Original Contribution

Current Perspectives and Practices on Chronic Total Occlusion Percutaneous Coronary Interventions

Siddharth M. Patel, MD1;  Rohan V. Menon, MD2;  M. Nicolas Burke, MD3;  Farouc A. Jaffer, MD, PhD4;  Robert W. Yeh, MD, MBA5;  Minh Vo, MD6;  Dimitri Karmpaliotis, MD, PhD7;  Lorenzo Azzalini, MD8;  Mauro Carlino, MD8;  Kambis Mashayekhi, MD9;  Alfredo R. Galassi, MD10;  Stephane Rinfret, MD11;  Stephen G. Ellis, MD12;  Mitul Patel, MD13;  Bavana V. Rangan, BDS, MPH14;  Aris Karatasakis, MD14;  Barbara A. Danek, MD14;  Judit Karacsonyi, MD14;  Erica Resendes, BS, MPH14;  Subhash Banerjee, MD14;  Emmanouil S. Brilakis, MD, PhD3,14

Siddharth M. Patel, MD1;  Rohan V. Menon, MD2;  M. Nicolas Burke, MD3;  Farouc A. Jaffer, MD, PhD4;  Robert W. Yeh, MD, MBA5;  Minh Vo, MD6;  Dimitri Karmpaliotis, MD, PhD7;  Lorenzo Azzalini, MD8;  Mauro Carlino, MD8;  Kambis Mashayekhi, MD9;  Alfredo R. Galassi, MD10;  Stephane Rinfret, MD11;  Stephen G. Ellis, MD12;  Mitul Patel, MD13;  Bavana V. Rangan, BDS, MPH14;  Aris Karatasakis, MD14;  Barbara A. Danek, MD14;  Judit Karacsonyi, MD14;  Erica Resendes, BS, MPH14;  Subhash Banerjee, MD14;  Emmanouil S. Brilakis, MD, PhD3,14

Abstract: Objectives. We sought to examine contemporary perspectives and practices on chronic total occlusion (CTO) percutaneous coronary intervention (PCI). Background. The frequency and success of CTO-PCI have been increasing in recent years. Methods. An online questionnaire was created and distributed to cardiologists within the United States and internationally. Results. A total of 1149 responses were obtained. The United States (n = 845; 73.5%), Asia (n = 98; 8.5%), Europe (n = 88; 7.7%), South America (n = 42; 3.7%), and Canada (n = 33; 2.9%) accounted for most responses. Mean practice duration of the respondents was 16.4 ± 11.5 years and 66.9% were interventional cardiologists. Most respondents agreed that CTO-PCI results in an improvement of patient symptoms (90.7%), left ventricular function (79.3%), arrhythmia risk (69.2%), and overall survival (63.1%). Interventional cardiologists had a more favorable view of the benefits of CTO-PCI as compared with non-interventional cardiologists (P<.001). Most respondents estimated the procedural success rates of contemporary CTO-PCI to be between 51%-75% (34.2%) and 76%-85% (30.2%), with interventional cardiologists estimating higher success rates than non-interventionalists (P<.001). Perforation, mortality, and tamponade were the three most concerning complications. Time and procedure complexity were reported to be the most significant barriers to the development of a CTO-PCI program. Conclusions. Most cardiologists believe that CTO-PCI can provide significant clinical benefits and can be accomplished with moderate to high success rates. Interventional cardiologists have a more favorable view of CTO-PCI as compared with non-invasive cardiologists. 

J INVASIVE CARDIOL 2018;30(2):43-50. Epub 2017 October 15.

Key words: chronic total occlusion, percutaneous coronary intervention, procedural success, complications, techniques

Chronic total occlusion (CTO) percutaneous coronary intervention (PCI) has rapidly evolved during recent years with the development of novel techniques and equipment, leading to high success rates among experienced centers.1 Christopoulos et al reported 91% technical success and a 1.7% rate of major adverse cardiac events among 1036 consecutive CTO-PCIs performed using the hybrid approach between 2012 and 2015 at 11 United States centers.2 Wilson et al reported 90% final success among 1156 patients undergoing CTO-PCI using the hybrid approach at 7 United Kingdom centers between 2012 and 2014.3 Galassi et al reported 82.9% procedural success among 1914 patients treated at 16 European centers between 2008 and 2010.4 Morino et al reported first-attempt procedural success rates of 88.6% among 498 patients treated at 12 Japanese centers.5 

