A Troubling New TAVR Risk: Delayed Coronary Obstruction

Patrice Wendling

April 12, 2018

Acute coronary obstruction during transcatheter aortic valve replacement (TAVR) has been a well-known and feared complication since preclinical studies, but it's the rare and deadly problem of delayed coronary obstruction that is being raised as a new concern.

In an international registry of 17,092 TAVRs, the incidence of delayed coronary obstruction (DCO) occurring in the days, weeks, and years following TAVR was 0.22%. Though a rare event, the in-hospital death rate was 50%.

In all but one of the 38 cases, post-implant aortography or selective cannulation of both coronary arteries had confirmed a lack of obstruction. Three fourths of DCO occurred in women, lead author Richard Jabbour, MD, a cardiology fellow at Imperial College London, UK, reported in a study published online in the April 10 issue of the Journal of the American College of Cardiology (JACC).

"The bottom line is we think of it as an acute event and the real point of this paper is that it's not," Neal Kleiman, MD, Houston Methodist DeBakey Heart and Vascular Center, Texas, author of an accompanying editorial, told theheart.org | Medscape Cardiology. "It may be less common when you leave the lab and certainly less commonly detected after the first week, but it is less rare than we recognize."

A uniform DCO definition should be added to the next Valve Academic Research Consortium (VARC) manuscript to help track the lethal complication in future trials and registries, he suggested.

In his editorial, Kleiman notes that although two thirds of patients had at least one classic risk factor for acute coronary obstruction, the index of suspicion was not high in a substantial number of patients. Left and right coronary heights exceeded 12 mm in more than one half and about two thirds of patients, respectively. Another 44% of patients had a mean sinus of Valsalva diameter greater than 30 mm and only about half of the occlusions involved implantation depths considered high.

"When someone gets sick or when you're told someone has died, this is something you need to think about," he said. "And when you finish a case, if you're left with not much sinus of Valsalva, if most of the sinus has been obliterated, I think you need to give some thought to this possibility. Especially as complications and mortality after TAVR get lower and lower, this assumes an increasing relative prominence."

Lead author Jabbour told theheart.org | Medscape Cardiology the study was prompted by the surprising death of two patients who went into cardiogenic shock after undergoing successful TAVR while he was working with senior author Azeem Latib, MD, at the San Raffaele Scientific Institute, in Milan, Italy.

Although a coronary guidewire was used as a preventive measure during TAVR in one patient, the autopsy confirmed valve leaflet obstruction.

"When the second case occurred, there were only a few cases in the literature," he said. "Physicians really didn't know about this; it's a relatively new complication."

The authors note that definitive evidence was needed to accurately characterize the phenomenon and, in fact, the incidence of DCO may be higher than reported because sudden cardiac death outside the hospital may be the first manifestation and thus DCO may go undiagnosed if no autopsy is performed.

"As we move to lower-risk patients, there could be a greater incidence of delayed coronary obstruction occurring due to patients having a longer life expectancy post-TAVR," Jabbour said. "Second, patients may be relatively protected from the symptoms of coronary obstruction if they've had a prior coronary artery bypass graft, so we need to have a lower threshold for imaging the coronary system post-TAVR."

Interestingly, there were no cases of DCO between 7 and 59 days of TAVR, with 18 cases occurring within 24 hours of the procedure, 6 cases from 24 hours to 7 days, and 14 cases after 60 days.

"We were surprised as well and think there may be two distinct pathogenetic mechanisms ongoing," Jabbour said.

For cases within 7 days of TAVR, the patient may leave the cath lab after a successful procedure but the valve may continue to expand and then cause an obstruction, he said. There also may be a thrombotic event or heavily calcified valve within the sinus of Valsalva causing obstruction. In contrast, some late occlusions may be due to a combination of turbulent flow, which could trigger fibrosis or persistent inflammation, leading to endothelialization and then obstruction.

This is reflected in the finding that early cases of DCO are more likely to present with cardiac arrest or ST-segment elevation MI and later cases more likely to present with stable or unstable angina, Jabbour observed.

Overall, the most common presentation was cardiac arrest (31.6%), followed by ST-segment MI (23.7%).

Valve-in-valve procedures were associated with a higher incidence of DCO than with native valves (0.89% vs 0.18%; P < .001), as is the case with acute coronary obstruction. By contrast, however, DCO was more common with self-expandable than balloon-expandable valves (0.36% vs 0.11%; P <.001).

The left coronary artery was obstructed in 92.1% of cases. Notably, DCO occurred in 27% of patients where an ostial coronary stent was deployed to protect the left main ostium, though this is not something interventionalists are likely to undertake in all TAVR cases to prevent such a rare event.

Both Kleiman and Jabbour agree there is no easy preventive strategy and suggest trials investigating the use of oral anticoagulant drugs after successful TAVR, such as ATLANTIS and GALILEO, may provide new insights.

"We may see people on anticoagulants to prevent valve thrombosis, and at the same time those anticoagulants could conceivably protect against the sinus filling up with clot," Kleiman said. "So it may be that this will turn out to be another indication for at least short-term anticoagulation after TAVR, but again that's speculative."

Jabbour and colleagues point out that placing a chimney stent or using stents with greater radial strength are possible solutions. For valve-in-valve procedures, the novel BASILICA technique, which involves intentionally lacerating the aortic leaflet before TAVR and is the subject of a simultaneous report in JACC: Cardiovascular Interventions, also should be pursued.

Jabbour report no relevant financial relationships. Kleiman reports receiving grant support for clinical trials from and providing educational services for Medtronic. Latib reports serving on the advisory board of and consulting for Medtronic, receiving speaker honoraria from Abbott Vascular, and receiving research grants from Edwards Lifesciences and Medtronic.

J Am Coll Cardiol. 2018;71:1513-1524, 1525-1527. Abstract, Editorial

Follow Patrice Wendling on Twitter: @pwendl. For more from theheart.org | Medscape Cardiology, follow us on Twitter and Facebook.

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