Aortic regurgitation identified via cardiovascular magnetic resonance (CMR) after transcatheter aortic valve replacement (TAVR) was associated with death and rehospitalization for heart failure, investigators observed, although they didn’t suggest CMR as an echocardiography replacement.
Doppler echocardiography and CMR both flagged paravalvular leak (in 17.1% and 12.8% of patients, respectively). However, Josep Rodés-Cabau, MD, of Quebec Heart & Lung Institute in Canada, and colleagues failed to find evidence that moderate-to-severe regurgitation found on transthoracic echocardiography (TTE) had an impact on outcomes over 2 years.
On the other hand, a high regurgitant fraction on CMR was linked to greater odds of death (HR 1.18 for each 5% increase, 95% CI 1.08-1.30), as well as combined mortality and rehospitalization for heart failure (HR 1.19, 95% CI 1.15-1.23), they reported online in the Journal of the American College of Cardiology.
The authors did not find an association between clinical outcomes and regurgitant volume. “A small regurgitant volume may actually correspond to a large regurgitant fraction with a significant effect on clinical outcomes,” they suggested.
Rodés-Cabau’s group concluded: “These findings thus suggest that regurgitant fraction may be superior to regurgitant volume to assess the severity of paravalvular leak early after TAVR, and may help in further identifying those patients with truly significant aortic regurgitation. Therefore, such patients might benefit from additional interventions, including paravalvular leak closure, second valve/post-dilation, and possibly surgical aortic valve replacement, to improve late clinical outcomes.”
Even so, regurgitant fractions of 30% or more had modest predictive accuracy for 2-year mortality (area under the curve [AUC] 0.678, sensitivity 39%, specificity 70%, P=0.001) and for the combination of mortality and rehospitalization (AUC 0.679, sensitivity 39%, specificity 70%, P=0.001).
Roisin B. Morgan, MD, and Raymond Y. Kwong, MD, MPH, both of Boston’s Brigham and Women’s Hospital, called Rodés-Cabau’s study the largest yet to assess CMR for quantifying aortic regurgitation.
“CMR is particularly useful in patients with difficult echo windows,” they wrote in an accompanying editorial. “Although an eccentric regurgitant jet may not be adequately seen by the 2D slice position of phase-contrast imaging, CMR can quantify regurgitant flow regardless of whether the regurgitant jet can be visualized. This is in contrast to echocardiography, in which operator-dependent visualization of the regurgitant jet is key to evaluating velocity and regurgitant volume.”
“Although TTE has been the most commonly used method to quantify aortic regurgitation post-TAVR, this technology still has a number of shortcomings, partially due to the frequent observation of the multiple, irregular, and eccentric paravalvular jets … The precise quantification of paravalvular jets by TTE may be compromised by an ensuing underestimation or overestimation of aortic regurgitation severity.”
The investigation included 135 patients from three TAVR centers. CMR quantification was feasible in 97% of the study group.
Regurgitant fraction was measured by phase-contrast velocity mapping CMR at a median of 40 days after TAVR, while Doppler echocardiography was performed at 6 days.
That these assessments were made at different time points precluded any direct comparison between the two imaging modalities, the authors acknowledged. Importantly, the study also did not use consecutive patients and may have therefore suffered from selection bias.
The editorialists also noted the lack of 3D echo data in Rodés-Cabau’s investigation. “Three-dimensional transesophageal echocardiography [TEE] or TTE may have improved the ability of echo-based assessments to detect eccentric jets and increased detection of paravalvular leak,” Morgan and Kwong argued. “Limitations of 2D and standard Doppler measurements for quantifying regurgitation have largely been overcome with 3-dimensional echocardiography.”
For now, the pair wrote that CMR after TAVR is best for “patients with poor echo windows, those with inconclusive TTE and/or TEE, those in whom there is difficulty acquiring accurate quantitative data, those with mild to moderate paravalvular leak on TTE, but who have symptoms and/or signs of heart failure, and those with moderate to severe paravalvular leak on echocardiography.”
Rodés-Cabau reported receiving research grants from Edwards Lifesciences, Medtronic, and St. Jude Medical.
Morgan and Kwong reported no relevant conflicts of interest.
Journal of the American College of Cardiology
Ribeiro HB, et al “Cardiovascular magnetic resonance to evaluate aortic regurgitation after transcatheter aortic valve replacement” J Am Coll Cardiol 2016; DOI: 10.1016/j.jacc.2016.05.059.
Journal of the American College of Cardiology
Morgan RB and Kwong RY “When accurate flow quantitation matters: the case of CMR assessment of aortic regurgitation after TAVR” J Am Coll Cardiol 2016; DOI: 10.1016/j.jacc.2016.04.063.