Transcatheter Pulmonary Valve Replacement with the Harmony Valve in Patients Who Do Not Meet Recommended Oversizing Criteria on the Screening Perimeter Plot.

Transcatheter Pulmonary Valve Replacement with the Harmony Valve in Patients Who Do Not Meet Recommended Oversizing Criteria on the Screening Perimeter Plot.

McElhinney DB, Gillespie MJ, Aboulhosn JA, Cabalka AK, Morray BH, Balzer DT, Qureshi AM, Hoskoppal AK, Goldstein BH. Circ Cardiovasc Interv. 2024 May;17(5):e013889. doi: 10.1161/CIRCINTERVENTIONS.123.013889. Epub 2024 Apr 12. PMID: 38606564

Take Home Points

  • The Harmony valve was FDA approved for treatment of post intervention pulmonary valve regurgitation in 2021
  • The stent Medtronic generates a screening report to help determine candidacy for a successful valve implantationis delivered by the Minima Delivery System which has an outer diameter equivalent to a 4 Fr sheath.
  • Successful Harmony valve implantation with good results is possible in some patients that do not technically meet screen in criteria

Commentary from Dr. Ryan Romans (Kansas City, MO), section editor of Congenital Heart Disease Interventions Journal Watch: 

The Harmony valve received FDA approval in 2021 for transcatheter pulmonary valve replacement (TPVR) for the treatment of post intervention pulmonary regurgitation. The Harmony valve is made of a covered self-expanding nitinol wire frame in an hourglass shape (rows 1 and 2 in the outflow/PA portion of the device, rows 5 and 6 the inflow/RV portion of the device) with a porcine pericardial valve in the center (rows 3 and 4). The inflow and outflow segments are designed to anchor the valve within the RVOT and prevent paravalvar leak. A pre procedure CT angiogram is performed and then analyzed by Medtronic using an algorithm designed to ensure adequate oversizing to secure the device in the RVOT. A screening report is generated and details various important anatomical features of the RVOT, including a perimeter plot (PP) that is generated based on measurements from the CT angiogram at end diastole and peak systole. A patient’s anatomy is typically considered a fit when the screening report predicts adequate oversizing of both the inflow and outflow portions of the device (approximately 70% of screened patients). While the screening report has been very useful with excellent specificity (unsuccessful valve implantation is extremely rare when fit predicted). However, the RVOT anatomy is complex, and it is unclear how many patients that don’t have a positive screening report could still undergo successful transcatheter pulmonary valve replacement. This retrospective multicenter study looked at patients with borderline or inadequate oversizing on the fit analysis who ultimately underwent successful Harmony valve implantation.

Perimeter plot with green shading meeting criteria for minimum oversizing, yellow shading borderline oversizing (50-99% recommended), and red shading insufficient oversizing (<50% recommended).  The landing zone is the length for which this oversizing is met.  

There were 22 patients at 8 different centers who underwent Harmony TPV25 implant despite not meeting recommended oversizing criteria; 13 of these were coded green-yellow and 9 green-red (meaning all had adequate oversizing on at least 1 end of the device). The RVOT anatomy of these patients were grouped into three different anatomic types with strategy for valve implantation being somewhat specific for each. The figures below show the PP on the left, diastole in the middle, and systole on the right.

Type 1 (n=9): Long RVOT with a clear choke point (often at the level of the annulus) and large MPA that flared out toward the branch PAs. More than 50% of these patients had diagnoses other than TOF. The large, flared MPA did not allow for oversizing of both ends simultaneously. The valve was typically implanted in an annular position (valve housing/rows 3-4 at the level of the annulus).

Type 2 (n=6): Short RVOT that was often pyramidal with a large degree of MPA expansion (in length and diameter) during systole. The RVOT length was too short during diastole for adequate oversizing of both ends and there was not usually a choke point. The valve was typically implanted high with the outflow rows flowering into the PA bifurcation or within the distensible distal MPA.

Type 3 (n=7): Short and bulbous MPA with a discrete choke point that did not screen in because of the large MPA and short RVOT. More than 50% of these patients had diagnoses other than TOF. The valve was typically implanted high or at the annular level.

The implant was annular in 15 patients and supra-annular in 7 patients. There was trivial pulmonary regurgitation via echocardiography in 5 patients, trivial paravalvar leak in 3 , and mild paravalvar leak in 2. 41% (9) of patients were started on antiarrhythmic medications for new non-sustained VT/frequent ventricular ectopy. 

This study shows that patients with inadequate oversizing at one end of the device on the Harmony valve screening report may still be able to undergo successful Harmony TPVR with excellent short term results as long as there is adequate oversizing at one end of the device. This is possible because the anatomy of the RVOT in these cases allowed for device stability. Also, the anatomy of the RVOT is complex and while there may not be apposition of the device along the entire circumference of the RVOT that may not be necessary to ensure device stability. While it is challenging to draw broad conclusions from this study (it is unclear who screened out that could have undergone successful TPVR and who when attempted would have failed) this study highlights the importance of looking at the individual anatomical features when deciding whether or not to attempt TPVR with the Harmony valve.