Objectives To observe the change of platelet function in the coronary circulation before and after percutaneous coronary intervention (PCI) in the patients with coronary heart disease and provide a guide to clinical drug usage.

Methods Blood was obtained from the coronary sinus before and after PCI. The levels of platelet-activating factor (PAF) were determined by the bioassay and the concentration of thromboxane B₂ (TXB₂), 6-keto-PGF_1a in plasma were determined using radioimmunoassay.

Results 108 patients with unstable angina and 121 patients with stable angina pectoris were compared, we found patients with unstable angina platelet activating factor was significantly higher than those with stable angina before PCI (p<0.05). The levels of platelet-activating factor were significantly increased after PCI, 10 min to reach the peak, then back to normal at 30 min, both had the same trend. The levels of TXB₂ in unstable angina group were clearly higher than those with stable angina before PCI, both significantly increased after PCI, 10 min to peak, 30 min down to preoperative levels; and 6-keto-PGF_1a in both groups showed a transient ischaemic decline, 10 min to restore to the preoperative level after PCI.

Conclusions The change of PAF, TXB₂ and 6-keto-PGF_1a levels in patients with coronary heart disease after PCI, were associated with platelet activation.