BACKGROUND:Recanalization of chronic total coronary occlusions (CTO) is associated with a high incidence of periprocedural myocardial ischemia (PMI). AIMS:This study should assess its causes with special focus on the relation to side branch occlusions (SBO) of the right coronary artery (RCA) with its specific anatomy of side branches. METHODS:1574 recanalizations of a RCA CTO were analyzed with high-sensitive troponin T (hsTnT) drawn before and after the procedure. All angiograms were checked for SBO after the procedure. PMI was defined as hsTnT increase >5× upper limit of normal. Additional thresholds were > 18× (PMI18) and > 35× (PMI35). RESULTS:PMI occurred in 51.6 %, PMI18 in 19.9 %, and PMI35 in 8.9 %. Excluding procedures with major complications (3.1 %), the major determinants of PMI were chronic kidney disease, a long fluoroscopy time, and single and multiple SBO. Overall side branch occlusions occurred in 26.8 % even without PMI, and with increasing rate with higher PMI thresholds up to 56.4 % with PMI35. Proximal SBO caused the highest hsTnT increase, followed by mid and distal location. The highest incidence occurred with retrograde approach (50.8 %) and antegrade dissection re-entry (71.4 %). The combination of PMI and SBO would lead to the diagnosis of type IVa myocardial infarction in 23.4 %, with PMI18 in 10.2 %, and with PMI35 in 4.7 %. CONCLUSIONS:SBO occur frequently after CTO PCI of the RCA and are a major determinant of PMI. Even without clinical complications the combination of various thresholds of PMI and SBO would yield a high incidence of type IVa myocardial infarction.

Background: Coronary imaging is increasingly used in chronic total occlusion percutaneous coronary intervention (CTO-PCI), but the impact of different imaging strategies on procedural decisions and outcomes remains unclear. Methods: We retrospectively analyzed 171 consecutive patients undergoing CTO-PCI, stratified by imaging strategy into four groups: angiography-only (n = 48), IVUS-guided (n = 42), CT-guided (n = 40) and CT + IVUS-guided (n = 41). Procedural and in-hospital clinical outcomes were compared. A multivariable logistic regression identified predictors of intense debulking techniques (defined as the use of rotational atherectomy or intravascular lithotripsy). Results: Imaging guidance was associated with progressively longer procedural (p < 0.001) and fluoroscopic time (p = 0.007). Similarly, an increased number of guidewires (p = 0.005) and balloons (p = 0.003) was used in the imaging groups, with the CT + IVUS groups showing the highest features. Regarding stenting characteristics, higher stent length and diameter (p = 0.01) were observed in the imaging groups. In patients with J-CTO score > 2, procedural success rates significantly increased with the use of coronary imaging (p = 0.01). Multivariable analysis showed that both J-CTO score (OR 2.0; 95% CI 1.3–3.0; p = 0.001) and imaging strategies (OR 1.6; 95% CI 1.02–2.4; p = 0.04) independently predicted the use of intense debulking techniques. Importantly, no significant differences were observed in in-hospital complications across groups. Conclusions: The use of coronary imaging, particularly the combination of IVUS and CT, is associated with more complex CTO lesions and led to increased procedural time, fluoroscopic time and more extensive stenting, as well as higher debulking usage. In complex CTO cases, coronary imaging was associated with higher procedural success rates. Imaging strategies independently predicted the need for advanced lesion preparation, beyond anatomical complexity, without compromising safety. Despite higher procedural demands, coronary imaging enables a more tailored and successful approach to CTO-PCI, particularly in complex cases. These findings underscore the pivotal role of multimodal imaging in the procedural planning and optimization of CTO-PCI.

Coronary calcium significantly increases complexity in chronic total occlusion percutaneous coronary intervention (CTO-PCI). Coronary computed tomography angiography (CCTA) enables precise CTO assessment. However, no prior study has proposed a CCTA–based morphological classification of calcium patterns and assessed its procedural impact. To propose and validate a novel seven-point CCTA-derived classification of calcium morphology, ranging from “spot” (≤ 10