However, less-experienced sites have less-favorable outcomes. In an analysis of 594,510 PCI cases performed between 2009 and 2013 in patients with stable coronary artery disease in the National Cardiovascular Data Registry, CTO-PCI represented 3.8% of the total PCI volume and was associated with lower procedural success (59% vs 96%; P<.001) and higher risk for complications (1.6% vs 0.8%; P<.001) when compared with non-CTO PCI.6 Moreover, there is ongoing controversy on the relative benefits and risks of CTO-PCI, since nearly all currently available data are derived from observational, non-randomized registries.7

We performed a large, international survey to investigate the current perspectives of the cardiology community with regard to the risks and benefits of contemporary CTO-PCI, as well as commonly used techniques and practices.


Questionnaire. We designed a dedicated CTO-PCI based questionnaire covering: (1) respondent characteristics; (2) perceived risks/benefits; (3) technical aspects; and (4) overall comments (Appendix 1, available at www.invasivecardiology.com). The number of questions was dependent on the type of respondent: 9 questions for non-interventional cardiologists, 11 questions for interventional cardiologists not performing CTO-PCI, and 28 questions for interventional cardiologists performing CTO-PCI.

The survey was designed using the internet-based software Survey Monkey. To ensure that the questions covered all appropriate CTO-PCI related topics and could be finished in approximately 10 minutes, the survey was initially sent to a group of 5 selected cardiologists with extensive experience with CTO-PCI. After revisions, the final survey was made live on the internet on January 27, 2016. To encourage responses, we contacted key opinion leaders in CTO-PCI in several countries. The survey was closed on April 20, 2016. In order to ensure privacy and consistency, the identity of respondents remained anonymous and each respondent was allowed to answer the questionnaire only once. 

The software allowed monitoring results at all times as well as downloading results in a spreadsheet at any time. Exported data were descriptive. Values were reported as percentages of the total number of responses.

Statistical analysis. Continuous data were summarized as mean ± standard deviation for normally distributed data or median and interquartile range (IQR) for non-normally distributed data and compared using t-test or Wilcoxon rank-sum test, as appropriate. Categorical data were presented as frequencies or percentages and compared using Chi-square or Fisher’s exact test, as appropriate. Statistical analyses were performed with JMP 11.0 (SAS Institute) and SPSS 22.0 (IBM Corporation). A P-value of <.05 was considered statistically significant.


Respondent demographics. A total of 29,408 cardiologists were contacted and 1149 unique responses were obtained (3.9%) from various countries (Figure 1). The top 5 locations were the United States (n = 845; 73.5%), Asia (n = 98; 8.5%), Europe (n = 88; 7.7%), South America (n = 42; 3.7%), and Canada (n = 33; 2.9%). Participants reported being in clinical practice for 16.4 ± 11.5 years. Most respondents were interventional cardiologists (n = 769; 66.9%) (Figure 2) and most were board certified in cardiology (n = 1024; 89.1%); of those who were interventional cardiologists, the majority were also board certified in interventional cardiology (n = 640; 83.4%).

Clinical benefits and success rates. Most participants believed that when compared with optimal medical therapy (OMT) alone, OMT with CTO-PCI results in improvement of patient symptoms (n = 1043; 90.7%), left ventricular function (n = 911; 79.3%), arrhythmia risk (n = 795; 69.2%), and overall survival (n = 725; 63.1%). Interventional cardiologists reported greater benefit with CTO-PCI as compared with non-invasive cardiologists (P<.001) (Figure 3). Most respondents estimated CTO-PCI procedural success to be between 51%-75% (n = 393; 34.2%) and 76%-85% (n = 347; 30.2%), with interventional cardiologists perceiving higher success rates as compared with non-interventional cardiologists (P<.001) (Figure 4).

Complications. When asked to select the most concerning complications of CTO-PCI, the most frequent response was perforation (n = 872; 84.3%), followed by tamponade (n = 675; 65.3%) and contrast-induced nephropathy (n = 651; 63.0%). When further polled about the single most concerning complication of CTO-PCI, perforation (n = 413; 39.9%), followed by death (n = 175; 16.9%) and tamponade (n = 173; 16.7%), were the most common answers (Figure 5).

