Baseline characteristics
Two hundred fifty patients underwent CRT implantation; among them, 7 were excluded because of missing follow-up data. Hence, our study population comprised the remaining 243 patients, of which 102 (42%) were ≥75 years old. The baseline characteristics according to the age groups are summarized in Table 1. The patients were predominantly male, but there were more females in the ≥75-year-old group (23%) than in the <75-year-old group (13%) (p=0.04). A larger proportion of the patients ≥75 years old compared with those ≥75 years old had severe symptoms according to the NYHA class, had chronic kidney disease (CKD, defined by estimated glomerular filtration <60 ml/min/1.73 m²), and were receiving loop diuretics, but fewer patients in this group were receiving aldosterone antagonists. However, patients ≥75 years old were less likely to have defibrillator than those <75 years old (52% versus 87%, respectively; p<0.001). Both groups had a comparable level of LVEF impairment, with a median LVEF of 28% (23.5-30), and mostly a LBBB QRS morphology (79%). There was no difference regarding the proportion of upgraded devices, CRT for rescue therapy and time of the procedure.
Table 1. Baseline characteristics and outcomes
|
<75 years old (n=141)
|
≥75 years old (n=102)
|
p value
|
Age (years)
|
64 (10)
|
79 (7)
|
<0.001
|
Male sex, n (%)
|
122 (87)
|
78 (77)
|
0.04
|
Ischemic cardiomyopathy, n (%)
|
71 (50)
|
63 (62)
|
0.08
|
Atrial fibrillation, n (%)
|
66 (47)
|
56 (57)
|
0.14
|
Diabetes mellitus, n (%)
|
44 (31)
|
29 (29)
|
0.71
|
CKD, n (%)
|
62 (49)
|
68 (72)
|
0.001
|
NYHA functional class, n (%)
|
|
|
|
I
|
3 (2)
|
1 (1)
|
0.01
|
II
|
57 (40)
|
22 (21)
|
III
|
52 (37)
|
62 (61)
|
IV ambulatory
|
7 (5)
|
7 (7)
|
IV in hospital
|
22 (16)
|
10 (10)
|
Rescue CRT, n (%)
|
14 (10)
|
8 (8)
|
0.58
|
Beta blocker, n (%)
|
119 (85)
|
78 (79)
|
0.21
|
ACEI or ARB, n (%)
|
112 (80)
|
71 (72)
|
0.14
|
Aldosterone antagonist, n (%)
|
71 (51)
|
36 (36)
|
0.03
|
Loop diuretic, n (%)
|
105 (75)
|
85 (86)
|
0.04
|
Ivabradine, n (%)
|
21 (15)
|
11 (11)
|
0.38
|
Anticoagulation therapy, n (%)
|
73 (52)
|
59 (58)
|
0.33
|
Anti-platelet agent, n (%)
|
73 (52)
|
55 (54)
|
0.60
|
QRS morphology, n (%)
|
|
|
|
LBBB
|
110 (78)
|
82 (80)
|
0.50
|
RBBB
|
10 (7)
|
6 (6)
|
NIVCD
|
3 (2)
|
0
|
Paced QRS
|
18 (13)
|
14 (14)
|
LVEF (%)
|
28 (6)
|
28 (7)
|
0.47
|
CRT-D, n (%)
|
122 (87)
|
53 (52)
|
< 0,001
|
Upgrade, n (%)
|
41 (29)
|
25 (25)
|
0.43
|
Effectiveness, n (%)
|
70 (50)
|
48 (47)
|
0.69
|
One-year survival
|
124 (88)
|
85 (83)
|
0.31
|
NYHA improvement
|
86 (61)
|
67 (66)
|
0.72
|
No admission for HF
|
107 (76)
|
71 (70)
|
0.33
|
Complications, n in n patients (%)
|
55 in 30 (21)
|
27 in 15 (15)
|
0.19
|
Reintervention, n (% of complications)
|
24 (44)
|
9 (33)
|
0.07
|
Lead displacement, n (% of complications)
|
19 (34)
|
7 (26)
|
0.10
|
Implantation failure, n (% of complications)
|
3 (5)
|
5 (19)
|
0.23
|
Infection, n (% of complications)
|
6 (11)
|
3 (11)
|
0.59
|
Pneumothorax, n (% of complications)
|
2 (4)
|
2 (7)
|
0.74
|
Perforating lead, n (% of complications)
|
0
|
1 (4)
|
0.24
|
Pericardial effusion, n (% of complications)
|
1 (2)
|
0
|
0.39
|
Hematoma, n (% of complications)
|
0
|
0
|
|
Continuous variables are reported as medians and interquartile ranges; categorical variables are reported as numbers and percentages. ACEI: angiotensin-converting enzyme inhibitor; ARB: angiotensin II receptor blocker; CKD: chronic kidney disease (defined by estimated glomerular filtration <60 ml/mn/1.73 m²); CRT: cardiac resynchronization therapy; CRT-D: CRT with defibrillator; HF: heart failure; LBBB: left bundle branch block; LVEF: left ventricular ejection fraction; NYHA: New York Heart Association; NIVCD: nonspecific intraventricular conduction delay; RBBB: right bundle branch block.
