Low-Dose Radiation Advances in Coronary Computed Tomography Angiography in the Diagnosis of Coronary Artery Disease.

BACKGROUND: Coronary computed tomography angiography (CCTA) is now widely used in the diagnosis of coronary artery disease since it is a rapid, minimally invasive test with a diagnostic accuracy comparable to coronary angiography. However, to meet demands for increasing spatial and temporal resolution, higher x-ray radiation doses are required to circumvent the resulting increase in image noise. Exposure to high doses of ionizing radiation with CT imaging is a major health concern due to the potential risk of radiation-associated malignancy. Given its increasing use, a number of dose saving algorithms have been implemented to CCTA to minimize radiation exposure to "as low as reasonably achievable (ALARA)" without compromising diagnostic image quality. OBJECTIVE: The purpose of this review is to outline the most recent advances and current status of dose saving techniques in CCTA. METHOD: PubMed, Medline, EMBASE and Scholar databases were searched to identify feasibility studies, clinical trials, and technology guidelines on the technical advances in CT scanner hardware and reconstruction software. RESULTS: Sub-millisievert (mSv) radiation doses have been reported for CCTA due to a combination of strategies such as prospective electrocardiogram-gating, high-pitch helical acquisition, tube current modulation, tube voltage reduction, heart rate reduction, and the most recent novel adaptive iterative reconstruction algorithms. CONCLUSION: Advances in radiation dose reduction without loss of image quality justify the use of CCTA as a non-invasive alternative to coronary catheterization in the diagnosis of coronary artery disease.

Cancer risk from medical radiation procedures for coronary artery disease: a nationwide population-based cohort study.

To assess the risk of cancer incidence after medical radiation exposure for coronary artery disease (CAD), a retrospective cohort study was conducted based on Taiwan's National Health Insurance Research Database (NHIRD). Patients with CAD were identified according to the International Classification of Diseases code, 9th Revision, Clinical Modification (ICD-9-CM), and their records of medical radiation procedures were collected from 1997 to 2010. A total of 18,697 subjects with radiation exposure from cardiac imaging or therapeutic procedures for CAD were enrolled, and 19,109 subjects receiving cardiac diagnostic procedures without radiation were adopted as the control group. The distributions of age and gender were similar between the two populations. Cancer risks were evaluated by age-adjusted incidence rate ratio (aIRR) and association with cumulative exposure were further evaluated with relative risks by Poisson regression analysis. A total of 954 and 885 subjects with various types of cancers in both cohorts after following up for over 10 years were found, with incidences of 409.8 and 388.0 per 100,000 person-years, respectively. The risk of breast cancer (aIRR=1.85, 95% confidence interval: 1.14-3.00) was significantly elevated in the exposed female subjects, but no significant cancer risk was found in the exposed males. In addition, cancer risks of the breast and lung were increased with the exposure level. The study suggests that radiation exposure from cardiac imaging or therapeutic procedures for CAD may be associated with the increased risk of breast and lung cancers in CAD patients.

Association of metabolic syndrome and diabetes with subclinical coronary stenosis and plaque subtypes in middle-aged individuals.

AIMS: The presence of subclinical stenosed coronary segments and plaque subtypes has not been compared among those with metabolic syndrome, diabetes, or neither condition in middle-aged individuals. In select, intermediate-risk subjects, it may be reasonable to directly measure atherosclerosis burden by low-dose, multidetector-row computed tomographic coronary angiography. METHODS: We performed a cross-sectional analysis of 1024 consecutive, newly self-referred subjects (692 men, 332 women; mean age 53.0±9.7 years) who underwent health evaluation at the China Medical University Hospital. Participants had at least one cardiac risk factor, but no known coronary heart disease. RESULTS: Among our 1024 subjects, 135 had diabetes, 334 had metabolic syndrome and 555 had neither condition. The subjects with diabetes and those with metabolic syndrome had a higher prevalence of non-calcified, calcified and mixed-type plaques and stenosed coronary segments than the subjects with neither condition (P<0.05). The odds ratios for diabetes and the presence of any plaque, mixed plaque, calcified plaque and stenosed segment compared with neither metabolic syndrome nor diabetes were 2.893, 3.629, 2.099 and 2.036, respectively, all of which were significant (P<0.05). The odds ratio for metabolic syndrome and the presence of any plaque compared with neither metabolic syndrome nor diabetes was 1.606 (95% CI 1.063-2.426; P<0.05). CONCLUSION: In middle-aged subjects, diabetes was related to an increased risk of the presence of mixed plaques, calcified plaques and stenosed coronary segments. However, metabolic syndrome was related to an increased risk of the presence of any coronary plaque, but not related to stenosed coronary segments.

