The Mean Transmitral Gradient in Pure Mitral Stenosis: Is It an Element of Severity or an Indicator of Tolerance in Severe Mitral Stenosis?

Abstract

Background: Rheumatic Mitral Stenosis (MS) remains a frequent valvulopathy in developing countries. Objectives: Our aims were to evaluate the existence of a direct correlation between the Mean Transmitral Gradient (MTG) and the severity of MS in patients with severe or very severe MS, as well as to analyze the different parameters that condition the MTG. Methods and Results: Between January and December 2014, 50 patients (41.7 years of average age, 75% were females) were enrolled for pure and severe or very severe Mitral Stenosis (MS) in the Cardiology department of Ibn Rochd University hospital. All patients underwent complete clinical evaluation with a 12-lead ECG and transthoracic echocardiography. We first studied the correlation between the Mitral Valve Surface (MVS) and the MTG. We then separately analyzed two groups of patients: those with a MTG <10 mmHg (group 1) and those with a MTG≥10 mmHg (group 2). For each group, we performed a univariate correlation of MTG with the clinical, electrocardiographic and echocardiographic data.64% of patients had a severe MS and 36% had a very severe MS. 52% had a MTG <10mmHg and 48% had a MTG≥10mmHg, 80% of patients in group 1 were dyspneic stage II of the NYHA classification and 70% of patients in group 2 were dyspneic stage III (41%) or IV (29%) of the NYHA classification, which means the existence of a significant correlation between MTG and severity of dyspnea. The analytical study of heart rate and the presence of cardiac failure in relation to the MTG showed a significant correlation. The study of sPAP in both groups revealed the existence of a statistically significant correlation (r =0.518 and P <0.001) between sPAP and MTG. Discussion: The MTG is a good indicator of mitral stenosis tolerance, but it is imperfectly reflecting its severity as it depends on several hemodynamic parameters. Authentic severe MS may exist with MTG <10 mmHg, which is why the value of the MTG should never be interpreted alone.