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Lead complications, device infections, and clinical outcomes in the first year after implantation of cardiac resynchronization therapy-defibrillator and cardiac resynchronization therapy-pacemaker

Andreas Schuchert, Carmine Muto, Themistoklis Maounis, Robert Frank, Eric Boulogne, Alexander Polauck, Luigi Padeletti
DOI: http://dx.doi.org/10.1093/europace/eus247 71-76 First published online: 26 August 2012


Aims The decision to implant a cardiac resynchronization therapy (CRT) system with (defibrillator, CRT-D) or without (pacemaker, CRT-P) cardioverter defibrillator should weigh its benefits and risks. This study examined the (i) incidence of loss of capture and infectious complications and (ii) 1-year clinical outcomes of 402 CRT-D and CRT-P recipients enrolled in the MASCOT study.

Methods and results The indications for CRT-D or CRT-P were posed by the implanting physicians. All (i) losses of atrial and right and left ventricular capture, (ii) system-related infections, and (iii) clinical outcomes, including hospitalizations for worsening heart failure (HF) and deaths from all causes, were recorded up to 1 year of follow-up. Cardiac resynchronization therapy-defibrillator was implanted in 228 (57%) and CRT-P in 174 (43%) patients. The incidence of loss of capture was greater in CRT-D with 21 patients (9.2%) than in CRT-P with 6 patient (3.5%) recipients (P = 0.01), while the infection rates were 1.3% (3 patients) and 1.2% (2 patients), respectively (ns). In the CRT-D group, 42 of 228 patients (18.4%) died or were hospitalized for HF, compared with 38 of 174 patients (21.8%) in the CRT-P group (ns). In the CRT-D group, 23 patients (10.1%) were hospitalized for worsening HF and 20 (8.8%) patients died, vs. 22 (12.6%) and 19 (10.9%) patients, respectively, in the CRT-P group (ns for both comparisons).

Conclusions Cardiac resynchronization therapy-defibrillator was implanted in 57% of candidates for CRT. Within 1 year after device implant, the incidence of loss of capture at any lead was nearly three-fold greater among CRT-D than among CRT-P recipients. System-related infections were infrequent and clinical outcomes were similar in both groups.

  • Cardiac resynchronization therapy
  • Implantable cardioverter defibrillator
  • Defibrillator lead
  • Pacing lead
  • Lead complication
  • Cardiac device infection


The current management of patients suffering from advanced chronic heart failure (HF) often includes pharmaceuticals and devices with the aims of alleviating symptoms, preventing major morbidity, and lowering mortality. Patients presenting with moderate or severe chronic HF and bundle branch block on resting electrocardiogram are candidates for adjunctive cardiac resynchronization therapy (CRT).1 Whether all these patients are also candidates for an implantable defibrillator (CRT-D) or should simply receive CRT-pacemaker (CRT-P) remains controversial.25 The more frequent implantation of CRT-D is supported by the lower sudden cardiac death rate associated with an implantable cardioverter defibrillator (ICD), in large patient populations presenting with a depressed left ventricular (LV) systolic function.6,7 While a large proportion of CRT recipients may be eligible for an ICD, combined treatment might not necessarily confer a greater benefit than single therapy, as no randomized trial has shown the superiority of CRT-D over CRT-P.

The benefits and potential harms of CRT-D and CRT-P should be weighed carefully before device implantation. We examined the incidence of loss of capture and of system-related infectious complications in CRT-D and CRT-P recipients within 1 year after device implantation, and the clinical outcomes in both patient groups.


Patient population and methods

The patients included in this analysis were enrolled in the MASCOT study and followed for 1 year.8 They were eligible for enrolment in MASCOT, if they fulfilled the following criteria: (i) New York Heart Association (NYHA) functional class III or IV despite optimal medical therapy, (ii) QRS duration ≥130 ms, (iii) LV ejection fraction (EF) ≤35%, and (iv) LV end-diastolic diameter ≥55 mm. They were excluded if (i) they were in permanent atrial fibrillation, (ii) had suffered a myocardial infarction, cardiac surgery, or a coronary revascularization procedure within the previous 3 months, or (iii) were pregnant.

