Clinical profile and immediate outcomes of balloon mitral valvotomy in low gradient rheumatic mitral stenosis

The objective of this study was to assess the clinical, hemodynamic characteristics and immediate outcomes of Percutaneous Balloon Mitral Valvotomy (PBMV) in low gradient severe rheumatic mitral stenosis (LGMS) with normal cardiac index.

The optimal management of LGMS remains incompletely understood.

We examined 200 consecutive patients with severe rheumatic mitral stenosis (MS) who underwent PBMV between January 2014 and March 2020.

Of the 149 patients (who satisfied inclusion criteria), 51 (34.2 %) had LGMS. The mean diastolic pressure gradient (DPG) was 8.70 ± 1.34 mm of Hg in LGMS as compared to 16.2 ± 4.3 mm of Hg in HGMS (p < 0.001). Patients of LGMS were older (39.5 ± 9.7 vs.34.9 ± 11.0 years, p = 0.012), had lower baseline heart rate (76.8 ± 9.5 vs 81.9 ± 12.5, p = 0.010), higher Mitral valve area (MVA) (1.16 ± 0.19 vs 0.99 ± 0.21 cm²,p < 0.001),higher Wilkins score (5.8 ± 1.7 vs 4.9 ± 1.5, p = 0.002) and elevated left ventricular end diastolic pressure (LVEDP) (9.2 ± 2.8 vs 5.8 ± 1.2 mm of Hg,p=<0.001) but lower Pulmonary artery systolic pressure (PASP) (53.1 ± 14.5 vs 62.6 ± 17.8 mm of Hg, p = 0.001) and left atrial (LA) pressure (18.0 ± 3.1vs 22.0 ± 4.4 mm of Hg,p=<0.001). Although, the procedural success rate of PBMV was comparable between LGMS and HGMS (92.2 % vs 96.9 % p = 0.231) but increment in MVA and fall in DPG were significantly higher in HGMS in comparison to LGMS (p-value<0.05).

Significant MS may have "low" gradients during catheterization and yet be symptomatic, and thus low gradients cannot be alone used as a marker of disease severity. LGMS with normal CI is characterized by unique clinical and hemodynamic features. The immediate outcome of PBMV is comparable to HGMS but the hemodynamic parameters to monitor the success of PBMV are significantly different.