P763 Asymptomatic severe organic mitral regurgitation: Does the anatomic substrate affect the functional response to supine ergometry?

Abstract

Abstract Asymptomatic severe mitral regurgitation (MR) remains a grey zone in decision making for intervention. The predictive role of left ventricular (LV) functional reserve remains uncertain and the potential role of the anatomical substrate has not been elucidated. Aim of the study was to compare the LV function and hemodynamic changes during supine ergometry (Ex) in asymptomatic severe MR between myxomatous (Myx) and degenerative (Deg) substrate. Methods 32 patients with Deg (male M/female F = 15/17) and 19 with MyxS (M/F = 7/12) were studied at rest (R) and Ex. We estimated heart rate (HR), rate-pressure product (HRxBP), LV endsystolic (LVESV)- enddiastolic volume (LVEDV), ejection fraction (EF), LV longitudinal strain (GLS), transmitral E wave (E), ratio E/e, peak tricuspid gradient (TrPG). To adjust for a potential volume effect on GLS, GLS was normalized to volumes and respective ratios were considered (GLS/LVESV, GLS/LVEDV). Parameters were measured at R and Ex and % changes were calculated : %d (Ex-R). Results Myx and Deg had similar chronotropic reserve and HR-BP. Myx were younger, and during Ex they had a greater LVEDV, a greater EF. a smaller E/e, and a smaller TrPG compared with Deg. Myx group, despite having a better GLS both at R and Ex, revealed a smaller % GLS improvement from R to Ex (15% vs 32%). The normalized GLS/LVESV and GLS/LVEDV were similar at R between Myx and Deg, but they showed a smaller improvement during Ex in Myx. (table-results) Conclusion Despite similar severity of MR, asymptomatic patients with MyxS revealed a different dynamic profile during Ex compared with Deg. The underlying MV substrate in organic MR might be related with a different LV adaptation to volume loading combined with subsequent uneven stress induced hemodynamic response. The disparities found might have implications both in the nature history of MR as well as in the decision making for intervention. RESULTS Parameter DegS MyxS p Age(years) 65 ± 11 44 ± 12 <0. 001 LVEDV Ex (ml) 85 + 32 117 ± 41 =0. 007 EF Ex(%) 65 + 7 69 ± 8 =0. 05 GLS R(%) -17.6 ± 6.8 -22.2 ± 4.3 =0. 04 GLS Ex(%) -22 ± 4 -25.0 ± 5.7 =0. 05 % d (Ex-R) LV strain/endsystolic volume 0.84 ± 0.4 -0.54 ± 0.5 =0. 05 E/e" Ex 16.7 ± 8.8 9.7 ± 2.2 =0. 004 TrPG Ex(mmHg) 59 ± 11 44 ± 11 =0. 0001