The prevalence of chronic total occlusion (CTO) is high, with approximately one in three patients undergoing diagnostic coronary angiography, and may reach up to 50% in studies of patients with previous coronary artery bypass grafting (CABG). The condition is also one of the most frequent causes of incomplete revascularization. Percutaneous coronary intervention (PCI) for CTO has been traditionally associated with lower success rates and more complications compared to PCI for stenosis and antegrade flow. This is related to technical difficulties in crossing occlusion with the guidewire but also to greater angiographic complexity, higher risk profile, and presence of comorbidities.^1-3 In recent years, major advances in techniques and devices to recanalize CTOs have been seen, with international CTO PCI registries reporting success rates near 90%.⁴ However, there are limited contemporary data on the characteristics and outcomes of these procedures in Brazil. This study aimed to describe the clinical and angiographic characteristics, procedural aspects, complications, and clinical outcomes of contemporary patients with CTO undergoing PCI at Brazilian centers dedicated to CTO PCI.

Data on 1,196 CTO PCI procedures performed at 26 Brazilian hospitals participating in the LATAM CTO Registry were included. The mean age was 63.46±10.56 years, and most patients were male, White, and had a diagnosis of hypertension (Table 1). More than a third of patients had a diagnosis of diabetes mellitus, half had a history of MI, and more than half had previous percutaneous or surgical myocardial revascularization. The mean left ventricular ejection fraction was 55.50±12.18%. Angina control was the most frequent indication for procedures (85%), followed by treatment of moderate/severe ischemia (24%).

Table 1

Age, years	63.46±10.56
Male	887 (74%)
White	869 (77%)
Hypertension	1,064 (90%)
Dyslipidemia	816 (69%)
Active smoking	177 (15%)
Diabetes mellitus	462 (39%)
Positive family history	394 (35%)
Past medical history
Myocardial infarction	529 (48%)
PCI	520 (47%)
Previous attempt at CTO PCI	156 (13%)
Coronary artery bypass grafting	157 (14%)
Congestive heart failure	132 (12%)
Stroke	39 (3.5%)
Peripheral arterial disease	142 (13%)
Chronic kidney disease	82 (7.4%)
Ejection fraction, %	55.50±12.18
Procedural indications
Angina control	1010 (85%)
Moderate/severe ischemia	284 (24%)
Heart failure	120 (10%)
Ventricular arrhythmia	11 (0.9%)
Other	22 (1.9%)

PCI: percutaneous coronary intervention; CTO: chronic total occlusion.

Regarding medications at the time of CTO PCI, the vast majority of patients were taking more than one antianginal drug, predominantly beta-blockers. Most were also on dual antiplatelet therapy, angiotensin-converting enzyme inhibitors, and statins (Table 2).

Table 2

Statin	1034 (87.9%)
ACEI	478 (40.6%)
ARA II	457 (38.9%)
ASA	1094 (93.0%)
Other antiplatelet	825 (70.2%)
Beta-blocker	838 (71.3%)
Nitrate	415 (35.3%)
Calcium-channel blocker	205 (17.4%)
Trimetazidine	50 (4.3%)
Coumarin	3 (0.3%)
NOAC	7 (0.6%)

AAS: acetylsalicylic acid; ACEI: angiotensin-converting enzyme inhibitor; ARA II: angiotensin II receptor antagonist; NOAC: novel oral anticoagulants.

The left anterior descending artery and the right coronary artery were the most common target vessels, with a mean lesion size of 25±15 mm and a proximal stump shaped like a pencil tip in most lesions (Table 3). Moderate/severe calcification was observed in approximately one third of patients, and 43% had no collaterals and/or grafts suitable for a retrograde approach. The mean J-CTO score in the study patients was 1.84±1.18.

