CT-Based Artery Assessment May Reduce Vascular Complications in Transfemoral TAVR

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Computed tomographic (CT) imaging can be used as a screening tool to assess the iliofemoral artery and predict the risk of vascular complications in candidates for transcatheter aortic valve replacement (TAVR), according to a study published online April 15, 2014, in Catheterization and Cardiovascular Interventions.

Researchers led by Samir R. Kapadia, MD, of the Cleveland Clinic (Cleveland, OH), evaluated iliofemoral CT imaging in 255 consecutive patients undergoing attempted TAVR as part of the PARTNER, PARTNER II, or REVIVAL trials or receiving commercial implantation after FDA approval at their institution from May 2006 to December 2012. In all cases, devices were the SAPIEN or SAPIENT XT balloon-expandable prosthesis (Edwards Lifesciences; Irvine, CA). Patients were a mean age of 80.7 years, and 58.4% were men. Transfemoral sheath delivery was successful in all but 8 patients. A closure device was used in 91.3%.

CT imaging was used to assess:

  • Minimal lumen diameter (MLD)
  • Minimal lumen area (MLA)
  • Maximum lumen diameter
  • Degree of calcification
  • Greatest area of tortuosity in the iliofemoral system

The researchers used these measurements, along with published sheath size, to calculate the sheath-to-femoral artery diameter ratio and sheath-to-femoral artery area ratio in 3 segments: the common and external iliac arteries and the common femoral artery.

Artery Size Matters

Thirty-day rates of mortality and stroke were 0.4% and 1.6%, respectively. Vascular complications occurred in 28 patients (11%). The vast majority of complications (82%) were managed percutaneously with balloon aortic valvuloplasty or transapical TAVR.

Patients who experienced vascular complications were more likely to have a smaller mean MLD and MLA but greater mean femoral artery diameter and area ratio (table 1).

Table 1. Artery Characteristics by Presence/Absence of Vascular Complications

 

Vascular Complications

No Vascular Complications

P Value

Mean MLD, mm

    Common Femoral

    External Iliac

 

5.81

6.17

 

6.55

6.99

 

< .001

.006

Mean MLA, mm2

    Common Femoral

    External Iliac

 

39.23

42.6

 

50.1

49.5

 

< .001

.01

Femoral Artery Diameter Ratio

1.50

1.36

.006

Femoral Artery Area Ratio

1.60

1.32

.008

In receiver operating characteristic (ROC) curve analysis, a femoral artery area ratio cutoff of 1.35 was predictive of vascular complications (sensitivity 78.6%, specificity 62.9%). By comparison, a diameter ratio cutoff of 1.45 also was predictive but with lower sensitivity and specificity (64.2% and 67.4%, respectively).

Regression modeling identified 4 predictors of vascular complications:

  • Diameter ratio (OR 8.3; 95% CI 1.8-39.1)
  • Log-transformed area ratio (OR 40.1; 95% CI 2.4-650.0)
  • Female gender (OR 4.6; 95% CI 1.6-13.7)
  • Prior stroke (OR 5.7; 95% CI 1.7-18.9)

Three Dimensions Better Than 2

According to Dr. Kapadia and colleagues, the findings strengthen previous work showing that a diameter ratio of 1.05 predicted vascular access complications during transfemoral TAVR (Hayashida K, et al. JACC Cardiovasc Interv. 2011;4:851-858). However, that calculation was based on mainly 2-D angiography.

“Angiography does not provide as precise a measurement of the artery as does CTA and does not allow an appreciation of the elliptical nature of the artery (and ergo its distensibility) that may be reflected by measuring the area of the artery as opposed to the MLD alone,” they write. Furthermore, the authors say, the current data suggest that area-based measurement provides improved sensitivity compared with the MLD-based measurement alone.

“In our series, use of the [area ratio] would have predicted a vascular complication in 25 patients (12.5%) considered ‘safe’ with use of the [diameter ratio] alone,” they report. “We therefore recommend the use of both the [diameter and area ratios] in selection of patients for [transfemoral] TAVR,” they conclude, adding, “The specificity of 63% in the [area ratio] is low for ‘ruling in’ safety, but the improved sensitivity would allow operators more confidence in ‘ruling out’ a complication.”

Proper Imaging Increases Procedural Success, Safety

In a telephone interview, Hasan Jilaihawi, MD, of Cedars-Sinai Heart Institute (Los Angeles, CA), told TCTMD that while the findings are hypothesis generating and need validation, the paper is an important step forward in “efforts to not only reduce vascular complications and perform the procedure in a generally safe manner but to refine and polish the procedure [in order to achieve] near-perfect outcomes.”

He noted that the study validates the use of cross-sectional imaging to enhance procedural success, which is important because few data of this sort are available despite increasing interest in use of imaging in TAVR.

In addition, the results are likely generalizable, Dr. Jilaihawi said, because the ratio of the external dimension of the sheath to the vessel size is consistent across currently available devices. The investigators did not find a significant impact of the learning curve on the rate of vascular complications nor was there any association with calcification, he added.

 


Source:

Krishnaswamy A, Parashar A, Agarwal S, et al. Predicting vascular complications during transfemoral transcatheter aortic valve replacement using computed tomography: a novel area-based index. Catheter Cardiovasc Interv. 2014;Epub ahead of print.

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Disclosures
  • Dr. Kapadia reports no relevant conflicts of interest.
  • Dr. Jilaihawi reports serving as a consultant for Edwards Lifesciences.

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