CMR Confirms Link Between Moderate Aortic Regurgitation Post-TAVR and Poor Outcomes, Mortality


If there was ever any doubt, a new study using cardiovascular magnetic resonance (CMR) to diagnose and quantify aortic insufficiency after TAVR has confirmed worse prognosis with even moderate regurgitation.

Though TAVR technology and implantation techniques have improved at a rapid pace, residual aortic regurgitation remains a key concern with the procedure. Previous studies have pointed to a direct, negative effect on prognosis, but these have typically relied on echocardiographic findings, leading some question the clarity and conclusiveness of the evidence.

“We’ve had a lot of meta-analyses before that said that probably patients left with regurgitation are at worsened prognosis, but the signal was somewhat muddied by the poor test to quantify it,” Jonathon A. Leipsic, MD (St. Paul’s Hospital, Vancouver, Canada), who was not involved in the study, told TCTMD. The new findings show that “those with moderate paravalvular regurgitation do really poorly,” he added.

The study, which was published in the August 9, 2016, issue of the Journal of the American College of Cardiology, was led by Henrique Ribeiro, MD, PhD (Laval University, Quebec City, Canada), and included 135 patients who underwent TAVR at three hospitals. All were examined with CMR within a median of 40 days (range 6 to 105 days) and transthoracic echocardiography within a median of 6 days (range 6 to 22 days).

According to the echocardiograms, aortic regurgitation was moderate or severe in 17.1% of patients. However, CMR put this number at 12.8%.

Overall mortality was 23.0% at a median follow-up of 26 months, and just over half of deaths were cardiac-related. Greater regurgitant fraction (RF) as determined by CMR independently predicted all-cause mortality (HR 1.18 for each 5% increase in RF; 95% CI 1.08-1.30) and the combined endpoint of mortality and rehospitalization for heart failure (HR 1.19 for each 5% increase in RF; 95% CI 1.15-1.23).

CMR performed better than early echocardiography post-TAVR on prediction models (P < 0.05 for all models). Moreover, an RF of 30% or higher best classified patients at higher risk of mortality at 2 years (AUC 0.678; P = 0.001) as well as mortality and rehospitalization for heart failure (AUC 0.679; P = 0.001).

CMR ‘Far Better’ Than Echocardiography

“Although [echocardiography] 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 authors write, citing previous studies that have misclassified post-TAVR aortic regurgitation grades using this imaging modality in the past.

CMR on the other hand “is particularly useful in patients with difficult echo windows,” write Rόisίn Morgan, MD, and Raymond Y. Kwong, MD, MPH (both Brigham and Women’s Hospital, Boston, MA), in an accompanying editorial. “CMR can evaluate valvular morphology, mechanism of dysfunction, and consequences of stenosis and/or regurgitation on ventricular function and remodeling.”

There may be limitations to using CMR post-TAVR “depending on access and desired early discharge as well as cost and claustrophobia and issues like that,” Leipsic said. “But at the end of the day, should you have issues with paravalvular regurgitation, I think what this data shows us nicely is that it’s important to really understand how severe the paravalvular regurgitation is and MRI is far better at doing that than echo.”

Not all patients will need to be examined by CMR going forward, senior author on the study Josep Rodés-Cabau, MD (Laval University), told TCTMD in an email. “However, CMR may help in further identifying those patients with truly significant aortic regurgitation” or those with “doubtful transthoracic echocardiography (TTE) results or discordances between clinical symptoms and regurgitation severity as evaluated TTE,” he said.

Patients with “poor echo windows,” those with mild to moderate regurgitation on echo but with signs of heart failure, and patients with severe leak on echo would also be served better with CMR examination, the editorialists write.

All of the above groups could benefit from “additional interventions, including paravalvular leak closure, second valve/post-dilation, and possibly surgical aortic valve replacement to improve late clinical outcomes,” Rodés-Cabau suggested.

In this regard, though, “due to the presence of hardware artefacts, CMR offers little anatomical information regarding why and how significant [paravalvular leak] occurred, which could be helpful in cases in which repeat TAVR is indicated,” write Morgan and Kwong.

Cause for Pause

With aortic regurgitation, “once you have it, there’s not a huge amount of opportunities to fix it,” Leipsic explained, adding that these data should help emphasize the reality of how the complication affects outcomes. “Therefore, you need to use proper sizing, you need to have proper device selection, [and] you have to tailor the device selection to the patient’s anatomy,” he suggested.

This study’s implications are particularly important for operators starting to think about offering TAVR to lower-risk patients and/or performing minimalist TAVR. “In many ways people are looking at minimization in all these things, which is great,” Leipsic said. “But when you’re dealing with a patient that has surgical options, perfection is what you are really aiming for.

“If you’re doing a 93-year-old who is hoping to get 2 years of life, you're relieving their symptoms,” he continued. “But if you take a 68-year-old with a low-to-medium surgical risk and you leave them with moderate paravalvular aortic regurgitation, you've not done that person a service.”

Ultimately, this complication “is a big deal” and should give operators pause, Leipsic concluded. This study “slam dunks it, saying yes, moderate paravalvular regurgitation—when we are accurate in diagnosing it, when we are accurate in characterizing the severity—there is no doubt it is associated with a poor prognosis.”

 


Sources:

 

  • Ribeiro HB, Orwat S, Hayek SS, et al. Cardiovascular magnetic resonance to evaluate aortic regurgitation after transcatheter aortic valve replacement. J Am Coll Cardiol. 2016;68:577-585.
  • Morgan RB, Kwong RY. When accurate flow quantitation matters: the case of CMR assessment of aortic regurgitation after TAVR. J Am Coll Cardiol. 2016;68:586-588.

 

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Disclosures
  • This study was funded, in part, by research grants from the Canadian Institutes of Health Research.
  • Ribeiro reports receiving a research PhD grant from CNPq, Conselho Nacional de Desenvolvimento Científico e Tecnológico–Brasil.
  • Rodés-Cabau reports receiving research grants from Edwards Lifesciences, Medtronic, and St. Jude Medical.
  • Morgan and Kwong report no relevant conflicts of interest.
  • Leipsic reports that his institution serves as a core lab for Edwards Lifesciences and Medtronic.

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