Intravascular ultrasound evidence of perivascular trauma during routine percutaneous coronary intervention.

We assessed whether intravascular ultrasound (IVUS) can detect evidence of coronary perforation that is not visible by coronary angiography. Approximately 15,000 consecutive percutaneous coronary interventions (PCI) performed with IVUS guidance were reviewed retrospectively, pre- and post-PCI IVUS images were compared, and IVUS findings were compared with coronary angiography and in-hospital outcomes. We detected three distinct patterns that were not present pre-PCI and that were suggestive of perforation or perivascular trauma: perivascular blood speckle in 67 % (51/76), perivascular hematoma in 17 % (13/76), and new echolucent perivascular layer in 16 % (12/76). Angiographic appearance included perforation in 24 % (18/76), dissection in 33 % (25/76), lumen irregularity in 17 % (13/76), new stenosis in 5 % (4/76), and no abnormalities in 21 % (16/76). The site of a break in arterial wall with communication between the lumen and perivascular space could be detected in 61 % (46/76). This extended proximally and distally with equal frequency, but was primarily located within the lesion in 80 % (61/76), although the lumen was rarely compromised. Within 24 h, there were four emergent coronary artery bypass grafting procedures, one repeat PCI, and six periprocedural myocardial infarctions (defined as CK-MB ≥10 times the upper limit of normal), but there were no episodes of cardiac tamponade. Although infrequent, IVUS detected three distinct patterns of post-PCI perivascular trauma suggestive of a perforation that was detected angiographically in only 24 % of cases.

Intravascular ultrasound lumen area parameters for assessment of physiological ischemia by fractional flow reserve in intermediate coronary artery stenosis.

BACKGROUND: A fractional flow reserve (FFR) of <0.8 is currently used to guide revascularization in lesions with intermediate coronary stenosis. Whether there is an intravascular ultrasound (IVUS) measurement or a cutoff value that can reliably determine which of these intermediate lesions requires intervention is unclear. AIMS: We assessed IVUS measurement accuracy in defining functional ischemia by FFR. METHODS: The analysis included 205 intermediate lesions (185 patients) located in vessel diameters >2.5 mm. Positive FFR was considered present at <0.8. IVUS measurements were correlated to the FFR findings in intermediate lesions with 40%-70% stenosis. Fifty-four (26.3%) lesions had FFR<0.8. RESULTS: There was moderate correlation between FFR and IVUS measurements, including minimum lumen area (MLA) (r=0.36, P<.001), minimum lumen diameter (MLD) (r=0.25, P=<.001), lesion length (r=-0.43, P<.001), and area stenosis (r=-0.33, P=.01). A receiver operating characteristic curve (ROC) identified MLA<3.09 mm(2) (sensitivity 69.2%, specificity 79.5%) as the best threshold value for FFR<0.8. The correlation between FFR and IVUS was better for large vessels compared to small vessels. ROC analysis identified the best threshold value for FFR<0.8 of MLA<2.4 mm(2) [area under curve (AUC)=0.74] in lesions with reference vessel diameters of 2.5-3 mm, MLA<2.7 mm(2) (AUC=0.77) in lesions with reference vessel diameters of 3-3.5 mm, and MLA<3.6 mm(2) (AUC=0.70) in lesions with reference vessel diameters >3.5 mm. CONCLUSION: Anatomic measurements of intermediate coronary lesions obtained by IVUS show a moderate correlation to FFR values. The correlation was better for larger-diameter vessels. Vessel size should always be taken into account when determining the MLA associated with functional ischemia.

Correlation between fractional flow reserve and intravascular ultrasound lumen area in intermediate coronary artery stenosis.

