QRS fusion complex analysis using wave interference to predict reverse remodeling during cardiac resynchronization therapy.
BACKGROUND
Biventricular (BV) electrical wavefront fusion can induce improvement in left ventricular (LV) size and function during cardiac resynchronization therapy (CRT). Changes in BV wave propagation sequence and duration register in the QRS complex on the standard electrocardiogram. We developed a wave interference method for the characterization of BV fusion to predict LV reverse remodeling.


OBJECTIVE
To develop a simple electrocardiographic method for predicting reverse remodeling during CRT.


METHODS
QRS complexes during left bundle branch block (LBBB) and CRT were analyzed in 375 patients with ejection fraction ≤35% and New York Heart Association class III-IV (Leiden study: n = 226) as well as in patients with ejection fraction ≤40% and New York Heart Association class I-II (REVERSE trial: n = 149) for predictors of ≥10% reduction in left ventricular end-systolic volume at 6 months. CRT-induced changes in ventricular activation (QRS fusion contour), electrical asynchrony (QRS difference = BV-paced QRS - LBBB QRS, in milliseconds), and LBBB substrate (LV activation time and QRS score for LV scar) were quantified.


RESULTS
Multivariable predictors of reverse remodeling were as follows: (1) either of 2 BV fusion patterns: QRS normalization in leads V1 and V2 (n = 66 [18%]; odds ratio [OR] 3.71; 95% confidence interval [CI] 1.26-10.94) or a new or an increased R wave in leads V1-V2 (n = 267 [71%]; OR 1.55; 95% CI 0.65-3.65); (2) QRS difference ≤ -25 ms (OR 2.35; 95% CI 1.12-4.91); and (3) good substrate (low to moderate QRS score and LV activation time ≥110 ms; OR 2.94; 95% CI 1.68-5.14). Remodeling rates were 40% for poor substrate and persistent LBBB QRS complex (absent BV fusion; QRS type 3: n = 42 [11%]) and 97% for the best BV QRS fusion pattern and greater reduction in electrical asynchrony (larger QRS difference).


CONCLUSIONS
Easily determined QRS complex attributes before and after CRT predict LV reverse remodeling.
Brigham and Women's Hospital, Boston, Massachusetts. Electronic address: mosweeney@partners.org.
Michael O
MO
Sweeney
Brigham and Women's Hospital, Boston, Massachusetts.
Anne S
AS
Hellkamp
Leiden University Medical Center, Leiden, The Netherlands.
Rutger J
RJ
van Bommel
Leiden University Medical Center, Leiden, The Netherlands.
Martin J
MJ
Schalij
Leiden University Medical Center, Leiden, The Netherlands.
C Jan Willem
CJ
Borleffs
Leiden University Medical Center, Leiden, The Netherlands.
Jeroen J
JJ
Bax
D000368:Aged; D002037:Bundle-Branch Block / Q000503:physiopathology / Q000628:therapy*; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D004452:Echocardiography; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D016896:Treatment Outcome; D016277:Ventricular Function, Left / Q000502:physiology*; D020257:Ventricular Remodeling / Q000502:physiology*
Bundle branch block; Cardiac resynchronization therapy; Heart failure; Pacing; Waves