Development and Validation of Artificial Intelligence-Based Algorithms for Predicting the Segments Debulked by Rotational Atherectomy Using Intravascular Ultrasound Images.

We develop and evaluate an artificial intelligence (AI)-based algorithm that uses pre-rotation atherectomy (RA) intravascular ultrasound (IVUS) images to automatically predict regions debulked by RA. A total of 2106 IVUS cross-sections from 60 patients with de novo severely calcified coronary lesions who underwent IVUS-guided RA were consecutively collected. The 2 identical IVUS images of pre- and post-RA were merged, and the orientations of the debulked segments identified in the merged images were marked on the outer circle of each IVUS image. The AI model was developed based on ResNet (deep residual learning for image recognition). The architecture connected 36 fully connected layers, each corresponding to 1 of the 36 orientations segmented every 10°, to a single feature extractor. In each cross-sectional analysis, our AI model achieved an average sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 81%, 72%, 46%, 90%, and 75%, respectively. In conclusion, the AI-based algorithm can use information from pre-RA IVUS images to accurately predict regions debulked by RA and will assist interventional cardiologists in determining the treatment strategies for severely calcified coronary lesions.

Trans-coronary pacing via Rota wire prevents bradycardia during rotational atherectomy: a case report.

Back ground: Rotational atherectomy (RA) is used for plaque modification in patients with heavily calcified coronary lesions. Rotational atherectomy can induce significant bradycardia or atrioventricular block requiring for temporary pacemaker insertion. In this report, we present a case of trans-coronary pacing via a Rota wire to prevent bradycardia during RA in the proximal right coronary artery (RCA). Case summary: A 72-year-old woman with a 1 month history of worsening effort angina was admitted to our hospital. Computed tomography coronary angiography disclosed significant coronary stenosis with severe calcification in proximal RCA. Coronary angiography revealed significant coronary stenosis with severe calcification in the proximal RCA. Subsequently, percutaneous coronary artery intervention was performed under the guidance of intravascular ultrasound (IVUS). The pull-back IVUS showed a circumferential calcified lesion in the proximal RCA that was treated using RA, which induced significant bradycardia requiring temporary pacemaker insertion. Immediately, trans-coronary pacing was provided via a Rota wire placed in the far distal RCA; this was used for back-up pacing during RA. Rotational atherectomy was completed by safely modifying the calcified lesion. After successful debulking of the calcified lesion, we dilated with a balloon, and a drug-eluting stent was implanted at the proximal RCA. Final IVUS and angiography showed good stent apposition and expansion. We did not observe any serious intraprocedural complications. Discussion: Rotational atherectomy is used for plaque modification in patients with heavily calcified coronary lesions. Rotational atherectomy can induce significant bradycardia or atrioventricular block requiring for temporary pacemaker insertion via the transvenous route. This method could be an effective method to prevent bradycardia during RA.

A novel treatment using a guide extension catheter and distal protection device for refractory coronary embolism: case report.

BACKGROUND: A large thrombus burden in patients with acute myocardial infarction is associated with worse outcomes. Although various methods of thrombus aspiration have been described, there is a potential limitation in the mechanism of eliminating a thrombus with only the use of an aspiration device. In this report, we present a novel method of retrieving massive thrombus using a guide extension catheter and a filter device. CASE SUMMARY: An 80-year-old man was diagnosed with anterior ST-elevation myocardial infarction (STEMI). Emergency coronary angiography revealed that the left anterior descending artery (LAD) showed an acute thrombotic occlusion in the mid-section. The percutaneous coronary intervention was performed to recanalize an occluded LAD. Although thrombectomy using an aspiration catheter and a guide catheter extension system was performed repeatedly, only a small amount of the thrombus was retrieved, and the LAD was still occluded. Therefore, we planned to remove the large thrombus burden by capturing the entire thrombus between the tip of the guide extension catheter and distal protection device, followed by pulling them out of the guide catheter together. A large amount of red thrombus, which adhered to the axis of the filter device, was successfully retrieved. The occluded LAD was successfully recanalized without balloon dilatation or stent implantation. DISCUSSION: Although a variety of aspiration devices are available, removal of large coronary artery thrombi with the use of an aspiration catheter alone can at times prove difficult. To solve this problem, we developed a novel technique for retrieving large thrombi. This method is effective in removing refractory thrombi for the treatment of STEMI patients.

