Preemptive Stents Feasible for TAVR Patients at High Risk for Coronary Occlusion

For the small proportion of TAVR patients at high risk of coronary obstruction, a new registry study confirms that preventive stent implantation across the coronary ostia is safe, with good survival and low rates of stent thrombosis at 3 years.

“The value of our registry is that for the first time we have a considerable number of patients that have been treated with coronary protection and stenting and have 3-year follow-up,” lead author Tullio Palmerini, MD (Polo Cardio-Toraco Vascolare, Bologna, Italy), told TCTMD. “I think that this paper may have important and profound clinical implications because this technique can be extended to those hospitals that do not use [it] to protect coronary arteries and it's reassuring for people that are already using this technique.”

While it’s not always easy to tell if a patient will be at high risk for coronary obstruction before TAVR, he estimated that 2% of patients will end up with blocked coronary arteries after TAVR if nothing is done to prevent it. Preemptive coronary wire protection and eventual stenting can help to maintain coronary patency in these patients, but it has to be done at the time of TAVR. Another option currently in development is the more-complex BASILICA procedure, which involves radiofrequency directed by catheters and guidewires to split the aortic leaflet before TAVR.

For the study, published online Wednesday in JACC: Cardiovascular Interventions, Palmerini and colleagues identified 236 patients who received coronary protection with preventive coronary wiring among a cohort of 10,508 patients undergoing TAVR among 19 international centers between 2011 and 2019. A total of 143 had stents implanted across the coronary ostia after valve deployment.

At 3 years, there were no statistical differences in all-cause (14.3% vs 26.9%; adjusted HR 0.57; 95% CI 0.25-1.31) or cardiac mortality (7.8% vs 15.7%; adjusted HR 0.42; 95% CI 0.14-1.28) between those who received coronary protection with stents versus wiring only. There were also no differences in the rates of MI and stroke. The total rate of stent thrombosis was 0.9%, which occurred in two patients receiving valve-in-valve procedures with self-expanding valves.

There were four cases of delayed coronary occlusion (4.3%), occurring between 5 minutes and 6 hours following wire removal, all in patients not receiving stents and three following valve-in-valve procedures. Three were fatal, while the fourth was rescued successfully through rewiring the jailed coronary ostium and stenting the left main.

Of note, on CT the virtual distance between the transcatheter valve and the coronary ostia (VTC) was less than 4 mm in more than double the number of patients receiving stents than those who received wiring alone (78.2% vs 33.7%; P < 0.001). A VTC < 4 mm was also present in 75% of patients with a delayed coronary occlusion compared with 30.4% without (P = 0.19).

Many Variables

Palmerini called the data reassuring given that the “cardiac mortality is acceptable and in the range of other randomized trials and the risk of stent thrombosis was very, very low.”

The results comparing patients who received stents versus wiring alone carry a “very important message because evaluating coronary flow with the wire in the coronary artery may be sometimes deceiving,” he said. “In one case, coronary occlusion occurred 5 minutes after wire removal. That means that the wire itself is able mechanically to displace the leaflet and to guarantee the flow to the coronary artery. You remove the wire and then you have the occlusion and you get in trouble. In the other cases, it took a couple hours after and therefore the mechanism is less clear, but probably thrombotic phenomenon may have played a role in these cases.”

The ultimate message, Palmerini explained, is that “sometimes it's very difficult to decide whether you need a stent or not. A lot of variables should be considered. . . . The distance between the virtual transcatheter valve and the coronary ostia less than 4 mm was a risk factor for coronary occlusion. So in all these cases, if you had a wire in and you think the flow is good but this distance is less than 4 mm, I think you should put a stent.”

In an accompanying editorial, Philippe Garot, MD (Institut Cardiovasculaire Paris-Sud, Massy, France), writes that “for patients at high risk of coronary obstruction, the present report suggests that preemptive wire placement is only effective during the procedure, whereas preventive stenting is a valuable alternative with acceptable 3-year survival rates.”

He mentions other options, including BASILICA as well as “newly designed valve systems securing the leaflets into the valve complex during the device delivery,” but states that dedicated trials on these technologies are needed.

Not a Common Occurrence

Commenting on the study for TCTMD, Neal Kleiman, MD (Houston Methodist DeBakey Heart and Vascular Center, TX), said he is familiar with the preemptive stenting technique but that it’s rare: “If we do it twice a year, that's a lot.” On the other hand, after screening patients for their risk of coronary obstruction, certain anatomies might preclude them from doing the TAVR in the first place.

The results of this study are what he would expect, “but you wonder if there's a selection factor in there, too,” Kleiman said. “It takes extra time and effort to put a preemptive stent in. It means you have to have another source of access as well, so that may exclude some patients with more extensive vascular disease. And truthfully some coronaries would be easier to wire than others, both to wire and get an undeployed stent into.”

Everyone's a little skittish about throwing a perfectly good stent away. Neal Kleiman

Current practice for treating patients at high risk for coronary obstruction varies widely by operator, he explained. “Some people will leave a guide catheter actually in the coronary while they're deploying. I'm always afraid to do that, because I'm afraid that either the valve or balloon will shove the catheter into the coronary and dissect it. Some people will leave a stent in the ostium of the vessel itself. Some people will push the stent down the coronary and then pull it back to the ostium if there's a problem. That's what we've done.”

But given the rarity of these occurrences, it’s probably not worth standardizing practice for these situations, Kleiman said.

This study makes him more likely to consider preemptive stenting given the circumstance, but he acknowledged that cost will also factor in, especially in the United States. “Everyone's a little skittish about throwing a perfectly good stent away,” Kleiman said.

The 4-mm VTC cutoff for using a stent seems “reasonable” to Kleiman. However, he said, “remember virtual distances are virtual, so how the valve frame expands is not always easy to predict, what happens to the native leaflet is not always easy to predict, and then you've got those original sinuses that may or may not fill up with clot, which may cause some of the delayed occlusions.”

Also commenting on the study for TCTMD, Danny Dvir, MD (University of Washington Medical Center, Seattle), cautioned that if physicians follow the researchers’ suggestion to “utilize stent protection in all TAVR patients at risk for coronary occlusion, we may do harm to some patients.”

Specifically, he pointed out in an email, there's the potential for stent thrombosis as well as an “alarming increased risk” of post-TAVR MI of 9.8%. “In addition, coronary reengagement behind the transcatheter heart valve, the original failed valve, and through the stent could be extremely challenging. Therefore, we clearly see that wire protection alone is risky and that stent protection is suboptimal,” Dvir explained.

In his opinion, BASILICA “seems to be an appealing approach that may target the origin of the problem—which is the deflected valve leaflet that come in close proximity to the coronary ostium,” Dvir added. “It is true that this new technique [BASILICA] requires training, dedicated equipment, and may still be associated with adverse events; however, this approach eliminates the need to implant foreign material in the aortic root.”