Table 3

Target vessel
Left anterior descending artery	453 (39%)
Right coronary artery	476 (40%)
Circumflex artery	234 (20%)
Left main coronary artery	7 (0.6%)
Lesion size, mm	25.21±14.87
Tapered proximal stump	697 (60%)
Moderate/severe calcification	176 (15%)
Moderate/severe tortuosity	176 (15%)
Distal stump bifurcation	360 (34%)
No collaterals for intervention	493 (43%)
Collateral channel size (Werner score)
0	238 (21%)
1	572 (51%)
2	283 (25%)
In-stent restenosis	158 (14%)
Angiographic complexity scores
J-CTO score	1.84±1.18
PROGRESS CTO score	0.97±0.86
CL score	2.81±1.57
ORA score	1.04±0.68

The Central Figure shows success rates in general international registries. Technical success rate at Brazilian centers was 84%, and procedural success was 82%. The strategy showing the highest success rate was that of antegrade wires, with ADR and retrograde approaches being used in approximately 10% of cases each. A single femoral access was used in 26% of the procedures, and a single radial access in 20%. A contralateral injection was used in half of all cases, and the most commonly combined access sites were radial and femoral (27%), followed by bifemoral (22%). A microcatheter was used in three quarters of the procedures—the Finecross^® microcatheter was the most frequent. Whisper^® and PT2^® were the guidewires that most frequently crossed the occlusions, and the median crossing time was around 15 minutes, which is considered short. An average of 1.98±1.19 drug-eluting stents were implanted per procedure (Table 4). MACE and complication rates were approximately 2%, which is low (Figures 1A and 1B).

Central Illustration

Table 4

Arterial access site
Radial and femoral	322 (27%)
Femoral alone	307 (26%)
Bifemoral	259 (22%)
Radial alone	236 (20%)
Biradial	49 (4%)
Contralateral injection	631 (54%)
Crossing time	15 min (8-33 min)
Guidewire crossing CTO
Whisper ®	238 (28%)
PT2 ®	187 (22%)
Fielder FC ®	63 (7.5%)
Runthrough NS ®	45 (5.4%)
Progress 80 ®	41 (4.9%)
ProVia 9 ®	27 (3.2%)
Progress 40 ®	26 (3.1%)
MiracleBros 3 ®	23 (2.8%)
Confianza Pro 12 ®	21 (2.5%)
Progress 200T ®	21 (2.5%)
Use of microcatheter	897 (75%)
Types of microcatheter
Finecross ®	478 (44%)
Over-the-wire balloon	147 (18%)
Turnpike Spiral ®	85 (8.4%)
Turnpike ®	73 (6.8%)
Supercross ®	42 (4.1%)
Other (n = 832)	173 (21%)
Number of balloons/procedure	3.04±3.48
Stents/procedure	1.98±1.19
Successful strategy
AW	795 (81%)
ADR	88 (9%)
Retrograde	97 (10%)
Use of retrograde strategy	166 (14%)
Rotational atherectomy	28 (3%)
IVUS	95 (10%)
Dedicated microcatheter – CrossBoss®	36 (3.8%)
Dedicated balloon – StinGray®	24 (2.6%)
Fluoroscopy time, min	37.33±22.44
Contrast volume, ml	221.11±106.29
Technical success	84%
Clinical success	82%

ADR: antegrade dissection and re-entry; AW: antegrade wire; IVUS: intravascular ultrasound.

Figure 1

In this study, we report contemporary CTO PCI data from Brazilian centers participating in the LATAM CTO Registry, including clinical and angiographic characteristics, procedural aspects, and MACEs. There is a broad collection of reports on these procedures from North America, Western Europe, and Japan,^1,15-18 but Brazil still lacks information. In this contemporary analysis of Brazilian practice, we found encouraging results, with success rates above 80% and low rates of complications and MACEs. Also relevant was the demonstration that the main indications for performing interventions—angina control and treatment of significant myocardial ischemia—, as well as the clinical treatment received by patients before the interventions, were in accordance with current guidelines.^15,16 The present analysis is the first medical practice report of Brazilian centers of excellence in CTO PCI using contemporary techniques and approaches recommended by international consensus groups.¹⁷

The indications for CTO PCI were recently questioned by randomized clinical trials that did not show the benefit of these procedures in reducing cardiovascular events or improving ventricular function, although several methodological limitations were observed in those studies.^19-21 Conversely, CTO PCI significantly improved symptoms and quality of life compared to optimal drug therapy in two recent randomized trials.^22,23 Therefore, we are encouraged to report that 85% of the procedures in the present study were performed to relieve symptoms, which reflects substantial adherence of Brazilian centers to good clinical practices and international guidelines.