Late peri-stent contrast staining appearance due to rupture of atherogenic neointima following drug-eluting stent.

The development of peri-stent contrast staining (PSS) after coronary intervention with implantation of a stent is observed in approximately 1-3% of patients treated with drug-eluting stent. Although the cumulative incidences of late in-stent restenosis and stent thrombosis are significantly higher in lesions with PSS than in those without the finding, the mechanisms for the development of PSS have not yet been fully elucidated. In this report, we describe a case of rapid development of PSS with ulcer formation caused by rupture of atherogenic neointima, which was observed by serial optical coherence tomography examinations over 6 months. Protrusion of the stent-jailed underlying necrotic core toward the lumen by the contracting force might have resulted in formation of atherogenic neointima within the stent. Subsequently, rupture of this necrotic core induced by iatrogenic neointimal injury due to balloon dilation and dissolution of the accumulated necrotic core may have resulted in PSS formation 6 months after the procedure. These findings may be helpful for consideration of etiology and therapeutic strategy for lesions with PSS. .

Acute myocardial infarction in a patient with uncorrected tetralogy of Fallot accompanied by coronary artery ectasia: A case report.

A 63-year-old male with a medical history of uncorrected tetralogy of Fallot (TOF) presented to our hospital due to acute myocardial infarction (AMI). Emergency coronary angiography (CAG) was performed and it showed a severe thrombotic stenosis in the middle right coronary artery (RCA) and total thrombotic occlusion of the posterior descending branch of the RCA. Subsequently, percutaneous coronary artery intervention (PCI) under the guidance of intravascular ultrasound (IVUS) was performed. He was discharged on the 14th day in stable condition. Nine months after the PCI procedure, coronary computed tomography angiography was performed for follow-up, which revealed tetralogy of Fallot and complete resolution of the thrombus and ectasic coronary artery without stenosis. When he was 70 years old, he was transferred to our hospital because of recurrent AMI. As emergency CAG showed total thrombotic occlusion of the middle RCA, IVUS-guided PCI was performed. We experienced a very rare case of AMI in an adult patient with uncorrected TOF accompanied by coronary artery ectasia (CAE). To the best of our knowledge, this is the first case of AMI in an adult patient with uncorrected TOF accompanied by CAE. .

Short- and mid-term influence of drug-coated stent implantation on structural and functional vascular healing response: An optical coherence tomography and acetylcholine testing study.

OBJECTIVE: This study investigated the effect of a drug-coated stent (DCS) that has a novel microporous abluminal surface without a polymer on 1-month and 1-year functional and morphological healing response as assessed using acetylcholine (Ach) testing and optical coherence tomography (OCT). BACKGROUND: DCS is expected to induce favorable morphological and physiological arterial healing after its implantation. METHODS: A total of 11 patients who underwent vascular response examinations 1-month and 1-year after the index PCI with DCS implantation were enrolled. The vascular response was evaluated by the functional response test by acetylcholine infusion, the morphological response test by OCT. RESULTS: Although 94.5% of the DCS struts were covered by homogeneous smooth neointima at 1 month, the percentage of neointimal coverage increased to 98.5% at 1 year (p = .02). Conversely, the proportion of uncovered struts and malapposed struts at 1 year were 1.2 and 0.7%, respectively. Furthermore, the coronary vasomotor response to incremental doses of Ach were impaired especially in the distal segments at each period, although the responses to Ach at 10-6 mol/L in the distal segment tended to improve over time from baseline to 1 month and 1 year later (-19 ± 20%, -9 ± 17%, and -5 ± 14%, respectively; p = .27). CONCLUSIONS: The morphological assessment of DCS with OCT revealed a high degree of strut coverage and apposition at 4 weeks after implantation. The impaired endothelium-dependent vasomotor response tended to improve chronologically from baseline to 1 month and 1 year later.

Successful percutaneous removal of dislodged ring-marker of optical coherence tomography catheter using the twisted wire technique with a guide-extension catheter: A case report.

