(15,16)
Dyssynchrony is considered one of several mechanisms that RV pacing can cause myocardial dysfunction. Pacing of RV apex leads to both inter-ventricular and intra-ventricular dyssynchrony which in turn reduces LV systolic function and leads to adverse clinical outcomes.(17) Long-term studies suggested that more than 40% of RV pacing in rate modulated (DDDR) mode is predictive of unfavorable events as HF hospitalization.