Mitral Stenosis and Atrial Fibrillation

In moderate or severe mitral stenosis, pressure overload and progressive remodeling of the left atrium occur. This creates a substrate for atrial fibrillation (AF) and thrombus formation (most commonly in the left atrial appendage).

Mitral Stenosis – Classification (Echocardiography)
Echo parameter	Mild	Moderate	Severe
MVA (cm²) Mitral Valve Area	> 1,5	1 – 1,5	< 1
MV meanPG (mmHg) Mitral Valve mean Pressure Gradient	< 5	5 – 10	> 10
RVSP (mmHg) Right Ventricular Systolic Pressure	< 30	30 – 50	> 50

Due to the stenosis, blood stasis develops in the left atrium and its appendage. A hypercoagulable state arises in the atrium, further potentiated by AF.

Therefore, AF and moderate or severe mitral stenosis require anticoagulant therapy with Warfarin (not NOAC), regardless of the CHA₂DS₂-VA score.

Warfarin is more effective than NOAC because it blocks the coagulation cascade at four levels,
whereas NOAC block the coagulation cascade at only one level.

Illustration of valvular atrial fibrillation in moderate to severe mitral stenosis with an ECG recording of atrial fibrillation and indication for anticoagulation with warfarin.

The prevalence of mitral stenosis in the population is < 1%.

of which 10–20% have moderate or severe mitral stenosis.

AF is present in 50–80% of patients with moderate or severe mitral stenosis.

AF with moderate or severe mitral stenosis carries a thromboembolic risk of 5–10% per year.

in patients without anticoagulant therapy.

Anticoagulant Therapy and Mitral Stenosis	Class
In patients with atrial fibrillation and moderate or severe mitral stenosis, Warfarin is always indicated, regardless of the CHA₂DS₂-VA score.	I