AIMS: Fractional flow reserve (FFR) of <0.8 or 0.75 is currently used to guide revascularisation in lesions with intermediate coronary stenosis. We assessed whether there is an intravascular ultrasound (IVUS) measurement that can reliably be used to predict when patients should undergo intervention. METHODS AND RESULTS: The analysis included 92 intermediate lesions (84 patients) located in vessel diameters >2.5 mm. Positive FFR was considered present at <0.8 and 0.75. IVUS minimum lumen area (MLA) was correlated to the FFR findings in intermediate lesions with 40-70% stenosis. The mean FFR value was 0.89 ± 0.08. Twenty-four patients (26.1%) had FFR <0.8; 17 (18.5%) <0.75. Positive correlations between FFR and IVUS measurements included MLA (r = 0.34, p<0.001), minimum lumen diameter (MLD) (r=0.31, p=0.004), lesion length (r=-0.5, p<0.001), and area stenosis (r=-0.31, p=0.01). There was no significant correlation between FFR and quantitative coronary angiography in MLD (r=0.19, p=0.06), diameter stenosis (r=0.08, p=0.4), or lesion length (r=-0.14, p=0.17). A receiver operating characteristic curve identified MLA <2.8 mm2 (sensitivity 79.7%, specificity 80.3%) as the best threshold value for FFR <0.75; and MLA <3.2 mm2 as best for FFR <0.8 (sensitivity 69.2%, specificity 68.3%). CONCLUSIONS: Anatomic measurements of intermediate coronary lesions obtained by IVUS show a moderate correlation to FFR values, although they differ according to vessel size. IVUS MLA may be used as an alternative to FFR when assessing the need for intervention in intermediate coronary lesion. Vessel size, however, should always be taken into account.

Intravascular ultrasound and 3D angle measurements of coronary bifurcations.

OBJECTIVE: To standardize the intravascular ultrasound (IVUS) analysis of coronary bifurcations. BACKGROUND: Percutaneous treatment of bifurcation lesions is difficult particularly at the side branch ostium. Imaging techniques may improve our understanding of treatment options. There is no established IVUS methodology to assess the bifurcation. The present study aims to develop standards for bifurcation imaging. METHODS: Quantitative IVUS analysis and 3D bifurcation angle measurements were performed in 34 patients who were selected from the Washington Hospital Center Database. Patients were included if both left anterior descending (LAD) and first diagonal (DX) pullbacks in the same procedure were done. Angiograms were available in 27 patients to measure the 3D bifurcation angle using specialized software. Pullbacks were analyzed proximal and distal to the bifurcation, and at the bifurcation. RESULTS: Prox(LAD) versus Prox(LAD(DX)) were similar for vessel area (15.5 +/- 4.6 mm(2) vs. 15.9 +/- 4.0 mm(2), P = 0.19), lumen area (8.3 +/- 3.6 mm(2) vs. 8.6 +/- 3.3 mm(2), P = 0.25), and plaque area (7.2 +/- 2.0 mm(2) vs. 7.3 +/- 1.9 mm(2), P = 0.55). However, Bifurcation(LAD) was larger than Bifurcation(DX) for vessel area (17.3 +/- 4.0 mm(2) vs. 16.6 +/- 3.9 mm(2), P = 0.0083). The 3D angiographic bifurcation angle was 50 degrees +/- 13 degrees (range of 26 degrees -84 degrees), and did not affect the IVUS measurements. IVUS analysis showed that bifurcation lesions did obey Murray's Law, as Prox(LAD) lumen area measured 36.7 +/- 25.1 mm(3) versus Dist(LAD)/Dist(DX) measured 38.0 +/- 29.1 mm(3), P = 0.56. CONCLUSIONS: Two IVUS pullbacks should be performed for a complete assessment of the bifurcation and comparison with Murray's Law. The proposed IVUS analysis was not influenced by the bifurcation angle.

Optical coherence tomography and intravascular ultrasound imaging of bioabsorbable magnesium stent degradation in porcine coronary arteries.

BACKGROUND: Absorbable metallic stents (AMS) composed of magnesium alloy were designed to complete degradation within 90-120 days. Among the potential advantages of these stents, when compared to conventional stents, are the elimination of late stent thrombosis, chronic inflammation, and artifacts during noninvasive imaging. METHODS: Magnesium-based AMS were deployed in juvenile domestic pig coronary arteries. Angiography, optical coherence tomography (OCT), and intravascular ultrasound (IVUS) were performed before and after implant and then at 28 days and 3 months following stenting. The animals were sacrificed at 28 days or 3 months following stent implantation. Stented vessels were harvested and analyzed by histomorphometry. RESULTS: Over time, OCT, IVUS, and histologic images revealed a progressive degradation of the stents. Mean stent strut width in the OCT images after implantation was 0.24+/-0.032 mm, then decreased to 0.12+/-0.007 mm (P<.0001) at 28 days and to 0.151+/-0.032 mm at 3 months (P<.0001 vs. implant, P=.078 vs. 28 days). CONCLUSION: Magnesium-based AMS degrade over a 3-month time period in a porcine model. Its structure is not apparent by angiography but is well-visualized by OCT and IVUS. OCT allowed quantitative assessment of stent degradation.

