Aortic Regurgitation Risk, Consequences Vary Between First-Generation TAVR Devices

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The odds that aortic regurgitation (AR) will develop after transcatheter aortic valve replacement (TAVR) are higher when patients receive a self-expanding rather than balloon-expandable valve, reports a registry study of first-generation devices published online July 22, 2014, ahead of print in Heart. Paradoxically, however, the complication is associated with greater mortality risk for the balloon-expandable valves only.

After TAVR, 57% of patients developed mild AR and 10% had moderate/severe AR. Multivariate analysis identified several factors that independently predicted risk of moderate/severe AR (table 1).

Table 1. Independent Predictors of Moderate/Severe vs No/Mild AR

Death rates were 6.3% at 30 days and 19.3% at 1 year. Patients with moderate/severe AR had higher rates of 30-day mortality (11.1%) compared with those with mild AR (5.8%) or no AR (5.2%; P = .006); they also had significantly more complications including periprocedural death and cardiac shock, postprocedural blood transfusion, and acute kidney injury.

Patients receiving CoreValve were more likely to have moderate/severe AR compared with those receiving Sapien (13.6% vs 7.6%; P < .0001), though mortality rates did not differ by device type.

In a Cox regression model, moderate/severe AR strongly predicted mortality in the Sapien group (HR 1.97; 95% CI 1.47-2.61) but not in the CoreValve group (HR 1.13; 95% CI 0.83-1.51). Further analysis of the clinical characteristics of transfemorally treated patients failed to reveal a reason for that difference.

An ‘Unexplained’ Paradox

Although this is not the first time that a higher rate of moderate/severe AR has been reported for CoreValve compared with Sapien, evidence has been mixed, the researchers report, adding, “Most experts in the field accept there is a difference between the 2 devices.”

The paradox that AR appears to only influence mortality in Sapien-treated patients, however, “is unexplained,” Dr. MacCarthy told TCTMD in an email.

“[I]t may be that there is more AR early with CoreValve but this decreases as time goes on with further expansion of the prosthesis,” he proposed, noting that all AR in the study was measured before hospital discharge. “It may also be an artifact relating to how the AR was measured in the presence of different devices (eg, more acoustic shadowing with one or the other devices), or it may be a mechanism that we do not yet know about.”

Steps Can Be Taken to Limit AR

Notably, he said, the dataset is from early in the evolution of TAVR when large valve sizes were unavailable and annulus sizing was done with 2D transthoracic echocardiography or transesophageal echocardiography (TEE). Dr. MacCarthy mentioned several ways that today’s operators can reduce the risk of AR:

• Proper annulus sizing with 3D TEE or CT
• Use of newer devices designed to reduce AR
• Judicious use of postdilatation

It is also important, he added, to be aware of risk factors such as eccentric heavy calcification and oval annulus.

Management of patients who develop the complication “is challenging, and certain types of patients tolerate AR less well,” Dr. MacCarthy said. “Proper medical therapy helps, and some operators have used paravalvular leak closure devices—with limited success. The role of late postdilatation of the valve is not known but is unlikely to be helpful.”

Dr. MacCarthy acknowledged it is unclear what relevance these findings have to newer TAVR devices. “What we do know,” he concluded, “is that AR is a bad thing and that we should do all we can to minimize/eradicate it…. The latest data from the newest generation of devices certainly seem to show less AR—let's hope that translates into better patient outcomes.”

Source: 
Dworakowski R, Wendler O, Halliday B, et al. Device-dependent association between paravalvular aortic regurgitation and outcome after TAVI. Heart. 2014;Epub ahead of print.

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