Assessment of atrial conduction time and electromechanical coupling by tissue Doppler echocardiography and p-wave dispersion in patients with mitral annular calcification

Abstract

SUMMARY M itral annular calcification is a common degenerative process involving the fibrous annulus of the mitral valve. It is generally an incidental finding associated with aging although it is occasionally associated with significant mitral regurgitation and can rarely cause symptomatic mitral stenosis. In addition, MAC is associated with atrial fibrillation, conduction system disease, atherosclerotic disease and adverse cardiovascular events, including stroke and mortality. The aim of this study was to investigate atrial conduction time and electro-mechanical coupling in patients with mitral annular calcification non-invasively using 12-lead surface ECG and tissue Doppler echocardiography. This study included 50 patients diagnosed as having mitral annular calcification (MAC) (patients' group) and 50 healthy volunteers (control group). Mitral annular calcification was furtherly divided into mild, moderate and severe. The 100 candidates were subjected to the following: 1- Full history taking and analysis. 2- Complete clinical examination. 3- Twelve-lead surface electrocardiogram recording after 20 minutes resting period in supine position measuring the P-wave duration where the P-wave dispersion was calculated as the averaged P max – the averaged P min. (PWD= P max – P min). 4- Conventional 2D and M- mode echocardiography measuring the LA volume index, LV diameters and LV ejection fraction. MAC was divided into three grades by Chan KL et al., 2007 by the manipulation in the echo gains as follows: A- MILD MAC: involvement of one third or less of the annulus. B- MODERATE MAC: involvement is between one third and two third of the annulus. C- SEVERE MAC: involvement exceeds two third of the annulus. 5- Tissue Doppler imaging was performed while one lead ECG is recorded continuously, and the monitor sweep speed was adjusted at 100 mm/sec to optimize the spectral display of myocardial velocities. Imaging was be studied in the apical 4-chamber view at the level of LV lateral mitral annulus, septal mitral annulus and the right ventricular tricuspid annulus calculating the time interval from the onset from the P- wave on surface ECG to the beginning of the late diastolic wave (A wave) obtained from the different sites.