CARDIAC RESYNCHRONIZATION THERAPY IN HEART FAILURE PATIENTS: HOW TO PREDICT RESPONDERS
M. Pitzalis
The Brody School of Medicine, East Carolina University, Greenville, NC, USA

Cardiac resynchronisation therapy (CRT) has shown beneficial effects including reverse remodeling, improvement in ejection fraction, decrease in mitral regurgitation as well as clinical improvements in exercise tolerance; quality of life and hospitalization rate have been well documented, thus supporting the routine use of CRT as a relevant therapeutic option for patients with severe heart failure (HF) and left intraventricular conduction delay (QRS duration >120ms) who remain symptomatic despite receiving “optimal” medical treatment. However, not all patients have subjective and/or objective responses to CRT. Given the complexity of the procedure and the associated costs, there is a need for parameters other than QRS duration that could prospectively identify the patients who would benefit most.

The benefits of CRT are due to the fact that it corrects dyssynchrony consequent to inter- and intraventricular conduction delay thus counteracting its negative hemodynamic effects. Left ventricular conduction delay induce a particular pathophysiological condition in which abrupt anterior septal motion occurring at the time of decreasing right ventricular volume with pulmonary ejection is associated with a delayed contraction of the postero-lateral left ventricular wall.

On the basis of these considerations, CRT should be offered to those patients with heart failure in whom a consistent degree of asynchrony can be detected. This is why echocardiographic parameters have been investigated. Echo-Doppler-derived measures of asynchrony have the advantage of being non-invasive and therefore, they can be used for patient selection, before the decision of implanting the device is taken.