1. QRS axis and the benefit of cardiac resynchronization therapy in patients with mildly symptomatic heart failure enrolled in MADIT-CRT.
- Author
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Brenyo A, Rao M, Barsheshet A, Cannom D, Quesada A, McNitt S, Huang DT, Moss AJ, and Zareba W
- Subjects
- Action Potentials, Aged, Bundle-Branch Block diagnosis, Bundle-Branch Block etiology, Bundle-Branch Block mortality, Bundle-Branch Block physiopathology, Canada, Chi-Square Distribution, Electrocardiography, Europe, Female, Heart Failure complications, Heart Failure diagnosis, Heart Failure mortality, Heart Failure physiopathology, Humans, Kaplan-Meier Estimate, Male, Middle Aged, Multivariate Analysis, Patient Selection, Proportional Hazards Models, Risk Assessment, Risk Factors, Severity of Illness Index, Stroke Volume, Time Factors, Treatment Outcome, United States, Ventricular Function, Left, Ventricular Remodeling, Bundle-Branch Block therapy, Cardiac Resynchronization Therapy adverse effects, Cardiac Resynchronization Therapy mortality, Cardiac Resynchronization Therapy Devices, Heart Conduction System physiopathology, Heart Failure therapy
- Abstract
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., (© 2012 Wiley Periodicals, Inc.)
- Published
- 2013
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