The implanted devices were Frontier® or Frontier® II CRT-P or Epic® HF or Atlas® HF CRT-D (St Jude Medical, Sylmar, CA, USA). Leads from all manufacturers were implanted. A Quicksite® LV stimulation lead (St Jude) was used in 369 patients. Isoflex® (St Jude) atrial leads were implanted in 119, Membrane® (St Jude) in 66, and Tendril® (St Jude) in 97 patients. Isoflex® right ventricular (RV) leads (St Jude) were implanted in 29, and Tendril® RV leads (St Jude) in 92 patients. Riata® defibrillation leads (St Jude) were implanted in 221 patients.

Study design

MASCOT was a multicentre, single-blind, randomized, parallel study, which examined the safety and efficacy of a specific atrial overdrive pacing algorithm in CRT recipients.9 Follow-up visits were scheduled at hospital discharge and 3, 6, 9, and 12 months after device implantation. The study protocol was reviewed and approved by the Institutional Ethics Committee of each participating medical centre, and all patients granted their informed consent to participate in the study.

Since the implant of a CRT-P or CRT-D was neither a primary or secondary endpoint in MASCOT, and was therefore not specified by the study protocol, the decision to implant a CRT-D or CRT-P was made by the implanting team of each participating centre.

Data collection and analysis

All losses of capture at the atrial, RV or LV leads, and biventricular stimulation thresholds >4 V during two follow-up visits were recorded. All infections related to the implanted system were defined as cardiac device infection. Adverse events resolution was defined as lead repositioning, system revision, and device or lead replacement. Deaths from all causes and the number of hospitalizations for management of worsening HF were recorded.

We compared the losses of capture, the cardiac device infections, and the frequency of adverse event resolutions between CRT-D and CRT-P recipients. Clinical outcome was the combined endpoint of all-cause mortality and hospitalization for management of worsening HF. The rate of sudden death was also calculated.

Statistical analyses

Data collected in the two groups were compared at 12 months. Normality of the data was verified using box-and-whisker plots, normal probability plots, and Kolmogorov–Smirnov tests for normality. Continuous variables from the normal distribution were compared using the two-sample t-test for independent variables. The non-parametric Wilcoxon signed-rank test was used for non-normal variables. Categorical variables were compared using Fisher's exact test or the χ2 test, as applicable. A P value <0.05 was considered significant.


Between September 2003 and March 2006, 402 patients were enrolled in MASCOT, by 34 medical centres in 10 countries (Appendix). These were all academic or academic-related hospitals which had a profound experience in CRT implantation.

Their mean age was 68 ± 9 years, and mean LVEF 25 ± 7%. The underlying heart disease was ischaemic in 201 patients (50%), 344 (86%) were in NYHA functional class III, and 75 patients (19%) had a history of paroxysmal atrial fibrillation. Based on the physicians' choices, 228 patients (57%) received CRT-D and 174 (43%) received CRT-P. Compared with the CRT-P, the CRT-D recipients more often were men, more often presented with ischaemic cardiomyopathy, had a shorter mean QRS duration, less often were prescribed spironolactone and more often received antiarrhythmic drugs (Table 1). Left ventricular ejection fraction, LV end-diastolic diameter, NYHA functional class, and other medications prescribed for HF were similar in both groups.

View this table:
Table 1

Baseline characteristics of the cardiac resynchronization therapy-defibrillator and cardiac resynchronization therapy-pacemaker groups

CRT-P (n = 174)CRT-D (n = 228)P
Age (years)68 ± 1068 ± 90.30
Men121 (70)197 (86)<0.0001
Non-ischaemic cardiomyopathy109 (62)92 (40)<0.0001
QRS duration (ms)169 ± 31159 ± 26<0.0005
Systemic blood pressure (mmHg)
 Systolic118 ± 19121 ± 180.20
 Diastolic71 ± 1172 ± 110.58
New York Heart Association functional class III145 (83)199 (87)0.41
Left ventricular
 Ejection fraction (%)25 ± 725 ± 70.36
 End-diastolic diameter (mm)69 ± 1071 ± 90.09
Left atrial diameter in longitudinal view (mm)47 ± 1047 ± 80.59
History of atrial fibrillation37 (16)38 (22)0.15
Quality of life score49 ± 2242 ± 200.002
Drug therapy
 Angiotensin-converting enzyme inhibitor/ARB150 (86)189 (83)0.42
 Beta adrenergic blockade123 (71)166 (73)0.64
 Diuretics169 (97)211 (93)0.05
 Spironolactone58 (34)37 (17)<0.0001
 Digitalis49 (28)58 (26)0.62
 Antiarrhythmic42 (24)79 (35)0.0222
  • Values are means ± SD or numbers (%) of observations.

