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With protamine routinely given at the end of transcatheter aortic valve replacement or implantation (TAVR or TAVI), patients achieved hemostasis quicker and with greater success, according to the ACE-PROTAVI trial.

Successful hemostasis within 20 minutes was significantly more likely when protamine was administered routinely rather than on a selective basis after upfront placebo (97.9% vs 91.6%, P=0.006). Time to hemostasis (TTH) was also over a minute shorter with the anticoagulation reversal agent given upfront (181 seconds vs 279 seconds, P=0.002).

"The beneficial effect of protamine was reflected in a reduction in minor vascular complications, procedural time, and postprocedural hospital stay duration in patients receiving routine protamine compared with patients receiving placebo," reported Antony Walton, MBBS, of the Alfred Hospital in Melbourne, Australia, and colleagues in .

They noted that in clinical practice, vascular complications remain an important cause of procedure-related morbidity from transfemoral TAVR for people with aortic stenosis.

While protamine is well studied and established in cardiac surgery, it is more controversial in interventional cardiology. The older was unable to show that protamine administered helped resolve bleeding complications after TAVR. However, that study had been small, unblinded, and had substantial crossovers, Walton's team noted.

There were no adverse events associated with protamine use in ACE-PROTAVI.

However, Walton's group acknowledged that the present study, with around 400 people, was too small to assess the risk of protamine causing anaphylaxis and other feared side effects. A larger study may be needed to confirm safety, they suggested.

"We anticipate that the results of this study will provide robust evidence to guide decision-making by TAVI teams," the authors maintained.

was a double-blind trial conducted at three Australian hospitals from 2021 to 2023. Results were first presented last fall at the Transcatheter Cardiovascular Therapeutics meeting.

Walton and colleagues included 410 people undergoing transfemoral TAVR who had been randomized to routine protamine or placebo at the conclusion of transfemoral TAVR (prior to femoral sheath removal and arteriotomy closure). Median age was around 80 years old and fewer than 40% of patients were women. Over half got a self-expandable TAVR valve.

The investigators designed the study such that one of each treatment syringe was prepared for each participant; both syringes were masked to primary operators but made available in case protamine was desired due to ongoing bleeding.

As for the trial's co-primary endpoints, hemostasis success was defined as hemostasis achieved within 20 minutes (without further compression required), and TTH was defined as time between sheath removal and confirmed arterial hemostasis.

The secondary endpoint, a composite of all-cause deaths, major and minor bleeding complications, and major and minor vascular complications after 30 days, was significantly lower for the upfront protamine group (5.2% vs 12.8%, OR 0.37, 95% CI 0.1-0.8), mainly driven by the reduction in minor vascular complications (2.1% vs 8.4%, P=0.01).

"Heparin reversal might improve closure and hemostasis and reduce minor vascular complications, but it is unlikely to affect catastrophic vascular complications, such as the rupture or perforation of arteries," Walton and colleagues therefore cautioned.

They also noted that the trial excluded people with a known protamine allergy, history of anaphylaxis, or a recent percutaneous coronary intervention with drug-eluting stents implanted.

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