EVALUATION OF MITRAL VALVE DIMENSIONS IN THE TERTIARY CARDIAC CENTRE OF KARACHI

Abstract

Background: Current standards for assessing mitral valve dimensions are predominantly based on data from Western populations, which may not be applicable to diverse demographic settings. This study aims to establish normative data for mitral valve dimensions using Transthoracic 2D Echocardiography in the Pakistani population and to explore the variation of these dimensions with demographic variables such as age, gender, body surface area, and ethnicity and to assess the associations between mitral valve dimensions and left ventricle dimensions. Methods: This cross-sectional study was conducted in the period of six months from March to August 2024, that constituted three hundred and eighty-five individuals who fulfilled the inclusion criteria coming to National Institute of Cardiovascular Diseases. Subject evaluation forms were used to note the measurements made by Transthoracic 2D Echocardiography. The mitral valve geometry was assessed based on parameters like age, gender, body surface area, ethnicity. The echocardiographic parameters included annular diameter (long axis and 4-chamber view), annular area, anterior leaflet length, anterior leaflet thickness, posterior leaflet length, posterior leaflet thickness, intercommissural distance, C-septal distance, interpapillary distance, left ventricle’s systolic and diastolic dimensions, septal thickness and posterior wall thickness. Statistical analyses were performed using the Shapiro-Wilk test, Mann-Whitney U tests, Kruskal-Wallis and Spearman’s correlation coefficient test. Results: The echocardiographic measurements reveal significant variations across several factors. Males had a significantly longer posterior mitral valve leaflet compared to females and c-septal distance was found to be larger in males than in females. Similarly, both systolic and diastolic dimensions of the left ventricle were significantly larger in males compared to females. This also extended to left ventricular wall thickness, where males had thicker walls. The diastolic dimension of the left ventricle increased with advancing age and was found to be largest in individuals aged between 46-65 years and then decreased in individuals aged over 65 years. Both the septal thickness and posterior wall thickness increased with age, the walls of the left ventricles were thickest in individuals older than 65 years. Ethnic variations were significant in annular diameter measured in 4-chamber view and posterior wall thickness. Specifically, the Hindku and then Balochi ethnic groups show the largest annular viii diameter, followed by Pashtun, Punjabi, and Sindhi, while the Urdu-speaking group had the smallest annular diameter. The posterior wall of the left ventricle was significantly thicker in Punjabi, followed by Hindku and Balochi, Pashtun and Urdu-speaking had almost similar posterior wall thickness while Sindhi had the thinnest posterior wall. A family history of cardiac diseases was associated with a significantly larger annular diameter and area along with larger systolic and diastolic dimensions of the left ventricle in individuals. Smokers exhibited larger C-septal distances and larger systolic and diastolic left ventricular dimensions compared to non-smokers. Additionally, the majority of mitral valve parameters (annular diameter, area, leaflet lengths, and interpapillary distances) and left ventricular dimensions (systolic and diastolic) showed significant positive correlations with the body surface area, indicating that as the body surface area increases, these parameters also tend to increase. Importantly, these variations in mitral valve geometry were correlated with changes in left ventricular dimensions and wall thicknesses, suggesting that alterations in mitral valve structure could impact left ventricle structure. Conclusion: In conclusion, this study highlights significant variations in echocardiographic measurements influenced by gender, age, ethnicity, family history of cardiac diseases, smoking status, and body surface area. Males exhibited longer posterior mitral valve leaflets and larger C-septal distances, alongside greater left ventricular dimensions and wall thicknesses compared to females. Age-related changes revealed that the diastolic dimension of the left ventricle peaked in individuals aged 46- 65 years before decreasing in those over 65, while both septal and posterior wall thickness increased with age. Ethnic differences were notable, with the Hindku and Balochi groups showing the largest annular diameters and Punjabi individuals having the thickest posterior walls. A family history of cardiac diseases correlated with larger mitral valve annular diameter and area and left ventricular dimensions. Additionally, smokers demonstrated larger C-septal distances and left ventricular dimensions compared to non-smokers. The study found significant positive correlations between most mitral valve parameters and left ventricular dimensions with body surface area.