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Background: It is assumed that patients with non-ST-elevation myocardial infarctions (NSTEMI) showing an infero- or posterolateral occluded culprit artery (OCA) during diagnostic angiography frequently elude standard 12-lead electrocardiogram diagnosis. In addition, coronary collaterals may have beneficial effects in patients with OCA., Methods: We examined 448 consecutive NSTEMI patients within 72 h of symptom onset. All patients underwent early invasive angiography plus optimal medical therapy. We compared clinical characteristics and 30-days/6-month major adverse cardiovascular events (MACE) between patients with OCA and non-OCA. The secondary objective was to investigate the effect of angiographically visible coronary collaterals on 6-month MACE in patients with OCA., Results: The angiograms revealed OCA in 130 (29%) of 448 patients. Patients with OCA showed more often infero- or posterolateral lesions (75 vs. 53%, p < 0.001) and more collaterals (57 vs. 8%, p < 0.001) compared with those with non-OCA. Patients with OCA had larger infarcts (peak CK-MB 2.1 ± 2.3 vs. 1.2 ± 1.1 μmol/L/s, p < 0.001), lower left ventricular ejection fraction (42 ± 21 vs. 48 ± 20%, p = 0.01), were more often revascularized (89 vs. 78%, p = 0.005), and had higher risk-adjusted 6-month MACE largely driven by its association with non-fatal reinfarctions (HR 2.16, 95% CI 1.04-4.50, p = 0.04). Patients with OCA and angiographically absent collaterals had significantly higher risk-adjusted 6-month MACE than those with OCA and angiographically visible collaterals (HR 1.96, 95% CI 1.02-3.76, p = 0.04)., Conclusions: 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.

The objective of this study was to develop an analysis method for the automatic detection of intracoronary microemboli triggered high intensity signals (HITS) during percutaneous coronary interventions (PCI). The recorded ultrasonic Doppler velocity spectra from an intracoronary ultrasonic guide-wire were decomposed into 13 wavelet scales applying the continuous wavelet transform. From 7 wavelet scales which were most suitable for a differentiation between HITS and pulsatile flow, envelopes were calculated and combined to improve the HITS-to-background noise ratio. For different intensity thresholds the resulting number of HITS was automatically counted and compared with the number estimated by experienced observers. In a first validation trial HITS were detected within a simplified in vitro model with a sensitivity of 89.2% and a positive predictive value of 87.6%. In a following clinical study 211 HITS from 18 patients during PCI were counted manually by the observers. With the developed wavelet-based method 189 HITS were correctly detected (sensitivity of 89.6%, positive predictive value of 85.5%). The introduced new method automatically detects intracoronary HITS for the first time with a reliable accuracy. This may support further studies evaluating the incidence and consequences of coronary microembolization during 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.

Background: A good collateral function in patients with regional myocardial dysfunction may indicate viability with the potential for left ventricular (LV) recovery after revascularization of a chronic total coronary occlusion (CTO)., Methods: A CTO (duration > 2 weeks) was successfully recanalized in 126 patients. During this procedure, the collateral function was assessed before the first balloon inflation by intracoronary Doppler and pressure wires. Collateral function indexes were calculated. Left ventricular function was assessed by the LV ejection fraction (LVEF) and the wall motion severity index (WMSI [SD/chords]). A repeat angiography was available in 119 patients after 4.9 +/- 1.4 m. An improvement of WMSI > or =1 SD/chord was considered significant., Results: Left ventricular function was normal in 42%, regional dysfunction with LVEF > or = 0.60 was observed in 16%, and regional dysfunction with LVEF < 0.60 in 42%. The former had a better collateral function than patients with LV dysfunction. In 39% of patients with LV dysfunction, a significant myocardial recovery was observed at follow-up. The collateral function was similar in patients with and without recovery. However, patients with recovery had a lower peripheral resistance as an indicator of a better preserved microvascular integrity., Conclusions: Recovery of impaired LV function after revascularization of a CTO is not directly related to the quality of collateral function, as collateral development does not appear to require the presence of viable myocardium. However, a preserved microvascular integrity may be of relevance for myocardial recovery.

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 5.0+/-1.3 months. Doppler (CFI) and pressure-derived collateral function indexes (CPI) and collateral (RColl) and peripheral resistance indexes (RP) 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 (P<0.001) and decreased further by another 23% at follow-up (P<0.001). The RColl increased immediately after recanalization by 82% (P<0.001) and by a further 273% at follow-up (P<0.001). In contrast, RP increased only by 22% after recanalization (P<0.001) and by an additional 12% at follow-up (P<0.05). 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 >0.30, 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.

Objectives: The goal of this study was to assess the influence of collateral function, coronary hemodynamics, and the angiographic result on the risk of target vessel failure (TVF) after recanalization of a chronic total coronary occlusion (CTO)., Background: Collaterals may have an adverse effect on TVF., Methods: In 111 consecutive patients, a CTO (duration >2 weeks) was successfully recanalized with stent implantation. Collateral function was assessed by intracoronary Doppler flow velocity and pressure recordings distal to the occlusion. Baseline collateral function was determined before the first balloon inflation, and recruitable collateral function after stenting during a balloon reocclusion. Finally, the coronary flow velocity reserve (CFVR) and the fractional flow reserve (FFR) were measured., Results: Angiographic follow-up after 5 +/- 4 months in 106 patients showed a reocclusion in 17% and a restenosis in 36%. The major determinants of TVF were the stent length (p < 0.01) and number of implanted stents (p < 0.01). No difference was observed in baseline or recruitable collateral function between patients with and without TVF; 52% of patients had a CFVR >or= 2.0, and only 18% a CFVR >or=2.5 after percutaneous transluminal coronary angioplasty, but neither cutoff-value predicted TVF. A low FFR discriminated patients with reocclusion (0.81 +/- 07 vs. 0.86 +/- 08, p < 0.05) but not with restenosis (0.87 +/- 0.06)., Conclusions: This study showed that there is no relation between a well-developed collateral supply and the risk of TVF in recanalized CTOs. This was rather determined by the stented segment length. There was also no adverse effect of the frequently observed impaired CFVR on TVF, whereas a low FFR was associated with a higher risk of reocclusion.