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Background: Balloon uncrossable lesions are defined as lesions that cannot be crossed with a balloon after successful guidewire crossing. Methods: We analyzed the association between balloon uncrossable lesions and procedural outcomes of 8671 chronic total occlusions (CTOs) percutaneous coronary interventions (PCIs) performed between 2012 and 2022 at 41 centers. Results: The prevalence of balloon uncrossable lesions was 9.2%. The mean patient age was 64.2 ± 10 years and 80% were men. Patients with balloon uncrossable lesions were older (67.3 ± 9 vs. 63.9 ± 10, p < 0.001) and more likely to have prior coronary artery bypass graft surgery (40% vs. 25%, p < 0.001) and diabetes mellitus (50% vs. 42%, p < 0.001) compared with patients who had balloon crossable lesions. In-stent restenosis (23% vs. 16%. p < 0.001), moderate/severe calcification (68% vs. 40%, p < 0.001), and moderate/severe proximal vessel tortuosity (36% vs. 25%, p < 0.001) were more common in balloon uncrossable lesions. Procedure time (132 (90, 197) vs. 109 (71, 160) min, p < 0.001) was longer and the air kerma radiation dose (2.55 (1.41, 4.23) vs. 1.97 (1.10, 3.40) min, p < 0.001) was higher in balloon uncrossable lesions, while these lesions displayed lower technical (91% vs. 99%, p < 0.001) and procedural (88% vs. 96%, p < 0.001) success rates and higher major adverse cardiac event (MACE) rates (3.14% vs. 1.49%, p < 0.001). Several techniques were required for balloon uncrossable lesions. Conclusion: In a contemporary, multicenter registry, 9.2% of the successfully crossed CTOs were initially balloon uncrossable. Balloon uncrossable lesions exhibited lower technical and procedural success rates and a higher risk of complications compared with balloon crossable lesions.

BACKGROUND:The prevalence, treatment and outcomes of balloon undilatable chronic total occlusions (CTOs) have received limited study. METHODS:We examined the prevalence, clinical and angiographic characteristics, and procedural outcomes of percutaneous coronary interventions (PCIs) for balloon undilatable CTOs in a contemporary multicenter US registry. RESULTS:Between 2012 and 2017 data on balloon undilatable lesions were available for 425 consecutive CTO PCIs in 415 patients in whom guidewire crossing was successful: 52 of 425 CTOs were balloon undilatable (12%). Mean patient age was 65 ± 10 years and most patients were men (84%). Patients with balloon undilatable CTOs were more likely to be diabetic (67 vs. 41%, P

ObjectiveTo assess the spatial distribution of chronic total occlusions (CTOs) within the coronary arteries and describe procedural strategies and outcomes during CTO percutaneous coronary intervention (PCI).BackgroundAcute occlusions due to plaque rupture tend to cluster within the proximal third of the coronary artery.MethodsWe examined the clinical and procedural characteristics of 1,348 patients according to lesion location within the coronary tree.ResultsA total of 1,369 lesions in 1,348 patients (mean age 66 ± 10 years, 85% male) were included. CTO PCI of proximal segments (n = 633, 46%) was more common than of mid (n = 557, 41%) and distal segments (n = 179, 13%). Patients undergoing CTO PCI of proximal segments were more likely to be smokers (P