An 81-year-old male with diabetes and hypertension was admitted to our hospital due to chest pain on exertion. Coronary angiography revealed a severe stenosis at the middle of right coronary artery (RCA). We performed percutaneous coronary intervention under the guidance of optical coherence tomography (OCT) to the lesion in the middle RCA. After balloon dilations, a drug-eluting stent was deployed to the lesion. Then, OCT examination was performed. At that time, fluoroscopy revealed a foreign body over the 0.014-inch guidewire in the distal RCA, which was the ring-marker of OCT catheter. As RCA blood flow was well preserved, percutaneous removal of the dislodged ring-marker was immediately attempted. At first, we tried to remove the dislodged ring-marker with the guide-extension catheter trapping technique. However, it failed and advanced balloon catheter made the dislodged ring-marker migrate more distally. Therefore, we tried the twisted wire technique with the guide-extension catheter and finally the dislodged ring-marker was removed with it. To the best of our knowledge, this is the first case report of a successful percutaneous removal of a dislodged ring-marker of OCT catheter using the twisted wire technique with a guide-extension catheter. .

Evaporation kinetics of continuous water and dispersed oil droplets.

Drying of volatile oil droplets immersed in a continuous water phase was observed and analysed. Drying sample solutions were sandwiched between two glass plates and the water and oil phases were observed by confocal microscopy. In the initial stage of drying, evaporation of water was dominant and drying of the oil droplets was negligible. However, the rate of water evaporation decreased when the oil droplets were compressed. Comparison of experimental data with a diffusion model of water vapour showed that the decline in drying rates occurred earlier in the experiment than in the theoretical prediction. This implies that compression and narrowing of water paths caused the decline in the rate of water evaporation. After most water had evaporated, evaporation of the oil droplets occurred. The oil droplets did not shrink isotropically and the air-liquid interface invaded into the drying oil droplets. Cross-sectional observation by z-scanning revealed direct exposure of the oil droplets and they were pinned by the residual water phase. The water network between the oil droplets collapsed after the oil droplets had evaporated. The correlation between changes in structures and drying kinetics in both liquid phases was discussed.

Effect of neointimal tissue morphology on vascular response to balloon angioplasty in lesions with in-stent restenosis after drug-eluting stent deployment: an optical coherence tomography analysis.

This study aimed to evaluate the vascular response to balloon angioplasty for drug-eluting stent (DES) in-stent restenosis (ISR) lesions based on our novel optical coherence tomography (OCT) classification to establish the optimal treatment strategy for ISR lesions after DES implantation. A total of 104 ISR lesions after DES implantation were imaged by OCT and categorized into the following six patterns: type I-homogeneous high-intensity tissue, type II-heterogeneous tissue with signal attenuation, type III-speckled heterogeneous tissue, type IV-mixed tissue containing poorly delineated region with invisible strut, type V-mixed tissue containing sharply delineated low-intensity region, and type VI-bright protruding tissue with an irregular surface. Serial volumetric OCT analysis was performed before and after balloon dilation to evaluate the vascular response to balloon angioplasty. After balloon dilation, the minimal decrease in neointimal volume was noted in type I lesions and maximal in type III lesions. In contrast, the increase in stent volume was significantly more in type I lesions than others. Neointimal tissue characterization by OCT allows us to provide useful information about the vascular response to balloon dilation, which can influence the therapeutic strategy for DES ISR lesions.

Impact of optical coherence tomography-derived neointimal tissue morphology on development of very late in-stent restenosis.

OBJECTIVES: This study evaluated the progression of very late in-stent restenosis (VL-ISR) by analyzing four serial coronary angiography (CAG) images and its correlation with neointimal tissue characterization of the VL-ISR lesions on optical coherence tomography (OCT). BACKGROUND: Recently, VL-ISR is occasionally observed beyond a few years after drug-eluting stents (DESs) implantation. METHODS: This study analyzed 50 VL-ISR lesions after DES in which 4 serial CAGs over a period of 2 years, including at baseline procedure, 9 months after baseline procedure, 12 months before VL-ISR, and at the time of VL-ISR, were performed. Neointimal tissue characteristics by OCT were categorized as homogeneous, heterogeneous with invisible strut (Type I), heterogeneous with visible strut (Type II), speckled (Type III), or heterogeneous with sharply delineated border (Type IV). RESULTS: From the development process, 23 VL-ISRs (46%) were categorized as rapid progression and 27 (54%) as gradual progression. The five categories of neointimal tissue composition significantly differed between lesions with rapid and gradual progression. Homogeneous neointima and Type IV heterogeneous neointima were observed only in lesions with gradual progression. Moreover, most Type I heterogeneous neointima was identified in lesions with gradual progression. Instead, main neointimal tissue components of lesions with rapid progression were Type II (43%) and Type III (43%) heterogeneous neointima. CONCLUSION: The progression rate of in-stent atherosclerotic changes is gradual, whereas organized thrombus could be associated with an increased risk of rapid neointimal growth. The two types of stenosis progression provide a new insight into the mechanism of VL-ISR development after DES implantation.

