Abstract 12810: Defining the Role of Mitral Regurgitation on Left Atrial Function During Exercise in Left Heart Disease: Insights From CPET Combined With Exercise Echocardiography

Abstract

Background: The role of mitral regurgitation (MR) on left atrial dynamics has not been characterized especially during exercise. Its definition might provide additional clues on the pathogenesis of exercise intolerance in patients with cardiac disorders. We aimed at this goal. Methods: 73 heart failure with reduced (n=51) and preserved (n=21) ejection fraction, 53 aortic stenosis, 27 primary mitral regurgitation, 14 hypertrophic cardiomyopathy, and 42 control subjects underwent cardiopulmonary exercise testing evaluation combined with Echo-Doppler with assessment of left atrial strain (LAS) and MR entity. Patients were divided according to the severity of MR and no MR. Results: LAS during exercise compared to rest was significantly increased in no MR (n=92, 27 ± 10 vs 33 ± 13%, P <0.001) and mild MR (n=41, 24 ± 11 vs 26 ± 15%, P <0.05) group but not in mild-moderate MR (n=31, 20 ± 9 vs 23 ± 14%, P=0.05), moderate-severe MR (n=23, 18 ± 12 vs 19 ± 16%, P=0.4), and severe MR (n=19, 17 ± 14 vs 19 ± 14%, P=0.01) group by visual assessment of the severity of MR during exercise (figure). In 54 patients with MR assessed using proximal isovelocity surface area method both at rest and exercise, effective regurgitant orifice (ERO: 19 ± 12 vs 26 ± 16 mm 2 , P <0.001) and regurgitant volume (31 ± 19 vs 40 ± 24 mL, P <0.001) were significantly increased during exercise, and there was no change in LAS during exercise (17 ± 11 vs 18 ± 14%, P=0.4). A progressive impairment in exercise ventilation efficiency assessed by minute ventilation-carbon dioxide production (VE/VCO2 slope) was observed according to ERO entity (ERO: <20 mm 2 , VE/VCO2 slope: 30 ± 7; ERO: 20-40 mm 2 , VE/VcO2 slope: 33 ± 6; ERO: >40 mm 2 , VE/VCO2 slope: 39 ± 17, P <0.05). Conclusions: In left heart disease patients of any origin, an impaired LAS response during exercise is associated with the presence of MR during exercise. This unfavorable pathophysiological and functional response leads to an impaired exercise tolerance and ventilatory inefficiency.