Impact of plaque rupture and elevated C-reactive protein on clinical outcome in patients with acute myocardial infarction: an intravascular ultrasound study.

BACKGROUND: Ruptured plaques are associated with elevated C-reactive protein (CRP) that, in turn, are associated with a poor prognosis in acute myocardial infarction (AMI) patients. OBJECTIVES: The purpose of this study was to evaluate the impact of plaque rupture and elevated CRP on major adverse cardiac events (MACE) in patients with AMI treated with coronary stenting. METHODS: We used pre-intervention intravascular ultrasound (IVUS) to evaluate infarct-related arteries in 72 AMI patients treated with coronary stenting to study the impact of plaque rupture and CRP levels on MACE. RESULTS: Infarct-related artery plaque rupture was observed in 30 patients (42%), and multiple infarct-related artery plaque ruptures were observed in 10 patients (14%). The CRP level was higher in patients with plaque rupture than in those without plaque rupture (31.3 +/- 20.3 vs. 4.2 +/- 5.8 mg/l; p < 0.001). Patients with elevated CRP levels had more plaque rupture and more multiple plaque ruptures than the normal CRP group (26/42 [62%] vs. 4/30 [13%]; p < 0.001, and 10/42 [24%] vs. 0/30 [0%]; p = 0.004, respectively). Plaque rupture and ST-segment elevation MI independently predicted CRP elevation (Hazard ratio [HR] = 5.329; p < 0.001 and HR = 3.790; p = 0.032, respectively). At 1-year follow up, MACE occurred in 9 plaque-rupture patients (30%), in 5 non-plaque rupture patients (12%) and in 29% of elevated CRP patients versus 7% of normal CRP patients. Patients with elevated CRP plus plaque rupture had more MACE than patients with normal CRP and no plaque rupture (31% vs. 4%; p = 0.010). In the multivariate analysis, an elevated CRP was the only independent predictor of MACE (HR = 6.561; p = 0.012). CONCLUSIONS: Plaque rupture and elevated CRP were associated with poor prognosis; however, an elevated CRP was the only independent predictor of 1-year MACE in AMI patients treated with coronary stenting.

Peri-stent reference segment plaque burden is associated with disease progression in saphenous vein grafts (a serial intravascular ultrasound assessment).

We are aware of no studies of peri-stent disease progression or luminal compromise in saphenous vein graft (SVG) lesions. We used serial intravascular ultrasound (IVUS) to assess disease progression in peri-stent saphenous vein bypass graft reference segments. We studied 37 peri-stent SVG reference segments in 21 patients; 16 were proximal and 21 were distal to the stent. The same anatomic image slice was analyzed after the intervention and at follow-up; this site was 3.68 +/- 2.22 mm from the stent edge. Graft age was 10.1 +/- 5.4 years, and mean follow-up duration was 13 months (range 3 to 61). Overall, change in SVG area, change in lumen area, and change in plaque burden correlated with postintervention plaque burden (r = 0.448, p = 0.005; r = -0.584, p <0.001; and r = 0.507, p = 0.001, respectively). For the proximal edge, change in lumen area correlated with change in plaque area (r = -0.951, p <0.001), but not with change in SVG area (r = -0.337, p = 0.201). For the distal edge, change in lumen area correlated more strongly with change in plaque area (r = -0.982, p <0.001) than with change in SVG area (r = -0.624, p = 0.003). When peri-stent reference segments were divided into 2 groups according to postintervention plaque burden (>50% [n = 20] vs <50% [n = 17]), there was a greater decrease in lumen area (-1.12 +/- 0.81 vs -0.33 +/- 0.26 mm(2), p <0.001) and greater increases in SVG area (0.26 +/- 0.29 vs 0.09 +/- 0.09 mm(2), p = 0.027), plaque area (1.37 +/- 0.96 vs 0.42 +/- 0.30 mm(2), p <0.001), and plaque burden (8.2 +/- 5.6% vs. 2.8 +/- 1.6%, p <0.001) in segments with a plaque burden >50%. In conclusion, peri-stent reference segment SVG disease progression and lumen loss were more significant in segments with a greater postintervention plaque burden after implantation of a bare metal stent or drug-eluting stent.

