Definitions and Clinical Trial Design Principles for Coronary Artery Chronic Total Occlusion Therapies: CTO-ARC Consensus Recommendations.

Over the past 2 decades, chronic total occlusion (CTO) percutaneous coronary intervention has developed into its own subspecialty of interventional cardiology. Dedicated terminology, techniques, devices, courses, and training programs have enabled progressive advancements. However, only a few randomized trials have been performed to evaluate the safety and efficacy of CTO percutaneous coronary intervention. Moreover, several published observational studies have shown conflicting data. Part of the paucity of clinical data stems from the fact that prior studies have been suboptimally designed and performed. The absence of standardized end points and the discrepancy in definitions also prevent consistency and uniform interpretability of reported results in CTO intervention. To standardize the field, we therefore assembled a broad consortium comprising academicians, practicing physicians, researchers, medical society representatives, and regulators (US Food and Drug Administration) to develop methods, end points, biomarkers, parameters, data, materials, processes, procedures, evaluations, tools, and techniques for CTO interventions. This article summarizes the effort and is organized into 3 sections: key elements and procedural definitions, end point definitions, and clinical trial design principles. The Chronic Total Occlusion Academic Research Consortium is a first step toward improved comparability and interpretability of study results, supplying an increasingly growing body of CTO percutaneous coronary intervention evidence.

Diagnostic performance of coronary angiography utilizing intraprocedural 320-row computed tomography with minimal contrast medium.

Recently developed coronary angiography with intraprocedural 320-row computed tomography can be performed in a catheterization laboratory (XACT) by injecting contrast medium from a place close to the coronary arteries, thereby requiring a minimal amount of contrast medium. However, its clinical application has not yet been established. This study aimed to evaluate the diagnostic accuracy of XACT angiography with a minimal volume of contrast medium in patients with suspected coronary artery disease (CAD). A total of 167 coronary segments were analyzed in 14 patients (9 males, median age 70 years) with suspected CAD by XACT angiography with 7.5 ml of contrast medium and invasive coronary angiography (ICA) with standard techniques. The segmental-based diagnostic accuracy of XACT angiography in detecting stenosis of ≥ 50% and ≥ 75% and visualized by ICA was good (sensitivity: 74% and 62%, specificity: 99% and 99%, positive predictive value: 93% and 80%, and negative predictive value: 97% and 97%, respectively). These results suggest that XACT angiography with a very low amount of contrast medium may have strong clinical utility for screening coronary arteries in patients with renal dysfunction or undergoing clinical procedures such as pacemaker implantation.

Predictive performance of dual modality of computed tomography angiography and intravascular ultrasound for no-reflow phenomenon after percutaneous coronary stenting in stable coronary artery disease.

Attenuated plaque on intravascular ultrasound (IVUS) and low attenuation plaque on computed tomography angiography (CTA) are associated with no-reflow phenomenon during percutaneous coronary intervention (PCI). However, evaluation by a single modality has been unable to satisfactorily predict this phenomenon. We investigated whether the combination of IVUS and CTA findings can ameliorate the predictive potential for no-reflow phenomenon after stent implantation during PCI in stable coronary artery disease (CAD). A total of 988 lesions of 707 stable CAD patients who underwent coronary CTA before PCI were enrolled. PCI was performed with preprocedural IVUS and stent implantation. As for plaque characters, very low attenuation plaque (CTA v-LAP) whose minimum density was < 0 Hounsfield units on CTA and attenuated plaque (IVUS AP) on IVUS were evaluated. No-reflow phenomenon was observed in 22 lesions (2.2%) of 19 patients (2.7%). Both CTA v-LAP and IVUS AP were much more frequently observed in patients with no-reflow phenomenon. Positive (PPV) and negative predictive values (NPV) and accuracy for prediction of no-reflow were almost equivalent between CTA v-LAP (13.2, 99.6, and 87.0%) and IVUS AP (15.7, 99.8, and 89.0%). The combination of CTA v-LAP and IVUS AP markedly ameliorated PPV (31.7%) without deterioration of NPV (99.7%) and increased the diagnostic accuracy (95.5%). These findings showed that the combination of CTA v-LAP and IVUS AP improved the predictive power for no-reflow phenomenon after coronary stenting in stable CAD patients, suggesting the usefulness of combined estimation by using CTA and IVUS for predicting no-reflow phenomenon during PCI in clinical practice.

