Quantifying the Effects of LVOT Calcification After TAVR

Neil Osterweil

August 03, 2020

A new SWISS TAVI registry analysis provides some of the strongest evidence to date that the presence of left ventricular outflow tract (LVOT) calcification is a harbinger of worse outcomes in transcatheter aortic valve replacement (TAVR).

Among 1635 patients who underwent TAVR over more than 10 years, risks for annular rupture, residual aortic regurgitation, and need for a bailout valve-in-valve implantation were all significantly greater for patients with moderate to severe LVOT calcification than for those with only mild or no calcification.

"The effect was largely consistent across the valve designs and the generations. However, in patients with moderate or severe LVOT calcification, balloon-expandable valves were associated with higher rates of annular rupture, compared with self-expanding and mechanically expandable valves," senior author Thomas Pilgrim, MD, Bern University Hospital, Switzerland, and colleagues report today in JACC: Cardiovascular Interventions.

Previous studies have shown that LVOT calcification and aggressive annular area oversizing are associated with increased risk for aortic root rupture during TAVR with balloon-expandable prostheses. But those studies were based on small case series and did not fully explore the effects of LVOT calcification across different transcatheter heart valve designs and generations.

"This study quantifies what we've all experienced with this particular issue. I think this is right on target," commented Pinak Bipin Shah, MD, director, cardiac catheterization lab, Brigham and Women's Hospital, Boston, who was not involved in the study.

Retrospective Look at Prospective Database

The investigators reviewed data on all patients who underwent TAVR at Bern University Hospital from 2007 through 2018, of whom 45.4% were treated with the balloon-expandable SAPIEN THV/XT or SAPIEN 3 (Edwards Lifesciences), 47.2% with the self-expanding CoreValve, Evolut R/PRO (Medtronic), Portico (Abbott), or Symetis ACURATE/ACURATE neo (Boston Scientific), and 7.3% with the mechanically expandable Lotus/Lotus Edge (Boston Scientific) devices.

Multidetector CT images, independently re-evaluated by two investigators blinded to clinical outcomes, were used to classify LVOT calcification as follows:

  • Mild  the presence of one nodule of calcification extending less than 5 mm in any dimension and covering less than 10% of the LVOT perimeter

  • Moderate  two nodules of calcification or one extending more than 5 mm in any direction or covering more than 10% of the LVOT perimeter

  • Severe  multiple nodules of calcification of single focus extending more than 10 mm in length or covering more than 20% of the LVOT perimeter.

LVOT calcification was present in 650 patients (39.8%) and determined to be mild in 243, moderate in 153, and severe in 254.

Patients with moderate or severe calcification were significantly less likely than those with mild or no calcification to have diabetes (20.4% vs 26.9%) but had a lower mean body mass index (25.60 vs 26.93 kg/m2).

Among the 407 patients with moderate or severe LVOT calcification, the incidence of annular rupture was 2.3% vs 0.2% for patients with mild or no calcification (P < .001). Similarly, the incidences of bailout valve-in-valve implantation and residual moderate or severe aortic regurgitation were also higher in patients with more severe calcification, at 2.9% vs 0.8% (P = .004) and 11.1% vs 6.3% (P = .002), respectively.

Annular rupture was seen in 10 patients, nine treated with balloon-expandable valves and one with a self-expanding valve. Although the use of balloon-expandable valves was associated with a significantly higher risk for annular rupture in patients with more severe than mild or no calcification (4.0% vs 0.4%; = .002), there were no significant interactions between valve design or generation and LVOT calcification with the incidence of either bailout valve-in-valve implantation or residual aortic regurgitation.

The investigators noted that valve designs but not sizing recommendations have largely evolved over recent years, pointing out that in eight of the 10 patients who experienced annular rupture, the valve was oversized by more than 10%, including two for whom the valves were oversized by more than 20%.

Annular rupture might have been avoided had the patients received smaller-size valves, they stated.

Seven of the 10 patients with annular rupture died in the hospital as a consequence of the complication.

Overall, 1-year all-cause mortality was numerically higher in patients with moderate or severe LVOT calcification (15.4% vs 11.6%; hazard ratio [HR], 1.35; = .048), but moderate or severe LVOT calcification was not an independent predictor in the multivariate analysis (HR, 1.16; P = .472).

Convert to Open Surgery?

Although annular rupture is still an infrequent complication in experienced hands, "patients with LVOT calcification need to be informed about the increased risk of periprocedural complications and should be on board for a transcatheter approach," Pilgrim told theheart.org | Medscape Cardiology.

The preprocedure discussion should include a review of contingency plans and an escalation strategy, such as conversion versus no conversion to open heart surgery. Should an annular rupture occur, the hemodynamic outcome will depend on the extent and the site of rupture, he explained.

Shah pointed out that "sometimes — actually not infrequently — these patients are not candidates for open-heart surgery, in which case we'll do what we can to try to manage this conservatively or through catheter-based techniques, including the use of vascular plugs and coils."

If patients are good candidates for an open procedure, they will be taken to the operating room for surgical correction, Shah added.

Elaborating on the management of patients with serious complications from TAVR, Pilgrim explained that "while cardiac tamponade is associated with rapid hemodynamic deterioration, intramural hematoma, self-contained or limited rupture, VSD [ventricular septal defect] and fistulae are better tolerated."

Transesophageal echocardiography can help to define the localization and the extent of the rupture.

"In patients with hemodynamic instability associated with cardiac tamponade, a pericardial drainage and reversal of systemic anticoagulation should be performed," Pilgrim said. "Autotransfusion and hemodynamic support may be needed as a bridge to surgical repair. Implantation of a second transcatheter heart valve a little bit proximal or distal to the original valve may seal a rupture in proximity to the skirt."

In an editorial accompanying the study, Miralem Pasic, MD, PhD, Deutsche Herzzentrum Berlin, said that Pilgrim and colleagues "have provided strong data to support the use of TAVR as a primary strategy, even among 'high-risk' patients with severe calcification in the device landing zone."

"TAVR is a revolutionary step in medicine, a real breakthrough," but future technical developments are needed in order to "eliminate its drawbacks, such as annular rupture and paravalvular insufficiency," he commented.

Pasic recommends development of a technique and equipment for clean excision of native aortic valve tissues for more precise implantation of a TAVR prosthesis. He also stressed the need for a better understanding of the effects on cognition of ischemic microlesions and cerebral microembolization associated with valve implantation.

"These factors should be considered critically before the procedural indication is broadened to yet younger and lower-risk patients," he wrote.

Shah agreed with that assessment. "TAVR is revolutionary and it has changed the landscape dramatically. I still think we have a ways to go to get it even better so that we can routinely achieve outcomes that we get with open-heart surgery."

The study was sponsored by University Hospital Inselspital, Berne . Pilgrim disclosed research grants to the institution from Edwards Lifesciences, Boston Scientific, and Biotronik; speaker fees from Biotronik and Boston Scientific; and consultancy fees from HighLife SAS. Pasic reported no relevant disclosures. Shah has served as principal investigator for a trial sponsored by Medtronic.

J Am Coll Cardiol Intv. 2020;13:1789-1799. Abstract, Editorial

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