Primary endpoint
There was no difference in CRT effectiveness between age groups; 70 patients were considered responders out of the 141 (50%) in the <75-year-old group, whereas 48 patients out of the 102 (47%) in the ≥75-year-old group were considered responders (p=0.69). The outcomes are detailed in Table 1. In univariate and multivariate analyses, NYHA class ≥III before implantation was associated with the CRT response in the overall population (OR=3.30; 95% confidence interval (CI95%) [1.70-6.51], p<0.001). NYHA class ≥III was strongly predictive of CRT effectiveness among older patients (OR=6.02; CI95% [1.33-18.77], p=0.002). In the <75-year-old group, there was a trend towards a better CRT response in patients with a previous NYHA class ≥III (p=0.07). In univariate analysis, AF, CKD and rescue CRT were negatively associated with the CRT response. Only AF and CKD remained predictors of CRT nonresponse in the multivariate analysis of the overall population. Moreover, the AF negative impact was significant only in the <75-year-old group (OR=0.28; CI95% [0.13-0.62], p=0.001) and was not significant in the ≥75-year-old group. Defibrillator use was not associated with the primary endpoint. The results of the univariate and multivariate analyses in the ≥75-year-old group are listed in Table 2 and those in the <75-year-old group are provided in Table 3.
Table 2. Univariate and multivariate analyses of outcomes in the ≥75-year-old group
|
Univariate analysis
|
Multivariate analysis
(model 1 with atrial fibrillation)
|
Multivariate analysis
(model 2 with anticoagulation)
|
Primary endpoint
|
OR (95% CI)
|
p value
|
OR (95% CI)
|
p value
|
OR (95% CI)
|
p value
|
NYHA ≥III
|
5.91 (2.02-17.30)
|
0.001
|
6.02 (1.33-18.77)
|
0.002
|
6.30 (2.04-19.67)
|
0.001
|
Rescue CRT
|
0.49 (0.40-0.60)
|
0.01
|
|
|
|
|
CKD
|
0.41 (0.16-1.03)
|
0.06
|
|
|
|
|
Loop diuretics
|
0.32 (0.09-1.11)
|
0.06
|
|
|
|
|
Anticoagulation
|
0.51 (0.23-1.15)
|
0.10
|
|
|
|
|
Atrial fibrillation
|
0.51 (0.23-1.15)
|
0.10
|
|
|
|
|
ACEI-ARB
|
2.07 (0.84-5.11)
|
0.11
|
2.55 (0.91-7.11))
|
0.07
|
2.38 (0.87-6.49)
|
0.09
|
Surgery duration
|
1.87 (0.85-4.11)
|
0.12
|
|
|
|
|
QRS= 130-150 ms
|
0.50 (0.20-1.27)
|
0.14
|
|
|
|
|
One-year mortality
|
OR (95% CI)
|
p value
|
OR (95% CI)
|
p value
|
OR (95% CI)
|
p value
|
Rescue CRT
|
58.8 (6.55-528-28)
|
<0.001
|
44.67 (2.91-686)
|
0.01
|
63.28 (4.47-896)
|
0.002
|
CRT-D
|
0.23 (0.07-0.75)
|
0.01
|
|
|
|
|
Atrial fibrillation
|
4.03 (1.07-15.20)
|
0.03
|
6.72 (0.99-45.61)
|
0.04
|
|
|
QRS>150 ms
|
2.64 (0.86-8.15)
|
0.08
|
3.79 (0.79-18.21)
|
0.10
|
|
|
Surgery duration
|
0.39 (0.13-1.2)
|
0.09
|
0.11 (0.02-0.63)
|
0.01
|
0.14 (0.03-0.76)
|
0.02
|
CKD
|
3.54 (0.75-16.67)
|
0.09
|
|
|
|
|
Upgrade
|
0.36 (0.08-1.69)
|
0.10
|
|
|
|
|
Anticoagulation
|
2.43 (0.72-8.13)
|
0.14
|
|
|
|
|
Beta-blockers
|
0.42 (0.12-1.42)
|
0.15
|
|
|
|
|
Ivabradine
|
2.63 (0.60-11.41)
|
0.18
|
9.99 (1.17-85.42)
|
0.04
|
6.36 (1.10-36.90)
|
0.04
|
ACEI-ARB
|
0.47 (0.15-1.49)
|
0.19
|
|
|
|
|
Anticoagulation and atrial fibrillation were significantly correlated in the ≥75-year-old group (Pearson coefficient 0.79, p<0.001). We performed two different regression models if the p values were both <0.2 in the univariate analysis. We reported here variables with p values ≤0.2 in the univariate analysis and ≤0.10 in the multivariate analysis. ACEI: angiotensin-converting enzyme inhibitor; ARB: angiotensin II receptor blocker; CKD: chronic kidney disease (defined by estimated glomerular filtration <60 ml/mn/1.73 m²); CRT: cardiac resynchronization therapy; CRT-D: CRT with defibrillator; NYHA: New York Heart Association.
