Chronic Total Occlusion (CTO) is a coronary artery disorder where a full or near-complete blockage in one or more coronary arteries for over three months worsens the disease. Such blockage, whether partial (functional CTO) or full (true CTO), puts the heart in danger since collateral circulation may be deficient under stress or rest. Thus, CTO increases ischemia, arrhythmias, heart failure, and myocardial infarction, especially without prompt Percutaneous Coronary Intervention (PCI) or Coronary Artery Bypass Grafting (CABG).

How Common is Chronic Total Occlusion?

Chronic Total Occlusion (CTO) is more common among individuals with coronary artery disease. Approximately 15-30% of patients undergoing coronary angiography for CAD also present with a CTO^[1]. Note that the prevalence of CTO rises with age. Nearly 40% of those aged 65-79, and 41% of individuals over 85 show some form of CTO^[2]. It can be asymptomatic when collateral circulation compensates for the blocked artery for underdiagnoses in many patients.

Moreover, functional CTOs are where arteries are narrowed rather than fully occluded. They add a complex layer since they may need intervention strategies compared to "true" CTOs, which are entirely blocked. The true prevalence of CTOs might be higher than reported. The reason is that imaging techniques (intravascular ultrasound and coronary CT angiography) now reveal blockages that old angiograms may miss. It raises estimations in progressing atherosclerosis patients.

Causes of Chronic Total Occlusion

• Coronary artery disease (CAD).
• Smoking.
• Body mass index (BMI) of 30 or higher.
• Diabetes.
• Family history of heart disease.
• High blood pressure (hypertension).
• High cholesterol (hyperlipidemia).
• History of heart attacks.
• History of coronary artery bypass surgery.
• Inactive lifestyle.
• High-sodium diet.

Typical Symptoms of Chronic Total Occlusion

A Chronic Total Occlusion occurs when a coronary artery faces complete or near-complete blockage for three or more months. The blockage may develop due to progressive atherosclerosis. That's where lipid-laden plaques accumulate and harden within the arterial walls. Over time, it causes narrowing of the coronary artery to restrict blood flow to the myocardium. Contemporary imaging techniques might help assess the magnitude of plaque deposition and coronary damage.

Symptoms of a Chronic Total Occlusion

• Chest pain, tightness, or pressure.
• Dizziness.
• Fatigue.
• Heart palpitations.
• Irregular heart rhythms (arrhythmia).
• Racing or rapid heartbeat.
• Shortness of breath (dyspnea).
• Upper arm pain.
• Nausea.
• Symptoms worsening with exertion, easing at rest.
• Asymptomatic presentation (not uncommon in CTO).

If you suspect symptoms of Chronic Total Occlusion, consult a cardiologist. Given the CTO of coronary artery disease, coronary angiography or nuclear stress testing can help determine the severity of the occlusion. Whether through percutaneous coronary or coronary artery bypass grafting, early intervention could prevent further cardiovascular compromise and optimize outcomes. A bespoke treatment plan can address symptom relief and future cardiac risk reduction.

Diagnosis of Chronic Total Occlusion

• Coronary angiography.
• Coronary artery calcium scan (CT scan for calcium or plaque buildup).
• Echocardiogram.
• Electrocardiogram (EKG).
• Electron-beam computed tomography (EBCT).
• Exercise stress test.
• Heart CT scan.
• Intravascular ultrasound (IVUS).
• Nuclear stress test.
• Cardiac MRI.

How is Chronic Total Occlusion Treated?

(1) Medication

In Chronic Total Occlusion, medication alone might not be sufficient to clear the blockage, but it manages symptoms and decreases progression risks.

Anti-anginal drugs, including nitrates, beta-blockers, and calcium channel blockers, improve blood flow while relaxing and dilating blood vessels for lower chest pain. Statins lower LDL cholesterol to slow down plaque accumulation within the coronary arteries. Antiplatelet agents, like aspirin or clopidogrel, prevent clot formation after interventional procedures to cut re-occlusion risk.

Further, ACE inhibitors or ARBs can lower blood pressure and strain on the heart in CTO cases with a history of heart attack or left ventricular dysfunction. The combined approach to Chronic Total Occlusion therapy soothes symptoms and decreases risk factors for the patient's long-term prognosis with procedural interventions.

(2) Percutaneous Coronary Intervention (PCI)

PCI requires the dual-access CTO-PCI for Chronic Total Occlusion, which addresses blockages from various entry points. It counts on CTO-specific guidewires with better torque, stiffness, and hydrophilic coatings for navigation through challenging, heavily calcified plaques. The "antegrade" and "retrograde" techniques are CTO-PCI methods. The former proceeds through the blockage. The latter advances a wire from a collateral vessel to approach the blockage in reverse. IVUS or OCT may be used to view and characterize lesion features. Atherectomy or IVL may prepare hardened vasculature for surgery.

Given the nature of CTOs, CTO-PCI demands an experienced operator and a high-tech catheter lab because complications can include vessel perforation or dissection. Yet, successful CTO-PCI can restore myocardial perfusion to boost the quality of life for patients who otherwise have limited revascularization options.

(3) Coronary Artery Bypass Graft (CABG)

Chronic Total Occlusion patients with illness may benefit from CABG if PCI is high-risk or fails. CABG for CTO creates a new route for blood to circumvent the obstructed coronary artery.

Surgeons can use the internal mammary artery, which shows better long-term patency in comparison to other grafts, or the saphenous vein from the leg. During CABG, complex CTOs need precise graft placement and orientation for adequate perfusion to ischemic myocardial regions. While CABG has a risk due to its invasive nature, it provides a solution for multi-vessel disease and left main coronary artery involvement with common CTOs.

It is worth noting that CABG offers lower recurrence rates than PCI in certain CTO patients, particularly those with a high plaque burden or multiple CTOs. For patients with ischemia, CABG dulls symptoms and improves survival rates for complex CTO presentations.

The Importance of CTO Guidewires in Interventional Therapy

Managing Chronic Total Occlusion requires guidewires that exhibit high torque responsiveness, accurate tip stiffness, and higher penetration force to navigate through dense, calcified lesions.

Our Shunmei PTCA Guide Wire (CTO) features an ultra-fine, hydrophilic-coated distal end, which allows it to be easily tracked in tortuous arteries while ensuring lesion passage without compromising vascular integrity. Thanks to the guidewire's high tensile core, which maintains its shape and responsiveness, operators can control its direction and adapt to challenging anatomical structures. This design significantly enhances the success rate of CTO procedures and reduces both the duration and complexity of the operation.

Conclusion

As an international medical equipment manufacturer, Shunmei Medical specializes in high-precision devices for Chronic Total Occlusion(CTO) therapy, including hydrophilic-coated coronary microcatheters and ultra-low profile crossover catheters, tailored for complex coronary interventions.

Our manufacturing facilities in Huizhou and Hunan, spanning 28,000 m² and 25,000 m² respectively, employ precision engineering and adhere to stringent quality standards. Our multinational R&D centers, driven by the expertise of cardiac specialists, continuously achieve innovative breakthroughs to meet the needs of more than 120 countries. With industry-leading efficiency and global presence, Shunmei Medical is well-equipped to tackle CTO challenges with professional expertise and impact.

References:

[1] Percutaneous Treatment of Coronary Chronic Total Occlusions Part 1: Rationale and Outcomes. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC5808625/ (Accessed: 30 October 2024)

[2] Chronic Total Occlusion. Available at: https://my.clevelandclinic.org/health/diseases/17567-cad-total-coronary-occlusions (Accessed: 30 October 2024)