Vancouver, BC and Quebec City, QU - Moderate to severe mitral regurgitation (MR) is relatively common in patients undergoing transcatheter aortic-valve implantation (TAVI) and is associated with a doubling in risk of 30-day death, a new series suggests [1]. Beyond this initial period, however, survival among MR patients is just as good as among patients with no MR, and MR itself is likely to improve over time, authors of a new analysis say.
The paper, by Dr Stefan Toggweiler (St Paul's Hospital, Vancouver, BC) and colleagues, is published online April 4, 2012 in the Journal of the American College of Cardiology.
To heartwire, Toggweiler explained that the percentage of patients undergoing TAVI who also have moderate to severe MR has varied across reports, ranging from 25% to 45%. Severe MR was actually an exclusion criterion in the pivotal PARTNER trials, but many patients made it into the trial with a diagnosis of "moderate" MR that was only upgraded after the core lab reviewed the echocardiograms, meaning that even in PARTNER there are subset data on patients with significant MR.
Toggweiler et al tracked outcomes of 478 patients treated over a five-year period at two centers in Canada. (Devices used over this period were the Edwards-Cribier valve [n=56], Edwards Sapien [n=270], and Sapien XT [n=115]). Although the bulk of patients had mild or no MR, 89 had moderate MR, and 43 had severe MR.
At 30 days, mortality among patients with moderate or severe MR was twice as high as among those with mild or less MR (hazard ratio [HR] 2.10, p=0.02); after 30 days and up to two years, however, mortality rates were no different between these groups (HR 0.82, p=0.42).
Of note, among survivors, MR had improved in 55% of subjects, remained the same in another 16%, and had worsened in just 1%. Among those with moderate or severe MR at baseline, 61% of patients experienced some improvement post-TAVI.
"Short-term mortality is a bit higher after TAVI, and in general, these patients are a bit older and have more comorbidities, so certainly immediately postoperative, the risk is a bit higher and they require careful monitoring," Toggweiler summarized. "But again, if they are not treated, they probably don't do well because the combination of MR and aortic stenosis is not well tolerated at all."
To heartwire, he noted that a similar pattern of early hazard post-TAVI, followed by improved outcomes after the 30-day mark, was seen in PARTNER, although the numbers were very low.
Given these findings, he continued, "the advice would be that these patients [who also have moderate to severe MR at the time of their TAVI procedures] need careful monitoring, and we have identified some factors that actually are associated with good outcomes." These include patients with higher mean transaortic gradient at baseline, no atrial fibrillation, no pulmonary hypertension, and functional as opposed to structural MR. "So these [patients] may be candidates for isolated TAVI," Toggweiler said.
Pointing to the fact that MR actually improved in 61% of subjects, Toggweiler noted that there are likely different mechanisms by which patients, if they survive the early postop period, actually do better in the long term.
"What is most likely [happening] is, because the afterload is reduced immediately—because there is no stenosis—there is less pressure gradient between the left ventricle and left atrium, and that leads to reduced MR in the short term. And then some patients have positive remodeling post-TAVI, ejection fraction improves, and that leads to improvement in the long term."
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