Registration Identification Number: NCT00180271.
QRS Axis and the Benefit of Cardiac Resynchronization Therapy in Patients with Mildly Symptomatic Heart Failure Enrolled in MADIT-CRT
Article first published online: 17 DEC 2012
© 2012 Wiley Periodicals, Inc.
Journal of Cardiovascular Electrophysiology
Volume 24, Issue 4, pages 442–448, April 2013
How to Cite
BRENYO, A., RAO, M., BARSHESHET, A., CANNOM, D., QUESADA, A., McNITT, S., HUANG, D. T., MOSS, A. J. and ZAREBA, W. (2013), QRS Axis and the Benefit of Cardiac Resynchronization Therapy in Patients with Mildly Symptomatic Heart Failure Enrolled in MADIT-CRT. Journal of Cardiovascular Electrophysiology, 24: 442–448. doi: 10.1111/jce.12057
The MADIT-CRT study was supported by a research grant from Boston Scientific, St. Paul, Minnesota, to the University of Rochester School of Medicine and Dentistry.
Alon Barsheshet is a Mirowski-Moss Career Development Award Recipient in Cardiology.
Dr. Moss reports receiving honoraria and Dr. Cannom reports receiving travel support from Boston Scientific. Other authors: No disclosures.
- Issue published online: 1 APR 2013
- Article first published online: 17 DEC 2012
- Accepted manuscript online: 15 NOV 2012 08:38PM EST
- Manuscript received 15 August 2012; Revised manuscript received 24 September 2012; Accepted for publication 23 October 2012.
- cardiac resynchronization therapy;
- heart failure;
- implantable cardioverter defibrillator;
- left bundle branch block
Cardiac Resynchronization Therapy and QRS Axis. Background: Mildly symptomatic heart failure (HF) patients derive substantial clinical benefit from cardiac resynchronization therapy with defibrillator (CRT-D) as shown in MADIT-CRT. The presence of QRS axis deviation may influence response to CRT-D. The objective of this study was to determine whether QRS axis deviation will be associated with differential benefit from CRT-D.
Methods : Baseline electrocardiograms of 1,820 patients from MADIT-CRT were evaluated for left axis deviation (LAD: quantitative QRS axis -30 to -90) or right axis deviation (RAD: QRS axis 90–180) in left bundle branch block (LBBB), right bundle branch block (RBBB), and nonspecific interventricular conduction delay QRS morphologies. The primary endpoints were the first occurrence of a HF event or death and the separate occurrence of all-cause mortality as in MADIT-CRT.
Results: Among LBBB patients, those with LAD had a higher risk of primary events at 2 years than non-LAD patients (20% vs 16%; P = 0.024). The same was observed among RBBB patients (20% vs 10%; P = 0.05) but not in IVCD patients (22% vs 23%; P = NS). RAD did not convey any increased risk of the primary combined endpoint in any QRS morphology subgroup. When analyzing the benefit of CRT-D in the non-LBBB subgroups, there was no significant difference in hazard ratios for CRT-D versus ICD for either LAD or RAD. However, LBBB patients without LAD showed a trend toward greater benefit from CRT therapy than LBBB patients with LAD (HR for no LAD: 0.37, 95% CI: 0.26–0.53 and with LAD: 0.54, 95% CI: 0.36–0.79; P value for interaction = 0.18).
Conclusions: LAD in non-LBBB patients (RBBB or IVCD) is not associated with an increased benefit from CRT. In LBBB patients, those without LAD seem to benefit more from CRT-D than those with LAD. (J Cardiovasc Electrophysiol, Vol. 24, pp. 442-448, April 2013)