Eight-year clinical outcome after radioactive stent implantation: a treatment failure without irreversible long-term clinical sequelae.

AIMS: To assess the long-term outcome of patients who underwent radioactive stent (RS) implantation. METHODS AND RESULTS: The RS study population consisted of 133 consecutive patients who underwent RS implantation between November 1997 and July 2000. They were matched using the propensity score method with 266 patients who underwent bare metal stenting (BMS) in the same span. Long-term survival status and information on MACE (death, non-fatal myocardial infarction or any re-intervention) was retrospectively obtained. Eight-year cumulative survival (90.2% vs. 87.4%, p = 0.57) was similar between the RS and BMS group respectively, while 8-year cumulative MACE-free survival was significantly lower in RS patients (42.1% vs. 64.3%, p < 0.001) due to the difference in events (mainly target lesion revascularisations [TLRs]) during the first year of follow-up (cumulative 1-year MACE-free survival: 59.4% vs. 86.7%, p < 0.001); there was no difference in the MACE rate after the first year (p = 0.71). The TLR rate at six months in the RS group was 29.3%, mainly due to edge restenosis and at one year 36.2% (control group: 9.5%, p < 0.001). CONCLUSIONS: A high incidence of MACE and re-intervention was observed during the first year following RS implantation, mainly related to TLR for edge restenosis. After the first year, the clinical outcome of RS patients was similar to the control group indicating that there are no late adverse effects related to low dose-rate intracoronary radiation therapy.

Late outcome after intracoronary beta radiation brachytherapy: a matched-propensity controlled ten-year follow-up study.

AIMS: Increased major adverse cardiac events (MACE) beyond six months after intracoronary ß radiation brachytherapy (IRBT) are a major concern. The aim of this study was to evaluate the 10-year clinical outcome after IRBT. METHODS AND RESULTS: From 1997 to 2002, 301 consecutive patients treated with IRBT were included prospectively, whereafter 602 control patients treated with conventional percutaneous coronary intervention (PCI) were matched by propensity score methodology. MACE was defined as all-cause death, any myocardial infarction or any revascularisation. Median follow-up duration was 9.7 years. Mortality rates in both groups were similar. Cumulative 5-month, 2-, and 10- year MACE-free survival rates of IRBT patients were 89%, 56% and 29%, respectively, while those of the control patients were 90%, 76% and 52%, respectively (p < 0.001). The difference in the MACE rate was mainly driven by target vessel revascularisation (TVR) (p < 0.001). Furthermore, two or more repeat TVRs were needed in 12% of IRBT patients and in only 6% of control patients (p < 0.01). Adjusted hazard ratios for IRBT-associated all-cause mortality and MACE were 1.0 (95% CI 0.7-1.5) and 1.8 (95% CI 1.5-2.2), respectively. CONCLUSION: IRBT was associated with increased MACE between five months and two years of follow-up, mainly driven by repeat revascularisations. Similar event rate after two years indicate that there were no very late adverse effects related to IRBT.

Implementation of the transradial approach for coronary procedures is not associated with an elevated complication rate and elevated radiation patient exposure.

