Left atrial mechanical functions in patients with the metabolic syndrome.

OBJECTIVE: Metabolic syndrome (MS) is a cluster of risk factors leading to cardiometabolic diseases.The aim of the present study was to investigate the effect of MS on left atrial function, which is an important determinant of left ventricular filling.

METHODS: Left atrial (LA) volumes were measured echocardiographically in 32 MS patients and 32 age- and sex-matched controls. LA volumes were determined at the time of mitral valve opening (maximal, Vmax), at the onset of atrial systole (p wave on the electrocardiogram, Vp) and at the mitral valve closure (minimal, Vmin) according to the biplane area-length method in apical 4-chamber and 2-chamber view. All volumes were corrected to the body surface area, and following left atrial emptying functions were calculated. LA passive emptying volume =Vmax- Vp LA passive emptying fraction = LA passive emptying volume/Vmax . Conduit volume= LV stroke volume - (Vmax- Vmin), LA active emptying volume =Vp- Vm,, LA active emptying fraction= LA active emptying volume/Vp, LA total emptying volume = (Vmax -Vmin), LA total emptying fraction = LA total emptying volume/Vmax. RESUITS: LA maximal volume and LA presystolic volume were significantly higher in MS patients than in controls (P <0.001). But LA minimum volume was significantly lower in MS patients than in controls (P <0.001). Although LA passive emptying volume (P <0.03), LA passive emptying fraction (P <0.001) and conduit volume (P <0.001) were found to be significantly lower in MS patients than in controls, LA active emptying volume (P <0.001) and LA active emptying fraction (P< 0.001) were significantly greater in MS patients than in controls. Conclusion In our study, metabolic syndrome was associated with increased left atrial volume, decreased left atrial passive emptying function and increased pump function. Increased left atrial pump function represents a compensatory mechanism in patients with MS.Thus, these results underline the importance of maintaining a sinus rhythm in these patients.