High success rates are achievable for chronic total occlusion (CTO) percutaneous coronary intervention (PCI) using the hybrid approach, but periprocedural complications remain of concern. Although scores estimating success and efficiency in CTO PCI have been developed, there is currently no available score for estimation of the risk for periprocedural complications. We sought to develop a scoring tool for prediction of periprocedural complications during CTO PCI. We analyzed data from 1569 CTO PCIs in the Prospective Global Registry for the Study of Chronic Total Occlusion Intervention (PROGRESS CTO) using a derivation and validation sampling ratio of 2:1. Variables independently associated with periprocedural complications in multivariable analysis in the derivation set were assigned points based on their respective odds ratios. Forty-four (2.8%) patients experienced complications. Three factors were independent predictors of complications and were included in the score: patient age >65 years, +3 points (odds ratio, OR=4.85, CI 1.82-16.77); lesion length ≥23 mm, +2 points (OR=3.22, CI 1.08-13.89); and use of the retrograde approach +1 point (OR=2.41, CI 1.04-6.05). The resulting score showed good calibration and discriminatory capacity in the derivation (Hosmer-Lemeshow χ2 6.271, P=0.281, receiver-operating characteristic [ROC] area=0.758) and validation (Hosmer-Lemeshow χ2 4.551, P=0.473, ROC area=0.793) sets. Score values of 0 to 2, 3 to 4, and ≥5 were defined as low, intermediate, and high risk of complications (derivation cohort 0.4%, 1.8%, 6.5%, P

Intravascular imaging can facilitate chronic total occlusion (CTO) percutaneous coronary intervention. We examined the frequency of use and outcomes of intravascular imaging among 619 CTO percutaneous coronary interventions performed between 2012 and 2015 at 7 US centers. Mean age was 65.4±10 years and 85% of the patients were men. Intravascular imaging was used in 38%: intravascular ultrasound in 36%, optical coherence tomography in 3%, and both in 1.45%. Intravascular imaging was used for stent sizing (26.3%), stent optimization (38.0%), and CTO crossing (35.7%, antegrade in 27.9%, and retrograde in 7.8%). Intravascular imaging to facilitate crossing was used more frequently in lesions with proximal cap ambiguity (49% versus 26%, P

The contemporary frequency and outcomes of antegrade dissection and re-entry (ADR) for chronic total occlusion (CTO) percutaneous coronary intervention (PCI) have received limited study. The aim of this study was to determine the frequency and outcomes of ADR use in a large multicenter CTO PCI registry. The characteristics and outcomes of ADR were examined among 12,568 patients who underwent 12,841 CTO PCIs at 46 U.S. and non-U.S. centers between 2012 and 2023. ADR was used in 2,385 of the procedures (18.6%). ADR use declined from 37.9% in 2012 to 14.5% in 2022 (P < 0.001). Patients in whom ADR was used had a high prevalence of comorbidities. Compared with cases that did not use ADR, ADR cases had more complex angiographic characteristics, higher mean J-CTO (Multicenter CTO Registry in Japan) score (2.94 ± 1.11 vs 2.23 ± 1.26; P < 0.001), lower technical success (77.0% vs 89.3%; P < 0.001), and higher in-hospital major adverse cardiac events (3.7% vs 1.6%; P < 0.001). The use of the CrossBoss declined from 71% in 2012 to 1.4% in 2022 and was associated with higher technical success (87%) compared with wire-based techniques (73%). The Stingray device displayed higher technical success (86%) compared with subintimal tracking and re-entry (STAR) (74%) and limited antegrade subintimal tracking (78%); however, its use has been decreasing, with STAR becoming the most used re-entry technique in 2022 (44% STAR vs 38% Stingray). The use of ADR has been decreasing. ADR was used in more complex lesions and was associated with lower technical success and higher major adverse cardiac events compared with non-ADR cases. There has been a decrease in Stingray use and an increase in the use of STAR for re-entry. [Display omitted] [ABSTRACT FROM AUTHOR]