Comparative intravascular ultrasound analysis of ostial disease in the left main versus the right coronary artery.

BACKGROUND: Significant aorto-ostial disease is difficult to evaluate with angiography and sometimes even with intravascular ultrasound (IVUS). METHODS: We used IVUS to compare ostial lesions in the left main coronary (LMCA, n = 45) versus the right coronary artery (RCA, n = 50). IVUS measurements were performed each 1 mm beginning within the ostium and continuing to the distal reference segment. Negative remodeling was defined as a remodeling index (lesion/distal reference arterial area) < 0.95. RESULTS: Patient age was 66 +/- 11 years in the LMCA group and 66 +/- 11 years in the RCA group; 56% of the LMCA ostial lesions and 46% of RCA ostial lesions were in males, and 35% of the LMCA ostial lesions and 20% of the RCA ostial lesions were in diabetics. With the exception of a smaller minimum lumen area (p < 0.0001) and distal reference plaque burden (p = 0.002) in ostial RCA lesions and a larger eccentricity index in ostial LMCA lesions (p = 0.001), both sites were remarkably similar. Both ostial LMCA and RCA lesions were short, had modest amounts of calcium, had modest plaque burdens, but had a marked frequency of negative remodeling (84% in LMCA and 86% in RCA; p = 1.0). CONCLUSION: IVUS morphometry is similar in ostial LMCA and RCA lesions; negative remodeling is the dominant contributor to lumen compromise in both locations.

Impact of remodeling on cardiac events in patients with angiographically mild left main coronary artery disease.

BACKGROUND: The clinical significance of intravascular ultrasound (IVUS) assessed remodeling in left main coronary artery (LMCA) lesions has not been studied. Thus, we evaluated the impact of coronary arterial remodeling on cardiac events in patients with angiographically mild LMCA disease. METHODS: Two hundred thirty-six patients who underwent IVUS evaluation to determine the severity of angiographically mild LMCA lesions (diameter stenosis < 50%) were included. Negative remodeling (NR) was defined as a remodeling index (lesion/reference external elastic membrane crosssectional area [CSA]) < 0.95, intermediate remodeling (IR) as between 0.95-1.05, and positive remodeling (PR) as > 1.05. RESULTS: NR was observed in two-thirds of patients (156/236). NR lesions were more proximal in location (45.6% vs. 25.0%; p = 0.003), less frequently associated with soft plaque morphology (23.1% vs. 43.8%; p = 0.001), and had smaller plaque burdens (34.0 +/- 12.0 vs. 40.3 +/- 10.7%; p < 0.001) than IR/PR lesions. At 1-year follow up, LMCA-related cardiac events occurred in 15 patients (6.3%). NR was less frequently associated with LMCA-related cardiac events than IR/PR [6/156 (3.8%) vs. 9/80 (11.3%); p = 0.027]. In lesions associated with LMCA-related events, lumen CSA was smaller, plaque burden was larger, and the remodeling index was greater than in lesions not associated with cardiac events, but only non-NR was an independent predictor of LMCA-related events in patients with mild LMCA disease (hazard ratio 4.095; 95% CI, 1.275-13.149; p = 0.018). CONCLUSIONS: Angiographically mild LMCA disease was more frequently associated with NR, and NR was associated with fewer LMCA-related cardiac events in patients with mild LMCA lesions.

Impact of the acute results on the long-term outcome after the treatment of in-stent restenosis: a serial intravascular ultrasound study.

