175 Changes in Systolic Pulmonary Arterial Pressure during Exercise are Related to Changes in Mitral Regurgitation

Abstract

Current guidelines recommend mitral surgery for asymptomatic patients with severe organic mitral regurgitation (OMR) and preserved LV systolic function when exercise pulmonary hypertension (PHT) is present. However, the determinants of exercise-induced PHT in such patients have not been evaluated. Resting and exercise transthoracic echocardiography were performed in 66 consecutive patients (61±15 years, 55% of male) with significant OMR. MR severity evaluated using effective regurgitant orifice (ERO) area. Systolic pulmonary arterial pressure (PAP) was derived from tricuspid regurgitation peak velocity and exercise PHT was defined as transtricuspid pressure gradient ≥50mmHg. Compared to patients with exercise PAP <50mmHg, those with exercise PHT (n=28, 42%) were significantly older. There was no significant difference between the 2 groups with regard to resting and exercise LV functions and to resting ERO. Nonetheless, patients with exercise PHT had higher exercise ERO (50±22 vs. 38±14mm 2 , p=0.03). The changes in ERO during exercise were significantly higher in patients with PHT (8±12 vs. -2±12mm 2 , p=0.004). Regarding to peak exercise PAP, the best correlations were found with age (r=0.39, p=0.007) and exercise ERO (r=0.47, p=0.0009). Moreover, changes in PAP during exercise were only correlated with the changes in ERO (r=0.50, p=0.0012). On multivariate analysis, after adjustment for age, sex and resting PAP, exercise-induced changes in ERO were independently associated with the changes in PAP (ERO: β=0.4, p=0.002). In addition, changes in MR severity were also independent predictors of exercise PHT (ERO: odds-ratio (OR) =1.2, 95%CI: 1.1-1.4, p=0.0008). Exercise PHT is frequent in patients with OMR. Changes in MR severity during exercise are the main determinants of exercise-induced changes in systolic PAP. Further studies are needed to evaluate whether changes in MR severity during exercise may have a prognostic impact in patients with OMR.