Although CTO is found in up to 18-52% of coronary angiograms,^19,24,25 most cases have no clinical indication for intervention. However, some of these patients have significant angina, refractory to clinical treatment and impairing quality of life, while those with multivessel disease require CTO intervention as a complete revascularization strategy. We believe that the present report demonstrates feasibility of providing an effective treatment for these patients in Brazil, with satisfactory success rates and low complication rates in a real-world context.

Table 5 compares CTO treatment outcomes in our setting with those of contemporary literature, which we categorized as national registries of nondedicated CTO PCI centers^26,27 and registries of dedicated CTO PCI centers in the United States (US), Europe, Japan, and Latin America.^2,4,10,28-31 Data from dedicated CTO PCI centers in developed countries demonstrate success rates higher than those of the present study, which can be explained by procedures being performed by experienced operators in the global context using a wide range of devices and materials. Conversely, success rates in our study, as well as in the LATAM registry, were higher than those of national registries of developed countries not restricted to dedicated CTO PCI centers, which shows considerable CTO PCI expertise in our setting.

Table 5

	n	Sucesso	ECAM	Óbito
National registries
NCDR26	22.365	59%	1,6%	0,4%
British Registry (2014)Cardiovascular (27)	28.050	67%	0,73%	0,2%
CTO PCI registries
OPEN CTO28	1.000	90%	7%	0.9%
PROGRESS4	3.055	87%	3%	0.85%
EURO CTO2	4.314	88%	0.5%	0.1%
RECHARGE10	1.253	89%	2.6%	0.2%
Japanese registry30	3.229	88%	0.5%	0.2%
LATAM31	1.040	81%	3%	1%
Brazil	1.196	82%	2,3%	0,75%

CTO: chronic total occlusion; PCI: percutaneous coronary intervention; MACE: major adverse cardiovascular event; NCDR: National Cardiovascular Data Registry; OPEN CTO: Outcomes, Patient Health Status, and Efficiency in Chronic Total Occlusion Hybrid Procedures; EURO CTO: European Registry of Chronic total occlusion; RECHARGE: REgistry of CrossBoss and Hybrid procedures in FrAnce, NetheRlands, BelGium and UnitEd Kingdom; LATAM: Latin American registry.

Occlusion complexity in our registry, as assessed by the J-CTO score, was similar to that of other dedicated CTO PCI registries, but information from national registries of developed countries was not available. The rates of complications and MACEs in our setting were also similar to those of dedicated CTO PCI registries. These comparisons, although putting Brazilian and Latin American practices into perspective against medical practice in other countries, should be viewed with caution because of potential biases in center selection, event measurement, and other confounding factors.

As we mentioned above, our lower success rates may be related to more limited resources and different stages of the learning curve shown by participating centers and operators.³² Unlike other dedicated CTO PCI registries (Japan, US, and Europe), we did not establish a minimum number of cases per operator or per center to participate in our study, similar to the experience of other Latin American centers. Our objective was to show an overview of CTO PCI practice at Brazilian services dedicated to CTO treatment, and all centers willing to participate were included. Our results may therefore be more generalizable and represent the reality of most interventional cardiology services that perform CTO PCI.

Microcatheters and contralateral injections are considered good practices in several reports.^1,4,26,28 The fact that only half of the procedures in our study were performed with a contralateral injection and only two thirds used a microcatheter may reflect the ongoing learning curve in our country. Although the use of microcatheters below recommendations may be related to reimbursement and financial issues, this is not the case with contralateral injections, which are used at the discretion of the operator. These observations highlight the importance of continuing education and adequate training for operators willing to perform CTO PCI.

Figure 2

CTOs can be treated effectively and safely at Brazilian centers dedicated to CTO PCI, with low complication rates. This reflects the scientific and technological development observed in this area in the past decade.