BACKGROUND:High radiation exposure is a significant risk with recanalizations for chronic total coronary occlusions (CTO). AIMS:To analyze the influence of radiographic equipment, radiation protocols, and operator experience on radiation exposure. METHODS:We analyzed 17,769 procedures by 27 operators from a multicenter European Registry between 2015 and 2023. Thirteen operators had an experience > 10 years (Gen1), and 14 entered the registry after 2015 (Gen2). AirKerma (AK), dose area product (DAP), the dose rate index (DRI) as AK per fluoroscopy time (FT), and the collimation index (CLI) as DAP per AK were calculated to assess inter-operator variability. RESULTS:Despite increased lesion complexity (2015-17: CASTLE score 1.83 ± 1.10, 2021-23: 2.20 ± 1.19; p < 0.001), AK and DAP were reduced by 45%. Gen1 operators treated more complex lesions than Gen 2 (2.05 ± 1.13 vs. 1.85 ± 1.16; p < 0.001) at more extended FT (38.4 [23-61] vs. 34.0 [20-57]; p < 0.001) than Gen2 with slightly higher AK (1.6 [0.89-2.8] Gy vs. 1.4 [0.8-2.54]; p < 0.001), but DRI was similar (42.9 [27.7-64.3] vs. [28.0-62.1]). In 2015-17, operators with Philips Clarity had a lower median AK (1.7 Gy; p < 0.001) than other vendors (Siemens 2.1 Gy; General Electric 2.8 Gy), but with updated equipment, Philips systems had slightly higher AK (1.2 Gy) than Siemens systems (1.0 Gy; p < 0.001). Inter-operator variability regarding DRI improved over time, but collimation did not change. CONCLUSIONS:Radiation exposure for CTO PCI was reduced for both long-time and recent CTO operators during 9 years. Equipment updates were instrumental to improved radiation management, but inter-operator differences remained regarding dose management and collimation.

BACKGROUND:Significant calcifications within a coronary chronic total occlusion (CTO) increase procedural complexity and the risk for complications. Expert consensus documents recommend the use of advanced calcific plaque modification devices (ACPMDs) for calcified CTO percutaneous coronary intervention (PCI), whereas data on their procedural impact are limited. OBJECTIVES:The aim of this study was to describe trends, settings, and outcomes of PCI of severely calcified CTO performed with and without ACPMDs. METHODS:Data from 15,329 CTO PCIs enrolled in the ERCTO (European Registry of Chronic Total Occlusion) between 2021 and 2023 were analyzed. On the basis of the presence of severe calcifications within the CTO, the study population was divided into 2 groups: nonsevere (n = 12,289) and severe (n = 3,040) calcium. Then, the severe group was divided into non-ACPMD (n = 2,253) and ACPMD (n = 787), according to the use of ACPMDs. RESULTS:Compared with the non-ACPMD group, the ACPMD group had higher rates of antegrade wiring (77.9% vs 49.2%; P < 0.001) and technical success (97.6% vs 79.1%; P = 0.001) and lower rates of periprocedural and in-hospital major adverse cardiac and cerebrovascular events (MACCE) (1.8% vs 3.5%; P = 0.001). A severe amount of calcium was independently associated with technical failure (OR: 3.13; 95% CI: 2.43-4.09; P < 0.001) but not with MACCE (OR: 0.88; 95% CI: 0.58-1.35; P = 0.15). Furthermore, extraplaque crossing was independently associated with MACCE (antegrade dissection and re-entry without retrograde contribution: OR: 3.12; 95% CI: 1.79-4.20; P < 0.001; antegrade dissection and re-entry with retrograde contribution: OR: 3.12; 95% CI: 1.67-4.11; P = 0.049; retrograde dissection and re-entry: OR: 1.90; 95% CI: 1.25-2.86; P = 0.002). CONCLUSIONS:Applying ACPMDs in severely calcified CTO to PCI was associated with higher technical success and lower MACCE rates. The presence of severe coronary calcification on coronary angiography was a marker of clinical and procedural complexity and was associated with technical failure but not with MACCE.

