|
|
||||||||||
|
J Am Coll Cardiol, 2007; 49:1899, doi:10.1016/j.jacc.2007.02.034
(Published online 20 April 2007). © 2007 by the American College of Cardiology Foundation |
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
* Medizinische Klinik 2, Universitätsklinikum Erlangen, Ulmenweg 18, DE-91054 Erlangen, Germany (Email: olebreithardt{at}gmx.de).
Cardiac resynchronization therapy is an electrical therapeutic approach to treat an electrical conduction delay that in turn causes mechanical failure, mainly within the left ventricle. This pathophysiologic concept has been elaborated and proven in numerous well-designed and well-controlled animal experiments, in hemodynamic studies in humans, and in mathematical models (36) but it is now challenged by a new approach that completely disregards the traditional electrical basis for resynchronization therapy and focuses solely on mechanical dyssynchrony.
Although it seems logical to look closer for the presence of mechanical dyssynchrony, by means of echocardiography or other imaging modalities, before recommending resynchronization therapy, I believe that we cannot completely ignore the electrocardiogram (ECG) at this time. Some important issues have not been addressed by both studies: how to deliver ventricular pacing in patients with normal electrical conduction and how to achieve sufficient ventricular capture to resynchronize ventricular contraction. It would be interesting to learn more about the intrinsic PR interval before pacemaker implantation and how the atrioventricular delays were set to ensure ventricular capture without interruption of atrial filling. How many patients had evidence of complete ventricular capture by the ECG at rest and in how many patients was mechanical resynchronization achieved by fusion between intrinsic activation and the pacing stimuli?
Both trials (1,2) are certainly very intriguing and stimulating, but they are also clearly limited by their design, mainly due to the lack of a control group with inactivated pacing. Thus, the 2 studies can only serve to initiate larger randomized multicenter trials before the ECG can be completely abandoned as a selection criterion for resynchronization therapy.
| References |
|---|
|
|
|---|
Related Articles
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | SUBSCRIPTIONS | CURRENT ISSUE | PAST ISSUES | CARDIOSOURCE | SEARCH | HELP | FEEDBACK |