BACKGROUND: The transradial approach for coronary procedures is associated with a low complication rate, but specific training is considered mandatory. METHODS: Procedural characteristics (contrast dye: CD; fluoroscopy time: FT, patient radiation dose: RD) and local complication rates were prospectively assessed in 784 consecutive patients who underwent transradial coronary procedures. The study was divided into an implementation (2008-IP) and an evaluation period (2009-EP). Transradial (N = 624) and transfemoral (N = 842) procedural characteristics were compared in the EP. RESULTS: The amount of CD (mL) of transradial coronary angiography was similar between IP (75 [IQR 60-100]) and EP (70 [55-100]; P = 0.630). In contrast, FT (min) of transradial coronary angiography could be reduced from IP (4.4 [3.2-6.8]) to EP (4.1 [2.7-6.5]; P = 0.036), whereas RD (µGy * qcm) was similar (IP: 1623 [1042-3026]); EP (1576 [944-2530]; P = 0.149). Safety data showed a low complication rate: 0.2% access failure, 0.1% dissection, 0.7% vessel closure. Transfemoral procedures were followed by significantly more procedure- related transfusions (1.3% vs. 0%; P = 0.003). The comparison between transfemoral and transradial procedures demonstrated prolonged FT for transradial procedures (transfemoral 2.9 [1.7-5.5]; transradial 4.1 [2.7-6.5]; P = 0.002), whereas CD was similar (transfemoral 70 [55-100]; transradial 70 [55-100]; P = 0.248). The prolonged FT was restricted to coronary angiography but did not differ for PCI (transfemoral 9.7 [5.8-18.1]; transradial 8.9 [5.3-16.5]; P = 0.433). CONCLUSION: A transradial program can be implemented with safety; therefore, the transradial approach should be preferred in suitable patients. Since spasm occurrence was the major determinant of procedural failure, further effort is need to develop better strategies for spasm prevention.

High-quality 3-D coronary artery imaging on an interventional C-arm x-ray system.

PURPOSE: Three-dimensional (3-D) reconstruction of the coronary arteries during a cardiac catheter-based intervention can be performed from a C-arm based rotational x-ray angiography sequence. It can support the diagnosis of coronary artery disease, treatment planning, and intervention guidance. 3-D reconstruction also enables quantitative vessel analysis, including vessel dynamics from a time-series of reconstructions. METHODS: The strong angular undersampling and motion effects present in gated cardiac reconstruction necessitate the development of special reconstruction methods. This contribution presents a fully automatic method for creating high-quality coronary artery reconstructions. It employs a sparseness-prior based iterative reconstruction technique in combination with projection-based motion compensation. RESULTS: The method is tested on a dynamic software phantom, assessing reconstruction accuracy with respect to vessel radii and attenuation coefficients. Reconstructions from clinical cases are presented, displaying high contrast, sharpness, and level of detail. CONCLUSIONS: The presented method enables high-quality 3-D coronary artery imaging on an interventional C-arm system.

Efficacy and safety of absorbable metallic stents with adjunct intracoronary beta radiation in porcine coronary arteries.

BACKGROUND: Absorbable metallic stents (AMS) utilizing Mg alloy carry advantages over permanent metallic stents because of their potential to eliminate stent thrombosis, chronic inflammation, or artifacts with noninvasive imaging. These stents, however, are associated with a modest degree of late recoil and intimal hyperplasia. The aim of the study was to test whether adjunct vascular brachytherapy (VBT) compared to AMS alone can overcome these limitations. METHODS: Juvenile domestic pig coronary arteries underwent implantation of either AMS (n = 11) with prior adjunct VBT utilizing Sr/Y-90 beta source seeds, with a dose of 24 Gy at 2 mm from the source, or AMS alone (n = 11). At 28 days following intravascular ultrasound, vessels were harvested and analyzed by histomorphometry. RESULTS: Intravascular ultrasound analysis indicated that at follow-up, though statistically not significant, lumen and stent areas in the segments deployed with AMS following radiation were larger than those deployed with AMS alone (3.94 +/- 1.38 and 3.53 +/- 1.75 vs. 2.99 +/- 1.05 and 3.58 +/- 1.48). Extrastent plaque and intrastent plaque areas in the same segments were smaller (2.76 +/- 0.82 and 0.24 +/- 0.47 vs. 3.25 +/- 1.94 and 0.58 +/- 0.81). Morphometric data indicate that vessels in the VBT + AMS group showed characteristics of delayed healing and re-endothelialization. Neointimal area was significantly lower in the VBT + AMS group (0.49 +/- 0.34) compared to AMS (1.3 +/- 0.62, P = 0.001). Lumen area of the VBT + AMS was larger when compared with AMS alone (2.49 +/- 0.82 vs. 1.75 +/- 0.51, P = 0.02). CONCLUSION: VBT as an adjunct to AMS further reduces the intimal hyperplasia and improves the lumen area when compared to AMS alone but does not have any impact on late recoil.

