Remodeling of Failed Pulmonary Valve Autografts After the Ross Procedure.

Failed pulmonary autografts showed qualitative structural alterations, including leaflet thickening, elastosis, fibrosis, and myxomatous matrix accumulation.

• Five autografts explanted because of regurgitation were examined with special stains and α-smooth muscle actin immunohistochemistry.
• Findings were compared with six autopsy control pulmonary valves.
• The authors state the findings demonstrate extracellular matrix alterations in the failed autografts.

Failed autografts had substantially greater maximum leaflet thickness than control pulmonary valves.

• Median maximum leaflet thickness was 1.540 mm in autografts vs. 0.447 mm in controls (P = 0.004).
• One histologically most affected section per valve was evaluated using QuPath digital morphometry.
• Sample sizes were 5 autografts and 6 controls.

Failed autografts had a larger leaflet cross-sectional area than controls.

• Cross-sectional area was 8.730 mm² in autografts vs. 3.045 mm² in controls (P = 0.004).
• Measurement used the single most affected section per valve (hotspot approach).

Failed autografts had a greater α-SMA-positive area than controls.

• α-SMA-positive area was 0.707 mm² in autografts vs. 0.046 mm² in controls (P = 0.008).
• Assessed by α-SMA immunohistochemistry with digital analysis in QuPath.

The fraction of leaflet area that was α-SMA-positive was higher in failed autografts than in controls.

• α-SMA-positive area fraction was 0.069 in autografts vs. 0.016 in controls (P = 0.017).
• The authors interpret increased α-SMA immunoreactivity in hotspot regions as suggesting a myxomatous-like remodeling pattern.

The study was exploratory with a small sample and a hotspot-based sampling approach.

• Only five failed autografts and six autopsy control valves were analyzed.
• Only one histologically most affected section per valve was evaluated, so results reflect hotspot regions rather than whole-valve averages.