Distal vessel quality is a key parameter in the global chronic total occlusion (CTO) crossing algorithm. The study sought to evaluate the association of distal vessel quality with the outcomes of CTO percutaneous coronary intervention. We examined the clinical and angiographic characteristics and procedural outcomes of 10,028 CTO percutaneous coronary interventions performed at 39 U.S. and non-U.S. centers between 2012 and 2022. A poor-quality distal vessel was defined as <2 mm diameter or with significant diffuse atherosclerotic disease. In-hospital major adverse cardiac events (MACE) included death, myocardial infarction, urgent repeat target vessel revascularization, tamponade requiring pericardiocentesis or surgery, and stroke. A total of 33% of all CTO lesions had poor-quality distal vessel. When compared with good-quality distal vessels, CTO lesions with a poor-quality distal vessel had higher J-CTO (Japanese chronic total occlusion) scores (2.7 ± 1.1 vs 2.2 ± 1.3; P < 0.01), lower technical (79.9% vs 86.9%; P < 0.01) and procedural (78.0% vs 86.8%; P < 0.01) success, and higher incidence of MACE (2.5% vs 1.7%; P < 0.01) and perforation (6.4% vs 3.7%; P < 0.01). A poor-quality distal vessel was independently associated with technical failure and MACE. Poor-quality distal vessels were associated with higher use of the retrograde approach (25.2% vs 14.9%; P < 0.01) and higher air kerma radiation dose (2.4 [IQR: 1.3-4.0] Gy vs 2.0 [IQR: 1.1-3.5] Gy; P < 0.01). A poor-quality distal vessel in CTO lesions is associated with higher lesion complexity, higher need for retrograde crossing, lower technical and procedural success, higher incidence of MACE and coronary perforation, and higher radiation dose. [Display omitted] [ABSTRACT FROM AUTHOR]

There are limited data on the limited antegrade subintimal tracking (LAST) technique for chronic total occlusion (CTO) percutaneous coronary intervention (PCI). The aim of this study was to analyze the frequency of use and outcomes of the LAST technique for CTO PCI. We analyzed 2,177 CTO PCIs performed using antegrade dissection and re-entry (ADR) in the PROGRESS-CTO (Prospective Global Registry for the Study of Chronic Total Occlusion Intervention) registry between 2012 and January 2022 at 39 centers. ADR was attempted in 1,465 cases (67.3%). Among antegrade re-entry cases, LAST was used in 163 (11.1%) (primary LAST in 127 [8.7%] and secondary LAST [LAST after other ADR approaches failed] in 36 [2.5%]), the Stingray system (Boston Scientific) in 980 (66.9%), subintimal tracking and re-entry in 387 (26.4%), and contrast-guided subintimal tracking and re-entry in 29 (2.0%). The mean patient age was 65.2 ± 10 years, and 85.8% were men. There was no significant difference in technical (71.8% vs 77.8%; P = 0.080) and procedural (69.9% vs 75.3%; P = 0.127) success and major cardiac adverse events (1.84% vs 3.53%; P = 0.254) between LAST and non-LAST cases. However, on multivariable analysis, the use of LAST was associated with lower procedural success (OR: 0.61; 95% CI: 0.41-0.91). Primary LAST was associated with higher technical (76.4% vs 55.6%; P = 0.014) and procedural (75.6% vs 50.0%; P = 0.003) success and similar major adverse cardiac event (1.57% vs 2.78%; P = 0.636) rates compared with secondary LAST. LAST was used in 11.1% of antegrade re-entry CTO PCI cases and was associated with lower procedural success on multivariable analysis, suggesting a limited role of LAST in contemporary CTO PCI. [Display omitted] [ABSTRACT FROM AUTHOR]

Percutaneous coronary or structural heart interventions may lead to complications, such as perforation and acute vessel closure that may in turn lead to cardiac arrest or cardiogenic shock. Moreover, acute coronary syndrome patients presenting with cardiogenic shock can be challenging to treat due to hemodynamic instability. In such cases, venoarterial extracorporeal membrane oxygenation (V-A ECMO) can provide hemodynamic stabilization and oxygenation allowing successful treatment of the complication or culprit lesion in acute coronary syndrome patients. We present 3 cases illustrating successful emergent use of V-A ECMO in the cardiac catheterization laboratory in the setting of acute left main dissection during a chronic total occlusion intervention, cardiogenic shock in the setting of non-ST segment elevation myocardial infarction and multivessel coronary artery disease, and aortic annular rupture during transcatheter aortic valve replacement. [ABSTRACT FROM AUTHOR]