Laser biostimulation in end-stage multivessel coronary artery disease--a preliminary observational study.

BACKGROUND: Low-energy laser radiation through its direct influence on tissue repair processes without heating effect may have vital importance in the therapy of patients with advanced coronary artery disease (CAD). AIM: The introductory assessment of the effects of laser biostimulation applied to patients with advanced multivessel CAD. METHODS: 39 patients with advanced CAD were assigned (mean age 64.8+/-9.6, male gender 64%, CCS class 2.5+/-0.5, EF=46+/-11%, 69% with a history of acute myocardial infarction), to undergo two sessions of irradiation of low-energy laser light on skin in the chest area from helium-neon B1 lasers. The time of irradiation was 15 minutes while operations were performed 6 days a week for one month. Before including the patients in the experimental group a full clinical evaluation, basic biochemical tests, ECG, 24h Holter recordings, 6-minute walk test, treadmill test using Bruce protocol and full echocardiographic examination were performed. After the first and second period of laser therapy with a one-month break between them analogical parameters with the initial examination were measured. RESULTS: No side effects associated with the laser biostimulation or performed clinical tests were noted. Lower CCS class (2.5+/-0.5 --> 2.2+/-0.4 --> 2.0+/-0.4, p<0.001), higher exercise capacity (5.1+/-2.2 --> 5.8+/-2.2 --> 6.6+/-2.5 [METS], p=0.023), longer exercise time (257+/-126 --> 286+/-127 --> 325+/-156 [s], p=0.06), less frequent angina symptoms during the treadmill test (65% --> 44% --> 38%, p=0.02), longer distance of 6-minute walk test (341+/-93 --> 405+/-113 --> 450+/-109 [m], p <0.001), lower systolic blood pressure values (SP 130+/-14 --> 125+/-12 --> 124+/-14 [mmHg], p=0.05) and trend towards less frequent 1 mm ST depression lasting 1 min during Holter recordings were noted. CONCLUSIONS: An improvement of functional capacity and less frequent angina symptoms during exercise tests without a significant change in the left ventricular function were observed. Laser biostimulation in short-term observation was a very safe method. These encouraging results should be confirmed in a larger, placebo-controlled study.

Edge restenosis: impact of low dose irradiation on cell proliferation and ICAM-1 expression.

BACKGROUND: Low dose irradiation (LDI) of uninjured segments is the consequence of the suggestion of many authors to extend the irradiation area in vascular brachytherapy to minimize the edge effect. Atherosclerosis is a general disease and the uninjured segment close to the intervention area is often atherosclerotic as well, consisting of neointimal smooth muscle cells (SMC) and quiescent monocytes (MC). The current study imitates this complex situation in vitro and investigates the effect of LDI on proliferation of SMC and expression of intercellular adhesion molecule-1 (ICAM-1) in MC. METHODS: Plaque tissue from advanced primary stenosing lesions of human coronary arteries (9 patients, age: 61 +/- 7 years) was extracted by local or extensive thrombendarterectomy. SMC were isolated and identified by positive reaction with smooth muscle alpha-actin. MC were isolated from buffy coat leukocytes using the MACS cell isolation kit. For identification of MC flow-cytometry analysis of FITC-conjugated CD68 and CD14 (FACScan) was applied. SMC and MC were irradiated using megavoltage photon irradiation (CLINAC2300 C/D, VARIAN, USA) of 6 mV at a focus-surface distance of 100 cm and a dose rate of 6 Gy min-1 with single doses of 1 Gy, 4 Gy, and 10 Gy. The effect on proliferation of SMC was analysed at day 10, 15, and 20. Secondly, total RNA of MC was isolated 1 h, 2 h, 3 h, and 4 h after irradiation and 5 microg of RNA was used in standard Northern blot analysis with ICAM-1 cDNA-probes. RESULTS: Both inhibitory and stimulatory effects were detected after irradiation of SMC with a dose of 1 Gy. At day 10 and 15 a significant antiproliferative effect was found; at day 20 after irradiation cell proliferation was significantly stimulated. Irradiation with 4 Gy and 10 Gy caused dose dependent inhibitory effects at day 10, 15, and 20. Expression of ICAM-1 in human MC was neihter inhibited nor stimulated by LDI. CONCLUSION: Thus, the stimulatory effect of LDI on SMC proliferation at day 20 days after irradiation may be the in vitro equivalent of a beginning edge effect. Extending the irradiation area in vascular brachytherapy in vivo may therefore merely postpone and not inhibit the edge effect. The data do not indicate that expression of ICAM-1 in quiescent MC is involved in the process.

