Predictors of persistence of functional mitral regurgitation after cardiac resynchronization therapy: Review of literature

Table 1 Variables that predict mitral regurgitation improvement or lack of improvement

Predictor category	Predictors of MR improvement	Ref.	HR	P value
Clinical parameters	ΔQRS (at least 20 ms) after CRT	[20]	1.242	0.028
	Non ischemic HF etiology	[20]	3.13	0.021
	Baseline presence of LBBB morphology	[20]	2.49	0.032
	QRS narrowing after CRT	[21]	NA	0.001
	Older age	[23]	NA	0.001
	Baseline longer QRS duration	[23]	NA	0.001
Echo imaging	Septal-lateral delay by TDI	[23]	NA	0.001
	Baseline tenting area < 3.8 cm2	[24]	NA	0.02
	Baseline tenting area	[21]	NA	0.01
	Septal-lateral delay by TDI	[22]	NA	0.001
	Baseline inferior papillary muscle time delay	[26]	NA	0.04
	Increase in posterior papillary muscle longitudinal negative strain	[26]	NA	0.01
	Combined presence of delayed longitudinal strain in the mid inferior LV segment and preserved systolic strain in the basal and mid posterior segments	[27]	NA	0.001
	Time to- peak 2-DRS between inferior and anterior LV segments of > 110 ms	[28]	8.4	0.02
	Preserved radial strain in posterior segments assessed by 2-DRS	[28]	7.6	0.006
	MR jet area/left atrium area ratio < 40%	[28]	8.9	0.02
	Anteroseptal to posterior wall radial strain dyssynchrony > 200 ms	[29]	NA	0.028
	Lack of severe left ventricular dilatation (end-systolic dimension index < 29 mm/m2)	[29]	NA	0.042
	Lack of echocardiographic scar at papillary muscle insertion sites	[29]	NA	0.036
Electric-Targeting LV Lead	Degree of delay at the LV lead site	[34]	1.13	0.02
	Predictors of lack of MR improvement
CT imaging	≥ 25% of LVWT < 6 mm inclusive of at least one papillary muscle insertion using CT	[30]	1.04	0.032
Biomarkers	Higher levels of galectin 3	[23]	0.16	0.01

CRT: Cardiac resyncronization therapy; TDI: Tissue Doppler imaging; 2DRS: 2D radial strain; MR: Mitral regurgitation; LVWT: Left ventricular wall thickness; CT: Computed tomography; LV: Left ventricular; NA: Not available.