A short-term follow-up of the first-in-human study for the Mistral tricuspid valve repair device found that patients with severe tricuspid regurgitation (TR) – a group with no standard-of-care options – had significant improvements in their condition.

The analysis at 30 days for the seven subjects, three men and four women with either severe or massive symptomatic TR, high surgical risk and a mean age of 73.14 years, was published in the Sept. 28 issue of JACC: Cardiovascular Interventions.

Damage to the tricuspid valve, often colloquially referred to as the “forgotten valve,” has traditionally been considered a bystander in advanced cardiovascular disease. However, recent studies suggest that transcatheter tricuspid valve intervention (TTVI) can improve prognosis, including better outcomes for right ventricular function and heart failure rehospitalization. The goal for treatment with Mistral, an investigational spiral-shaped transcatheter repair device, is in line with this more recent thinking.

In the Mistral study follow-up, David Planer, MD, of the Hadassah Hebrew University Medical Center in Israel, and two co-investigators found no procedural or adverse events, and TR reduction by at least one grade in all patients.

Mistral works by grasping the chordae tendineae internally, forming a "flower bouquet" shape in order to approximate the chordae and the leaflets, reducing the coaptation gap for the treated commissure, according to the three researchers, two of whom consult for the device manufacturer, Mitralix. The device was successfully implanted under transesophageal echocardiography guidance in procedures lasting between 58 and 125 minutes in all seven patients, one of whom received two devices. All were discharged home one to four days later.

Effective regurgitant orifice area was reduced from a median 0.52 cm² (interquartile range [IQR]: 0.40 to 0.60 cm²) at baseline, to 0.15 cm² (IQR: 0.14 to 0.21 cm²) at 30 days post-procedure (p < 0.01). Vena contracta width reduced from a baseline median of 0.95 cm (IQR: 0.81 to 1.16 cm) to 0.62 cm (IQR: 0.52 to 0.67cm, p < 0.05). Regurgitation volume decreased, from a baseline median of 49.4 ml/beat (IQR: 45.2 to 57.7 ml/beat) to 19.7 ml/beat (IQR: 12.4 to 23.9 ml/ beat, p < 0.01).

Right ventricular fractional area change also improved from 27% at baseline (IQR: 21.3% to 33.5%) to 38.5% (IQR: 29% to 47.1%) at 30 days (p < 0.05).

The patients all saw significant improvement on physical activity and quality of life measures including the New York Heart Association functional class (from a median score of III pre-procedure to II), Kansas City Cardiomyopathy Questionnaire score (from a median of 41.1 to 61.3), and the 6-minute walk test at 30 days (from a median of 186 meters at baseline to 288 meters post-procedure), the researcher noted.

The study warrants larger and longer-term studies in severe TR, the authors added. The concept of the device is different from existing transcatheter valve repair systems, they claimed, adding that there are “only very few devices” available for the treatment of the mitral and aortic valves, mostly investigational, and with limited experience in tricuspid valve use.

In an accompanying editorial comment, Holger Thiele, MD, and Philipp Lurz, MD, PhD, of the Heart Center Leipzig at University of Leipzig, Germany, called the Mistral approach “intriguing” as a procedure of modest complexity that was able to affect all three commissures in some patients (two patients had the device approximating all three leaflets). Thiel and Lurz expressed interest in the fact that multiple devices can be implanted into the same commissure to increase the effect if needed.

They also noted that device could be a “very valuable tool” for combined procedures because it does not directly interfere with the annulus or leaflets, potentially enabling edge-to-edge repair in TTVI even when there are larger coaptation gaps.

“The implications of ventricular remodeling on longevity of repair, device function, and the potential harm to involved structures need to be closely monitored. For now, these early results are encouraging and certainly justify further evaluation,” they concluded.

Sources:

Planer D, Beeri R, Danenberg HD. First-in-Human Transcatheter Tricuspid Valve Repair. JACC Cardiovasc Interv 2020;13:2091-6.

Thiele H, Lurz P. The Mistral Device for Transcatheter Tricuspid Valve Repair. JACC Cardiovasc Interv 2020;13:2097-8.