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 64Ϯ10 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-STsegment 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 (27Ϯ10 versus 16Ϯ8, PϽ0.001) was higher than in the group without pNSTEMI. Although high-sensitivity C-reactive protein plasma levels were similar before PCI (2.9Ϯ2.2 versus 3.4Ϯ1.7 mg/L, PϭNS), they were higher in the group with pNSTEMI after PCI (12.6Ϯ10.

Background-Collaterals can maintain myocardial function or preserve viability in chronic total coronary occlusions (CTOs). It is unknown whether and to what extent collaterals regress after successful recanalization of a CTO. Methods and Results-In 103 patients with successful recanalization of a CTO collateral function was assessed by intracoronary Doppler and pressure recordings before and after recanalization, and again after 5.0Ϯ1.3 months. Doppler (CFI) and pressure-derived collateral function indexes (CPI) and collateral (R Coll ) and peripheral resistance indexes (R P ) were calculated. In 10 patients with reocclusion, all without myocardial infarction during follow-up, collateral function had reached a similar level as before the first recanalization. In the other 93 patients with or without restenosis, collateral function was attenuated during follow-up. CPI had decreased by 23% immediately after recanalization (PϽ0.001) and decreased further by another 23% at follow-up (PϽ0.001). The R Coll increased immediately after recanalization by 82% (PϽ0.001) and by a further 273% at follow-up (PϽ0.001). In contrast, R P increased only by 22% after recanalization (PϽ0.001) and by an additional 12% at follow-up (PϽ0.05). The initial size of the collaterals but not the incidence of a restenosis influenced the collateral regression. Only 18% of patients at follow-up had collaterals with a CPI Ͼ0.30, presumably sufficient to prevent ischemia during acute occlusion. Conclusions-Collateral function regresses during long-term follow-up, especially in collaterals with a small diameter. In the majority of patients, collaterals are not readily recruitable in the case of acute occlusion. However, collaterals have the potential to recover in the case of chronic reocclusion.

Approximately one-fourth of patients with NSTEMI revealed OCA that was more frequently found in coronary arteries supplying the infero- or posterolateral myocardium. Patients with OCA had larger infarcts and more non-fatal reinfarctions than patients with non-OCA. Well-developed collaterals may limit the myocardial damage in these patients.

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