Retrograde Coronary Chronic Total Occlusion Intervention (JR-CTO) Score: From the Japanese CTO-PCI Expert Registry.

BACKGROUND: Despite the effectiveness of the retrograde approach for chronic total occlusion (CTO) lesions, there are no standardized tools to predict the success of retrograde percutaneous coronary intervention (PCI). OBJECTIVES: The aim of this study was to develop a prediction tool to identify CTO lesions that will achieve successful retrograde PCI. METHODS: This study evaluated data from 2,374 patients who underwent primary retrograde CTO-PCI and were enrolled in the Japanese CTO-PCI Expert Registry between January 2016 and December 2022 (NCT01889459). All observations were randomly assigned to the derivation and validation cohorts at a 2:1 ratio. The prediction score for guidewire failure in retrograde CTO-PCI was determined by assigning 1 point for each factor and summing all accrued points. RESULTS: The JR-CTO score (moderate-severe calcification, tortuosity, Werner collateral connection grade ≤1, and nonseptal collateral channel) demonstrated a C-statistic for guidewire failure of 0.72 (95% CI: 0.67-0.76) and 0.71 (95% CI: 0.64-0.77) in the derivation and validation cohorts, respectively. Patients with lower scores had higher guidewire and technical success rates and decreased guidewire crossing time and procedural time (P < 0.01). CONCLUSIONS: The JR-CTO (Japanese Retrograde Chronic Total Occlusion) score, a simple 4-item score that predicts successful guidewire crossing in patients undergoing retrograde CTO-PCI, has the potential to support clinical decision-making for the retrograde approach.

Incidence, predictors, and subsequent mortality risk of recurrent myocardial infarction in patients following discharge for acute myocardial infarction.

BACKGROUND: In the percutaneous coronary intervention (PCI) era, little evidence exists regarding the incidence, predictors and long-term mortality of recurrent myocardial infarction (Re-MI) following discharge for acute myocardial infarction (AMI). METHODS AND RESULTS: A total of 7,870 patients who survived AMI were studied with a median follow-up period of 3.9 years: 353 patients (4.5%) experienced Re-MI, with 7 of those dying within 30 days, which was classified as fatal Re-MI. The incidence of Re-MI per year was 2.65% for the first year, and 0.91-1.42% thereafter up to 5 years. Multivariate Cox regression analyses revealed that predictors of Re-MI were diabetes mellitus (hazard ratio (HR): 2.079, P<0.001), history of MI (HR: 1.767, P=0.001), and advanced age (HR: 1.021, P=0.001). These 3 predictors remained significant when angiographic and procedural parameters were incorporated into the analyses. The incidence and adjusted risk of Re-MI increased when these variables were clustered (P<0.001). The all-cause mortality rate was significantly higher in patients with Re-MI than in those without (HR: 2.206, P<0.001). CONCLUSIONS: In post-AMI patients treated in the PCI era, the incidence of Re-MI is low compared with that reported during the past 30 years. Patients' clinical factors of diabetes mellitus, history of MI, and advanced age appear to affect the occurrence of Re-MI after hospital discharge, and Re-MI still carries a risk for subsequent mortality.

Elevated serum heart-type fatty acid-binding protein in the convalescent stage predicts long-term outcome in patients surviving acute myocardial infarction.

