Influence of exercise-induced pulmonary hypertension on exercise capacity in asymptomatic degenerative mitral regurgitation

Background: Exercise capacity is helpful in the management of patients with mitral regurgitation (MR). However, the determinants of exercise capacity reduction in MR have remained unclear. This study was designed to objectively assess exercise capacity, identify the echocardiographic predictors of exercise capacity, and investigate its impact on development of symptoms in asymptomatic degenerative MR.

Methods: A total of 49 consecutive asymptomatic patients (age, 58.9±13.1 years; 82% males) with at least moderate degenerative MR (effective regurgitant orifice area=0.40±0.14cm(2); regurgitant volume=60.9±19.6mL) underwent the symptom-limited cardiopulmonary exercise testing for assessing exercise capacity (peak oxygen uptake, peak V˙O2; the minute ventilation/carbon dioxide production, V˙E/V˙CO2 slope). All patients also underwent exercise stress echocardiography for detecting exercise-induced pulmonary hypertension (EIPH) defined by systolic pulmonary arterial pressure (SPAP) ≥60mmHg.

Results: The mean peak V˙O2 was 22.6±5.1mL/kg/min (86.7±14.1% of age, gender-predicted); peak V˙O2 widely varied (48-121% of predicted), and was markedly reduced (<80.4% of predicted) in 24% of the study patients. The patients with EIPH had lower 2-year symptom-free survival than those without EIPH (p=0.003). The multivariable analysis demonstrated that EIPH was an independent echocardiographic determinant of peak V˙O2 (p=0.001) and V˙E/V˙CO2 slope (p=0.021). Furthermore, the area under curve of age- and gender-adjusted exercise SPAP was 0.88 (95% confidence interval: 0.78-0.97) for reduced exercise capacity.

Conclusions: In asymptomatic moderate to severe degenerative MR, EIPH was independently associated with exercise capacity and predicted the occurrence of symptoms. Exercise stress echocardiography is an important tool in managing patients with asymptomatic degenerative MR.