Complementary strategies to improve positive response and outcome in patients with advanced heart failure undergoing CRT therapy
Abstract: AbstractCardiac resynchronization therapy (CRT) has improved quality of life and survival in select heart faillure patients, however 30-40% of patients do not show objective benefit from the treatment. At the same time there is little evidence about the long term effect of changes in medical treatment in these patients. Several factors have been examined to improve the response rate in the ”non-responder” group, however this is still a challenge.Paper I. investigated the feasibility and incremental value of using an integrated bullseye model for presenting data from cardiac computed tomography, magnetic resonance imaging and echocardiography for evaluation of segmental mechanical delay for guiding optimal left ventricular lead placement in CRT. 39 patients were included in a prospective design, and it was found that the new method is conventient for identification of the appropiate site of LV lead placementPaper II. examined the value of speckle-tracking radial strain to predict the presence of scar in the left ventricle. The strain values in the respective segment were compared to magnetic resonance imaging in 34 prospectively included patients, in a total of 404 left ventricular segments. It was found that the prespecified 9.8% cut off value has low predictive value for identification of transmural scar, and therefore in patients with ischemic heart disease, magnetic resonance imaging should be considered as preoperative evaluation in order to avoid placing the left ventricular pacing electrode in scar tissue.Paper III examined the the correlation of echocardiographic and clinical response to baseline demographics in relation to change in NT-proBNP levels at 6 months post-implant. 211 CRT patients were included retrospectively and NT-proBNP, echocardiographical factors, NYHA class were compared, and 4 groups were identified; (nonresponder, echo reponder, clinical responder and double responder). A reduction of NT-proBNP of more than 25% was able to separate the nonresponders from the other groups, and the most pronounced reduction was in the double responder group. At the same time, lack of NT-proBNP reduction was associated with worse prognosis.Paper IV investigated the association of medical therapy changes on morbidity and mortality in CRT treated patients, with focus on diuretic therapy. 211 patients were included, and it was concluded that furosemide therapy more than 40mg daily was associated with higher risk for mortality and morbidity, but was not associated with an improvement of heart failure symptoms, or greater likelihood of positive remodelling from CRT.In this thesis it was found, that magnetic resonance imaging in combination with cardiac computed thomography and echocardiography is feasible to present the latest left ventricular segment with suitable vein acess on a bullseye plot. At the same time, using a cut-off radial strain value 9.8% alone has low sensitivity, but by using it in combination with data from neighbouring segments it was able to evaluate the presence of scar. Biochemical marker NT-proBNP reduction in CRT patients of less than 25% was associated with non-response to CRT. The reduction of this heart failure marker has a stronger colleration with clinical symptoms than with reverse remodelling on echocardiograpy. The long term effect of furosemide therapy in mortality and morbidity in CRT patients carries negative prognostic value. Optimization of medical therapy after CRT implantation may be important.
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