The present study is the first to evaluate the effect of CRT withdrawal in a reverse remodeled LV in a large group of patients. The current data demonstrate that withdrawal of CRT, even after long-term CRT with clear evidence of LV reverse remodeling, resulted in acute deterioration of LV function and mitral regurgitation. Importantly, this deterioration is accompanied by a more dyssynchronous contraction as demonstrated by an acute increase in LV dyssynchrony. This implies that the beneficial effect of LV reverse remodeling is pacing dependent and that continuous pacing is warranted. However, the parameters did not return to baseline levels, probably as a result of LV remodeling. Preliminary data suggested indeed that long- term withdrawal of CRT may result in return to baseline values (5). Furthermore, the current study evaluated the interruption effect after 6 months of CRT; it is currently unknown if this deterioration would be less during off state after e.g. 12 months or even disappear at some time. Further study is warranted to evaluate the precise effects of CRT over time.
The current data are supported by the findings in the non-responders patients; non-responder patients did not show echocardiographic improvement after CRT and consequently did not show deterioration during withdrawal of CRT.
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in te rru p tio n o f C R T C H A P T E R 1 1Conclusions
Despite the presence of LV reverse remodeling, interruption of long-term CRT resulted in recurrence of LV dyssynchrony as well as deterioration of LV function and mitral regurgitation. Therefore, continuous long-term biventricular pacing is warranted.
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