Author + information
- Niels Risum, MD, PhD∗ (, )
- Joseph Kisslo, MD,
- John Gorcsan 3rd, MD and
- Peter Sogaard, MD, DMSc
- ↵∗The Heart Centre, Department of Cardiology, Copenhagen University Hospital, Rigshospitalet, Blegdamsvej 9, Copenhagen 2100, Denmark
We appreciate Dr. Lim's interest in our recent paper (1).
We demonstrated that patients without typical left bundle branch block (LBBB) contraction by echocardiography, despite LBBB by electrocardiography, have more than a 3-fold risk of death, heart transplant, or left ventricular assist device within 4 years after cardiac resynchronization therapy (CRT) implantation (1). We agree that it is an important point that CRT results in correction of the echocardiographic LBBB-related contraction abnormality but in some cases may cause worsening of the contraction pattern. Indeed, recent studies suggest that CRT can be harmful (2). Our previous work supports that a typical contraction pattern can be reversed by CRT whereas other patterns cannot, in which case a poor outcome can be expected (3). Furthermore, it is evident that LBBB contraction and activation do not always agree. Despite the presence of complete LBBB-activation, scarring of the ventricle may abolish typical LBBB contraction in which case there is no mechanical substrate for CRT (4) and the patient is unlikely to respond favorably (5). This is part of the explanation why it can be important to address mechanical contraction in selection of CRT candidates and why we found identification of typical LBBB contraction by echocardiography to be superior to strict LBBB criteria by ECG (1). We welcome any publications that offer logical descriptors of pathophysiology that relate electrical to mechanical events in the heart. Such studies are important to understand why some patients respond to CRT and others do not.
Please note: Dr. Risum is a speaker consultant for GE Health Care.
Dr. Kisslo is a speaker consultant for GE Health Care and Phillips.
Dr. Gorcsan has received moderate research grants from Medtronic, Biotronik, Toshiba, and GE Health Care.
Dr. Sogaard has received moderate research grants from Biotronik and GE Health Care.
- American College of Cardiology Foundation
- Risum N.,
- Tayal B.,
- Hansen T.F.,
- et al.
- Lumens J.,
- Tayal B.,
- Walmsley J.,
- et al.