  • ARB, angiotensin receptor blocker.

Implantation procedures

Procedure time was 124.6 ± 50.4 min (median: 120.0 min) in CRT-D and 135.2 ± 61.9 min (median 122.5 min) in CRT-P patients (P = 0.09). The subclavian approach was used for the LV lead in 216 of 228 (94.7%) CRT-D and in 166 of 174 (95.4%) in CRT-P patients, for the RV-lead in 177 of 228 (77.6%) CRT-D patients and in 132 of 174 (75.9%) CRT-P patients, and for the atrial lead in 189 of 228 (82.9%) in CRT-D and in 137 of 174 (78.7%) CRT-P patients. The differences in the CRT-P and CRT-D were not statistically significant.

The final tip position of the LV lead was in the CRT-D group distal in 28 (12.3%), medial in 162 (71%), and proximal in 25 (10.9%) patients and in the CRT-P group distal in 34 (19.5%), medial in 104 (59.8%), and proximal in 29 (16.7%) patients. The LV lead had an anterior lateral position in 46 (20.2%) CRT-D and in 25 (14.4%) CRT-P patients, an anterior position in 18 (7.9%) CRT-D and in 7 (4%) CRT-P patients, a lateral position in 92 (40.4%) CRT-D and in 64 (36.8%) CRT-P patients, a posterolateral position in 52 (22.8%) CRT-D and in 66 (37.9%) CRT-P patients, and a posterior position in 8 (3.5%) CRT-D and in 6 (3.5%) CRT-P patients.

The final tip position of the RV lead was the apex in 205 (89.9%) CRT-D and in 122 (70.1%) CRT-P patients. The lead was implanted in the RV outflow tract in 5 (2.2%) CRT-D and in 17 (9.8%) CRT-P patients. Other lead positions were reported in the remaining patients. The final tip position of the atrial lead was the right atrial appendix in 214 (93.7%) CRT-D and in 150 (86.2%) CRT-P patients.

Loss of stimulation capture and cardiac device infections

Loss of capture occurred in 21 of 228 CRT-D (9.2%), vs. 6 of 174 CRT-P (3.5%) recipients (P = 0.01; Figure 1). Loss of (i) atrial capture occurred in 5 (2.2%) CRT-D vs. 1 (0.6%) CRT-P recipients, (ii) RV defibrillation lead capture in 8 (3.5%) CRT-D recipients vs. RV pacing in 0 CRT-P recipient, and (iii) LV stimulation in 11 (4.8%) CRT-D vs. 5 (2.8%) CRT-P recipients. The final lead position of the RV or the LV lead had no effect on a loss of capture.

Figure 1

Higher incidence of loss of capture among the cardiac resynchronization therapy-defibrillator than the cardiac resynchronization therapy-pacemaker recipients (Wilcoxon P value = 0.03). Time to loss of capture (number of days between date of implant and the date of first loss of capture).

System-related infectious complications occurred in three of 228 (1.3%) CRT-D vs. two of 174 (1.2%) CRT-P recipients (ns; Figure 2). The procedure in the three CRT-D patients was 163.3 + 15.3 min and in the remaining CRT-D patients 124.1 + 50.1 min. The procedure time of the two CRT-P patients was 120.0 + 84.9 min (60 and 180 min).

Figure 2

Similar incidence of system-related infections among the cardiac resynchronization therapy-defibrillator and cardiac resynchronization therapy-pacemaker recipients (Wilcoxon P value = 0.88). Time to first infection (number of days between date of implant and the date of first infection).

Adverse events resolutions

Advert event resolutions were performed in 24 of 231 CRT-D (10.3%), vs. 11 of 171 CRT-P (6.4%) recipients (P < 0.01). These procedures consisted in (i) epicardial electrode implantation in one CRT-P patient due to a complete thrombosis of the cava vein and a failed initial implantation of the LV lead, (ii) lead replacement in 7 CRT-D (loss of capture of 4 atrial leads, 1 RV lead, 2 LV leads) and 5 CRT-P patients (loss of capture of 1 atrial lead, 4 LV lead), (iii) lead repositioning in 14 CRT-D (loss of capture of 4 atrial leads, 8 RV leads, 2 LV leads) and 3 CRT-P patients (loss of capture of 3 LV leads), (iv) pacemaker replacement in 2 CRT-D patients due to high defibrillation thresholds, and (v) a system revisions in 1 CRT-D (a screw was unlocked and caused shock on noise) and 2 CRT-P patients. In addition reprogramming was performed in 23 CRT-D and 21 CRT-P patients (upgrade to CRT-D).