Operator training and experience. Most interventional cardiologists participating in the survey reported performing CTO-PCI in their current practice (n = 590; 76.7%) (Figure 2). These operators learned how to perform CTO-PCI through a variety of pathways, such as participation in courses (n = 344; 58.3%), interventional fellowship (n = 252; 42.7%), and proctorships (n = 247; 41.9%), although several were self-taught (n = 248; 42.0%). More than half of the participants reported using more than a single learning pathway (n = 355; 60.2%). When polled on annual volume and total number of career cases, there was significant variation in experience among survey respondents (Table 1). Linear regression showed a positive correlation between the operators’ reported CTO-PCI success rates and their estimated annual PCI volume (r = 0.255; P<.001) and career total CTO-PCI cases (r = 0.119; P<.01).

Procedural planning and technique. Less than half of operators (n = 240; 40.7%) utilized the J-CTO score for procedural planning. Mechanical cardiac support, if indicated for the procedure, was used by approximately half of operators (n = 320; 54.2%).

More than half of the participants used transfemoral access (n = 316; 53.6%), followed by both transfemoral and transradial access (n = 243; 41.2%) and transradial-only access (n = 31; 5.3%). Preferred guide/sheath sizes varied among operators, with 8 Fr being most commonly used for transfemoral access and 6 Fr for transradial access (Figure 6). Antegrade wire escalation was the most frequently utilized crossing strategy (median, 75%; IQR, 50%-90%), followed by antegrade dissection/re-entry (median, 20%; IQR, 10%-30%) and the retrograde approach (median, 10%; IQR, 0%-20%) (Figure 7). Most operators utilized all 3 crossing strategies on a case-by-case basis (n = 481; 81.5%).

Equipment utilization. Fielder XT (Asahi Intecc) was the most popular guidewire overall, followed by the Confianza Pro 12 (Asahi Intecc) and the Pilot 200 (Abbott Vascular) (Figure 8); the Gaia series of guidewires (Asahi Intecc) was more popular with European operators (Table 2). Corsair (Asahi Intecc) was the most widely utilized microcatheter, followed by the Finecross (Terumo). Guide-catheter extensions were commonly used. The CrossBoss and the Stingray system (Boston Scientific) accounted for the majority of dissection/re-entry equipment. Two-thirds of operators used rotational atherectomy (n = 382; 66.7%), and less than one-third used coronary laser (n = 144; 25.1%).

Barriers to CTO-PCI. Most respondents acknowledged that the time requirement (n = 242; 41.0%) and procedural complexity (n = 130; 22.0%) were significant barriers to developing a CTO-PCI program, followed by lack of a referral base (n = 104; 17.6%). Other reported barriers included cost (n = 73; 12.3%) and risk for complications (n = 41; 6.9%).

Additional comments. The most frequent additional comment was on the need for prospective, clinical randomized-controlled trials (RCTs) comparing CTO-PCI with OMT. Another frequent comment was on the importance of myocardial viability testing in identifying patients most likely to benefit from CTO-PCI.


To the best of our knowledge, this is the largest survey of the cardiology community performed to date on contemporary CTO-PCI perceptions and practices.

Clinical benefits. Most respondents indicated that CTO-PCI improves angina and left ventricular function, reduces the risk for arrhythmia, and possibly reduces mortality. This is in concordance with currently published data, most of which is observational.7 Although several studies have reported left ventricular function improvement after CTO-PCI,8-11 the only prospective, clinical RCT performed to date did not show any difference in the ejection fraction at 4 months post procedure among patients with recent ST-segment elevation acute myocardial infarction who did and those who did not undergo CTO-PCI;12 however, procedural success was low (73%). Nombela-Franco et al reported higher risk for ventricular arrhythmias among ischemic cardiomyopathy patients who had a CTO vs those who did not,13 although this finding was not confirmed in a subsequent study.14 As compared with failed CTO-PCI, successful CTO-PCI has been associated with lower mortality in several observational studies and meta-analyses.7 Many respondents reported a need for prospective RCTs. Since the survey, the results of the DECISION-CTO (Drug-Eluting stent Implantation versus optimal Medical Treatment in patients with ChronIc Total OccluSION) trial were presented at the 2017 American College of Cardiology meeting. DECISION-CTO randomized 834 patients with coronary CTOs to OMT alone vs OMT + CTO-PCI. Patients in the OMT + CTO-PCI group had similar clinical outcomes during a median follow-up of 3.1 years. However, the study has several limitations, including early termination before achievement of target enrollment, high cross-over rates (18% in the OMT alone group underwent CTO-PCI), performance of non-CTO PCI in a large proportion of patients in both study groups, and mild baseline symptoms in both study groups. The EuroCTO (A Randomized Multicentre Trial to Evaluate the Utilization of Revascularization or Optimal Medical Therapy for the Treatment of Chronic Total Coronary Occlusions) trial (NCT01760083) was presented at the 2017 EuroPCR meeting. This study was also stopped early due to slow enrollment after randomizing 407 patients. Compared with patients randomized to medical therapy alone, patients randomized to CTO-PCI had more improvement in angina frequency at 12 months, as assessed by the Seattle Angina Questionnaire. The ongoing SHINE-CTO (Sham-Controlled Intervention to Improve Quality of Life in CTOs) study (NCT02784418) is comparing CTO-PCI with a sham control and will provide additional insights on the quality-of-life improvement with the procedure.