BACKGROUND: Little is known about the prognostic significance of elevated serum heart-type fatty acid-binding protein (H-FABP) in post-acute myocardial infarction (post-AMI) patients. METHODS AND RESULTS: A total of 1,283 post-AMI patients with available serum samples collected in the convalescent stage were studied. During a median follow-up period of 1,785 days, 176 patients (14%) had adverse events (all-cause mortality, n=81; non-fatal MI, n=44; readmission for heart failure [HF], n=51). Patients were divided into 2 groups according to a serum H-FABP level of 6.08ng/ml, which was determined to be the optimal cut-off for discriminating all-cause mortality based on the maximum value of the area under the receiver operating characteristic curve. Patients with elevated H-FABP (>6.08ng/ml, n=224) had a significantly higher incidence of death (18.3% vs. 3.8%, P<0.001) and readmission for HF (10.3% vs. 2.6%, P<0.001), but not of non-fatal MI (4.5% vs. 3.2%, P=0.187), compared to those with H-FABP <6.08ng/ml. Multivariate Cox regression analysis indicated that elevated serum H-FABP was associated with an increased risk of mortality (hazard ratio [HR], 1.91; 95% confidence interval [CI]: 1.03-3.51, P=0.039) and readmission for HF (HR, 2.49; 95% CI: 1.15-5.39, P=0.020). CONCLUSIONS: Elevated serum H-FABP during the convalescent stage of AMI predicted long-term mortality and readmission for HF after survival discharge in the post-AMI patients.

Practical utilization of cardiac computed tomography for the success in complex coronary intervention.

Percutaneous coronary intervention (PCI) for complex lesions is still technically demanding and is associated with less favorable procedural parameters such as lower success rate, longer procedural time, higher contrast volume and unexpected complications. Because the conventional angiographic analysis is limited by the inability to visualize the plaque information and the occluded segment, cardiac computed tomography has evolved as an adjunct to invasive angiography to better characterize coronary lesions to improve success rates of PCI. Adding to routine image reconstructions by coronary computed tomography angiography, the thin-slab maximum intensity projection method, which is a handy reconstruction technique on an ordinary workstation, could provide easy-to-understand images to reveal the anatomical characteristics and the lumen and plaque information simultaneously, and then assist to build an in-depth strategy for PCI. Especially in the treatment of chronic total occlusion lesion, these informations have big advantages in the visualization of the morphologies of entry and exit, the occluded segment and the distribution of calcium compared to invasive coronary angiography. Despite of the additional radiation exposure, contrast use and cost for cardiac computed tomography, the precise analysis of lesion characteristics would consequently improve the procedural success and prevent the complication in complex PCI.

Occlusion patterns, strategies and procedural outcomes of percutaneous coronary intervention for in-stent chronic total occlusion.

BACKGROUND: In-stent chronic total occlusion (CTO) presents various occlusion patterns, which complicate percutaneous coronary intervention (PCI). AIMS: The aim of the study was to investigate the initial outcome and strategy of PCI for in-stent CTO according to the angiographic occlusion patterns. METHODS: This study assessed 791 in-stent CTOs from the Japanese CTO-PCI Expert Registry from 2015 to 2018. They were divided into four patterns: pattern A (n=419), CTO within the stent segment; pattern B (n=196), CTO beyond the distal edge; pattern C (n=85), CTO beyond the proximal edge; and pattern D (n=69) CTO beyond both the proximal and distal edges. RESULTS: There were significant differences in the technical success rates (96.2%, 86.2%, 92.9%, and 75.4% for patterns A-D, respectively; p<0.001), guidewire crossing times (22 [interquartile range: 10-46], 52 [24-102], 40 [20-78], and 86 [45-127] min, respectively; p<0.001), and the rates of antegrade approach alone (90.9%, 61.2%, 67.1%, and 31.9%, respectively; p<0.001). CONCLUSIONS: PCI for CTO within the stent segment was associated with excellent initial outcomes with the antegrade approach. However, PCI for CTO beyond both the proximal and distal edges was associated with the poorest outcomes, even with the bidirectional approach.

Analysis of the long-term effects of drug-eluting stents on coronary arterial wall morphology as assessed by virtual histology intravascular ultrasound.

