Left ventricular systolic deformation in subclinical metabolic cardiomyopathies
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Cardiovascular disease is a significant contributor to morbidity and mortality in patients with inherited metabolic disorders or chronic kidney disease. Conventional echocardiography typically identifies cardiac involvement at a more established stage of the disease. Strain echocardiography, which assesses the deformation of the myocardium, has the potential for early detection of subclinical myocardial dysfunction.
This thesis consists of 3 studies of left ventricular myocardial deformation in patients with diseases causing metabolic myocardial alterations, associated with development of cardiomyopathy. In study 1, Doppler strain echocardiography was performed in 40 patients with Stage II and III chronic kidney disease. In study 2, speckle strain echocardiography was performed in 68 patients who underwent renal transplantation in childhood, and in study 3, speckle strain echocardiography was performed in 38 patients with Fabry disease. In all studies, the ability of strain echocardiography to detect subclinical cardiac dysfunction not detected by conventional echocardiography was studied.
As demonstrated by the results of this thesis, echocardiography, using Doppler or speckle strain, detected impaired left ventricular long axis function in the studied patient groups. In particular, left ventricular longitudinal strain was reduced, while ejection fraction, measured by conventional echocardiography, was generally preserved in patients with early-stage chronic kidney disease and in patients with mild Fabry disease compared to healthy subjects. Furthermore, having metabolic disease was associated with lower left ventricular systolic strain independent of left ventricular mass. In patients who underwent childhood renal transplantation, hypertension was common and a main covariate of left ventricular diastolic dysfunction. In contrast, left ventricular systolic deformation was comparable between patients and healthy subjects.
In conclusion, Doppler or speckle strain echocardiography, may detect impaired myocardial function in patients with diseases causing metabolic myocardial alterations, in spite of normal findings on conventional echocardiography and without clinical evidence of heart disease.