Note: Read the accompanying case at Laocoön’s Revenge: A Novel Non-Drug Eluting Two-Stent Strategy for Complex Bifurcation Intervention
Dr. Kumar, can you talk about your strategy in this case?
This was a very complex case where we had to deal with both a bifurcation and a chronic total occlusion (CTO) in a patient at high bleeding risk. We have stented bifurcations with the Tryton stent (Tryton Medical) and have placed Cobra stents (Celonova Biosciences Inc.) in high bleeding risk patients, but this was the first case where both were used in a single patient. The delivery of the stents was very simple. We performed it as we would perform any typical CTO and/or bifurcation case. Getting the wire down was the difficult part. Once we were able to get that done, the rest of the case was accomplished efficiently. These two stents are not drug-eluting stents, which is really the important message of this case. The Cobra stent is a special coated stent — not with a polymer and anti-proliferative drug, but with a special polyzene-F nanocoating that inhibits adhesion to platelets and actually decreases the risk of stent thrombosis. The Cobra stent is also involved in an ongoing high bleeding risk patient population trial, the COBRA REDUCE trial, with 14-day dual anti-platelet therapy (DAPT).
What are some of the characteristics to look for when considering if a patient is at a high bleeding risk?
Age >75 certainly increases the risk. Other big risks will include whether the patient is already on anticoagulation, which means that they will potentially be on triple therapy for some duration. If that is the case, we might need to drop aspirin early and then remain on a P2Y12 inhibitor and anticoagulation alone (a strategy studied in the WOEST trial). Blood count abnormalities is another risk factor — perhaps the patient is already starting out with thrombocytopenia or anemia. Significant renal dysfunction or being on dialysis, which has been associated with platelet dysfunction, is a risk factor. On average, the high bleeding risk cohort, depending on the center, can be from between 10-20% of the total PCI population. Patients who have blood disorders or problems with bleeding will have greater risks when you put them on dual antiplatelet therapy. This field has undergone significant changes in the past 5 years. The DAPT trial showed that DAPT for an additional 18 months (over 1 year) after placement of a drug-eluting stent, as compared with aspirin therapy alone, significantly reduced the risks of stent thrombosis and major adverse cardiovascular and cerebrovascular events, but was associated with an increased risk of bleeding. The increased clinical prevalence of bleeding alerted us to the fact that perhaps we should be considering shorter DAPT. To this effect, there are several ongoing trials of short DAPT in the US, a few of which include EVOLVE Short DAPT, XIENCE 90, and perhaps others. The SENIOR trial was reported in Europe. The COBRA REDUCE trial is also ongoing and this does not involve a drug-eluting stent platform.
Can you talk about your use of intravascular ultrasound (IVUS)?
I routinely use IVUS for most of my cases. Pre procedure, it is helpful (if I am able to cross), in order to assess for a number of different things, including lesion size, lesion length, vessel size, and potential compliance issues. For example, if there is significant calcification, IVUS can help determine whether there will be a need for atherectomy, as well as demonstrate evidence of significant lipid burden, dissection, or plaque rupture. These are all things that can be assessed up front. After lesion preparation, i.e., after atherectomy and/or ballooning, we use IVUS to see whether the lesion preparation has been successful, such as whether there has been sufficient disruption of the tight areas of the lesion. After stent deployment, IVUS helps show whether there has been adequate expansion and apposition, and helps ascertain whether further post dilatation may be necessary.