Optical coherence tomography characteristics of in-stent restenosis after drug-eluting stent implantation: a novel classification and its clinical significance.

This study aimed to establish a novel classification of in-stent restenosis (ISR) morphological characteristics after drug-eluting stent (DES) implantation as visualized by optical coherence tomography (OCT) and determine its clinical significance. A total of 133 lesions with intrastent restenosis after DES implantation were imaged by OCT. Neointimal tissue characteristics were categorized according to the classical classification as either homogeneous, heterogeneous, or layered. Then all tissues were also classified into six types as follows: homogeneous high-intensity tissue (type I), heterogeneous tissue with signal attenuation (type II), speckled heterogeneous tissue (type III), heterogeneous tissue containing poorly delineated region with invisible strut (type IV), heterogeneous tissue containing sharply delineated low-intensity region (type V), or bright protruding tissue with an irregular surface (type VI). The kappa value for interobserver agreement between the two observers was higher in the modified classification than in the classical classification (0.97 and 0.72, respectively). Most lesions classified as type V and VI were likely to be identified in patients on hemodialysis and located at the ostial right coronary artery. The duration from stent implantation to ISR was significantly longer in types IV and VI than in others. The incidence of stent fracture was significantly higher in types I and IV. This new modified classification enabled us to classify most ISR lesions easily with higher reproducibility. The clinical significance of neointimal restenotic tissue classification by OCT became clear while using the modified classification.

Streamlined reverse wire technique for the treatment of complex bifurcated lesions.

Inserting a guidewire into an extremely angulated side branch (SB) is difficult. Reverse wire technique (RWT) method was developed to specifically overcome this challenging situation, and it has become common among operators performing percutaneous coronary intervention. The first step of RWT involves the delivery of a reverse wire (RW) beyond the bifurcation, together with dual lumen catheter (DLC). This step is sometimes difficult, due to the stenosis proximal to bifurcation. Balloon dilatation of the stenosis is sometimes required to make space for the RW passage, but this lesion modification involves a potential risk of vessel damage, plaque shift, or carina shift, which results in the occlusion of the target SB. Streamlined RWT is a novel method we developed to facilitate RW delivery. It consists of the following three steps: (a) Advancing a DLC alone beyond the occlusion and inserting a preshaped RW into a non-target SB distal to the bifurcation. (b) Adjusting the position of the bending part of RW and the exit port of DLC together at the ostium of the non-target SB. (c) Advancing the RW and DLC simultaneously, while holding them both together. All procedures subsequent to the delivery of RW are the same as those required in conventional RWT. This technique enables us to deliver a RW through severe stenosis without the risk of either vessel injury or the occlusion of target SB. It also helps us to save time and effort in accomplishing SB access, even during the treatment of complex bifurcated lesions.

Utility and Validity of Intracoronary Administration of Nicorandil Alone for the Measurement of Fractional Flow Reserve in Patients With Intermediate Coronary Stenosis.

BACKGROUND: Intracoronary (IC) administration of nicorandil has been proposed as an alternative choice of hyperemic agent for fractional flow reserve (FFR) measurements. This study evaluated the utility and validity of IC nicorandil administration alone to induce maximal hyperemia.Methods and Results:Two-hundred-seven patients with coronary artery disease listed for coronary angiography with FFR were prospectively enrolled. FFR was measured after (1) IC administration of nicorandil 2 mg (ICNIC2 mg); (2) continuous intravenous (IV) adenosine triphosphatase (ATP) infusion at 150 µg/kg/min (IVATP150); (3) IV ATP infusion at 210 µg/kg/min (IVATP210); (4) IC administration of 0.5 mg nicorandil during IVATP150 (ICNIC0.5 mg+IVATP150); (5) IC administration of 1 mg nicorandil during IVATP150 (ICNIC1 mg+IVATP150); and (6) IC administration of 2 mg nicorandil during IVATP150 (ICNIC2 mg+IVATP150). The average FFR values and the rate of achieving maximum hyperemia after ICNIC2 mg, IVATP150, IVATP210, ICNIC0.5 mg+IVATP150, ICNIC1 mg+IVATP150, and ICNIC2 mg+IVATP150 were 0.85±0.08, 0.89±0.08, 0.85±0.09, 0.84±0.08, 0.83±0.08, 0.83±0.08 (P<0.01), and 92%, 54%, 91%, 96%, 99%, 99% (P<0.01), respectively. The incidence of systolic aortic pressure drop, chest discomfort, and transient atrioventricular block increased in a dose-dependent manner after IV ATP infusion, but almost no adverse effects were observed after ICNIC2 mg. CONCLUSIONS: ICNIC2 mg produced a more pronounced hyperemia than continuous IV ATP, and might be the preferred method for assessment of FFR.

