Koronarinės intervencijos

Chronic total occlusion (CTO) is one of the most complex and clinically significant areas of coronary intervention. It occurs when a coronary artery is completely blocked for at least three months, preventing blood flow to the affected part of the heart. This lack of circulation deprives the heart of oxygen and nutrients, leading to angina. TOs are present in up to 30% of patients with coronary artery disease [1] Historically, these cases were considered technically challenging and difficult to treat using invasive methods. However, advancements in percutaneous techniques and specialized equipment have significantly improved outcomes. The procedural risks associated with CTO percutaneous coronary intervention (PCI) have steadily declined in experienced centers [0] Recent developments in interventional cardiology and new CTO treatment strategies have resulted in higher success rates, improved patient survival, and better quality of life. The most current data from CTO-experienced sites in the US show technical success rates > 90%.[20]

What is CTO PCI?

Previously, patients with CTO who experienced angina (chest pain, shortness of breath, fatigue) despite optimal medical therapy required open-heart surgery – Coronary Artery Bypass Grafting (CABG). Today, CTO can be treated using a minimally invasive method called Percutaneous Coronary Intervention (PCI). This procedure involves reopening the artery with balloons, stents and specialized equipment. Continuous advancements in techniques, equipment and specialized training have increased success rates, making CTO PCI a predictable and effective treatment. European guidelines for myocardial revascularization recommend CTO PCI to reduce ischemia in the affected myocardial territory and alleviate angina symptoms [2].

Patient Selection

With modern techniques and equipment, patient selection should not rely solely on the type of lesion (total, subtotal, or severely obstructive) but should focus on symptoms and diagnostic findings [3].
Current expert consensus highlights four main indications for CTO PCI:

Alleviation of lifestyle-limiting symptoms and improved exercise capacity.
Reduction of ischemic burden detected by non-invasive testing.
Improvement of dyspnea related to left ventricular (LV) dysfunction, with evidence of viable myocardium.
Enhancement of long-term prognosis in patients with high-risk, multi-vessel coronary artery disease (CAD) [23][24][25][26][27].

CTOs are more common in older patients. Studies show a CTO prevalence of 36.5% in patients under 65 years, 39.1% in those aged 65–79 years, and 40.7% in patients over 80 years [16]. The right coronary artery is the most frequently affected vessel, followed by the left anterior descending and left circumflex arteries.

The presence of collateral circulation does not eliminate ischemia in the occluded territory. Therefore, the size of collateral circulation should not be a contraindication for revascularization [4]. Evaluating ischemia and myocardial viability is crucial.
For asymptomatic patients, ischemia assessment is recommended before CTO PCI. The procedure’s success depends on whether the heart tissue retains the potential to recover. Comprehensive diagnostic methods – such as transmural infarction assessment, contractile reserve evaluation with dobutamine, and cardiac MRI for normal myocardial wall thickening – are recommended, particularly in cases of significant but non-extensive infarcts [5].

Procedure Planning

Pre-procedural planning involves angiographic scoring to estimate success probability and determine the approach. The J-CTO score is one of the most widely used tools. The development of the hybrid algorithm has further optimized success rates by reducing procedure time, radiation exposure, and contrast use, while also standardizing techniques and minimizing variability among operators. This algorithm enables a systematic transition between strategies, maximizing success and reducing risk [11][12]
High-volume centers in North America and Europe have reported success rates exceeding 90% by implementing a standardized hybrid algorithm. This method includes placing two guiding catheters -one in each coronary artery (or bypass graft)- to facilitate dual injections and allow seamless switching between antegrade and retrograde wiring approaches. A dual injection angiogram assesses lesion characteristics, including length and collateral artery anatomy. Based on these findings, operators determine the optimal wiring approach and monitor procedural parameters such as time, radiation exposure, and contrast volume. This algorithm has proven successful even in high-risk patients with prior CABG, achieving an 87.5% procedural success rate [11].

CTO Procedure Steps

The procedure is similar to an Cardiac Catheterisation. To establish a clear clinical indication, patients should undergo a thorough pre-procedural evaluation that includes tests for symptoms, ischemia, and viability [9]The main steps of the procedure include:

Insertion of a guiding catheter – allows access to the CTO lesion.
Guidewire crossing – specialized CTO wires and microcatheters are used.
Dissection/reentry techniques – for complex cases, a retrograde approach via collateral arteries may be used.
Balloon angioplasty – once the guidewire is successfully advanced, the artery is dilated.
Stenting – to maintain patency and reduce the risk of restenosis.

CTO PCI Techniques and Approaches

CTO PCI requires advanced skills and specialized equipment. Key techniques include:

Antegrade wire escalation (AWE): Uses progressively stiffer guidewires to penetrate the occlusion.
Antegrade dissection and re-entry (ADR): Employs controlled subintimal dissection for lesion crossing.
Retrograde approach: Accesses the CTO lesion via collateral arteries, often used when antegrade attempts fail.
Hybrid approach: Integrates multiple strategies for optimal success. Recent studies report an 85–90% success rate using this approach [6][7][8] and US-based CTO centers report a technical success rate exceeding 90%. Following a strict hybrid approach, success rates reach 93.4% in patients without prior CABG and 88.1% in those with previous CABG [20].

