Page 115 - Simplicity is Key in CRT

the primary endpoint than the patients with a QRS area <109ųVs, with a relative risk reduction of 49% (p<0.001, HR 0.51 [0.36, 0.73]). (Figure 4C) In the group of patients with a class I indication for CRT, patients with QRS area ≥109ųVs also showed a significantly higher event free survival that those with QRS area <109ųVs, with a relative risk reduction of 46% (p<0.001, HR 0.54 [0.41, 0.70]). (Figure 4D)
A multivariable regression model for the entire cohort, including the combination of LBBB and QRS duration and quartiles of QRS area showed that only QRS area remained significantly associated with the primary endpoint (p<0.001, HR 0.75 [0.69, 0.83]), whereas the combination of LBBB and QRS duration was not independently associated to the occurrence of events (p=0.134). (Table 2) Also in patients other than those with LBBB and QRS duration ≥150ms the association with the primary endpoint was only significant for QRS area (p<0.001, HR 0.49 [0.34, 0.71]), and not for QRS duration or LBBB morphology (p=0.094 and p=0.671 respectively). (Table 2)
Table 2. Uni- and multivariable logistic regression for ECG parameters and the association with clinical outcomes and echocardiographic response to CRT.
Univariable Regression
Multivariable Regression
Variable
p
OR/HR* [95% CI]
p
OR/HR* [95% CI]
LVAD, cardiac transplantation, all-cause mortality
All
LBBB + QRSd QRS area quartiles
<0.001 <0.001
0.80 [0.73, 0.86] 0.73 [0.67, 0.79]
0.134 <0.001
0.93 [0.69, 1.02] 0.75 [0.69, 0.83]
Non-Class I
LBBB morphology QRSd
QRS area
0.032 0.049 <0.001
0.76 [0.59, 0.98] 0.77 [0.59, 0.99] 0.51 [0.36, 0.73]
0.671 0.094 <0.001
0.93 [0.66, 1.30] 0.74 [0.52, 1.05] 0.49 [0.34, 0.71]
Class I
QRS area
<0.001
0.54 [0.41. 0.70]
-
-
HF hospitalization within 1 yr of implantation
All
LBBB + QRSd QRS area quartiles
0.030 0.004
0.81 [0.67, 0.98] 0.74 [0.61, 0.91]
0.711 0.019
0.96 [0.76, 1.21] 0.76 [0.60, 0.96]
Non-Class I
LBBB morphology QRSd
QRS area
0.483 0.891 0.085
0.81 [0.45, 1.46] 1.05 [0.55, 1.99] 0.44 [0.17, 1.12]
- - -
- - -
Class I
QRS area
0.001
0.43 [0.27, 0.70]
-
-
Echocardiographic responder
All
LBBB + QRSd QRS area quartiles
<0.001 <0.001
1.69 [1.47, 1.96] 1.82 [1.61, 2.07]
0.002 <0.001
1.29 [1.09, 1.52] 1.65 [1.43, 1.90]
Non-Class I
LBBB morphology QRSd
QRS area
0.004 0.324 0.007
1.85 [1.22, 2.80] 0.79 [0.50, 1.26] 1.90 [1.19, 3.03]
0.20 - 0.031
2.01 [1.12, 3.62] -
1.70 [1.05, 2.76]
Class I
QRS area
<0.001
3.54 [2.38, 5.28]
-
-
*Odds and Hazard ratio are reported for Logistic and Cox regressions respectively, used when appropriate for the selected endpoint. HF, heart failure; LBBB, left bundle branch block; LVAD, left ventricular assist device; LVESV, left ventricular end-systolic volume, QRSd = QRS duration
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