Case Study

Improving CTO PCI Outcomes Using Coronary CTA Fusion and Synchronization in the Cath Lab

Alpesh Shah, MD, FACC, FSCAI, Houston Methodist Hospital, Houston, Texas

Alpesh Shah, MD, FACC, FSCAI, Houston Methodist Hospital, Houston, Texas

Percutaneous coronary intervention (PCI) of chronic coronary total occlusion (CTO) has been considered the final frontier in percutaneous intervention. There have been vast improvements in the initial success and safety of the procedure, as well as a better understanding of appropriateness and benefits. Advances in technology and technique allow for increased utilization of PCI in cases of chronic CTO, with benefits regarding symptoms and quality of life. PCI for chronic CTO allows for correction of ischemia and complete revascularization, avoiding the need for traditional coronary bypass grafting while offering increased survival benefits.

However, coronary CTO still remains the most likely reason for patients to be referred for coronary artery bypass graft (CABG) surgery.1 This is primarily due to the concerns regarding lack of success as well as a high rate of procedural complications, such as perforation. The availability of antegrade re-entry and retrograde techniques has led to greater success, but there are still a number of complications associated with these techniques. Antegrade CTO crossing using wire escalation remains the safest technique. We have learned that patients who have undergone successful CTO PCI tend to do much better than patients who have had unsuccessful attempts, but success depends on CTO complexity, as well as operator experience.2 Even in highly experienced hands, complex cases tend to have higher radiation exposure as well as contrast dose. Therefore, there are still potential risks to the patient, even if the lesion is treated.

Case Report

This is the case of a 56-year-old male who was active and used to play tennis regularly. However, his activity became limited for about 6 months due to exertional chest heaviness and shortness of breath. He was found to have a right coronary artery (RCA) CTO (Figure 1) and medical therapy was initiated with anti-anginal medication. He remained symptomatic and underwent RCA CTO PCI that was unsuccessful. Additionally, greater than 400 ml contrast was used, and the procedure had to be aborted as the 5 Gray radiation exposure threshold was reached. An experienced PCI operator was unable to advance a wire successfully via an antegrade approach.

The patient was referred for retrograde PCI. A computed tomography angiography (CTA) scan (Figure 2) was performed using a third-generation dual-source CT SOMATOM Force scanner (Siemens Healthineers). After discussing the case and reviewing the CT images (Figure 3) with our imaging expert, the patient was scheduled for an intervention and to retry the antegrade approach. In the cath lab, syngo CTO guidance software (Siemens Healthineers) was incorporated and with the help of the CT-fluoroscopic image fusion capabilities (CT Fusion, Siemens Healthineers), antegrade wiring was successful (Figure 4). CTA co-registration with a live overlay of CTA findings was helpful in navigating  the lesion in the RCA, while avoiding side branches and an extraluminal path. Wire position was confirmed with a retrograde injection and successful intravascular ultrasound-guided stent placements were performed in the RCA with an excellent result (Figure 5).

Discussion

Fluoroscopy in the cath lab has obvious limitations, such as two-dimensional imaging and an inability to visualize the vessel wall, as well as the occluded CTO segment. Often, angulations and side branch take-off become guesswork which, in turn, reduces the operator’s ability to advance the wire with confidence and results in unsuccessful attempts to cross the CTO. Coronary CTA increases our ability to visualize the occluded segment of the vessel as well as any bends, calcifications, and side branch segments. We recommend delayed arterial CT imaging at 10 seconds in CTO cases.

CTA fusion and synchronization in the cath lab while performing complex anatomical cases such as CTO PCI reduces complications such as perforations, along with providing for a reduction in contrast use and radiation exposure. This technique allows for higher success with an antegrade approach. 

Disclosure: Dr. Shah reports no conflicts of interest regarding the content herein.

Alpesh Shah, MD, FACC, FSCAI can be contacted at arshah@houstonmethodist.org.

References
  1. Christofferson RD, Lehmann KG, Martin GV, et al. Effect of chronic total coronary occlusion on treatment strategy. Am J Cardiol. 2005 May 1; 95(9): 1088-1091. 
  2. 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.