Factors that influence radiation dose in percutaneous coronary intervention.

AIM: To explore the factors that may influence the radiation dose imparted to the patient in PCI, and investigate whether the use of the latest digital X-ray system based on FP detector technology can have an impact on dose. MATERIALS AND METHOD: Demographic and clinical data such as number of lesions treated, number of stents placed, grade of tortuosity, and stage of occlusion, as well as use of double wire and double balloon technique, ostial stenting or bifurcation stenting, and presence of major complications were recorded, together with radiation parameters. RESULTS: The factors that increased patient radiation dose were (1) patient gender, as men exhibited higher doses than women; (2) complex lesion; (3) increasing number of stents; (4) position of stent; (5) grade of tortuosity; and (6) stage of occlusion. The FP digital system appeared to be settled in a lower-dose rate for fluoroscopy (a factor of 6) and higher for dose per frame in cine (a factor of 3) in comparison with the image intensifier (II) system. There was a marked reduction of DAP when the FP technology was introduced. CONCLUSION: More extensive studies should be performed in the future so as to further investigate the influence of the FP detector in IC.

Optimizing dosimetry with high-dose intracoronary gamma radiation (21 Gy) for patients with diffuse in-stent restenosis.

BACKGROUND: The efficacy of intracoronary gamma radiation (IRT-gamma) in reducing recurrent in-stent restenosis (ISR) is well established using doses of 14-18 Gy. We sought to examine whether an escalation in dose to 21 Gy is safe and confers additional benefit in reducing repeat revascularization and major adverse cardiac events (MACE) in patients with diffuse ISR. METHODS: Forty-seven patients with diffuse ISR (lesion length 20-80 mm) in native coronary arteries (n=25) and saphenous vein grafts (n=22) underwent percutaneous transluminal coronary angioplasty and/or additional stents followed by IRT-gamma using the Checkmate system (Cordis) with a dose of 21 Gy. All patients were discharged with clopidogrel for 12 months and aspirin indefinitely. Six-month angiographic and 12-month clinical outcomes of these patients were compared to 120 patients treated with 18 Gy using the same system. RESULTS: At baseline, patients in the 21-Gy group had more multivessel, vein graft disease and history of prior myocardial infarctions and coronary artery bypass grafts (P<.001). The use of debulking devices and stents was less in this group (P<.001). Procedural and in-hospital complications were similar. Follow-up at 6 months revealed nonsignificant but lower late loss (in-stent, 0.33+/-0.7 mm; in-lesion, 0.41+/-0.6 mm) in the 21-Gy group compared to the 18-Gy group; follow-up at 12 months revealed a trend toward less overall myocardial infarction, although repeat revascularization and MACE rates were similar. CONCLUSIONS: IRT-gamma therapy for diffuse ISR lesions with a 21-Gy dose is clinically safe and feasible with marked reduction in late loss but does not confer additional benefit with regard to repeat revascularization and MACE when compared to a dose of 18 Gy.

Intracoronary beta-irradiation prevents excessive in-stent neointimal proliferation in de novo lesions of patients with high plasma ACE levels. The BetAce randomized trial.