Stent loss can occur during percutaneous coronary interventions (PCIs) and can lead to complications such as coronary occlusion, perforation or dissection. Stent retrieval is often attempted but may lead to additional complications. We describe a case of stent loss during chronic total occlusion PCI. The small balloon technique failed to retrieve the stent. The stent was snared but could still not be removed. Retrieval attempts were complicated by large vessel perforation. A covered stent was deployed covering the lost stent and successfully sealing the perforation. [ABSTRACT FROM AUTHOR]

There is limited information on use of laser in complex percutaneous coronary interventions (PCI). We examined the impact of laser on the outcomes of balloon uncrossable and balloon undilatable chronic total occlusion (CTO) PCI. We reviewed baseline clinical and angiographic characteristics and procedural outcomes of 4845 CTO PCIs performed between 2012 and 2020 at 32 centers. Of the 4845 CTO lesions, 752 (15.5%) were balloon uncrossable (523 cases) or balloon undilatable (356 cases) and were included in this analysis. Mean patient age was 66.9 ± 10 years and 83% were men. Laser was used in 20.3% of the lesions. Compared with cases in which laser was not used, laser was more commonly used in longer length occlusions (33 [21, 50] vs. 25 [15, 40] mm, p = 0.0004) and in-stent restenotic lesions (41% vs. 20%, p < 0.0001). Laser use was associated with higher technical (91.5% vs. 83.1%, p = 0.010) and procedural (88.9% vs. 81.6%, p = 0.033) success rates and similar incidence of major adverse cardiac events (3.92% vs. 3.51%, p = 0.805). Laser use was associated with longer procedural (169 [109, 231] vs. 130 [87, 199], p < 0.0001) and fluoroscopy time (64 [40, 94] vs. 50 [31, 81], p = 0.003). In a contemporary, multicenter registry balloon uncrossable and balloon undilatable lesions represented 15.5% of all CTO PCIs. Laser was used in approximately one-fifth of these cases and was associated with high technical and procedural success and similar major complication rates. [Display omitted] • Information on laser use in complex percutaneous coronary interventions is limited. • Balloon uncrossable/undilatable lesions represented 15% of chronic total occlusions. • Laser was used in approximately one-fifth of these cases. • Laser was associated with higher technical and procedural success rates. • Laser was associated with similar major cardiac complication rates. [ABSTRACT FROM AUTHOR]

Objective: The outcomes of chronic total occlusion (CTO) percutaneous coronary intervention (PCI) in octogenarians and nonagenarians have received limited study. Methods: We compared in‐hospital outcomes of CTO PCI between patients ≥80 vs. <80‐years‐old in 6233 CTO PCIs performed between 2012 and 2020 at 33 U.S. and international centers. Results: There were 415 octogenarians and nonagenarians in our study (7% of the total population). Compared with younger patients, octo‐ and nonagenarians were less likely to be men (73% vs. 83.2%, p < 0.0001) and more likely to have atrial fibrillation (27% vs. 12%, p < 0.0001) and prior coronary artery bypass graft surgery (CABG) (43% vs. 29%, p < 0.0001). They were more likely to have CTOs with moderate/severe calcification (71% vs. 46%, p < 0.0001), but had similar mean J‐CTO scores (2.5 ± 1.3 vs. 2.4 ± 1.3, p = 0.08). They had lower technical and procedural success (82.2% vs. 86.3%, p = 0.0201; 80.3% vs. 84.8%, p = 0.016, respectively) and higher incidence of in‐hospital major adverse cardiovascular events (3.4% vs. 1.8%, p = 0.021). On multivariable analysis PCI in octo‐ and nonagenarians was not independently associated with technical and procedural success or with in‐hospital MACE. Conclusion: CTO PCI is feasible in octo‐ and nonagenarians, although success rates are lower, and the risk of complications is higher compared with younger patients, likely related to more comorbidities and higher coronary lesion complexity. [ABSTRACT FROM AUTHOR]

