How to discriminate responders from non-responders to cardiac resynchronisation therapy
Medizinische Klinik I, Klinikum der RWTH Aachen, Pauwelsstrasse, Aachen, Germany
Received 3 May 2004; accepted 24 May 2004.
* Christoph Stellbrink, Medizinische Klinik I, Klinikum der RWTH Aachen, Pauwelsstrasse 30, 52057 Aachen, Germany. Tel.: +49-241-8089945; fax: +49-241-8082414
cstellbrink{at}ukaachen.de
Abstract
Cardiac resynchronisation therapy (CRT) has been increasingly accepted as an adjunct therapy to drug treatment for heart failure patients with ventricular conduction delay. Nevertheless, using implant criteria from current guidelines, 20–30% of patients show no or only minor functional benefit. One important reason for this is the fact that these criteria rely mainly on QRS width as a measure of left ventricular dyssynchrony. However, QRS width may not always correlate well to mechanical dyssynchrony which is the main abnormality to be treated by CRT. Several methods have been proposed to assess left ventricular dyssynchrony, such as cardiac magnetic resonance imaging (MRI) or echocardiography. Because MRI is not repeatedly available in pacemaker patients, echocardiography is emerging as the most promising technique both for the identification of therapy responders and the assessment of optimal CRT delivery. However, none of the proposed echocardiographic criteria has yet been validated in prospective trials. This review summarizes the current knowledge on the optimal identification of therapy responders to CRT.
Key Words: Cardiac resynchronisation therapy • Pacemaker • Heart failure • Left bundle branch block