Table 3. Univariate and multivariate analyses of outcomes in the <75-year-old group
|
Univariate analysis
|
Multivariate analysis
|
Primary endpoint
|
OR (95% CI)
|
p value
|
OR (95% CI)
|
p value
|
Atrial fibrillation
|
0.36 (0.18-0.71)
|
0.003
|
0.28 (0.13-0.62)
|
0.001
|
CRT-D
|
2.39 (0.85-6.70)
|
0.09
|
|
|
Male sex
|
2.39 (0.85-6.70)
|
0.09
|
|
|
CKD
|
0.53 (0.26-1.07)
|
0.08
|
|
|
Ivabradine
|
2.25 (0.85-5.97)
|
0.10
|
|
|
NYHA ≥III
|
1.74 (0.89-3.41)
|
0.11
|
2.09 (0.95-4.59)
|
0.07
|
QRS<130 ms
|
0.51 (0.21-1.24)
|
0.13
|
|
|
QRS>150 ms
|
1.63 (0.83-3.17)
|
0.15
|
|
|
|
Univariate analysis
|
Multivariate analysis
(model 1 with atrial fibrillation)
|
Multivariate analysis
(model 2 with anticoagulation)
|
One-year mortality
|
OR (95% CI)
|
p value
|
OR (95% CI)
|
p value
|
OR (95% CI)
|
p value
|
Atrial fibrillation
|
23.68 (3.04-184.30)
|
<0.001
|
14.35 (1.6-125.90)
|
0.02
|
|
|
Rescue CRT
|
17.48 (4.97-61.44)
|
<0.001
|
14.32 (2.61-79.20)
|
0.002
|
15.81 (3.35-75.10)
|
<0.001
|
CRT-D
|
0.11 (0.04-0.34)
|
<0.001
|
|
|
|
|
Beta-blockers
|
0.16 (0.05-0.51)
|
0.001
|
|
|
|
|
CKD
|
5.93 (1.61-21.83)
|
0.003
|
5.96 (1.13-31.30)
|
0.04
|
7.65 (1.47-39.61)
|
0.02
|
Anticoagulation
|
7.71 (1.68-33.26)
|
0.003
|
|
|
5.32 (0.96-29.40)
|
0.06
|
ACEI-ARB
|
0.26 (0.09-0.78)
|
0.01
|
|
|
|
|
Diabetes mellitus
|
2.86 (1.02-8.01)
|
0.04
|
|
|
|
|
Loop diuretics
|
5.67 (0.72-44.56)
|
0.07
|
|
|
|
|
NYHA ≥III
|
4.24 (1.16-15-48)
|
0.02
|
|
|
|
|
QRS>150 ms
|
0.46 (0.15-1.38)
|
0.16
|
|
|
|
|
Complications
|
2.06 (0.69-6.08)
|
0.19
|
4.20 (0.91-18.91)
|
0.07
|
|
|
Anticoagulation and atrial fibrillation were significantly correlated in the <75-year-old group (Pearson coefficient 0.69, p<0.001). We performed two different regression models if the p values were both <0.2 in the univariate analysis. We reported here variables with p values ≤0.2 in the univariate analysis and ≤0.10 in the multivariate analysis. ACEI: angiotensin-converting enzyme inhibitor; ARB: angiotensin II receptor blocker; CKD: chronic kidney disease (defined by estimated glomerular filtration <60 ml/mn/1.73 m²); CRT: cardiac resynchronization therapy; CRT-D: CRT with defibrillator; NYHA: New York Heart Association.
Secondary endpoints
All-cause mortality
At one year, the mortality rates were 12% and 17% in the <75- and ≥75-year-old groups, respectively (p=0.31). The survival curves are represented in Figure 1. Defibrillator use was associated with better survival in the univariate analysis (p=0.01) but not after the logistic regression. The multivariate analysis showed that rescue CRT (p=0.01 and 0.002 in the ≥75- and <75-year-old groups, respectively) and AF (p=0.04 and 0.02 in the ≥75- and <75-year-old groups, respectively) were associated with mortality in both groups. CKD was predictive of one-year mortality only in the <75-year-old group (p=0.04), whereas ivabradine use was associated with mortality only in the ≥75-year-old group (p=0.04).
Complications
Eighty-two complications were reported in 45 patients (19%) in the study population. There was no difference in the one-year complication rates between age groups, which were 15% and 21% in the ≥75- and <75-year-old groups, respectively (p=0.19). Lead dislodgment and reinterventions were the most frequent issues, with a trend towards a greater rate of reinterventions in the <75-year-old group (p=0.07). Only defibrillator use (p=0.003) and QRS duration (p=0.02) were found to be independent predictive factors in the overall population. There was no age-related predictor of complications.
Device therapies in patients with a defibrillator (n=175)
Nine (17%) patients ≥75 years old received appropriate therapies, whereas 11 (9%) patients <75 years old received appropriate therapies (p=0.2). Only four patients, who were all in the <75-year-old group, received inappropriate therapies.