Success rates. Reported procedural success rates of CTO-PCI range from as low as 41.2% among less experienced sites1 to as high as 99% for experienced operators.15 Most respondents estimated the average success rate to be between 51%-75%, consistent with these published reports. However, interventional cardiologists estimated the average procedural success rate to be higher than non-interventional cardiologists (76%-85% vs 51-75%; P<.001), regardless of whether they performed CTO-PCI in their practice or not. The wide range of estimated success rates is likely due at least in part to variation in experience and procedural volume. Greater CTO-PCI experience has been associated with higher success and lower complications rates in multiple studies.16 Case selection is also a determinant of success rates, although experienced operators can achieve high success rates even among very complex lesions.2,17 Moreover, a commitment to continued learning is critical, as CTO-PCI is rapidly evolving from an equipment and procedural strategy standpoint. Many respondents (42%) were self-taught, which demonstrates an opportunity to engage these operators in contemporary training programs to stay current with ongoing advances in the field of CTO-PCI. Multiple online interactive curriculum platforms have been developed to address this need (http://www.ctofundamentals.org; https://www.ctomanual.org; and http://apcto.club/introduction).

Complications. In our survey, coronary perforation was the most feared complication of CTO-PCI. The use of detailed pre-PCI angiogram review and dual injection can help reduce the risk of perforation. Equipment to treat perforations (such as covered stents and coils) should be available at all catheterization laboratories performing PCIs (especially CTO-PCIs). Several developments have recently improved the treatment of perforations through the use of autologous fat particles, sometimes through a single guide catheter. 18-20 Survey respondents also expressed concern for periprocedural death, a devastating complication in a stable patient that occurs most commonly due to tamponade from perforation.21 Better understanding of the mechanisms of these complications can help limit such events. For example, there is increasing awareness of the risk for hemodynamic collapse due to localized hematoma and tamponade in patients with prior coronary bypass graft surgery who develop a perforation (especially in the atrioventricular groove).22,23 Radiation-induced skin injury was also of concern; however, there are currently several strategies to minimize the radiation dose to the patient and operator, by using low-frame rate fluoroscopy, no magnification, real-time radiation monitoring, the fluoro-store function, or implementation of newer x-ray systems with radiation dose-reduction features.24-26

Crossing strategies. Antegrade wire escalation remains the most common crossing strategy, reported to be used in up to 70% of cases. However, the majority of our survey respondents (81.5%) acknowledged having used all 3 crossing strategies during CTO-PCI. These findings suggest the increasing popularity of the hybrid approach,27 which advocates rapidly changing the crossing strategy if the initial one fails to achieve progress during the procedure. The overall use of antegrade dissection/re-entry28 and especially the retrograde approach29 was substantially lower than that reported by experienced centers (approximately 40% vs <20% of all cases), likely reflecting limited experience and comfort with use of these newer techniques. Caution may be appropriate, however, as the retrograde approach has been associated with increased risk for complications when compared with antegrade-only techniques.30,31

Equipment utilization. Polymer-jacketed guidewires (eg, Fielder XT, Pilot 200) were the most commonly reported wires for CTO-PCI. This finding agrees with a recent analysis of guidewire utilization from a multicenter CTO-PCI registry.32 The Corsair continues to be the most commonly used microcatheter during CTO-PCI.32 The CrossBoss and the Stingray system accounted for over 80% of dissection/re-entry equipment used, likely because they are designed to facilitate controlled re-entry into the distal true lumen.33

