Impact of interlead distance on immediate and mid-term response to cardiac resynchronization therapy

Figures & data

Figure 1. Echocardiography taken during implantation. aVTI of at least three beats were averaged (A). Myocardial velocity curves obtained and Ts measured in each segment from 4-chamber view (B).

Figure 2. Interlead distance measured as DD, HD and VD on posteroanterior (A) and left lateral (B) fluoroscopy views.

Table I. Baseline characteristics of responders versus non-responders (n = 35).

	Total (n = 35)	Responder (n = 18)	Non-responder (n = 17)	P value
Age (years)	63.0 ± 12.9	63.3 ± 14.1	62.8 ± 12.1	0.938
Gender (male/female)	23/12	12/6	11/6	0.903
Etiology (ischemic/non-ischemic)	8/27	3/15	5/12	0.369
Systemic hypertension	11 (31%)	7(39%)	4 (24%)	0.328
Diabetes mellitus	5 (14%)	3(17%)	2 (12%)	0.679
NYHA functional class (III/IV)	20/15	9/9	11/6	0.380
Systolic blood pressure (mmHg)	114 ± 13	112 ± 11	116 ± 16	0.428
Diastolic blood pressure (mmHg)	70 ± 7	70 ± 7	71 ± 7	0.762
QRS duration (ms)	164 ± 28	168 ± 27	159 ± 30	0.429
LVEF (%)	29 ± 7	27 ± 7	32 ± 7	0.140
LVEDD (mm)	77 ± 11	75 ± 11	78 ± 10	0.422
LVESD (mm)	65 ± 10	65 ± 12	66 ± 10	0.889
MV regurgitation (moderate-to-severe)	22 (63%)	12 (67%)	10 (59%)	0.631
TV regurgitation (moderate-to-severe)	9 (26%)	4 (22%)	5 (29%)	0.627
aVTI (cm)	10.8 ± 1.8	10.6 ± 1.6	11.0 ± 2.0	0.578
Ts-SD (ms)	42 ± 12	44 ± 10	39 ± 13	0.311
Medication
ACEI/ARB	34 (97%)	18 (100%)	16 (94%)	0.296
β-blocker	33 (94%)	18 (100%)	15 (88%)	0.134
Diuretics	32 (91%)	17 (94%)	15 (88%)	0.512
aldosterone antagonist	29 (83%)	16 (89%)	13 (77%)	0.330
Digoxin	17 (49%)	10 (56%)	7 (41%)	0.395
CRT-D/CRT-P	22/13	10/8	12/5	0.358

NYHA, New York Health Association; LVEF, left ventricular ejection fraction; LVEDD, left ventricular end-diastolic diameter; LVESD, left ventricular end-systolic diameter; MV, mitral valve; TV, tricuspid valve; Ts-SD, standard deviation of the time to peak velocity; aVTI, aortic velocity time integral; ACEI, angiotensin-converting enzyme inhibitor; ARB, angiotensin receptor blocker; CRT-D, cardiac resynchronization therapy accompanied with implantable cardioverter defibrillator.

Table II. Comparison of interlead distance with different RV lead positioning.

	Better response site	Poorer response site	p value
aVTI (cm)	15.9 ± 2.3	14.7 ± 2.3	0.001
Ts-SD (ms)	33 ± 7	37 ± 6	0.009
QRS duration (ms)	145 ± 21	156 ± 24	0.047
Localization of RV lead			0.001
Apex	32 (91%)	3 (9%)
RVOT septum	3 (9%)	32 (91%)
Interlead distance/CTR (cm)
DD on P–A view	11.9 ± 4.7	9.7 ± 3.4	0.057
HD on P–A view	6.1 ± 4.2	7.8 ± 3.6	0.078
VD on P–A view	9.6 ± 4.7	4.4 ± 2.8	0.001
DD on lateral view	16.5 ± 4.4	12.4 ± 5.6	0.001
HD on lateral view	11.3 ± 7.0	11.1 ± 5.8	0.779
VD on lateral view	9.8 ± 4.8	4.3 ± 2.8	0.001

RVOT, right ventricle outflow tract; CTR, cardiothoracic ratio; DD direct interlead distance; HD, horizontal interlead distance; VD, vertical interlead distance.

Table III. Comparison of interlead distance between responders and non-responders at 6-month follow-up.

Interlead distance/ CTR (cm)	Responder (n = 18)	Non-responder (n = 17)	P value
DD on P–A view	11.1 ± 4.4	12.9 ± 4.7	0.168
HD on P–A view	5.8 ± 2.6	6.3 ± 5.3	0.568
VD on P–A view	9.1 ± 4.8	10.3 ± 4.4	0.377
DD on lateral view	18.1 ± 4.5	14.8 ± 3.5	0.011
HD on lateral view	14.1 ± 6.6	8.3 ± 6.1	0.004
VD on lateral view	9.4 ± 4.8	10.2 ± 4.96	0.570

CTR, cardiothoracic ratio; DD direct interlead distance; HD, horizontal interlead distance; VD, vertical interlead distance.