The current study used serial (postintervention and follow-up) intravascular ultrasound (IVUS) to assess the impact of acute results on long-term follow-up of patients with in-stent restenosis (ISR). All patients (n = 180) with serial IVUS studies of ISR lesions from the following gamma-irradiation brachytherapy trials were included: Washington Radiation for In-Stent Restenosis Trial (WRIST), Gamma-1, and Angiorad Radiation Technology for In-Stent Restenosis Trial in Native Coronaries (ARTISTIC). There were 106 irradiated and 74 placebo patients. Quantitative analysis was performed according to the American College of Cardiology Clinical Expert Consensus Document on Standards for Acquisition, Measurement and Reporting of IVUS. Images were acquired using motorized transducer pullback, cross-sectional analysis was performed every 1 mm, and volumetric and mean planar dimensions were calculated. The independent predictors for the absolute follow-up minimum lumen area (MLA) were the postintervention MLA, the postintervention minimum stent area, and the use of brachytherapy. Placebo patients lost 45% of the postintervention MLA while irradiated patients lost only 17% of the MLA. The independent predictors of the follow-up percent intimal hyperplasia (intimal hyperplasia volume divided by stent volume) and the independent predictors of the absolute increase in intimal hyperplasia were the postintervention percent intimal hyperplasia and the use of brachytherapy. Serial IVUS analysis shows that the follow-up MLA and percent intimal hyperplasia are dependent on the results obtained during the treatment of ISR lesions.

Intravascular ultrasound analysis of infarct-related and non-infarct-related arteries in patients who presented with an acute myocardial infarction.

BACKGROUND: Previous studies have reported diffuse destabilization of atherosclerotic plaques in acute myocardial infarction (AMI). METHODS AND RESULTS: We used intravascular ultrasound (IVUS) to assess 78 coronary arteries (38 infarct-related arteries [IRAs] with culprit and nonculprit lesions and 40 non-IRAs) from 38 consecutive AMI patients. IVUS analysis included qualitative and quantitative measurements of reference and lesion external elastic membrane (EEM), lumen, and plaque plus media (P&M) area. Positive remodeling was defined as lesion/mean reference EEM >1.0. Culprit lesions were identified by a combination of ECG, wall motion abnormalities (ventriculogram or echocardiogram), scintigraphic perfusion defects, and coronary angiogram. Culprit lesions contained more thrombus (23.7% versus 3.4% in nonculprit IRA plaques and 3.1% in non-IRA plaques; P=0.0011). Culprit lesions were predominantly hypoechoic (63.2% versus 37.9% of nonculprit IRA plaques and 28.1% of non-IRA plaques; P=0.0022). Culprit lesions were longer (17.5+/-10.1, 9.8+/-4.0, and 10.3+/-5.7 mm, respectively; P<0.0001), had larger EEM area (15.0+/-6.0, 11.5+/-5.7, and 12.6+/-5.6 mm2, respectively; P=0.0353) and P&M area (13.0+/-6.0, 7.5+/-3.7, 9.3+/-4.3 mm2, respectively; P<0.0001), smaller lumens (2.0+/-0.9, 4.1+/-3.1, and 3.4+/-2.5 mm2, respectively; P=0.0009), and more positive remodeling (79.4%, 59.0%, and 50.8%, respectively; P=0.0155). The frequency of plaque rupture/dissection was greater in culprit, nonculprit IRA, and non-IRA plaques in AMI patients than in a control group of chronic stable angina patients with multivessel IVUS imaging. CONCLUSIONS: Culprit plaques have more markers of instability (thrombus, positive remodeling, and large plaque mass); however, these markers of instability are not typically found elsewhere. This suggests that the vascular event in AMI patients is determined by local pre-event lesion morphologies.

Late thrombosis after gamma-brachytherapy.

Late stent thrombosis (> 30 days after treatment) is a new phenomenon occurring after vascular brachytherapy. We report the analysis of 11 patients with late thrombosis after gamma-irradiation treatment of in-stent restenosis. All patients had in-stent restenosis and angina. Contributing factors to late thrombosis include long stents, small distal vessels, and complex lesion morphology.

Safety and efficacy of manual stepping and overlapping of beta-emitter for diffuse in-stent restenosis lesions.