BACKGROUND:Drug-coated balloons (DCBs) are increasingly used in percutaneous coronary intervention (PCI). Their application for chronic total occlusions (CTOs) is a promising option to limit stent length in diffuse disease and avoid stent underexpansion and malapposition in negatively remodeled distal vessel segments. OBJECTIVES:The aim of this study was to analyze CTO PCI procedures recorded in ERCTO (European Registry of Chronic Total Occlusion) to investigate frequency of use, patient and lesion characteristics, and in-hospital outcomes of DCBs. METHODS:CTO cases entered into the database from 2016 to 2023 were examined and categorized according to DCB use. DCB-treated patients were further divided into 2 groups: DCBs only and DCBs in association with drug-eluting stents. To minimize the potential impact of confounding factors, 1:1 propensity score matching was applied. RESULTS:Of 40,449 CTO PCIs performed at 184 centers, DCBs were used in 2,506 (6.2%), increasing from 3.4% (n = 185 of 5,498) in 2016 to 14.9% (n = 705 of 4,722) in 2023. In-hospital complications were infrequent, but DCB-treated CTOs had significantly lower rates of pericardial tamponade (0.1% [n = 2 of 2,506] vs 0.4% [n = 169 of 37,943]; P = 0.006). After propensity score matching, DCB use led to reduced drug-eluting stent length (44.2 ± 36.9 mm [95% CI: 42.7-45.7 mm] vs 58.1 ± 35.9 mm [95% CI: 56.7-59.5] mm; P < 0.001). Contrast volume was lower in the DCB-treated patients (202.4 ± 109.8 mL [95% CI: 198.1-206.7 mL] vs 211.6 ± 123 mL [95% CI: 206.8-216.4 mL]; P = 0.005). CONCLUSIONS:The use of DCBs in CTO recanalization is increasing and is associated with a reduction in the length of stents implanted, as well as a decrease in contrast volume and a lower rate of pericardial tamponade.

Background Excess radiation exposure is a limiting factor in percutaneous coronary intervention (PCI) for chronic total coronary occlusion (CTO). Objectives The aim of this study was to analyze changes in radiation dose for CTO PCI with increasing risk awareness during the past decade and the determinants of these changes. Methods A total of 16,439 procedures performed by 14 operators continuously participating in the European Registry of CTO-PCI from 2012 to 2023 were analyzed. Changes in air kerma (AK) were assessed, and a dose rate index (DRI) was calculated as AK per fluoroscopy time (FT). Results Lesion complexity increased from a median J-CTO (Multicenter CTO Registry in Japan) score of 2 (Q1-Q3: 1-3) to 3 (Q1-Q3: 2-3) (P < 0.001), and technical success improved from 89.1% to 94.9% (P < 0.001), with stable FT. AK decreased from 2.50 Gy (Q1-Q3: 1.54-4.04 Gy) to 1.20 Gy (Q1-Q3: 0.66-2.12 Gy), a reduction of 52.0% (P < 0.001). Excess radiation of AK >5 Gy was reduced from 15.8% in 2012-2013 to 3.7% in 2022-2023. Clinical determinants of excess radiation were body mass index, gender, and previous bypass surgery; procedural determinants were FT, retrograde approach, and intravascular ultrasound use; and equipment determinants were radiographic equipment updates and fluoroscopy dose mode. Operators reduced DRI by 21.7% from 62.6 mGy/min (Q1-Q3: 44.7-89.3 mGy/min) to 49.0 mGy/min (Q1-Q3: 35.4-71.2 mGy/min) before a radiographic equipment update; after the update, DRI was further reduced to 31.5 mGy/min (Q1-Q3: 22.0-45.6 mGy/min), a decrease of 28.0% (P < 0.001) The interoperator comparison of DRI indicated considerable variability in radiation management. Conclusions AK for CTO PCI was reduced during the past decade to a level such that most procedures no longer must be aborted because of excess radiation. Equipment updates were instrumental, but interoperator differences remained.

BACKGROUND:The parallel wire technique (PW) is a classic part of the antegrade strategy to open chronic total coronary occlusions (CTO). AIMS:With modern wires and dual-lumen catheters (DLC) the approach has evolved, but this progress had not been evaluated in a contemporary registry of CTO interventions. METHOD:This analysis is based on 26,589 CTO procedures performed by 36 operators with > 50 procedures annually between 2015 and 2022. The different strategies and techniques were analyzed with respect to clinical and lesion characteristics, procedural resource use and periprocedural complications. Within the antegrade approach, PW was compared to antegrade wire escalation (AWE) and antegrade-dissection re-entry (ADR). RESULTS:The primary antegrade approach was used in 65.9%, primary retrograde in 16.9% and a strategy change in 17.2% with a wide inter-operator variability. In primary antegrade approach, PW was applied in 10.8% and ADR in 5.3%. Lesion complexity was higher in AWE and PW than with single wire, and highest in ADR procedures, leading to more complex procedures with higher contrast and radiation usage. Complications increased with ADR, while they were similar with PW and AWE. Through the observation period PW adoption increased steadily from 6.7% to 10.7%, as the DLC use facilitating PW increased from 8.3% to 17.0% over the observation period. CONCLUSION:In this largest database of contemporary CTO PCI from Europe, PW adoption increased over time but remained low at about 10%. While there was a wide individual variety among the operators, it was a safe and successful technique.

