(P265) THE ROSS PROCEDURE IS ASSOCIATED WITH LOWER LEFT VENTRICLE WORKLOAD WHEN COMPARED WITH MECHANICAL AORTIC VALVE REPLACEMENT

Background: Several studies have demonstrated better long-term outcomes after aortic valve replacement (AVR) with a pulmonary autograft (Ross procedure) compared with a mechanical prosthesis. This study seeks to evaluate whether the pulmonary autograft leads to lower left ventricle (LV) workload at rest and during exercise.

METHODS AND RESULTS: Forty participants were included (20 patients who underwent a Ross procedure and 20 patients with a mechanical AVR). Patients were matched in a 1:1 ratio. All participants underwent maximum oxygen consumption (peak VO2) measurements, rest and stress echocardiography. Left ventricle workload was assessed at rest and during exercise using valvulo-arterial impendance (Zva) and energy loss index (ELI). LV strain was also analyzed using cardiac magnetic resonance imaging. Patients had similar baseline characteristics. Ross and mechanical AVR patients reached similar levels of peak VO2 (23.2±6.2 mL/min/kg vs 23.7±6.0 mL/min/kg, p=0.79). Mean aortic valve gradients were lower in Ross patients (Rest: 2.7±1.5 mmHg vs 12.4±4.6 mmHg, p< 0.01; Exercise: 6.5±3.7 mmHg vs 23.1±9.1 mmHg). ELI at rest (3.0±1.2 cm2/m2 vs 1.3±0.5 cm2/m2, p< 0.01) and during exercise (2.5±1.0 cm2/m2 vs 1.2±0.3 cm2/m2, p< 0.01) were lower in the Ross group (Figure 1). Zva was similar between Ross and mechanical AVR patients at rest (3.4±0.8 mmHg·mL−1·m−2 vs 3.5±0.9 mmHg·mL−1·m−2, p=0.76) and during exercise (4.4±1.2 mmHg·mL−1·m−2 vs 5.1±1.3 mmHg·mL−1·m−2, p=0.06). The increase in Zva from baseline to peak exercise was lower in patients who underwent a Ross procedure (1.0±0.9 mm Hg·mL−1·m−2 vs 1.6±0.9 mm Hg·mL−1·m−2, p< 0.01). Global longitudinal strain was similar at rest (-14±2% vs -14±2%, p=0.75) but was significantly improved in the Ross group at peak exercise (p= 0.03 for difference in slopes). Furthermore, the proportion of patients reaching normal strain values at peak exercise was greater in the Ross group (from 10% to 65%, p< 0.01) when compared with mechanical AVR (from 10% to 35%, p=0.07). Similar findings were observed in analyzing radial long-axis ([Ross: 15% to 80%, p< 0.01] vs [mechanical AVR: 30% to 45%, p=0.45]) and radial short-axis strain ([Ross: 60% to 95%, p< 0.01] vs [mechanical AVR: 65% to 70%, p=0.13]).

Conclusion: These findings demonstrate that a living valve is associated with a lower LV workload and lower LV strain during exercise when compared to mechanical AVR. This characteristic may provide a physiological explanation for the better long-term survival after the Ross procedure.