incompletely understood. In this study we investigated
the role platelet activation in the pathogenesis of coronary MVO in STEMI patients.
We enrolled 48 STEMI patients (age 56.2 ± 11 years; 31 men), treated by primary percutaneous
coronary intervention (PCI) followed by double anti-platelet treatment, and 20 control
patients with stable coronary artery disease (CAD) on single antiplatelet treatment
(age 57.5 ± 6 years, 12 men). STEMI patients were divided into two groups: 35 patients
with complete myocardial reperfusion (MR) and 13 patients with coronary MVO despite
successful PCI. Platelet activation was assessed on admission and at one-month follow-up
by measuring platelet receptor expression and monocyteplatelet aggregates (MPAs).
Platelet receptor expression, platelet receptor conformational change for fibrinogen
binding availability and MPA formation were increased in STEMI patients with MVO compared
to both STEMI patients with MR and stable CAD patients, both on admission and at one-month
follow-up (p<0.05 for all). Among STEMI patients, platelet activation is greater in
those who display coronary MVO, compared to those with MR, after successful PCI, both
on admission and one month after STEMI, suggesting that enhanced platelet activation
might be involved in the pathogenesis of MVO. The persistence of enhanced platelet
activation despite double classical anti-platelet therapy suggests that new anti-platelet
strategies should be considered in patients with coronary MVO.
Keywords
Microvascular obstruction - platelet aggregation - monocyte-platelet aggregates -
adenosine - primary PCI