Introduction: Percutaneous coronary intervention (PCI) of chronic total occlusion (CTO) can be challenging, but high success rates (85-90%) are currently achieved at experienced centers with approximately 3% risk for a major periprocedural complication.Areas covered: CTO PCI complications can be categorized according to location such as cardiac and non-cardiac (vascular access complications, thromboembolic complications, contrast-related and radiation injury) complications. Cardiac complications are further subdivided into coronary (acute closure, perforation, and equipment loss or entrapment) and non-coronary (hypotension, myocardial infarction, tamponade, arrhythmias).Expert opinion: In this article, we review strategies to prevent and treat CTO PCI complications. Careful monitoring throughout the case enables prevention and early detection of a complication. If a complication occurs, rapid implementation of treatment using an algorithmic approach can minimize its adverse impact. [ABSTRACT FROM AUTHOR]

Introduction: Chronic Total Occlusion Percutaneous Coronary Intervention (CTO PCI) is now performed with high success rates and acceptable complication rates.Areas Covered: We describe recent clinical and technological developments in CTO PCI from 2018 to 2020.Expert Opinion: After publication of six randomized controlled trials, improving patient symptoms remains the principal indication for CTO PCI. Although good outcomes can be achieved with CTO PCI at experienced centers, success rates are significantly lower at less experienced centers, despite increased use in CTO crossing algorithms and development of novel and improved equipment and techniques. [ABSTRACT FROM AUTHOR]

The prevalence, treatment, and outcomes of balloon undilatable lesions encountered in chronic total occlusion (CTO) percutaneous coronary intervention (PCI) have received limited study. We examined the clinical characteristics and procedural outcomes of balloon undilatable lesions in the Prospective Global Registry for the Study of CTO Intervention (PROGRESS-CTO, NCT02061436). Of 6535 CTO PCIs performed between 2012 and 2022, 558 (8.5%) lesions were balloon undilatable. In this subset, patients were older (mean age 67 ± 10 vs. 64 ± 10, p < 0.001) and had higher prevalence of comorbidities: diabetes mellitus (54% vs. 40%, p < 0.001), prior PCI (71% vs. 59%, p < 0.001), prior myocardial infarction (52% vs. 45%, p = 0.003), and prior coronary artery bypass graft surgery (44% vs. 25%, p < 0.001). The CTO lesion length was estimated to be 34 ± 23 mm, mean J-CTO score was 2.9 ± 1.1 and mean PROGRESS-CTO score was 1.4 ± 1.0. A cutting balloon was used in 27%, a scoring balloon in 15%, laser in 14%, rotational atherectomy in 28%, orbital atherectomy in 10%, intravascular lithotripsy in 1% and other modalities/approaches in 5%. Balloon undilatable lesions had lower technical success (90.9% vs. 93.8%, p = 0.007) and higher incidence of major adverse cardiovascular events (MACE) (composite of in-hospital death, acute myocardial infarction, stroke, re-PCI, emergency CABG, and pericardiocentesis) (5.0% versus 1.3%, p < 0.001). Approximately 1 in 12 CTO (8.5%) lesions are balloon undilatable. Treatment of balloon undilatable lesions is associated with lower technical success and higher in-hospital MACE. • Approximately 1/12 chronic total occlusion (8.5%) lesions are balloon undilatable • Balloon undilatable lesions had lower technical success (90.9% vs. 93.8%, p = 0.007) • Balloon undilatable lesions had higher MACE (5.0% versus 1.3%, p < 0.001) [ABSTRACT FROM AUTHOR]