BACKGROUND: The effects of overlapping beta-emitter sources on the treatment of in-stent restenosis (ISR) lesions as a result of manual stepping are unknown. METHODS AND RESULTS: In the BETA WRIST (Beta Washington Radiation for In-stent Restenosis Trial), 17 out of the 50 patients who received radiation treatment had diffuse ISR in native coronaries that required manual stepping of the beta-emitter (90Y) source in order to cover the lesion and the edges. Fourteen of those patients received radiation with an overlap of up to 3 mm in the middle of the stented segment. The prescribed dose was 20.6 Gy to a distance of 1.0 mm from the surface of the inflated balloon, and the calculated dose to the vessel wall at the overlapped area did not exceed 75 Gy. There was no difference in late total occlusion (7.1% vs. 9.0%, P=NS) and target lesion revascularization (28.5% vs. 27.2%, P=NS) between patients with stepping and those without stepping. At 6 months, there was no evidence of perforation or aneurysm at the overlapped segments. Quantitative coronary angiographic (QCA) analysis revealed significantly reduced late loss in the overlapped segment compared to the adjacent segment (P=.04). Serial (postradiation vs. follow-up) IVUS measurement showed larger mean lumen cross-sectional area (CSA) (P=.0035) and smaller mean intimal hyperplasia (IH) CSA (P=.0010) in the overlapped segment compared to the adjacent segment. CONCLUSION: Manual stepping of beta-emitter source with a short overlapped segment is safe for diffuse ISR. Further increase in lumen dimension and reduction in IH formation are observed at the overlapped segment.

Morphologic and angiographic features of coronary plaque rupture detected by intravascular ultrasound.

OBJECTIVES: This study was designed to report the clinical and angiographic correlates of plaque rupture detected by intravascular ultrasound (IVUS). BACKGROUND: Acute coronary syndromes result from spontaneous plaque rupture and thrombosis. METHODS: We report 300 plaque ruptures in 257 arteries in 254 patients. Plaque ruptures were detected during pre-intervention IVUS. Standard clinical, angiographic, and IVUS parameters were collected and/or measured. One lesion per patient was analyzed. RESULTS: Multiple ruptures were observed in 39 of 254 patients (15%), 36 in the same artery. Plaque rupture occurred not only in patients with unstable angina (46%) or myocardial infarction (MI, 33%), but also stable angina (11%) or no symptoms (11%). The tear in the fibrous cap could be identified in 157 of 254 patients; 63% occurred at the shoulder of the plaque and 37% in the center of the plaque. Thrombi were more common in patients with unstable angina or MI (p = 0.02) and in multiple ruptures (p = 0.04). The plaque rupture site contained the minimum lumen area (MLA) site in only 28% of patients; rupture sites had larger arterial and lumen areas and more positive remodeling than MLA sites. Intravascular ultrasound plaque rupture strongly correlated with complex angiographic lesion morphology: ulceration in 81%, intimal flap in 40%, thrombus in 7%, and aneurysm in 7%. CONCLUSIONS: Plaque ruptures occur with varying clinical presentations, strongly correlate with angiographic complex lesion morphology, may be multiple, and usually do not cause lumen compromise.

Twelve versus six months of clopidogrel to reduce major cardiac events in patients undergoing gamma-radiation therapy for in-stent restenosis: Washington Radiation for In-Stent restenosis Trial (WRIST) 12 versus WRIST PLUS.

BACKGROUND: Intracoronary gamma-radiation reduces recurrent in-stent restenosis (ISR). Late thrombosis was attenuated with 6 months of aspirin and clopidogrel. We aimed to find out whether 12 months of aspirin plus clopidogrel is superior to a strategy of 6 months after radiation therapy for patients with ISR. METHODS AND RESULTS: One hundred twenty consecutive patients with diffuse ISR in native coronaries and vein grafts with lesions <80 mm in length underwent PTCA, laser ablation, or rotational atherectomy. Additional stents were placed in 39 patients (33%). After the intervention, a ribbon with different trains of radioactive 192Ir seeds was positioned to cover the treated site, and a dose of 14 Gy to 2 mm was prescribed. Patients were discharged with clopidogrel and aspirin for 12 months and followed up clinically. The cardiac clinical event rates at 15 months were compared with the gamma-treated (n=120) patients of the WRIST PLUS study (only 6 months of antiplatelet therapy). Whereas the late thrombosis rates were similar (3.3% for the group given 12 months of antiplatelet therapy versus 4.2% for the group given 6 months, P=0.72), the group treated with 12 months of antiplatelet therapy had a rate of 21% for major adverse cardiac events and 20% for target-lesion revascularization compared with 36% (P=0.01) and 35% (P=0.009), respectively, in patients who were treated with only 6 months of clopidogrel. CONCLUSIONS: Twelve months of clopidogrel is superior to 6 months in reducing overall major cardiac events and revascularization rates at 15 months for patients with ISR treated with gamma-radiation. At least 12 months of clopidogrel therapy should be recommended for patients undergoing radiation therapy for ISR.

