Assessing Aortic Valve Calcification May Help Predict Paravalvular Leak After TAVR

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The presence of valve calcification increases the odds of at least mild paravalvular regurgitation after transcatheter aortic valve replacement (TAVR), according to a study published in the August 2014 issue of JACC: Cardiovascular Interventions. Moreover, the authors suggest that asymmetry of the annulus and left ventricular outflow tract (LVOT) may better predict the need for postdilatation than that of the leaflets.

Among the 69 patients (46%) with paravalvular regurgitation at the end of the procedure, 6% had moderate (10 to 19 mm²), 13% had mild (5 to 9 mm²), and 27% had trace amounts (0 to 4 mm²). No patient had severe regurgitation. Patients with at least mild regurgitation had more calcification in all regions than those with less or no paravalvular leak. Similarly, those who received postdilatation showed more calcification in all regions than those without postdilatation. 

In addition, more asymmetry was seen in all regions in patients who had postdilatation (P < .01 for all) and—with the exception of the leaflet—in those with at least mild leak (19%; table 1).

Table 1. Asymmetry of Calcium Volume

Aortic calcification was further shown to predict mild or higher paravalvular leak in all regions except the leaflet in ROC analysis (table 2). 

Table 2. ROC Analysis: Calcification Predicting At Least Mild Leak

Multivariable analysis identified calcification in each of the 3 regions as independent predictors of mild or greater paravalvular leak and postdilatation (P < .0001 for all). 

In a telephone interview with TCTMD, coauthor Omar K. Khalique, MD, also of Columbia University Medical Center, said that paravalvular leak is still “poorly understood.” 

Even though leaflet calcification did not seem to be as important as calcification in the other aortic regions in the study, it should be studied further because “the leaflets may indirectly impact the overall deployment of the valve in terms of inhibiting the [optimal] position,…which may also lead to paravalvular leak in an indirect way,” he continued.

The overall take-home message, Dr. Khalique said, “is that when you have significant calcification, you can expect paravalvular regurgitation…. It won't stop you from doing the case necessarily, but it gives you a good way to know what to expect and plan.” 

A ‘Triple-Edged Sword’  

Peter C. Block, MD, of Emory University School of Medicine (Atlanta, GA), told TCTMD in a telephone interview that it is common knowledge that severe LVOT calcification centered in the leaflets makes it much more difficult to perform successful TAVR and achieve an appropriate seal, although the study is the first to quantify this. 

However, this issue becomes a kind of “triple-edged sword,” he commented. 

“You need the calcification in order to anchor the valve, but…without calcification, you would probably get a much better seal” and so less paravalvular regurgitation, he explained. In the presence of severe calcification in the LVOT or leaflets, surgery might be the best option, he continued, “but many of these patients truly cannot be operated on.”

The ultimate unanswered question, he said, is: “Given the improvement that you know you can achieve with [TAVR] in patients with severe calcification, is the benefit of relieving the stenosis worth the detriment of having a paravalvular leak?”

In an accompanying editorial, Paolo Raggi, MD, of the University of Alberta (Edmonton, Canada), agrees. “Once again, the ever-correct conclusion is that a careful selection of the most suitable patient for the most appropriate procedure is the desirable way to proceed,” he writes. Still, the study fails to indicate “‘how much is too much,’ that is, a threshold beyond which the risk of moderate-to-severe [paravalvular regurgitation] is too high to attempt the procedure,” Dr. Raggi says. 

Going forward, Dr. Block said, design improvements already being incorporated in newer-generation valves will drastically reduce the issue of paravalvular regurgitation. 

Note: Several co-authors of the paper are faculty members of the Cardiovascular Research Foundation, which owns and operates TCTMD.

Sources: 
1. Khalique OK, Hahn RT, Gada H, et al. Quantity and location of aortic valve complex calcification predicts severity and location of paravalvular regurgitation and frequency of post-dilation after balloon-expandable transcatheter aortic valve replacement. J Am Coll Cardiol Interv. 2014;7:885-894.

2. Raggi P. Paravalvular regurgitation and post-deployment balloon dilation after transcatheter aortic valve replacement: can we predict and prevent [editorial]? J Am Coll Cardiol Interv. 2014;7:895-897.

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