Post-TAVR Coronary Obstruction Risk Low, Linked to Unfavorable Anatomic Features

Download this article's Factoid (PDF & PPT for Gold Subscribers)

Coronary obstruction following transcatheter aortic valve replacement (TAVR), while uncommon, occurs more frequently in women and appears to be set into motion by specific anatomic characteristics, according to data from published cases of obstruction involving the left, right, or both coronary arteries. The study was published online April 17, 2013, ahead of print in JACC: Cardiovascular Interventions.

Researchers led by Josep Rodés-Cabau, MD, of Laval University (Quebec, Canada), identified 24 patients from 18 publications who experienced coronary obstruction related to a TAVR procedure between January 2002 and May 2012. The papers included single case reports and small series.

The majority of TAVR cases used the Sapien device (70.8%; Edwards Lifesciences, Irvine, CA), with the remaining cases split between the newer Sapien XT (16.7%; Edwards Lifesciences) and the CoreValve prosthesis (12.5%; Medtronic, Minneapolis, MN).

Women at Greater Risk

Coronary obstruction occurred more frequently in women (83.3%), patients with no prior CABG (95.8%), and those who had received a balloon-expandable valve (87.5%). Left main coronary artery obstruction occurred more often than right coronary artery obstruction (83.3% vs. 12.5%). Both arteries were obstructed in only 4.2% of patients.

Diagnosis was made in the majority of cases via coronary angiography. The mean height of the left coronary artery ostium in cases of obstruction was approximately 10 mm, and the mean diameter of the aortic root was approximately 28 mm.

Most patients with obstruction were treated with PCI, which was attempted in 23 patients (95.8%) and successful in all but 2 (91.3%). At least 1 BMS or DES was implanted at the coronary ostia in 20 patients. Significant compression of the stent requiring a second stent occurred in 3 patients, whereas conversion to open heart surgery was required in 2 patients. After a hospital stay of 7 ± 4 days, all patients who had successful PCI survived. There were no cases of stent thrombosis or repeat revascularization.

The overall in-hospital mortality rate for the entire cohort was 8.3%. At 10 ± 6 months, all 14 patients in whom follow-up was available were alive and in New York Heart Association functional class I or II. One patient needed repeat revascularization due to stent restenosis at 4 months.

Rare But Treatable

According to the study authors, the reported incidence of coronary obstruction following TAVR is less than 1%. In the PARTNER trial, for example, there was coronary obstruction reported in either the transfemoral or transapical arms, while in a multicenter Canadian experience, the rate was 0.6% in the transfemoral arm and 1.1% in the transapical arm. The SOURCE registry reported rates of 0.7% and 0.5%, respectively, while SOURCE XT reported rates of 0.3% in each arm.

“The vast majority of centers doing TAVR have seen this complication,” Dr. Rodés-Cabau told TCTMD in a telephone interview. “That being said, it is infrequent.”

The data confirm prior research showing that the most frequent mechanism associated with coronary obstruction post TAVR is displacement of the calcified native cusp over the coronary ostium, the investigators say. However, they note that while “the final mechanism leading to coronary obstruction after [TAVR] is well understood, the risk factors that predispose a patient to its occurrence remain largely unknown.”

The Search for Anatomical Clues

“What we did with this study is really a first step in trying to understand the characteristics surrounding this complication and look at it from many angles,” Dr. Rodés-Cabau said. A second step is exploring the incidence of coronary obstruction in TAVR patients enrolled in registries. Those data are scheduled to be presented later this month at the EuroPCR meeting in Paris, he added.

“This is an important topic because it’s such a devastating complication when it occurs,” Ted Feldman, MD, of Evanston Hospital (Evanston, IL), told TCTMD in a telephone interview.

He pointed out that critical variables, including left main ostium height, annulus and aortic root measurements were each reported in only one-half of the studies or less, reflecting “a poor job of leveraging our imaging modalities as well as we might.”

Dr. Feldman said automated CT analysis software is good at producing measurements of the subanular space, the sinuses of Valsalva and the sino-tubular junction, which can help the operator gauge the likelihood of coronary obstruction.

“We can do better at predicting which patients are at greatest risk,” he said. “This paper identifies a problem and shows that we have a ways to go to achieve a solution. . . . What is needed is a more proactive approach. I think this is comparable to the early days of TAVR when not everyone was doing CT angiograms. As we learn more and more about the procedure and the disease, we are understanding more and more about the patho-anatomy as well.”

Position of Coronary Ostium, Size of Aortic Root May Identify Risk

Low position of the coronary ostium with respect to the aortic annulus has been highlighted as an important factor, the paper reports, adding that a coronary ostia height cutoff of 10 mm or less has been said to increase risk. Since the mean value in the current study was 10 mm, with approximately 60% of cases greater than that, the authors suggest factors other than a short-distance between the aortic annulus and coronary ostium might also be involved.

Other possible culprits, they say, include the presence of bulky calcium nodules on the left or right aortic leaflets and a narrow aortic root with shallow sinuses of Valsalva that leave little room to accommodate the calcified native aortic leaflets after valve deployment.

Since it has been shown that women have a smaller aortic root, this characteristic together with lower coronary ostium height might partially explain the increased incidence of coronary obstruction in women. But Dr. Rodés-Cabau stressed that most of the coronary ostium height data are empirical and recommendations are diverse. In fact, Medtronic recommends an ostium height cutoff of 14 mm for CoreValve, which may be why so few cases of coronary obstruction were seen in the literature with that device, he added.

Study Details

The vast majority of patients presented with persistent severe hypotension after valve implantation, and approximately 50% and 25% also had ST-segment changes (approximately one-half of them with ST-segment elevation) and procedural ventricular arrhythmias, respectively.

 

---

Source:
Ribeiro HB, Nombela-Franco L, Urena M, et al. Coronary obstruction after transcatheter aortic valve implantation: A systematic review. J Am Coll Cardiol Intv. 2013;Epub ahead of print.

 

• Dr. Feldman reports serving as a consultant to and receiving research support from Boston Scientific and Edwards Lifesciences.

 

Related Stories:

• Most Anatomy Suitable for Contemporary TAVI Approaches
• CT Measurements of Aorta Underscore Shortcomings of Valve Sizing Guidelines