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During the last decade, cardiac resynchronization, as adjunctive therapy for patients with severe chronic heart failure has been the subject of many clinical trials. From its inception, although the idea of resynchronization had numerous supporters, chiefly those involved in pacing, while there were also a hardly insignificant number of skeptics.
The first encouraging results of cardiac resynchronization therapy (CRT) application were supported in studies that evaluated the hemodynamic benefits. A number of studies followed which examined results in exercise tolerance, quality of life and mortality. These study results showed that in a specific subgroup of patients with heart failure, CRT is an efficacious and beneficial therapy. However, these studies had weak points, mainly perhaps that they were not blinded. Thus, the benefits may be partly due to the closer monitoring of patients with the device. Additionally, a number of issues remain controversial, including the role of CRT in heart failure patients with narrow QRS, in patients with atrial fibrillation or right ventricular failure, as well as the ideal method of patient selection. The latter is particularly significant, as the cost of the therapy is quite high. Although the QRS duration was one of the inclusion criteria in most of the studies, the evidence suggests that inordinate contraction of the left ventricle is an essential for a favourable response. Therefore, for the moment, the progress from study results to clinical practice will have to be undertaken very carefully, to ensure that the patient will indeed benefit.