Cardiac Resynchronization Therapy Upgrade
This article requires a subscription to view the full text. If you have a subscription you may use the login form below to view the article. Access to this article can also be purchased.
The implant rates of cardiac resynchronization therapy (CRT) increased rapidly through the first decade of this millennium but have plateaued more recently and may even have started to decrease in Europe and the United States.1,2 The upgrade of existing pacemakers and implantable cardioverter defibrillators (ICDs) to CRT currently accounts for a quarter of all CRT procedures3 and is a potential growth area. Kiehl et al4 recently showed that 12.3% of patients with preserved left ventricular (LV) function who were implanted with a pacemaker for complete heart block developed pacing-induced cardiomyopathy, but the small proportion that underwent CRT upgrades responded well echocardiographically. The 2012 ACCF/AHA/HRS (American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society) Guideline5 gives a class IIA recommendation to CRT upgrade at generator replacement if LV function is severely impaired and the expected pacing requirement is high. The 2013 ESC (European Society of Cardiology) guideline6 goes further and gives a class I (level of evidence B) recommendation to CRT upgrade in device patients with LV ejection fraction <35% and high-percentage ventricular pacing. Advances in left ventricular lead design and lead delivery systems mean that CRT is usually technically straightforward and a much quicker procedure than ever before. Should we, therefore, be upgrading more patients with LV leads? The ACCF/AHA/HRS and ESC device upgrade guidelines are not based on any large randomized studies. Although data exist that heart failure patients with left bundle branch block and a QRS duration >150 ms are most likely to respond to de novo CRT therapy,7 it is not clear whether upgrade patients respond in the same way.
See Article by Vamos et al
In this respect, Vamos et al8 are to be congratulated for adding to the …