“…This approach can be of certain use probably in the majority of patients with a normal heart, however, in some cases, in particular with the preexisting structural heart disease, the episodes of tachyarrhythmia resulting from an inadequate beta-blockade, and/or a higher percentage of right ventricular pacing can deleteriously influence the left ventricle performance, leading to cardiac remodeling, and ultimately to heart failure. The atrial fibrillation, and the right ventricular pacing have both a well-known negative influence on the left ventricle mechanical performance [2]. Both circumstances decrease the cardiac output contributing, by different mechanisms, to the development of cardiomyopathy whose signs and symptoms could be more pronounced in a previously existing damage or in genetically susceptible individuals [3].…”