Long-Term Follow-Up in Severe Mitral Stenosis With Low Transmitral Diastolic Pressure Gradient: From MASTER Registry.

Background: Long-term follow-up studies in severe mitral stenosis (MS) with low transmitral mean diastolic pressure gradient (MDPG) are not available. We evaluated the prognostic implications of severe MS with low MDPG in our MASTER (Multicenter Mitral Stenosis with Rheumatic Etiology) registry.

Methods: We included patients with severe rheumatic MS (mitral valve area ≤1.5 cm²) from the long-term MASTER registry. Patients were categorized into high (≥5 mm Hg) or low (<5 mm Hg) MDPG groups. The primary outcome was a composite of all-cause mortality and stroke.

Results: Among 1248 patients with severe MS, 322 (25.8%) had low MDPG and 926 (74.2%) had high MDPG. Their mean age was 59±13 years, 25% were men, and 74% had atrial fibrillation. Patients with low MDPG were older and had a higher prevalence of atrial fibrillation. During a mean follow-up of 6.8±5.9 years, 194 (15.5%) patients experienced major adverse events. Patients who had low MDPG sustained more events than those with high MDPG (hazard ratio, 1.56 [95% CI, 1.15-2.12]; P=0.004), and low MDPG was independently associated with poor outcome (hazard ratio, 1.42 [95% CI, 1.02-1.97]; P=0.038) in the multivariable model. In the subgroup analysis of patients with low MDPG, decreased LA reservoir strain was independently associated with poor outcome (hazard ratio, 3.22 [95% CI, 1.25-8.31]; P=0.016).

Conclusions: Severe patients with MS and low MDPG carried a greater risk of adverse events than those with high MDPG and had less frequent and delayed mitral valve intervention. Also, it is not necessarily indicative of milder hemodynamic encumbrance. LA reservoir strain could help identify a subgroup associated with poor prognosis in patients with low MDPG.