BACKGROUND: Animal models show impairment of arterial healing after drug-eluting stents (DES) compared with bare-metal stents (BMS). Virtual histology intravascular ultrasound (VH-IVUS) offers an opportunity to assess lesion morphology in vivo. METHODS: We used VH-IVUS in 80 patients to assess long-term (median = 10 months) native artery vascular responses after 76 implantations of DES compared with 32 BMS. The presence of "necrotic core abutting the lumen" was evaluated at baseline and follow-up. RESULTS: At baseline, necrotic core abutting the lumen through the stent struts was observed in 76% of DES and 75% of BMS. Although the percentage of necrotic core within the plaque behind the stents did not change during follow-up in DES (23% [18%, 28%] to 22% [17%, 27%], P = .57) or BMS (22% [19%, 27%] to 20% [12%, 26%], P = .29), necrotic core abutting the lumen through the stent struts decreased more in BMS (75% to 19%, P < .001) than DES (76% to 61%, P = .036) because of the lack of an overlying, protective neointima in DES-treated lesions. Furthermore, within the adjacent reference segments, the incidence of necrotic core abutting the lumen decreased in BMS-treated lesions (proximal 23% to 0%, P = .023; distal 21% to 0%, P = .023), but not in DES (proximal 22% to 17%, P = .48; distal 23% to 21%, P = .82). CONCLUSIONS: Serial VH-IVUS analysis of DES-treated lesions showed a greater frequency of unstable lesion morphometry at follow-up compared with BMS. The apparent mechanism was a suppression of the protective neointimal hyperplasia layer coupled with a lack of vulnerable plaque resolution at reference segments in DES compared with BMS.

Successful guidewire crossing via collateral channel at retrograde percutaneous coronary intervention for chronic total occlusion: the J-Channel score.

AIMS: Guidewire (GW) tracking in a collateral channel (CC) is an important step during retrograde chronic total occlusion (CTO) percutaneous coronary intervention (PCI). The aim of this study was to create a prediction score model for CC GW crossing success. METHODS AND RESULTS: We analysed data on 886 CCs included in the Japanese CTO PCI Expert Registry during 2016. CCs were categorised as septal (n=610) and non-septal (n=276). CCs were randomly assigned to derivation and validation sets in a 2:1 ratio. The score was developed by multivariate analysis with angiographic findings. Small vessel, reverse bend, and continuous bends were independent predictors in the septal CC subset. Small vessel, reverse bend, and corkscrew were independent predictors in the non-septal CC subset. The extent of intervention was easy, intermediate, and difficult in 92.9%, 57.4%, and 16.7% in the septal CC subset and 91.7%, 54.3%, and 19.0% in the non-septal CC subset, respectively, in the validation set. The area under the receiver operating characteristic curve was >0.7 in the derivation and validation sets of both CC subsets. CONCLUSIONS: The prediction score model can suggest grading of the difficulty of CC GW crossing based on angiographic findings for each type of CC.

Impact of intravascular ultrasound-guided minimum-contrast coronary intervention on 1-year clinical outcomes in patients with stage 4 or 5 advanced chronic kidney disease.

This study aims to elucidate 1-year clinical outcomes using this technique for patients with stage 4 or 5 advanced chronic kidney disease (CKD). Research has proven that imaging-guided percutaneous coronary intervention (PCI) reduces contrast volume significantly; however, only short-term clinical benefits have been reported. Minimum-contrast (MINICON) studies are based on the registry design pattern to enroll PCI results in patients with advanced CKD stage 4 or 5 comorbid with coronary artery disease. We excluded cases of emergency PCI or maintenance dialysis from this study. In this study, we compared the intravascular ultrasound (IVUS)-guided MINICON PCI group (n = 98) with the angiography-guided standard PCI group (n = 86). Enrollment of the MINICON studies started in 2006. Before 2012, IVUS-guided MINICON PCI was performed only in 14% (stage 1), but it was 100% after 2012 (stage 2). The enrollment finished in 2016. The IVUS-guided MINICON PCI group exhibited a significantly reduced contrast volume (22 ± 20 vs. 130 ± 105 mL; P < 0.0001) and contrast-induced acute kidney injury (CI-AKI; 2% vs. 15%; P = 0.001). The PCI success rate was similarly high (100% vs. 99%; P = 0.35). At 1 year (follow-up rate, 100%), we observed less induction of renal replacement therapy (RRT; 2.7% vs. 13.6%; P = 0.01), but all-cause mortality or myocardial infarction was similar in both groups. The IVUS-guided MINICON PCI reduces CI-AKI significantly and induction of RRT at 1 year in patients with stage 4 or 5 advanced CKD.