Evaluation of repeated progression of native coronary artery stenosis by optical frequency domain imaging in a patient with essential thrombocytosis.

Essential thrombocytosis (ET) is a myeloproliferative disorder with abnormal proliferation of the megakaryocytes and is manifested clinically by the overproduction of dysfunctional platelets, leading to thrombus formation. Therefore, the accurate evaluation of the morphological features for coronary stenosis and initiation of appropriate treatment may be life-saving for ET patients. In this report, we describe a case of the rapid development of repeated stenosis in the native coronary artery in an ET patient, and optical frequency domain imaging confirmed the etiology of the stenoses. These findings may be helpful for consideration of etiology and therapeutic strategy for thrombotic complications in ET patients. .

Accuracy of J-CTO Score Derived From Computed Tomography Versus Angiography to Predict Successful Percutaneous Coronary Intervention.

OBJECTIVES: The aim of this study was to compare the ability of conventional versus computed tomography angiography (CTA) to predict procedural success and 30-min wire crossing rates in percutaneous coronary intervention (PCI) for chronic total occlusion (CTO) lesions. BACKGROUND: Coronary CTA can be used to assess the morphology of CTO lesions. METHODS: We examined 205 consecutive patients (218 CTO lesions) who underwent coronary CTA pre-PCI. The J-CTO (Multicenter CTO Registry of Japan) score (the sum of the following 5 binary parameters: blunt proximal cap, calcification, bending >45°, and length of occluded segment >20 mm plus previously failed PCI attempt) was calculated using both CTA and conventional coronary angiography and compared. RESULTS: The median patient age was 69 years (interquartile range: 62 to 75 years), 82.4% were male, and a retrograde approach was attempted in 72 (33.0%) cases. The procedural success rate of the CTO-PCI procedures was 82.6%, and 29.4% of cases achieved 30-min wire crossing. The areas under the curve of the CTA-derived J-CTO score for predicting procedural success and 30-min wire crossing were significantly greater than those derived from conventional angiography (0.855 vs. 0.698; p < 0.001 for procedural success and 0.812 vs. 0.692; p < 0.001, for 30-min wire crossing). In addition, the areas under the curve of CTA-derived evaluations of calcification, bending, and occlusion length were significantly higher than those of derived from angiography for predicting procedural success. CONCLUSIONS: The CTA-derived J-CTO score was a more useful predictor of both procedural success and 30-min wire crossing than the J-CTO score derived from conventional angiography.

Simultaneous occurrence of spontaneous coronary artery dissections of the left anterior descending and right coronary arteries in acute myocardial infarction.

Spontaneous coronary artery dissection (SCAD) is a rare and often fatal cause of ischemic heart disease that occurs predominantly in young or middle-aged patients who are otherwise healthy. Therefore, the accurate diagnosis of SCAD and initiation of appropriate treatment may be life-saving. Although recent case reports have described patients with SCAD who exhibited multiple coronary dissections in addition to the culprit lesion, the authors could not determine whether the multiple dissections occurred simultaneously or at different times. In this report, we describe a case involving the simultaneous occurrence of multiple SCADs in the right coronary artery and left anterior descending artery. Intravascular ultrasound helped us to confirm the diagnosis of multiple SCADs, confirm their simultaneous occurrence, and navigate the guidewire into the true lumen. .

Incidence and impact on midterm outcome of intimal versus subintimal tracking with both antegrade and retrograde approaches in patients with successful recanalisation of chronic total occlusions: J-PROCTOR 2 study.