Background Some reports have demonstrated increased risk with subadventitial chronic total occlusion (CTO) crossing, whereas others suggest equipoise between subadventitial and intraplaque crossing techniques. We sought to clarify the effect of subadventitial lesion crossing on mid-term outcomes of CTO percutaneous coronary intervention (PCI). Methods We conducted a systematic review and meta-analysis of studies reporting post-discharge outcomes after CTO PCI performed via subadventitial vs. intraplaque approaches. Results Five studies comprising a total of 2,539 patients were included. Compared with intraplaque crossing (n = 1,654, 65.1%), subadventitial cases (n = 885, 34.9%) had a higher J-CTO score (2.9 ± 1.2 vs. 1.6 ± 1.2, p < 0.001), and required significantly longer stent lengths (difference in means: 19.66 mm [95% confidence interval (CI), 11.23 to 28.08]; p < 0.001). At a median follow-up of 12.0 months, subadventitial CTO crossing was associated with a higher overall rate of target vessel revascularization (TVR, crude rate, 11.5% vs. 7.6%, odds ratio [OR]: 2.19 [95% CI, 1.62 to 2.95]; p < 0.001); the risk was higher in studies of extensive compared with limited dissection and re-entry techniques (OR: 3.46 [95% CI: 2.24 to 5.36] vs. 1.52 [95% CI, 0.94 to 2.46], p interaction = 0.013). The rates of stent thrombosis, myocardial infarction, and cardiovascular mortality did not vary significantly between subadventitial and intraplaque crossing. Conclusions CTOs treated with subadventitial crossing were significantly more complex as compared with CTOs treated with intraplaque crossing. Extensive subadventitial crossing techniques were associated with higher TVR rates as compared with limited techniques, supporting the important role of limited techniques in the treatment of complex CTOs. [ABSTRACT FROM AUTHOR]

Chronic total occlusion (CTO) percutaneous coronary intervention (PCI) is associated with a considerable risk of complications, and risk stratification is of utmost importance. To assess the clinical usefulness of the recently developed PROGRESS-CTO (NCT02061436) complication risk scores in an independent cohort. Individual patient data pooled analysis of 3 registries was performed. Of the 4569 patients who underwent CTO PCI, 102 (2.2%) had major adverse cardiovascular events (MACE). Patients with MACE were older (69 ± 11 vs. 65 ± 10, p < 0.001), more likely to have a history of prior coronary artery bypass graft surgery, and unfavorable angiographic characteristics J-CTO score (2.4 ± 1.2 vs. 2.1 ± 1.3, p = 0.007), including blunt stump (59% vs. 49%, p = 0.047). Technical success was lower in patients with MACE (59% vs. 86%, p < 0.001). The area under the receiver operating characteristic curve of the PROGRESS-CTO complication risk models were as follows: MACE 0.72 (95% confidence interval [CI], 0.67–0.76), mortality 0.73 (95% CI, 0.61–0.85), and pericardiocentesis 0.69 (95% CI, 0.62–0.77) in the validation dataset. The observed complication rates increased with higher PROGRESS-CTO complication scores. The PROGRESS-CTO MACE score showed good calibration in this external cohort, with MACE rates similar to the original study: 0.7% (score 0–1), 1.5% (score 2), 2.2% (score 3), 3.8% (score 4), 4.9% (score 5), 5.8% (score 6–7). Given the good discriminative performance, calibration, and ease of calculation, the PROGRESS-CTO complication scores could help assess the risk of complications in patients undergoing CTO PCI. • We evaluated the PROGRESS-CTO complication risk scores in an individual patient data pooled analysis of 3 CTO PCI registries. • The c-statistic of the models were 0.72, 0.73, and 0.69 for MACE, mortality, and pericardiocentesis, respectively. • The use of the PROGRESS-CTO complication risk should be considered to facilitate risk-benefit assessment in CTO PCI. [ABSTRACT FROM AUTHOR]