All-cause mortality and hospitalization for management of heart failure

The combined endpoint of all-cause mortality and hospitalization for management of HF (Figure 3) was reached by 42 of 228 CRT-D (18.4%) vs. 38 of 174 CRT-P (21.8%) recipients (ns). In the CRT-D group, 23 patients (10.1%) were hospitalized for worsening HF and 20 (8.8%) patients died, vs. 22 (12.6%) and 19 (10.9%) patients, respectively, in the CRT-P group (ns for both comparisons). Among 20 and 19 deaths that occurred, respectively, in the CRT-D and CRT-P groups, 5 (25.0%) and 8 (42.1%), respectively, were sudden (ns).

Figure 3

Similar incidence of deaths from all causes and hospitalizations for management of worsening heart failure among cardiac resynchronization therapy-defibrillator and cardiac resynchronization therapy-pacemaker recipients. (Wilcoxon P value = 0.43). Time to hospitalization or death (number of days between date of implant and the date of hospitalization or death).


In this study of candidates for CRT, who received a CRT-P vs. CRT-D depending on the decision of the implanting physician, CRT-D were implanted in nearly 60% of patients. The latter (i) were more likely to be men and to suffer from ischaemic cardiomyopathy and (ii) had a shorter mean QRS duration than the CRT-P group. At 1 year after device implantation, the cumulative rate of loss of capture at any lead and of secondary adverse events resolutions was nearly three-fold higher in the CRT-D than in the CRT-P recipients. The rate of CRT system-related infectious complications was similarly low, and the combined rates of all-cause mortality and hospitalizations for management of worsening HF were similar in both groups.

Cardiac resynchronization therapy-pacemaker vs. cardiac resynchronization therapy-defibrillator

CARE-HF was the first randomized trial showing a survival benefit conferred by CRT.9 In that study, the majority of patients received a CRT-P, and approximately one-third of deaths were sudden. One might hypothesize that the addition of an ICD to CRT would further lower these patients' mortality. However, neither clinical trials nor meta-analyses have, thus far, shown a survival benefit conferred by combined CRT and ICD therapy compared with CRT or ICD therapy alone. Lam and Owen10 systematically reviewed the overall evidence gathered from 12 randomized trials included 1636 events in 8307 patients, comparing the survival associated with CRT-D vs. medical therapy. While CRT-D lowered all-cause mortality by one-third compared with medical therapy, it was associated with mortality similar to that associated with CRT or ICD therapy alone. In a multicentre study of the 5-year outcomes of 573 CRT-P vs. 730 CRT-D recipients, the latter therapy was associated with a 20% (non-significant) lower overall mortality, though conferred a highly significant protective effect against sudden cardiac death.11 In another observational study comparing 117 CRT-P vs. 116 CRT-D recipients, overall mortality after a median follow-up of 58 months was also similar in both groups, although CRT-D was superior to CRT-P in lowering the sudden death rate.12 In the Cleveland registry of 542 patients, all-cause mortality was 18.5% among CRT-D, vs. 38.8% among CRT-P recipients, over a mean follow-up of 811 days (P < 0.001).13

At 1 year after device implantation, we found no statistically significant difference in overall or sudden death rates between the CRT-D and the CRT-P recipients. However, MASCOT was not designed to detect differences in mortality between the two study groups and may have enrolled an insufficient number of patients to settle this issue.

Complication rates

The choice of CRT-D vs. CRT-P must weigh the expected benefits against the potential complications or harm to each individual patient. The occurrence of a major complication within 45 days after implantation of an ICD has been associated with an increased risk of death,14 though this observation was not reported for CRT recipients in the RAFT study.15 The European CRT registry reported a 9% rate of peri-procedural complications in CRT-D vs. 12% in CRT-P recipients (ns).16 In contrast, we observed a three-fold higher rate of lead-related complications in our CRT-D than in our CRT-P recipients. On the other hand, variable technical skills among operators would not explain this observation, as both systems were implanted by the same physicians at each centre.

Furthermore, the sensing function of ICD leads must be flawless, which may explain the earlier and more frequent detection of adverse events than in CRT-P recipients. Despite the similarity of the atrial and LV stimulation leads in both study groups, we observed a higher rate of lead-related complications in the CRT-D than in the CRT-P group.

