Table 1. Summary of QRS area, QRS duration and morphology in relation to echocardiographic response and delayed LV-activation.

Study	Design	Patients (n)	Inclusion	Outcome	ECG/VCG Parameters	Results
*Adjusted for sex, age, iCMP, NYHA class, LBBB, kidney function, various ECG variables, and various mechanical dyssynchrony variables including variables from the CAVIAR score (see text). **Multivariabel model for QRS area, QRS duration and morphology. AHA: according to American Heart Association; AUC: area under the curve; ECG: electrocardiogram; ESC: according to European Society of Cardiology; iCMP: ischemic cardiomyopathy; LBBB: left bundle branch block; LVESV: left ventricular end-systolic volume; Ns: non-significant; NYHA: New York Heart Association; QRSd: QRS duration; Sens: sensitivity; Spec: specificity; VCG: vectorcardiogram.
Van Deursen, et al.[52] (2014)	Prospective	81	Class I and II	LVESV reduction ≥ 15% (echocardiographic response)	1. QRS area > 98 µVs 2. QRSd > 156 ms 3. LBBB 　- conventional 　- AHA 　- Strauss et al.	1. OR 10.2; 95% CI: 3.4 – 31.1) 2. OR 2.5; 95% CI: 0.9 – 6.6) 3. 　- OR 5.5; 95% CI: 0.9 – 32.4 　- OR 4.5; 95% CI: 1.6 – 12.6) 　- OR 10.0; 95% CI: 3.2 – 31.1
Mafi-Rad, et al. [9] (2016)	Prospective	51	Class I and II	LV activation time >75% of QRSd (delayed LV-activation)	1. QRS area　　QRS area > 69 µVs 2. QRS duration 3. LBBB (ESC)	1. AUC 0.89; 95% CI: 0.79 – 0.99　　Sens: 87%; spec: 92% 2. AUC 0.49; 95% CI: 0.33 – 0.65 (ns) 3. Sens 76%; spec 100%
Nguyen, et al.[53] (2018)	Prospective	33	Class I and II	LVESV reduction ≥ 15%	1. QRS area 2. QRS duration	1. AUC 0.74; 95% CI: 0.56 – 0.91 2. AUC 0.64; 95% CI: 0.44 – 0.83 (ns)
MARC[56] (2018)	Prospective	213	Class I and II	LVESVi reduction	1. QRS area 2. QRS duration 3. LBBB	*Adjusted effect estimate 1. -10.4% (P < 0.0001) 2. ns 3. ns
Van Stipdonk, et al.[57] (2018)	Retro- spective	1,491	Class I and II	LVESV reduction ≥15%	1. QRS area quartiles 2. LBBB + QRSd	1. **OR 1.65; 95%CI: 1.43–1.90 2. **OR 1.29; 95%CI: 1.09 – 1.52