Aims: We assessed early and long-term pulmonary function changes after percutaneous balloon mitral valvotomy (PBMV).
Methods and results: Mitral area, lung function, and exercise capacity were evaluated before, immediately after, and 3 months, 6 months, and 12 months after successful PBMV in 24 patients. PBMV resulted in a significant and sustained increase in mitral area, from 1.0 ± 0.1 to 1.9 ± 0.1 cm2 (p = 0.001) [mean ± SD], with a progressive increase in exercise tolerance at 6-month follow-up (from 22.6 ± 1.4 to 28.2 ± 1.2 mL/kg, p = 0.0001). An immediate drop in the diffusing capacity of the lung for carbon monoxide (Dlco) was observed (from 26.7 ± 1.5 to 22.3 ± 1.1 mL/min/mm Hg, p = 0.0002) after PBMV, followed by a gradual regression to baseline values at 3 months; at 1 year, the Dlco remained elevated (27.3 ± 6.3 mL/min/mm Hg). The flow in the small airways was reduced at baseline, and there was no significant change during follow-up.
Conclusions: PBMV produces an initial decrease in Dlco, suggesting a reduction of pulmonary congestion. During follow-up, the regression to the initial lung diffusion values despite a sustained hemodynamic improvement suggests that some irreversible interstitial changes were present. In patients with mitral stenosis, an impairment of lung function parameters suggests that PBMV must be performed early, even if patients have few symptoms.