"Full moon" is a central calcification that occludes the entire vessel on coronary computed tomography angiography (CCTA). We examined the association of full moon calcification as identified by CCTA, on clinical and procedural outcomes of chronic total occlusion (CTO) percutaneous coronary intervention (PCI). We studied patients who underwent elective CTO-PCI in 2 European centers and had preprocedural CCTA. The primary end point was the inability to cross the lesion and/or the need for extensive debulking techniques. Secondary end points were procedural success, in-hospital cardiac mortality, the need for extensive debulking techniques, myocardial infarction, major adverse cardiac events (defined as in-hospital death, myocardial infarction, and clinically driven target vessel revascularization), and stent thrombosis. Secondary procedural end points included procedural time, fluoroscopy time, number of guidewires and balloons, stent length, number and diameter, and contrast volume. Multivariable logistic regression analysis was performed, identifying potential covariates related to the primary outcome according to knowledge and previous studies. Subsequently, a stepwise selection approach was performed to select factors with the greatest predictive value. Of 140 patients included, 28 (20%) had a full moon calcified CTO plaque. Patients in the full moon group were older and had more cardiovascular risk factors. There was not significant difference in the need for retrograde approach and anterograde dissection and reentry techniques between the full moon group and the other groups (32.1% vs 37.5%, p = 0.59 and 0% vs 1.7%, p = 0.47, respectively). Patients in the full moon group had greater incidence of the primary outcome than did those who did not have full moon morphology (53.5% vs 12.5%, p <0.001). On multivariable analysis that included chronic kidney failure and previous coronary artery bypass surgery, full moon calcification was associated with greater incidence of the primary end point (odds ratio 6.5, 95% confidence interval 2.1 to 20.5, p = 0.001). Moreover, less procedural success (71.4% vs 87.5%, p = 0.03), greater incidence of coronary perforations (14.2% vs 3.5%, p <0.02), and greater procedural (172.5 [118.0 to 237.5] vs 144.0 [108.50 to 174.75], p = 0.02) and fluoroscopic time (62.6 [38.1 to 83.0] vs 42.8 [29.5 to 65.7], p = 0.03) were observed in the full moon group. Overall major adverse cardiac events did not differ between the 2 groups (1 patient in the full moon group vs 1 patient in the non-full moon group; 3.5% vs 0.8%, p = 0.29). In conclusion, full moon calcification on CCTA was independently associated with procedural complexity and adverse outcomes in CTO-PCI.

Bifurcation involvement close to or within the occluded segment poses increasing difficulties for chronic total occlusion (CTO)-percutaneous coronary intervention (PCI). However, this variable is not considered in the angiography-based CTO scoring systems nor has been extensively investigated in large multicenter series. Accordingly, we analyzed a CTO-PCI registry involving 92 European centers to explore the incidence, angiographic and procedural characteristics, and outcomes specific to CTO-PCIs with bifurcation involvement. A total of 3,948 procedures performed between January and November 2023 were examined (33% with bifurcation involvement). Among bifurcation lesions, 38% and 37% were located within 5 mm of the proximal and distal cap, respectively, 16% within the CTO body, and in 9% of cases proximal and distal bifurcations coexisted. When compared with lesions without bifurcation involvement, CTO bifurcation lesions had higher complexity (J-CTO 2.33 ± 1.21 vs 2.11 ± 1.27, p <0.001) and were associated with higher use of additional devices (dual-lumen microcatheter in 27.6% vs 8.4%, p <0.001, and intravascular ultrasound in 32.2% vs 21.7%, p <0.001). Radiation dose (1,544 [836 to 2,819] vs 1,298.5 [699.1 to 2,386.6] mGy, p <0.001) and contrast volume (230 [160 to 300] vs 190 [130 to 250] ml, p <0.001) were also higher. Technical success was similar (91.5% with bifurcation involvement vs 90.4% without bifurcation involvement, p = 0.271). However, the bifurcation lesions within the CTO segment (intralesion) were associated with lower technical success than the other bifurcation-location subgroups (83.7% vs 93.3% proximal, 93.4% distal, and 89.0% proximal and distal, p <0.001). On multivariable analysis, the presence of an intralesion bifurcation was independently associated with technical failure (odds ratio 2.04, 95% confidence interval 1.24 to 3.35, p = 0.005). In conclusion, bifurcations are present in approximately one-third of CTOs who underwent PCI. PCI of CTOs with bifurcation can be achieved with high success rates except for bifurcations within the occluded segment, which were associated with higher technical failure.