BACKGROUND: This study evaluated vascular brachytherapy (VBT) as a potent antiproliferative treatment to prevent in-stent restenosis (ISR) after coronary angioplasty of de novo lesions in patients carrying the D allele of the I/D polymorphism of the ACE gene and high ACE plasma levels (>34 U/l). METHODS AND MATERIALS: A prospective randomized trial was designed to detect a 30% improvement in the minimal lumen diameter (MLD) of the stenotic artery, as measured by quantitative coronary analysis (QCA), 6 months following VBT at the time of stented angioplasty. All patients were carriers of the D allele of the ACE gene, with plasma ACE levels >34 U/l. RESULTS: Thirty-one patients (33 stenoses) were allocated to stent implantation (control group) and 30 patients (31 stenoses) to VBT and stented angioplasty. After angioplasty, in-stent MLD was similar in the two groups. At 6 months in the control group, in-stent MLD had decreased to 1.74+/-0.8 versus 2.25+/-1.05 mm in the VBT group (P=.04). The mean in-stent diameter was 2.3+/-0.8 mm in the control group versus 2.9+/-1.05 mm after VBT (P=.02), and the restenosis rate was 37.5% versus 17.9%, respectively (P=.08). At 6 months, a higher need for target vessel revascularization (TVR) was observed in the control group: 35.5% versus 13.3% (P=.04). CONCLUSIONS: This randomized study confirms that patients with high plasma ACE concentrations are exposed to an increased risk for ISR after coronary stenting. The preventive use of VBT in these patients reduced neointimal formation by 65% such that the MLD at follow-up was increased by 29% compared with the control group.

[Laser correction of microcirculation disorders in patients having CHD with hypercholesterinemia].

The study demonstrates that hypercholesterinemia in patients with coronary heart disease (CHD) is associated with functional depression of microcirculation, increase in total peripheral vascular resistance, reduction in the functional efficiency of heart and decrease in activity tolerance. After receiving a course of low-intensity infrared laser radiation treatment the patients displayed positive changes in blood lipid spectrum, which was associated with improvement in microcirculation, decrease in afterload, increase in economization of heart functioning and activity tolerance. The obtained results demonstrate that the hypolipidemic effect of laser radiation is a substantial factor in the regression of CHD manifestations.

Calcificación coronaria en paciente en hemodiálisis / No disponible

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Intracoronary beta-irradiation with a rhenium-188-filled balloon catheter: a randomized trial in patients with de novo and restenotic lesions.

BACKGROUND: Restenosis requiring reintervention is the main limitation of coronary angioplasty. Intracoronary irradiation reduces neointimal proliferation. We studied the efficacy of a self-centering liquid rhenium-188-filled balloon catheter for coronary beta-brachytherapy. METHODS AND RESULTS: After successful coronary angioplasty with or without stenting, 225 patients (71% de novo lesions) were randomly assigned to receive 22.5 Gy intravascular beta-irradiation in 0.5-mm tissue depth (n=113) or to receive no additional intervention (n=112). Clinical and procedural data did not differ between the groups except a higher rate of stenting in the control group (63%) compared with the rhenium-188 group (45%, P<0.02). After 6 months of follow-up, late loss was significantly lower in the irradiated group compared with the control group, both of the target lesion (0.11+/-0.54 versus 0.69+/-0.81 mm, P<0.0001) and of the total segment (0.22+/-0.67 versus 0.70+/-0.82 mm, P<0.0001). This was also evident in the subgroup of patients with de novo lesions and independent from stenting. Binary restenosis rates were significantly lower at the target lesion (6.3% versus 27.5%, P<0.0001) and of the total segment (12.6% versus 28.6%, P<0.007) after rhenium-188 brachytherapy compared with the control group. Target vessel revascularization rate was significantly lower in the rhenium-188 (6.3%) compared with the control group (19.8%, P=0.006). CONCLUSIONS: Intracoronary beta-brachytherapy with a rhenium-188 liquid-filled balloon is safe and efficiently reduces restenosis and revascularization rates after coronary angioplasty.