What is the approach for cardiac catheterization of a chronic total occlusion (CTO) in the obtuse marginal 2 (OM2) artery and the obtuse marginal 1 (OM1) artery?

From the Guidelines

Cardiac catheterization of the obtuse marginal 2 (OM2) and obtuse marginal 1 (OM1) chronic total occlusion (CTO) is recommended for patients with refractory angina symptoms despite optimal medical therapy, or when there is evidence of significant myocardial ischemia in the territory supplied by these vessels, as it can improve symptoms and quality of life, as supported by the guiding principles for CTO percutaneous coronary intervention 1. The procedure should be performed by an experienced interventional cardiologist with expertise in CTO interventions, as emphasized in the 2011 ACCF/AHA/SCAI guideline for percutaneous coronary intervention 1.

Key Considerations

• Prior to the procedure, patients should receive dual antiplatelet therapy with aspirin 81-325mg daily and a P2Y12 inhibitor (clopidogrel 75mg daily, ticagrelor 90mg twice daily, or prasugrel 10mg daily) to reduce the risk of thrombotic complications.
• During the procedure, unfractionated heparin (70-100 units/kg) or bivalirudin should be administered to achieve an activated clotting time of 250-300 seconds, as recommended by current guidelines.
• The approach typically involves antegrade wire escalation techniques, but may require more advanced strategies such as retrograde approaches or dissection re-entry techniques for the CTO, as outlined in the guiding principles for CTO percutaneous coronary intervention 1.
• Success rates for OM branch CTOs range from 60-80% depending on lesion complexity and operator experience, highlighting the importance of operator expertise and proper patient selection.

Post-Procedure Care

• Following the procedure, patients should continue dual antiplatelet therapy for at least 6-12 months, along with high-intensity statin therapy, blood pressure control, and lifestyle modifications to reduce the risk of recurrent ischemic events and improve overall cardiovascular health.
• The potential benefits of this intervention, including improved myocardial perfusion to the lateral wall of the left ventricle, can significantly reduce angina symptoms and improve quality of life in appropriately selected patients, as supported by the EuroCTO multicenter trial 1.

From the Research

Approach for Cardiac Catheterization of CTO in OM2 and OM1 Arteries

• The approach for cardiac catheterization of a chronic total occlusion (CTO) in the obtuse marginal 2 (OM2) artery and the obtuse marginal 1 (OM1) artery involves a comprehensive risk-benefit analysis and discussion with the patient 2.
• Percutaneous coronary intervention (PCI) of CTOs has been shown to improve anginal symptoms, but it carries higher risks and a lower likelihood of success compared with non-CTO PCI 2, 3.
• The "hybrid" approach, which combines antegrade and retrograde techniques, has been developed to improve the success rate of CTO PCI 3, 4.
• Patient selection is crucial, and operators should consider the complexity of the lesion, the patient's clinical status, and the potential benefits and risks of the procedure 5, 6.
• The antegrade-only approach can be used for simpler anatomy, and core equipment and techniques are available for skilled operators who have not specialized in complex retrograde CTO techniques 4.
• The use of preprocedural ischemia testing and various procedural success and risk stratification scores can help guide the decision-making process 2, 6.