Use of mechanical valve prostheses in adults with tetralogy of Fallot

Use of mechanical valve prostheses in adults with tetralogy of Fallot.

Egbe AC, Miranda WR, Ammash NM, Said SM, Missula VR, Abdelsamid MF, Kothapalli S, Connolly HM.

Int J Cardiol. 2019 Feb 16. pii: S0167-5273(18)35800-5. doi: 10.1016/j.ijcard.2019.02.028. [Epub ahead of print]

PMID: 30803889

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Take Home Points:

  • Patients with Tetralogy of Fallot may need valve replacement during their lifetime, and there is limited data on the results of mechanical valve prostheses in these patients.
  • This retrospective, single-center study evaluated their experience with mechanical valve implantation in all valve positions – not just pulmonary.

 

Commentary from Dr. Timothy Pirolli (Dallas), section editor of Congenital Heart Surgery Journal Watch: Patients born with Tetralogy of Fallot typically undergo full repair within the first year of life (or within the first few years, from a historical perspective). Many of these patients have residual lesions, especially free pulmonary insufficiency due to transannular patch repair that may require surgery later in life. Currently, it is common practice for patients with free pulmonary regurgitation to undergo a redo sternotomy and implantation of a Bioprosthetic valve into the pulmonary position to preserve right ventricular function and decrease RV dilation. In some centers, surgeons may opt to use mechanical valves for high-risk patients or patients already on anticoagulation. Interestingly, this would lead the reader to believe that this study was about the results of implantation of mechanical valve in the pulmonary position at this center.

 

But, stop the presses! Though the title seems to infer that is the topic of this study, the authors actually present their results of their cohort of mechanical valve implantation in ALL valve positions, not just the pulmonary position! The authors sought to describe the incidence of mechanical valve related adverse events, reoperation and mortality in all TOF patients with mechanical valve prostheses. The first question that an inquisitive reader might ask is: why are the authors concerned about the results of the mechanical valves in the other positions? There is never a clear answer to this question. However, by using all valve positions, it is clear that the authors can increased the number in this study cohort relative to just studying those with pulmonary valve implantations.

 

The study reviewed patients from the Mayo Adult Congenital Heart Disease database who were born with Tetralogy of Fallot and underwent mechanical valve implantation in all valve positions between 1990-2017. A total of 29 patients were identified who had a total of 44 valve implantations were identified, with 40 of the valves implanted at Mayo. The median age was 44 years old ± 13 years and the interval between initial TOF repair and first mechanical valve implant was 37 ± 6 years. The valve types were 21 aortic, 6 mitral, 2 tricuspid and 11 pulmonary. Ten of the patients had more than one mechanical valve. It’s fascinating that only 11 of the mechanical valves implanted were in the pulmonary position, given the TOF substrate of the patients. It also indicates that the institutional preference of the Mayo is to place bioprosthetic valves in the pulmonary position. All patients were on Coumadin postoperatively with goal INR ranges specific for the highest risk valve. Figure 1 shows the discharge, 1 year and 5 year average gradients across each of the valve types (excluding tricuspid valve) from the incomplete follow-up of the dataset. The graphs show no significant progression of gradient

 

The MVRAE rate was 10 total events in 7 patients (24%). There were 4 endocarditis, one valve thrombosis and 5 major bleeds. There were no strokes. Figure 2 shows the freedom from MVRAE events as well as the freedom from reoperation and survival Kaplan Meier curves. There was basically no discussion about the survival curve and re-operation rates, which is bizarre.

 

The authors admit the limitations of the study include a small sample size, retrospective nature, incomplete follow-up, selection bias and the usual limitations related to this type of study. For some reason, they claim the study is novel because it looks at the mechanical valve implantation into all 4 valve positions instead of just the pulmonary position in TOF patients. This begs the question: what is the unique nature of the aortic, tricuspid and mitral positions in TOF patients as compared to non-TOF patients? As far as I can surmise, the authors saw that the topic had never been published on and decided to add this study to the cumulative knowledge without a significant explanation of how it is useful. I do not see how this study will alter the management of adult TOF patients who need valve surgery, as the same decision-making algorithms apply to these patients before this study was published as after it was.

 

 

 

 

Atarim

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