Benefits of CTO PCI

The CTO PCI is a rapidly advancing field. With the use of the right equipment and current techniques, high volume and expertise centers achieve high success rates. Successful CTO recanalization is associated with a number of clinical benefits, such as improved angina, quality of life and physical limitation, improved ventricular function, and decreased mortality when compared to patients whose recanalization was not successful.

The Italian CTO Registry assessed the clinical outcomes of 1,777 patients, showing lower cardiac mortality (1.4, 4.7 and 6.3%, p < 0.001) and MACE at one year (2.6, 8.2 and 6.9%, p < 0.001) in patients treated with PCI when compared to clinical treatment or surgery. In this study, the group receiving optimized medical treatment presented higher rates of MACE, death and re-hospitalization[13]
Sapontis et al. evaluated the quality of life of 1,000 patients submitted to OCT PCI. One month follow-up showed a significant improvement in all domains of the Seattle Angina Questionnaire (SAQ), Rose Dyspnea Scale and PHQ-8 scores [14]
In Japan, in a series of 904 consecutive procedures involving PCI for CTO between 2002 and 2008 (Rathore et al., 2009). Impressively, technical success was achieved in 87.5% of lesions, with a procedural success (defined as technical success without MACE) in 86.2% of lesions. Increases in the use of different guidewire crossing techniques (parallel wire, retrograde wire, intravascular ultrasound guidance, and CART) occurred each year. In-hospital MACE rates were 1.5% in the group with successful CTO PCI and slightly higher at 4.4% in the group with unsuccessful PCI (p = 0.027)[21]
In a recent meta-analysis including 9 studies with more than 6,400 patients, the long-term clinical outcomes of successful CTO recanalization were compared to those in whom the recanalization was unsuccessful. In this study, the risk of death, AMI and MACE was approximately 50% lower in patients with CTO recanalization, with a 90% lower incidence of myocardial revascularization [15]
The EuroCTO multicenter trial (A Randomized Multicentre Trial to Evaluate the Utilization of Revascularization or Optimal Medical Therapy for the Treatment of Chronic Total Coronary Occlusions) randomly assigned 396 patients to CTO-PCI versus optimal medical therapy alone. At 12 months, in comparison with patients randomly assigned to medical therapy only, patients randomly assigned to CTO-PCI had greater improvement in angina frequency (subscale change difference, 5.23; 95% CI, 1.75–8.71; P=0.003) and quality of life (subscale change difference, 6.62; 95% CI, 1.78–11.46; P=0.007), as assessed with the Seattle Angina Questionnaire.[22] Patients with successful CTO PCI were noted to have fewer physical limitations, less angina, better mobility, and increased physical activity after revascularization as compared with patients treated with OMT alone. Additionally, observed periprocedural risks were low, and 12-month MACE rates were comparable to the OMT group.[28]

CTO PCI Success Rates and Prognosis

The success rates of CTO-PCI have significantly improved due to advancements in guidewires, microcatheters, and imaging technologies. Currently, specialized centers with experienced operators achieve success rates exceeding 85–90%. Several key factors contribute to procedural success:
- Patient selection: Favorable anatomical characteristics and well-developed collateral circulation enhance outcomes.
- Operator experience: Skilled interventionalists using advanced techniques can manage complex cases more effectively.
- Advanced imaging support: Technologies such as intravascular ultrasound (IVUS) and optical coherence tomography (OCT) aid in optimizing stent placement and ensuring accurate wire positioning.
Long-term prognosis after successful CTO-PCI is favorable, with significant reductions in angina symptoms and improved left ventricular function in appropriately selected patients.

Conclusion

The role of CTO-PCI in modern interventional cardiology is rapidly expanding, reshaping treatment strategies for complex coronary artery disease. Despite historically low utilization accounting for only about 5% of PCI procedures worldwide [10] and attempted in just 10–15% of cases [16][17][18] – advancements in technology and operator expertise are driving a paradigm shift. Success rates have significantly improved, while complication rates have sharply declined, as demonstrated by Patel et al., who reported a reduction in major complications from 1.6% (2000–2002) to just 0.5% (2009–2011) [19].

Randomized clinical trials reaffirm CTO-PCI’s primary benefit: superior symptom relief. Moreover, continuous innovation is transforming previously “untreatable” lesions into viable targets for revascularization [29]. Compared to optimal medical therapy (OMT) alone, CTO-PCI delivers substantial improvements in patient health, including fewer physical limitations, reduced angina, enhanced mobility, and greater physical activity.

With ongoing advancements in imaging, guidewire technology, and procedural techniques, CTO-PCI is set to achieve even greater success in the coming years. For physicians managing CTO patients, a tailored, patient-centric approach remains essential – leveraging the latest techniques and evidence to optimize outcomes and quality of life.

Sources:

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