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Abstract

background Dilated cardiomyopathy (DCM) is characterized by a dilated left ventricle with systolic dysfunction that is not caused by ischemic or valvular heart disease. Left atrial (LA) size is a predictor of adverse cardiovascular outcome both in the general population and in selected clinical conditions. The left atrium modulates left ventricular filling through three components: a reservoir phase during systole, a conduit phase during diastole and an active contractile component during late diastole. During diastole the LA is directly exposed to the left ventricular (LV) cavity pressure. With progressive impairment of LV diastolic function, and the consequent increase in LV end-diastolic pressure, the LA increases in size with a reduction of both the LA passive emptying and conduit functions, with a compensatory increase of the active LA emptying, at least in the first stages of LV diastolic dysfunction.   Methods The study included 50 patients with the diagnosis of DCM (NYHA class I to IV and normal sinus rhythm) and 10 healthy control subjects. Two-dimensional (2D) conventional echocardiography was performed to assess LV dimensions, volumes, ejection fraction (EF), fractional shortening (FS), wall thickness, LA diameter, LA area, Mitral annular plane systolic excursion (MAPSE). Mitral E-wave (E) and A-wave (A) velocities, as well as their ratio (E/A), E’ wave and E/E’ ratio were measured. LA volumes including maximum (at the end of systole), minimum (at the end of diastole) and pre A LA volumes (before atrial contraction) were measured using the modified Simpson method. LA emptying volume (LAEV) and emptying fraction (LAEF), passive emptying volume (LAPEV) and passive emptying fraction (LAPEF) and active emptying volume (LAAEV) and active emptying fraction (LAAEF) were calculated in apical four-chamber view. We measured the peak LA strain, and strain rate during systole and late diastole using speckle tracking echocardiography in both apical four-chamber and apical two-chamber views.   Results Patients with DCM showed a significant increase in LA volumes (Maximum, Minimum and Pre-A volumes) compared with the control group. LAEV and LAEF (reservoir function), LAPEV and LAPEF (conduit function) were significantly lower in patients with DCM compared to normal subjects. No significant difference was observed in LAAEV and LAAEF (pump function) between patients and controls. LA strain and LA strain rate and late diastolic strain rate values were decreased in patients with DCM. A negative correlation between LA strain measured in septal, lateral, anterior, and inferior walls and NYH class was observed. Only LAEV and LAEF (reservoir function) was correlated with NYHA class.   Conclusion In patients with DCM, LA volumes, LA reservoir, Conduit, and pump functions were significantly reduced. Atrial myocardial deformation properties, assessed by strain and strain rate imaging, are abnormal in patients with DCM. The severity of HF symptoms correlated positively with the LA reservoir function and negatively with the LA strain parameters. These findings suggest that LA systolic and diastolic dysfunction assessed either by conventional echocardiography or speckle tracking imaging could be related to reduced functional capacity in patients with DCM.

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43

Last Page

56

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