Barriers. Respondents continue to acknowledge time and procedural complexity as the most significant barriers to developing a CTO program, signaling the need for simplification of techniques and development of novel equipment to achieve greater efficiency for CTO-PCI. Lack of sufficient referrals was also reported by respondents to be a significant problem. These findings support the need for increased awareness of the benefits and limitations of CTO-PCI, particularly within the non-interventional cardiology community. They also support some concentration of cases in centers of excellence where higher volumes, better success rates, and lower complication rates can be achieved.3,34

Study limitations. Our study has important limitations. First, given that this was a voluntary questionnaire and most respondents currently perform CTO-PCI, their perceptions on risks and benefits of CTO-PCI may be more positive than those held by the general cardiology community. Second, operator volumes and individual success rates were self reported and could not be objectively verified. Third, the majority of respondents were from the United States and as a result may mostly reflect the practices therein, although a substantial number of non-United States participants were included. Fourth, the responses to technical questions directed at CTO-PCI operators may reflect their propensity to use certain devices rather than objective utilization numbers, which could be much lower.


CTO-PCI is rapidly evolving. Our global survey suggests that most physicians have a positive view of the outcomes and success rates of CTO-PCI. Coronary perforation is the most feared complication and antegrade-wire escalation remains the most commonly used technique. The time required and procedural complexity of CTO-PCI remain significant barriers to CTO-PCI adoption, suggesting the need for development of simpler and more successful crossing techniques. Moreover, there is a need to perform adequately sized RCTs to critically evaluate the benefits and risks of CTO-PCI.

Appendix: Study Questionnaire


1.    Patel VG, Brayton KM, Tamayo A, et al. Angiographic success and procedural complications in patients undergoing percutaneous coronary chronic total occlusion interventions: a weighted meta-analysis of 18,061 patients from 65 studies. JACC Cardiovasc Interv. 2013;6:128-136.

2.    Christopoulos G, Kandzari DE, Yeh RW, et al. Development and validation of a novel scoring system for predicting technical success of chronic total occlusion percutaneous coronary interventions: the PROGRESS CTO (Prospective Global Registry for the Study of Chronic Total Occlusion Intervention) score. JACC Cardiovasc Interv. 2016;9:1-9.

3.    Wilson WM, Walsh SJ, Yan AT, et al. Hybrid approach improves success of chronic total occlusion angioplasty. Heart. 2016;102:1486-1493. Epub 2016 May 10.

4.    Galassi AR, Tomasello SD, Reifart N, et al. In-hospital outcomes of percutaneous coronary intervention in patients with chronic total occlusion: insights from the ERCTO (European Registry of Chronic Total Occlusion) registry. EuroIntervention. 2011;7:472-479.

5.    Morino Y, Kimura T, Hayashi Y, et al. In-hospital outcomes of contemporary percutaneous coronary intervention in patients with chronic total occlusion: insights from the J-CTO registry (multicenter CTO registry in Japan). JACC Cardiovasc Interv. 2010;3:143-151.

6.    Brilakis ES, Banerjee S, Karmpaliotis D, et al. Procedural outcomes of chronic total occlusion percutaneous coronary intervention: a report from the NCDR (National Cardiovascular Data Registry). JACC Cardiovasc Interv. 2015;8:245-253.

7.    Christakopoulos GE, Christopoulos G, Carlino M, et al. Meta-analysis of clinical outcomes of patients who underwent percutaneous coronary interventions for chronic total occlusions. Am J Cardiol. 2015;115:1367-1375.

8.    Baks T, van Geuns RJ, Duncker DJ, et al. Prediction of left ventricular function after drug-eluting stent implantation for chronic total coronary occlusions. J Am Coll Cardiol. 2006;47:721-725.

9.    Kirschbaum SW, Baks T, van den Ent M, et al. Evaluation of left ventricular function three years after percutaneous recanalization of chronic total coronary occlusions. Am J Cardiol. 2008;101:179-185.

10.    Danchin N, Angioi M, Cador R, et al. Effect of late percutaneous angioplastic recanalization of total coronary artery occlusion on left ventricular remodeling, ejection fraction, and regional wall motion. Am J Cardiol. 1996;78:729-735.

11.    Sirnes PA, Myreng Y, Molstad P, Bonarjee V, Golf S. Improvement in left ventricular ejection fraction and wall motion after successful recanalization of chronic coronary occlusions. Eur Heart J. 1998;19:273-281.