Cardiac troponin T predicts occult coronary artery stenosis in patients with chronic kidney disease at the start of renal replacement therapy.

BACKGROUND: The high prevalence of asymptomatic coronary artery stenosis (CAS) in chronic kidney disease (CKD) has emerged as an important predictor of outcome. However, diagnostic tools that can identify asymptomatic CAS have not yet been established. We investigated whether asymptomatic patients at the initiation of renal replacement therapy (RRT) could be screened using cardiac troponin T (cTnT) and atherosclerotic surrogate markers such as ankle-brachial blood pressure index (ABPI) and intima-media thickness (IMT). METHODS AND RESULTS: Among 142 patients who were about to start RRT, 60 who were asymptomatic underwent coronary evaluation by multi-slice computed tomography (MSCT) and/or coronary angiography (CAG). CAG diagnosed 35 patients (43.8%) as CAS positive and 27 of them had multi-vessel disease. Factors associated with CAS were smoking, elevated cTnT, low ABPI and high IMT. Moreover, the severity of CAS was associated with smoking, cTnT and ABPI. Stepwise logistic regression analyses revealed that cTnT was a powerful predictor of asymptomatic multi-vessel CAS. Receiver operating characteristic analysis documented the usefulness of cTnT as a screening tool with a cut-off point 0.05 ng/ml. The optimal screening tool for multi-vessel CAS was cTnT (sensitivity, 92.6%; 95% CI, 82.7-99.9; specificity, 63.6%; 95% CI, 47.2-80.0). CONCLUSION: We concluded that cTnT should be measured as part of a strategy for detecting asymptomatic CAS, especially multi-vessel disease in patients with CKD at the start of RRT.

Assessment of coronary stenosis by a 16-slice MDCT scanner in asymptomatic diabetic patients starting dialysis therapy.

BACKGROUND: The accuracy for the detection of coronary stenosis by multidetector row computed tomography (MDCT) has been getting more recognition. However, the usefulness of MDCT in patients with chronic kidney disease (CKD) has not been confirmed. METHODS: Weanalyzed 19 consecutive patients with asymptomatic diabetic CKD who underwent both MDCT and coronary angiography (CAG) at the initiation of dialysis. The definition of stenosis in this study was lesions with > or =50% stenosis by CAG. RESULTS: CAG revealed stenosis in 35 of 76 branches in 19 patients. Vessel diameter could not be evaluated by MDCT in 11 (14%) major vessels because of motion artifacts, pericardial effusion, pleural effusion, and severe calcification. Almost all of such lesions were located in the right coronary (4/11; 36%) or left circumflex (5/11; 45%) artery. The sensitivity, specificity, positive and negative predictive values of MDCT for a diagnosis of stenosis in the 65 evaluable major vessels were 86, 81, 78, and 88%, respectively. The severity of vessel calcification was increased in a stepwise manner with increments in the proportion of major vessels with > or =50% stenosis (p = 0.004 for trend). CONCLUSION: MDCT seemed to be an effective non-invasive method of screening patients with diabetic CKD for CAD.

Isolated dissecting aneurysm of the superior mesenteric artery: intravascular ultrasound (IVUS) images.