BACKGROUND:The CTO-ARC (Chronic Total Occlusion Academic Research Consortium) recognized that a nonstandardized definition of chronic total occlusion (CTO) percutaneous coronary intervention approaches can bias the complications' attribution to each crossing strategy. OBJECTIVES:The study sought to describe the numbers, efficacy, and safety of each final CTO crossing strategy according to CTO-ARC recommendations. METHODS:In this cross-sectional study, data were retrieved from the European Registry of Chronic Total Occlusions between 2021 and 2022. RESULTS:Out of 8,673 patients, antegrade and retrograde approach were performed in 79.2% and 20.8% of cases, respectively. The antegrade approach included antegrade wiring and antegrade dissection and re-entry, both performed with or without retrograde contribution (antegrade wiring without retrograde contribution: n = 5,929 [68.4%]; antegrade wiring with retrograde contribution: n = 446 [5.1%]; antegrade dissection and re-entry without retrograde contribution: n = 353 [4.1%]; antegrade dissection and re-entry with retrograde contribution: n = 137 [1.6%]). The retrograde approach included retrograde wiring (n = 735 [8.4%]) and retrograde dissection and re-entry (n = 1,073 [12.4%]). Alternative antegrade crossing was associated with lower technical success (70% vs 86% vs 93.1%, respectively; P < 0.001) and higher complication rates (4.6% vs 2.9% vs 1%, respectively; P < 0.001) as compared with retrograde and true antegrade crossing. However, alternative antegrade crossing was applied mostly as a rescue strategy (96.1%). CONCLUSIONS:The application of CTO-ARC definitions allowed the reclassification of 6.7% of procedures as alternative antegrade crossing with retrograde or antegrade contribution which showed higher MACCE and lower technical success rates, as compared with true antegrade and retrograde crossing.

Chronic total occlusions (CTOs) of coronary arteries can be found in the context of chronic or acute coronary syndromes; sometimes they are an incidental finding in those apparently healthy individuals undergoing imaging for preoperative risk assessment. Recently, the invasive management of CTOs has made impressive progress due to sophisticated preinterventional assessment, including advanced non-invasive imaging, the availability of novel and dedicated tools for CTO percutaneous coronary intervention (PCI), and experienced interventionalists working in specialised centres. Thus, it is crucial that referring physicians who see patients with CTO be aware of recent developments and of the initial evaluation requirements for such patients. Besides a careful history and clinical examination, electrocardiograms, exercise tests, and non-invasive imaging modalities are important for selecting the patients most suitable for CTO PCI, while others may be referred to coronary artery bypass graft or optimal medical therapy only. While CTO PCI improves angina and reduces the use of antianginal drugs in patients with symptoms and proven ischaemia, hibernation and/or wall motion abnormalities at baseline or during stress, the effect of CTO PCI on major cardiovascular events is still controversial. This clinical consensus statement specifically focuses on referring physicians, providing a comprehensive algorithm for the preinterventional evaluation of patients with CTO and the current evidence for the clinical effectiveness of the procedure. The proposed care track has been developed by members and with the support of the European Association of Percutaneous Cardiovascular Interventions (EAPCI), the European Association of Cardiovascular Imaging (EACVI), and the European Society of Cardiology (ESC) Working Group on Cardiovascular Surgery.

BACKGROUND: Percutaneous coronary interventions (PCI) of chronic total occlusions (CTO) have reached high procedural success rates thanks to dedicated equipment, evolving techniques, and worldwide adoption of state-of-the-art crossing algorithms. AIMS: We report the contemporary results of CTO PCIs performed by a large European community of experienced interventionalists. Furthermore, we investigated the impact of different risk factors for procedural major adverse cardiac and cerebrovascular events (MACCE) and trends of employment of specific devices like dual lumen microcatheters, guiding catheter extensions, intravascular ultrasound and calcium-modifying tools. METHODS: We evaluated data from 8,673 CTO PCIs included in the European Registry of Chronic Total Occlusion (ERCTO) between January 2021 and October 2022. RESULTS: The overall technical success rate was 89.1% and was higher in antegrade as compared with retrograde cases (92.8% vs 79.3%; p<0.001). Compared with antegrade procedures, retrograde procedures had a higher complexity of attempted lesions (Japanese CTO [J-CTO] score: 3.0 +/- 1.0 vs 1.9 +/- 1.2; p<0.001), a higher procedural and-hospital MACCE rate (3.1% vs 1.2%; p<0.018) and a higher perforation rate with and without tamponade (1.5% vs 0.4% and 8.3% vs 2.1%, respectively; p<0.001). As compared with mid-volume operators, high-volume operators had a higher technical success rate in antegrade and retrograde procedures (93.4% vs 91.2% and 81.5% 69.0%, respectively; p<0.001), and had a lower MACCE rate (1.47% vs 2.41%; p<0.001) despite a higher mean complexity of the attempted lesions (J-CTO score: 2.42 +/- 1.28 vs 2.15 +/- 1.27; p<0.001). CONCLUSIONS: The adoption of different recanalisation techniques, operator experience and the use of specific devices have contributed to a high procedural success rate despite the high complexity of the lesions documented in ERCTO.