12.    Henriques JP, Hoebers L, Råmunddal T, et al. TCT-8 First results of the EXPLORE trial, a global, randomized, prospective, multicenter trial investigating the impact of recanalization of a chronic total occlusion on left ventricular function in patients after primary percutaneous coronary intervention for acute ST-elevation myocardial infarction. J Am Coll Cardiol. 2015;66.

13.    Nombela-Franco L, Mitroi CD, Fernandez-Lozano I, et al. Ventricular arrhythmias among implantable cardioverter-defibrillator recipients for primary prevention: impact of chronic total coronary occlusion (VACTO Primary Study). Circ Arrhythm Electrophysiol. 2012;5:147-154.

14.    Raja V, Wiegn P, Obel O, et al. Impact of chronic total occlusions and coronary revascularization on all-cause mortality and the incidence of ventricular arrhythmias in patients with ischemic cardiomyopathy. Am J Cardiol. 2015;116:1358-1362.

15.    Tsuchikane E, Katoh O, Kimura M, Nasu K, Kinoshita Y, Suzuki T. The first clinical experience with a novel catheter for collateral channel tracking in retrograde approach for chronic coronary total occlusions. JACC Cardiovasc Interv. 2010;3:165-171.

16.    Michael TT, Karmpaliotis D, Brilakis ES, et al. Temporal trends of fluoroscopy time and contrast utilization in coronary chronic total occlusion revascularization: insights from a multicenter United States registry. Catheter Cardiovasc Interv. 2015;85:393-399.

17.    Christopoulos G, Wyman RM, Alaswad K, et al. Clinical utility of the Japan-Chronic Total Occlusion score in coronary chronic total occlusion interventions: results from a multicenter registry. Circ Cardiovasc Interv. 2015;8:e002171.

18.    Shemisa K, Karatasakis A, Brilakis ES. Management of guidewire-induced distal coronary perforation using autologous fat particles versus coil embolization. Catheter Cardiovasc Interv. 2017;89:253-258. Epub 2016 May 3.

19.    Boukhris M, Tomasello SD, Azzarelli S, Elhadj ZI, Marza F, Galassi AR. Coronary perforation with tamponade successfully managed by retrograde and antegrade coil embolization. J Saudi Heart Assoc. 2015;27:216-221.

20.    Tarar MN, Christakopoulos GE, Brilakis ES. Successful management of a distal vessel perforation through a single 8-French guide catheter: combining balloon inflation for bleeding control with coil embolization. Catheter Cardiovasc Interv. 2015;86:412-416.

21.    Azzalini L, Vo M, Dens J, Agostoni P. Myths to debunk to improve management, referral, and outcomes in patients with chronic total occlusion of an epicardial coronary artery. Am J Cardiol. 2015;116:1774-1780.

22.    Aggarwal C, Varghese J, Uretsky BF. Left atrial inflow and outflow obstruction as a complication of retrograde approach for chronic total occlusion: report of a case and literature review of left atrial hematoma after percutaneous coronary intervention. Catheter Cardiovasc Interv. 2013;82:770-775.

23.    Wilson WM, Spratt JC, Lombardi WL. Cardiovascular collapse post chronic total occlusion percutaneous coronary intervention due to a compressive left atrial hematoma managed with percutaneous drainage. Catheter Cardiovasc Interv. 2014;8:407-411.

24.    Christopoulos G, Makke L, Christakopoulos G, et al. Optimizing radiation safety in the cardiac catheterization laboratory: a practical approach. Catheter Cardiovasc Interv. 2015;87:291-301.

25.    Christopoulos G, Christakopoulos GE, Rangan BV, et al. Comparison of radiation dose between different fluoroscopy systems in the modern catheterization laboratory: results from bench testing using an anthropomorphic phantom. Catheter Cardiovasc Interv. 2015;86:927-932.

26.    Christopoulos G, Papayannis AC, Alomar M, et al. Effect of a real-time radiation monitoring device on operator radiation exposure during cardiac catheterization: the radiation reduction during cardiac catheterization using real-time monitoring study. Circ Cardiovasc Interv. 2014;7:744-750.

27.    Brilakis ES, Grantham JA, Rinfret S, et al. A percutaneous treatment algorithm for crossing coronary chronic total occlusions. JACC Cardiovasc Interv. 2012;5:367-379.

28.    Michael TT, Papayannis AC, Banerjee S, Brilakis ES. Subintimal dissection/re-entry strategies in coronary chronic total occlusion interventions. Circ Cardiovasc Interv. 2012;5:729-738.

