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Transcatheter pulmonary valve replacement (TPVR) with the Melody valve was shown to be safe and feasible even in native right ventricular outflow tracts (RVOTs) for congenital heart defect patients, a retrospective study showed.

Of 229 patients presenting for catheterization in this setting, 58% had successful TPVR, a group led by Mary Martin, MD, of the University of Utah in Salt Lake City, reported online in .

The rest did not get the procedure at all, largely because their native RVOT was too large (n=67) or because the aortic root or coronary arteries were compressed (n=18).

While none of the TPVR-treated patients died, five had serious complications -- all were patients who had stenting beforehand as a strategy to reduce the . Four pre-stent embolizations required surgery, and one case of arrhythmia occurred.

"As the largest report on TPVR in the native RVOT, this multicenter study showed excellent immediate outcomes in patients who had a Melody valve implant, results that are similar to those for Melody TPVR within an existing RV-PA [right ventricle-to-pulmonary artery] conduit or BPV [bioprosthetic pulmonary valve]," the group concluded.

TPVR with this device is currently FDA approved in the latter two indications.

TPVR in native RVOT was more likely to be successful when there was a higher pre-catheterization echocardiographic RVOT gradient (21.4 versus 14.8, P=0.001). Centers with higher procedural volumes tended to have more success, but this did not reach statistical significance.

Successfully getting TPVR was associated with smaller RVOT dimensions on MRI. However, the best cut-offs found had only "fair" ability to predict whether TPVR would be successful: maximum anterior-posterior diameter 20.9 mm, lateral diameter 22 mm, and elliptical area 330 mm² (C-statistic <0.7 for all).

"One of the most challenging aspects of TPVR in patients with a native RVOT is sizing the RVOT. This study highlights that challenge, with nearly half of the patients in the series undergoing cardiac catheterization only to find at the time of the procedure that they were not candidates for TPVR with the Melody valve...," according the authors.

In an , Carlos Ruiz, MD, PhD, and Tilak Pasala, MD, both of Hackensack University Medical Center in New Jersey, pointed out that the average pulmonary valve annular area of the non-implanted cohort was 348±95 mm².

That number "is within the range of the current Sapien S3 (Edwards Lifesciences, Irvine, CA) valves that clearly offers an alternative in many of those excluded patients. What makes it exciting is that based on these numbers, we could estimate that with the availability of larger valves, the success rate could increase by more than 25%."

"With evolving technologies, new devices, novel techniques the future of TPVR in native RVOT remains bright and this study's findings add to the growing body of evidence," they said.

Presenting to 11 centers across the U.S., the study population was age 21 years on average (split into the implanted and non-implanted groups at 18 and 24 years of age, respectively). The investigators acknowledged that their study missed patients referred directly to surgery, and that half of patients lacked pre-catheterization MRI data, precluding any multivariable analysis.

"The short-term results of this study are promising, but the long-term durability still needs to be investigated. Additionally, the risk of late endocarditis is higher with Melody valves," Ruiz and Pasala noted.