Electrical remodeling reflected by QRS and T vector changes following cardiac resynchronization therapy is related to survival in heart failure patients with left bundle branch block.
BACKGROUND
We investigated changes in electrocardiographic spatial QRS and T vectors as markers of electrical remodeling before and after cardiac resynchronization therapy (CRT) and their association with altered outcome.


RESULTS
In 41 patients with LBBB, ECGpost was recorded during intrinsic rhythm after interrupting CRT pacing and compared to the pre-implant ECGpre and the ECG during CRT (ECGCRT). Mean spatial angles between QRS and T vectors were determined with the Kors matrix conversion. Left ventricular ejection fraction (LVEF) was determined with nuclear isotope ventriculography before CRT implantation (LVEFpre) and at inclusion (LVEFpost). Following CRT, LVEF improved significantly from 26 ± 10 to 36 ± 14% (p=0.01). Duration of QRSpre (168 ± 15 ms) was not different from QRSpost (166 ± 15 ms). A smaller angle between QRSCRT and Tpost was related to a greater angle between Tpre and Tpost (Pearson's R -0.61 - p<0.001). During follow-up (30 ± 2 months) 9 patients (22%) died. Univariate Cox regression revealed higher mortality in the patients with lower LVEFpost (HR 1.10, p=0.01), a larger angle QRSCRTTpost (HR 1.03, p=0.03), a smaller angle QRSpreQRSpost (HR 0.97, p=0.03) and smaller angle TpreTpost (HR 0.95, p<0.01). After adjusting for LVEFpost, only smaller angle TpreTpost was associated with mortality (HR 0.96, p=0.03).


CONCLUSIONS
Electrical remodeling can be quantified by measuring the angles between spatial QRS and T vectors before, during and after CRT. In absence of QRS duration changes, more extensive electrical remodeling is associated with a significantly better survival. QRS and T vector changes deserve further investigation to better understand the individual response to CRT.
Cardiovascular Centre Aalst, OLV Clinic, Aalst, Belgium; Cardiology, University Hospitals of Leuven, Leuven, Belgium. Electronic address: vincent.flore@outlook.com.
V
V
Floré
Cardiovascular Centre Aalst, OLV Clinic, Aalst, Belgium.
J
J
Bartunek
Cardiovascular Centre Aalst, OLV Clinic, Aalst, Belgium.
M
M
Goethals
Cardiovascular Centre Aalst, OLV Clinic, Aalst, Belgium.
S
S
Verstreken
Cardiovascular Centre Aalst, OLV Clinic, Aalst, Belgium.
W
W
Timmermans
Cardiovascular Centre Aalst, OLV Clinic, Aalst, Belgium.
F
F
De Pauw
Cardiovascular Centre Aalst, OLV Clinic, Aalst, Belgium.
K
K
Van Bockstal
Cardiovascular Centre Aalst, OLV Clinic, Aalst, Belgium.
M
M
Vanderheyden
D000368:Aged; D001530:Belgium / Q000453:epidemiology; D002037:Bundle-Branch Block / Q000401:mortality* / Q000517:prevention & control*; D058406:Cardiac Resynchronization Therapy / Q000401:mortality*; D015897:Comorbidity; D004562:Electrocardiography / Q000379:methods / Q000706:statistics & numerical data*; D005260:Female; D006333:Heart Failure / Q000401:mortality* / Q000517:prevention & control*; D006801:Humans; D015994:Incidence; D008297:Male; D011379:Prognosis; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D015996:Survival Rate; D016896:Treatment Outcome; D020257:Ventricular Remodeling
Cardiac memory; Cardiac resynchronization therapy; Electrical remodeling; T-wave memory