Preprocedural coronary computed tomography angiography (CCTA) can be useful in procedural planning for chronic total occlusion (CTO) percutaneous coronary intervention (PCI). We examined the clinical, angiographic and procedural characteristics and outcomes of cases with vs. without preprocedural CCTA in PROGRESS-CTO (NCT02061436). Multivariable logistic regression was used to adjust for confounding factors. Of 7034 CTO PCI cases, preprocedural CCTA was used in 375 (5.3%) with increasing frequency over time. Patients with preprocedural CCTA had a higher prevalence of prior coronary artery bypass graft surgery (39% vs. 27%, p < 0.001) and angiographically unfavorable characteristics including higher prevalence of proximal cap ambiguity (52% vs. 33%, p < 0.001) and moderate/severe calcification (59% vs. 41%, p < 0.001) compared with those without CCTA. CCTA helped resolve proximal cap ambiguity in 27%, identified significant calcium not seen on diagnostic angiography in 18%, changed estimated CTO length by >5 mm in 10%, and was performed as part of initial coronary artery disease work up in 19%. CCTA cases had higher J-CTO (2.6 ± 1.2 vs. 2.3 ± 1.3, p < 0.001) and PROGRESS-CTO (1.3 ± 1.0 vs. 1.2 ± 1.0 p = 0.027) scores. After adjusting for potential confounders, cases with preprocedural CCTA had similar technical success (odds ratio [OR]: 1.18, 95% confidence interval [CI], 0.83–1.67) and incidence of major adverse cardiovascular events (OR: 1.47, 95% CI, 0.72–3.00). Preprocedural CCTA was used in ~5% of CTO PCI cases. While CCTA may help with procedural planning, especially in complex cases, technical success and MACE were similar with or without CCTA. • Of the 7,034 CTO PCI procedures performed between 2012-2022, preprocedural CCTA was used in 375 (5.3%). • CCTA helped resolve proximal cap ambiguity in 27%, identified calcium in 18%, and changed the estimated CTO length in 10%. • On multivariable analysis preprocedural CCTA was not associated with technical success or major adverse cardiovascular events. [ABSTRACT FROM AUTHOR]

Coronary calcification is common and increases the difficulty of chronic total occlusion (CTO) percutaneous coronary intervention (PCI). We examined the impact of calcium on procedural outcomes of 13,079 CTO PCIs performed in 12,799 patients at 46 US and non-US centers between 2012 and 2023. Moderate or severe calcification was present in 46.6% of CTO lesions. Patients whose lesions were calcified were older and more likely to have had prior coronary artery bypass graft surgery. Calcified lesions were more complex with higher J-CTO score (3.0 ± 1.1 vs. 1.9 ± 1.2; p < 0.001) and lower technical (83.0% vs. 89.9%; p < 0.001) and procedural (81.0% vs. 89.1%; p < 0.001) success rates compared with mildly calcified or non-calcified CTO lesions. The retrograde approach was more commonly used among cases with moderate/severe calcification (40.3% vs. 23.5%; p < 0.001). Balloon angioplasty (76.6%) was the most common lesion preparation technique for calcified lesions, followed by rotational atherectomy (7.3%), laser atherectomy (3.4%) and, intravascular lithotripsy (3.4%). The incidence of major adverse cardiovascular events (MACE) was higher in cases with moderate or severe calcification (3.0% vs. 1.2%; p < 0.001), as was the incidence of perforation (6.5% vs. 3.4%; p < 0.001). On multivariable analysis, the presence of moderate/severe calcification was independently associated with lower technical success (odds ratio, OR = 0.73, 95% CI: 0.63–0.84) and higher MACE (OR = 2.33, 95% CI: 1.66–3.27). Moderate/severe calcification was present in nearly half of CTO lesions, and was associated with higher utilization of the retrograde approach, lower technical and procedural success rates, and higher incidence of in-hospital MACE. • Moderate/severe calcification: • is present in nearly half of chronic total occlusion (CTO) lesions • requires more frequent use of the retrograde approach • requires more frequent use of intravascular ultrasound (IVUS) and advanced plaque modification techniques • is associated with lower technical and procedural success, and higher major adverse cardiovascular events (MACE) [ABSTRACT FROM AUTHOR]