AIMS: The aim of this study was to assess the incidence and impact on midterm outcomes of intimal versus subintimal tracking with both antegrade and retrograde approaches in patients undergoing successful percutaneous coronary intervention for chronic total occlusion (CTO). METHODS AND RESULTS: In 2012, a total of 1,573 CTO cases from 30 hospitals were enrolled in the Japanese CTO registry. Successful guidewire crossing was performed in 1,411 cases (89.7%). Among them, the guidewire penetration position was clearly identified using intravascular ultrasound (IVUS) imaging in 352 cases, and clinical follow-up at 12 months was performed in 323 cases. These 323 cases were enrolled in this retrospective study: 242 cases were treated with the antegrade approach (antegrade group) and 81 cases were treated with the retrograde approach (retrograde group). The endpoint of this study was target vessel revascularisation (TVR) and major adverse cardiac events (MACE) at 12-month follow-up. Subintimal tracking occurred more frequently in the retrograde group (11.6% vs. 30.9%, p<0.01). TVR was more frequent in the subintimal tracking group in the retrograde group (7.1% vs. 16.0%, p=0.03) but not in the antegrade group (2.8% vs. 3.6%, p=0.99). Although the occlusion length was similar, the subintimal tracking group required a longer stent length compared to the intimal tracking group in the retrograde approach (59.7±24.4 mm vs. 74.0±24.4 mm, p<0.01). CONCLUSIONS: Subintimal tracking was more frequent in the retrograde approach. Intimal tracking should be recommended in the retrograde approach to reduce stent length and to improve follow-up outcomes.

A multidirectional approach to risk assessment in patients with three-vessel coronary artery disease undergoing percutaneous intervention.

BACKGROUND: The SYNTAX score (SS) and Clinical SYNTAX score (CSS) have demonstrated utility as risk-stratifying tools following percutaneous coronary intervention (PCI). However, useful determinants for predicting hard clinical events (HCE: death, nonfatal myocardial infarction, and stroke) in the setting of routinely-performed-angiographic follow-up have yet to be elucidated. METHODS AND RESULTS: We retrospectively examined the clinical outcomes of 252 three-vessel disease (TVD) patients following PCI. The incidence of HCE at 3 years significantly differed according to CSS (High, 20.2%; Intermediate, 1.2%; and Low, 6.0%; log-rank p<0.001), but not according to SS (High, 14.0%; Intermediate, 5.8%; and Low, 7.3%; log-rank p=0.13). The incidence of repetitive revascularization at 3 years did not differ significantly both among SS (High, 45.2%; Intermediate, 36.5%; and Low, 38.2%; log-rank p=0.22) and CSS (High, 36.9%; Intermediate, 41.7%; and Low, 41.7%; log-rank p=0.88,). CONCLUSION: Prediction of HCE in patients with TVD following PCI was more accurate with CSS than with SS.

Comparison of percutaneous coronary intervention for chronic total occlusion outcome according to operator experience from the Japanese retrograde summit registry.

OBJECTIVES: This study was performed to evaluate the acute outcomes of percutaneous coronary intervention (PCI) for chronic total occlusion (CTO) based on operator experience. BACKGROUND: Despite developments in both technology and techniques, PCI procedures for CTO's remain challenging. METHODS: A total of 3,229 eligible subjects who underwent CTO-PCI were enrolled from 56 centers by a retrograde summit using a web registry system. To compare the acute outcomes of the CTO data, 18 centers were classified as higher volume centers (HC) and 38 centers as lower volume centers (LC) depending on the CTO-PCI experience of the operator. RESULTS: The mean procedural success rate of all centers was 88.4%. The overall procedural success rate was significantly higher in HC than LC (90.6% vs. 85.6%, respectively; P < 0.0001). In addition, overall antegrade success rate was also higher in HC than LC (91.0% vs. 83.9%, respectively; P < 0.0001). Although the overall retrograde approach success rate was significantly higher in HC than LC (85.0% vs. 77.6%, respectively; P < 0.0001), there was no significant difference in that of the retrograde alone (89.0% vs. 93.7%, respectively; P = 0.051). Major in-hospital adverse events were observed in 0.53% of cases, and the rates were similar between the two groups (0.45% vs. 0.62%, respectively; P = 0.25). CONCLUSIONS: Although CTO-PCI was safe in both groups, the procedural success rate was significantly higher in HC than LC, even in this new era of CTO-PCI. This difference was attributed to the difference in the antegrade procedural success rate. © 2015 Wiley Periodicals, Inc.