29.    Brilakis ES, Grantham JA, Thompson CA, et al. The retrograde approach to coronary artery chronic total occlusions: a practical approach. Catheter Cardiovasc Interv. 2012;79:3-19.

30.    El Sabbagh A, Patel VG, Jeroudi OM, et al. Angiographic success and procedural complications in patients undergoing retrograde percutaneous coronary chronic total occlusion interventions: a weighted meta-analysis of 3,482 patients from 26 studies. Int J Cardiol. 2014;174:243-248.

31.    Stetler J, Karatasakis A, Christakopoulos GE, et al. Impact of crossing technique on the incidence of periprocedural myocardial infarction during chronic total occlusion percutaneous coronary intervention. Catheter Cardiovasc Interv. 2016;88:1-6.

32.    Karatasakis A, Tarar MN, Karmpaliotis D, et al. Guidewire and microcatheter utilization patterns during antegrade wire escalation in chronic total occlusion percutaneous coronary intervention: insights from a contemporary multicenter registry. Catheter Cardiovasc Interv. 2017;89:253-258. Epub 2016 May 3.

33.    Wosik J, Shorrock D, Christopoulos G, et al. Systematic review of the BridgePoint system for crossing coronary and peripheral chronic total occlusions. J Invasive Cardiol. 2015;27:269-276.

34.    Christopoulos G, Karmpaliotis D, Alaswad K, et al. Application and outcomes of a hybrid approach to chronic total occlusion percutaneous coronary intervention in a contemporary multicenter US registry. Int J Cardiol. 2015;198:222-228.

From 1Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts; 2Children’s Medical Center and University of Texas Southwestern Medical School, Dallas, Texas; 3Minneapolis Heart Institute and Foundation, Minneapolis, Minnesota; 4Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts; 5Beth Israel Deaconess Medical Center, Boston, Massachusetts; 6University of Manitoba, St. Boniface Hospital, Winnipeg, Manitoba, Canada; 7Columbia University, New York, New York; 8San Raffaele Scientific Institute, Milan, Italy; 9Helios Vogtland Klinikum Plauen, Academic Teaching Hospital of Leipzig University, Leipzig, Germany; 10Cannizzaro Hospital, University of Catania, Catania, Italy; 11Quebec Heart and Lung Institute, Quebec City, Canada; 12Cleveland Clinic, Cleveland, Ohio; 13VA San Diego Healthcare System and University of California San Diego, San Diego, California; and 14VA North Texas Health Care System and University of Texas Southwestern Medical School, Dallas, Texas.

Disclosures: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Burke reports consulting and speaking honoraria from Abbott Vascular and Boston Scientific. Dr Azzalini reports grant funds from Acist Medical System and personal fees from Guerbet. Dr Jaffer reports consulting fees from Boston Scientific, Siemens, and Merck; non-financial research support from Abbott Vascular; research grants from National Institutes of Health (HL-R01-108229), Siemens, Canon, and Kowa. Dr Yeh reports a Career Development Award (1K23HL118138) from the National Heart, Lung, and Blood Institute; grant from Boston Scientific; personal fees from Abbott Vascular, Boston Scientific, and Medtronic; salary support from Harvard Clinical Research Institute. Dr Vo reports consulting fees/speaker honoraria and proctoring honoraria from Boston Scientific. Dr Karmpaliotis reports honoraria from Boston Scientific and Abbott Vascular. Dr Ellis reports consultant fees from Abbott Vascular, Boston Scientific, and Medtronic. Dr Rangan reports institutional research grants from Spectranetics and InfraRedX. Dr Banerjee reports research grants from Gilead and The Medicines Company; consultant/speaker honoraria from Covidien, Merck, and Medtronic; ownership in MDCare Global (spouse); intellectual property in HygeiaTel; and educational grant from Boston Scientific (spouse). Dr Brilakis reports consulting/speaker honoraria from Abbott Vascular, Asahi Intecc, Cardinal Health, Elsevier, GE Healthcare, and St. Jude Medical; research support from InfraRedx and Boston Scientific; spouse is an employee of Medtronic.

Manuscript submitted April 30, 2017, provisional acceptance given May 5, 2017, final version accepted May 22, 2017.

Address for correspondence: Emmanouil S. Brilakis, MD, PhD, Minneapolis Heart Institute, 920 E. 28th Street #300, Minneapolis, MN 55407. Email: esbrilakis@gmail.com