Dynamic assessment of 'valvular reserve capacity' in patients with rheumatic mitral stenosis

Mitral stenosis (MS) may exhibit a dynamic valvular reserve. When resting gradients and systolic pulmonary pressure (sPAP) do not reflect the real severity of the disease, a dynamic evaluation becomes necessary. The aim of the study was to assess the clinical utility of exercise echocardiography in symptomatic patients with apparently subcritical MS.

One hundred and thirty consecutive patients were referred for symptomatic MS. Patients with unimpressive resting MVA (>1-1.5 cm(2)) and mean PG (≥5-9 mmHg) underwent exercise echocardiography. Cardiac performance and mitral indices (MVA, peak/mean PG, sPAP) were measured. Exhaustion of valvular reserve capacity under exercise was defined as appearance of symptoms and sPAP > 60 mmHg. Forty-six patients (35%) (age: 53 ± 10 years; 74%, female) with resting MVA (1.2 ± 0.36 cm(2)), mean PG (6.8 ± 2.7 mmHg), and sPAP (38 ± 7 mmHg) inconsistent with symptoms underwent stress echocardiography. Exercise was stopped for dyspnoea (76%) or fatigue (24%). At peak workloads (57.2 ± 21.8 Watts), increased mean PG (17.2 ± 4.8 mmHg, P< 0.001) and sPAP (67.4 ± 11.4 mmHg; P< 0.0001) were observed, without change in MVA (1.25 ± 0.4 cm(2); P= n.s.). At univariate analysis, predictors of adaptation to exercise were age (-0.345; P = 0.024), mean PG (0.339; P= 0.023), and sPAP (0.354; P= 0.024); at multivariate analysis, best predictor was resting mean PG, although correlation was poor (-0.339; P= 0.015).

In MS with limiting symptoms despite unimpressive findings at rest, valvular capacity exhaustion should be tested on a dynamic background, as no single resting index can predict potential haemodynamic adaptation to exercise. In such context, the contribution of exercise echocardiography remains extremely valuable.