A case of the isolated dissection of the superior mesenteric artery (SMA) is presented, with the intravascular ultrasound (IVUS) images. Abdominal computed tomography revealed an intraluminal hematoma in the proximal portion of the SMA in a 57-year-old man complaining of persistent abdominal pain. Selective angiography showed narrowing of the SMA. The most compatible diagnosis was a dissection of the SMA, however, the possibility of SMA thromboembolisms could not be denied. Transcatheter suction removal of thrombi would be reconmmended for SMA thromboembolisms, however, intraarterial suction should be avoided so as not to injure the internal surface of the intima in cases of dissection of SMA. The IVUS images clearly demonstrated the condition of the true and false lumen of the dissecting region in detail. Transluminal balloon angioplasty of the true lumen and systemic anticoagulation treatment resulted in uneventful recovery. Demonstration of the exact condition in the dissecting region using IVUS is useful for selecting therapeutic strategies in cases with isolated dissecting aneurysm of the SMA.

Cardiac computed tomography-derived myocardial mass at risk using the Voronoi-based segmentation algorithm: A histological validation study.

BACKGROUND: Myocardial mass at risk (MMAR) is an important predictor of adverse cardiac events in patients with ischemic heart disease. This study aims to validate the accuracy of MMAR calculated from cardiac computed tomography (CCT) data using the Voronoi-based segmentation algorithm in comparison with actual MMAR measured on ex-vivo swine hearts prepared by injecting a dye into the coronary arteries. METHODS: Fifteen extracted swine hearts had India ink injected into one of the major coronary arteries. Subsequently, all coronary arteries manually injected with methylcellulose-based iohexiol-370 were imaged by 16-row CT. The ventricles were cross-sectioned perpendicularly to the long axis of the left ventricle (LV). The stained area and the total LV area of individual slices were measured, and actual MMAR was calculated as the ratio of the LV volume with the disc-summation method. CT-based MMAR of each coronary artery was calculated automatically with the Voronoi-based segmentation algorithm. The results were compared using Pearson's correlation coefficient. RESULTS: The median value of CT-based MMAR was 50.8% for the left anterior descending artery (LAD), 36.6% for the left circumflex artery (LCX), and 23.0% for the right coronary artery (RCA). Actual MMAR was 49.8% for LAD, 32.2% for LCX, and 25.9% for RCA. CT-based MMAR was significantly related to actual MMAR (r = 0.92, p = 0.02 for LAD; r = 0.96, p = 0.009 for LCX; r = 0.96, p = 0.009 for RCA). CONCLUSION: CT-based MMAR obtained by Voronoi-based segmentation algorithm reliably estimates actual MMAR measured on ex-vivo swine hearts.

Preliminary report on a cost-utility analysis of revascularization by percutaneous coronary intervention for ischemic heart disease.

Few socioeconomic studies have so far reported on revascularization for stable ischemic heart disease in Japan. This study aimed to validate the sensitivity of the health-related quality of life (HRQOL) scale for determining the pathology and medical technology to be used and to validate the application of a cost-utility analysis model. We studied 32 patients who had undergone percutaneous coronary intervention (PCI) (mean age 67.9 ± 7.3 years). For HRQOL, utility and quality of life (QOL) were examined using the EuroQol 5 Dimension (EQ-5D) and EuroQol Visual Analogue Scale (EQ-VAS), respectively. The changes in the utility index before and after PCI were compared between the PCI and coronary angiography (CAG) groups to determine the sensitivity of the EQ-5D that was used to calculate quality-adjusted life years (QALY). Additionally, to estimate the cost-utility of PCI 120 months after the procedure, we analyzed our study results and the results of previous reports using the Markov chain model. The utility index was found to improve in the PCI group (0.08 ± 0.15), whereas it decreased in the CAG group (-0.02 ± 0.11) (p = 0.049). The estimated result of the cost-utility analysis as the increase in utility above baseline level was the expected value, that is, 70,000 US$/QALY. Our findings suggest that QALY may be valid as a utility index in the clinical and economic evaluation of PCI in Japan.

Ideal Guiding Catheter Position During Bilaterally Engaged Percutaneous Coronary Intervention.