Dose heterogeneity may not affect the neointimal proliferation after gamma radiation for in-stent restenosis: a volumetric intravascular ultrasound dosimetric study.

OBJECTIVES: The goal of this study was to use serial (postirradiation and follow-up) volumetric intravascular ultrasound (IVUS): 1) to evaluate the actual distribution of gamma radiation in human in-stent restenosis (ISR) lesions, and 2) to analyze the relationship between neointimal regrowth and the delivered radiation dose. BACKGROUND: The relationship between the neointimal regrowth and delivered dose during the treatment of ISR remains unknown. METHODS: We analyzed 20 actively (gamma emitter) treated, native artery ISR patients from the Washington Radiation for In-Stent restenosis Trial (WRIST) that met the following criteria: on both postirradiation and six-month follow-up IVUS imaging, > or =80% of the external elastic membrane circumference could be identified throughout the treated length including the lesion and proximal and distal reference segments. Intravascular ultrasound images were digitized every 1 mm. Proximal and distal reference and stented segment luminal and adventitial contours were imported and reconstructed. The source was placed circumferentially at the site of the IVUS catheter and longitudinally according to the relationship between the radioactive seeds and stent edges. Using Monte Carlo simulations, dose volume histograms for the adventitia and intima were calculated. The relationship between the neointimal regrowth and calculated doses were evaluated. RESULTS: There was large dose heterogeneity at both the intimal and adventitial levels. Most of the sites (93%) received >4 Gy at the adventitia, and all of the sites received >4 Gy at the intima. There was no relationship between neointimal regrowth and radiation dose. CONCLUSIONS: Although there may be large dose heterogeneity, gamma irradiation (using a fixed dose prescription) appears to deliver a sufficient dose to prevent neointimal regrowth.

Incidence, morphology, angiographic findings, and outcomes of intramural hematomas after percutaneous coronary interventions: an intravascular ultrasound study.

BACKGROUND: Intramural hematomas during percutaneous coronary intervention (PCI) have not been well studied. METHODS AND RESULTS: We used intravascular ultrasound to determine the incidence, morphology, and clinical features of post-PCI intramural hematomas. In 905 patients with 1025 consecutive native coronary artery, non-in-stent restenosis lesions undergoing PCI, 72 hematomas were detected in 69 arteries in 68 patients. The incidence of intramural hematomas per artery was 6.7% (69 of 1025); 36% (26 of 72) involved the proximal reference artery, 18% (13 of 72) were confined to the lesion, and 46% (33 of 72) involved the distal reference artery. The entry site from the lumen into the hematoma was identified in 86% of hematomas (62 of 72) and had the appearance of a dissection into the media. Conversely, a re-entry site was identifiable in only 8% (6 of 72). The axial extension of the hematoma was distal in 63% and proximal in 37%. In 60% of the hematomas (42 of 72) the angiogram had the appearance of a dissection; in 11% (8 of 72), it appeared to be a new stenosis; and in 29% (22 of 72), no significant abnormality was detected. Non-Q-wave myocardial infarctions occurred in 26% of patients (17 of 65). In 3 patients, the creatine kinase-MB was not measured during the hospital stay. Repeat revascularization occurred in 2 patients in-hospital, 2 additional patients at 1 month, and 8 additional patients at 1 year. There were 3 sudden deaths at 1 year. CONCLUSIONS: Intravascular ultrasound identified intramural hematomas after 6.7% of PCIs. The mechanism appeared to be a dissection into the media where blood accumulated because of a lack of re-entry. A third of ultrasound-identified hematomas showed no angiographic abnormalities. There was a high rate of non-Q-wave myocardial infarction, need for repeat revascularization, and sudden death in patients with hematomas.