Detection of coronary microembolization by Doppler ultrasound in patients with stable angina pectoris undergoing elective percutaneous coronary interventions

Background - Intracoronary Doppler guidewires can be used for real-time detection and quantification of microembolism during percutaneous coronary interventions (PCIs). We investigated whether the frequency of Doppler-detected microembolism is related to the incidence of myonecrosis during elective PCI. Methods and Results - The study population included 52 consecutive patients (aged 64 +/- 10 years; 36 men, 16 women) with coronary artery disease who underwent elective PCI of a single-vessel stenosis. Using intracoronary Doppler ultrasound, we compared the frequency of microembolism during PCI in 22 patients with periprocedural non-ST-segment elevation myocardial infarctions (pNSTEMI) and 30 patients without pNSTEMI. The 2 groups were comparable with regard to their clinical and procedural characteristics. In the group with pNSTEMI, the total number of coronary microemboli after PCI (27 +/- 10 versus 16 +/- 8, P < 0.001) was higher than in the group without pNSTEMI. Although high-sensitivity C-reactive protein plasma levels were similar before PCI (2.9 +/- 2.2 versus 3.4 +/- 1.7 mg/L, P=NS), they were higher in the group with pNSTEMI after PCI (12.6 +/- 10.4 versus 6.1 +/- 5.1 mg/L, P < 0.05). Microembolic count independently correlated to postprocedural cardiac troponin I elevation (r=0.565, P < 0.001), coronary flow velocity reserve (r=-0.506, P < 0.001), and baseline average peak velocity (r=0.499, P < 0.001). Conclusions - Patients with pNSTEMI had a significantly higher frequency of coronary microembolization during PCI, and their systemic inflammatory response and microvascular impairment after PCI were more pronounced. Intracoronary Doppler ultrasound provides evidence that pNSTEMI in patients undergoing elective PCI is caused by microembolization during the procedure.