Using a novel combined angiography computed tomography (CT) system, we evaluated the impact of the intra-aortic root position of a right coronary artery (RCA) catheter on its coaxiality. We retrospectively enrolled 19 patients who underwent CT scans during bilaterally engaged percutaneous coronary intervention. Coaxiality was defined as the angle between the RCA and the RCA catheter. The coaxiality was better when the RCA catheter was placed anterior to the left main coronary artery catheter (median 27.0° vs 53.7°, p = 0.02). The position of the RCA catheter had a significant impact on the coaxiality of it, with a coaxiality improvement ratio of 0.506 (95% confidence interval 0.294 to 0.871, p = 0.017). Three-dimensional reconstructed CT images of the right anterior oblique projection could determine the position of catheters in all cases. In conclusion, the RCA catheter should be placed anterior, rather than posterior, to the left main coronary artery catheter for better coaxiality during bilaterally engaged percutaneous coronary intervention. The right anterior oblique projection is useful for determining the catheter position.

Contrast-free diagnosis and treatment of coronary artery disease guided by integrated cardiac imaging: concept and first clinical experience.

The use of iodinated contrast media (ICM) remains a potential hazard for patients undergoing diagnostic cardiac imaging and percutaneous coronary intervention. In particular patients with history of prior adverse reaction to a contrast agent are at a high risk in case of re-exposure, even if designated premedication is administered. Based on a patient with recurrent angina pectoris and history of systemic anaphylactic reaction to ICM, we describe the logical stepwise approach from diagnostic imaging to safe and successful imaging guided percutaneous coronary intervention without the use of contrast agent.

Reproducibility and clinical potential of myocardial mass at risk calculated by a novel software utilizing cardiac computed tomography information.

To select the best revascularization strategy a correct understanding of the ischemic territory and the coronary anatomy is crucial. Stress myocardial perfusion single photon emission computed tomography (SPECT) is the gold standard to assess ischemia, however, SPECT has important limitations such as lack of coronary anatomical information or false negative results due to balanced ischemia in multi-vessel disease. Angiographic scores are based on anatomical characteristics of coronary arteries but they lack information on the extent of jeopardized myocardium. Cardiac computed tomography (CCT) has the ability to evaluate the coronary anatomy and myocardium in one sequence, which is theoretically the ideal method to assess the myocardial mass at risk (MMAR) for any target lesion located at any point in the coronary tree. In this study we analyzed MMAR of the three main coronary arteries and three major side branches; diagonal (Dx), obtuse marginal (OM), and posterior descending artery (PDA) in 42 patients with normal coronary arteries using an algorithm based on the Voronoi method. The distribution of MMAR among the three main coronary arteries was 44.3 ± 5.6 % for the left anterior descending artery, 28.2 ± 7.3 % for the left circumflex artery, and 26.8 ± 8.6 % for the right coronary artery. MMAR of the three major side branches was 11.3 ± 3.9 % for the Dx, 12.6 ± 5.2 % for the OM and 10.2 ± 3.4 % for the PDA. Intra- and inter-observer analysis showed excellent correlation (r = 0.97; p < 0.0001 and r = 0.95; p < 0.0001, respectively). In conclusion, CCT-based MMAR assessment is reliable and may offer important information for selection of the optimal revascularization procedure.

Utility of Intravascular Ultrasound in Percutaneous Revascularization of Chronic Total Occlusions: An Overview.

Intravascular ultrasound has been used for >20 years to guide percutaneous coronary intervention in different subsets of coronary lesions. During the last decade, the interest in percutaneous coronary intervention for chronic total occlusion (CTO) has increased dramatically, leading to high success rates. Failure of guidewire crossing is the most common reason for failed CTO attempts. Certain angiographic features, such as blunt proximal CTO cap, tortuosity, heavy calcification, and lack of visibility of path in the distal vessel, increase procedural difficulty. A better understanding of the behavior of the guidewire within the CTO segment may represent a key issue to achieve successful outcome. In this respect, intravascular ultrasound imaging might have potential roles in the recanalization of CTOs. In this paper, we focused on the usefulness and the applications of intravascular ultrasound imaging in percutaneous CTO recanalization, underlying its impact on clinical outcome.