Effect of cardiac resynchronization therapy on right ventricular function

The focus only on the left ventricle (LV) for both evaluation of cardiac dyssynchrony and the efficacy of resynchronization therapy (CRT) is too limited to explain the nuances of clinical response to CRT. Right ventricular function, synchrony and remodeling are now commonly characterized noninvasively. This review presents new insights into the role of the right ventricle independently and in conjunction with the LV in determining the clinical efficacy of CRT.

There are patients with predominantly right ventricular dyssynchrony who respond to CRT without reverse remodeling of the LV. Studies of longitudinal axis function of the right ventricle show that contractile function improvement precedes right ventricular reverse remodeling in clinical responders to CRT. The discordance seen in some CRT responders between improvements in left ventricular and right ventricular morphology, function and markers of synchrony is best understood using multiple markers of cardiac longitudinal axis function and cardiac deformation analysis.

Advanced right ventricular dysfunction reduces the likelihood of clinical response to CRT. However, right ventricular contractile function may improve following CRT independent of changes in right ventricular size or volumetric measures of right ventricular function. The consequences of isolated improvements in right ventricular function on CRT-related prognosis deserve further study.