BACKGROUND:Gender-specific data addressing percutaneous coronary intervention (PCI) of chronic total occlusion (CTO) in female patients are scarce and based on small sample size studies.AIMS:We aimed to analyze gender-differences regarding in-hospital clinical outcomes after CTO-PCI.METHODS:Data from 35,449 patients enrolled in the prospective European Registry of CTOs were analyzed. The primary outcome was the comparison of procedural success rate in the two cohorts (women vs. men), defined as a final residual stenosis less than 20%, with Thrombolysis In Myocardial Infarction grade flow = 3. In-hospital major adverse cardiac and cerebrovascular events (MACCEs) and procedural complications were deemed secondary outcomes.RESULTS:Women represented 15.2% of the entire study population. They were older and more likely to have hypertension, diabetes, and renal failure, with an overall lower J-CTO score. Women showed a higher procedural success rate (adjusted OR [aOR] = 1.115, confidence interval [CI]: 1.011-1.230, p = 0.030). Apart from previous myocardial infarction and surgical revascularization, no other significant gender differences were found among predictors of procedural success. Antegrade approach with true-to-true lumen techniques was more commonly used than retrograde approach in females. No gender differences were found regarding in-hospital MACCEs (0.9% vs. 0.9%, p = 0.766), although a higher rate of procedural complications was observed in women, such as coronary perforation (3.7% vs. 2.9%, p < 0.001) and vascular complications (1.0% vs. 0.6%, p < 0.001).CONCLUSIONS:Women are understudied in contemporary CTO-PCI practice. Female sex is associated with higher procedural success after CTO-PCI, yet no sex differences were found in terms of in-hospital MACCEs. Female sex was associated with a higher rate of procedural complications.

Severe calcification is frequent in coronary chronic total occlusions (CTO), and its presence has been associated with increased procedural complexity and poor long-term outcomes following percutaneous coronary intervention (PCI) in an already challenging anatomical setting. The diagnostic characterisation of heavily calcified CTOs using non-invasive and invasive imaging tools can lead to the application of different therapeutic options during CTO PCI, in order to achieve adequate lesion preparation and optimal stent implantation. In this expert review, the European Chronic Total Occlusion Club provides a contemporary, methodological approach, specifically addressing heavily calcified CTOs, suggesting an integration of evidence-based diagnostic methods to tailored, up-to-date percutaneous therapeutic options.

Knowledge in the field of bifurcation lesions and chronic total occlusions (CTOs) has progressively improved over the past 20 years. Therefore, the European Bifurcation Club and the EuroCTO Club have decided to write a joint consensus statement to share general knowledge and practical approaches in this complex field. When percutaneously treating CTOs, bifurcation lesions with relevant side branches (SBs) are found in approximately one-third of cases (35% at the proximal cap, 38% at the distal cap, and 27% within the CTO body). Occlusion of a relevant SB is not rare and has been shown to be associated with procedural complications and adverse outcomes. Simple bifurcation rules are very useful to prevent SB occlusion, and provisional SB stenting is the recommended approach in the majority of cases: protect the SB as soon as possible by wiring it, respect the fractal anatomy of the bifurcation by using the 3-diameter rule, and avoid using dissection and re-entry techniques. A systematic 2-stent approach can be used if needed or sometimes to connect both branches of the bifurcation. The retrograde approach can be very useful to save a relevant SB, especially in the case of a bifurcation at the distal cap or within the CTO body. Intravascular ultrasound is also a very important tool to address the difficulties with bifurcations at the proximal or distal cap and sometimes also within the CTO segment. Double-lumen microcatheters and angulated microcatheters are crucial tools to resolve access difficulties to the SB or the main branch.