Infectious complications

The overall incidence of device-related infections is increasing.17 In an observational study, 24 infections were identified among 2417 patients (1%) undergoing cardiac device implantation.18 Implantation of dual- and triple-chamber devices was associated with a two-fold higher risk of infection than implantation of single-chamber devices.19,20 In a direct comparison between CRT-D and CRT-P, the former was associated with a nearly 5.5-fold higher risk of infection.21 The 1.7 and 2.1% rates of infection observed in our study among, respectively, CRT-P and CRT-D recipients, is concordant with these previous reports. More importantly, we observed no difference in the incidence of infections between the two patient groups, suggesting that the more complex CRT-D systems are not to be associated with a greater risk of infections.


The implantation of CRT-D and CRT-P was associated with similar clinical outcomes at 1 year, though the rate of lead complications was higher after implants of CRT-D.

The risks and benefits of the two systems must be evaluated for each patient undergoing CRT. The use of CRT-D should be based on indications for ICD therapy. Technological advances will further lower the device-related morbidity, and the expected decrease in device costs might allow the implant of CRT-D in all candidates for CRT.


The MASCOT study was sponsored by St Jude Medical.

Conflict of interest: A.S. was advisory board member of the MASCOT study for St Jude Medical; C.M. and Th.M. have had no involvement that might raise the question of bias in the work reported; R. F. was advisory board member of the MASCOT study for St Jude Medical; E.B. and A.P. were at the time of manuscript preparation full-time employee of St. Jude Medical. L.P. is consultant for Boston Scientific, Medtronic, St. Jude Medical, Sorin Biomedica.


The following investigators and institutions participated in MASCOT:

Fiorenzo Acquati, Ospedale Valduce, Como, Italy; Francesco Alessandrini, Università Cattolica del Sacro Cuore, Campobasso, Italy; Maria-Grazia Bongiorni, Ospedale Cisanello, Pise, Italy; Johannes Brachmann, Klinikum Coburg, Coburg, Germany; Valeria Calvi, Ospedale Ferrarotto, Catania, Italy; Ngai-yin Chan, Princess Margaret Hospital, Hong Kong, China; Per Dahl Christensen, Sygehus Viborg, Viborg, Denmark; Pierre Fiorello, CMC Parly II, Le Chesnay, France; Daniel Flammang, Centre Hospitalier Général Girac, Saint Michel, France; Francesco Foti, Ospedale di Melegnano, Melegnano, Italy; Robert Frank, Hopital Pitie-Salpetriere, Paris, France; Antonio Fusco, Clinica Pederzoli, Peschiera del Garda, Italy; Grahame Goode, Blackpool Victoria Hospital, Blackpool, United Kingdom; Daniel Gras, Nouvelles Cliniques Nantaises, Nantes, France; Michael Gruska, Hanusch Krankenhaus, Vienna, Austria; Gael Jauvert, InParys, Saint Cloud, France; Salem Kachboura, CHU Abderrahmane Mami, Ariana, Tunisia; Gert Kaltofen, Klinikum Chemnitz gGmbH Krankenhaus, Chemnitz, Germany; Wolfgang Kiowski, Herzgefäss Zentrum Klinik im Park, Zürich, Zürich, Switzerland; Francesco Lisi, Azienda Ospedaliera Cannizzaro, Catania, Italy; Themistoclis Maounis, Onassis Cardiac Surgery Center, Athens, Greece; Eraldo Occhetta, Ospedale Maggiore della Carita, Novara, Italy; Luigi Padeletti, Ospedale Careggi, Florence, Italy; Olivier Piot, Centre Cardiologique du Nord, St Denis, France; Jean-Ernst Poulard, Centre Hospitalier Général, Abbeville France Jean-Luc Rey, CHRU Hopital Sud, Amiens, France; Nadir Saoudi, Centre Hospitalier Princesse Grace, Monaco, Monaco; Andreas Schuchert, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany; Olivier Thomas, Clinique Ambroise Paré, Neuilly Sur Seine, France; Bernardo Tuccillo, Ospedale Loreto Mare, Naples, Italy; Thomas Vesterlund, Aalborg Hospital, Aalborg, Denmark; Paul Vock, A.ö. KH der Stadt St Pölten, St Pölten, Austria, Arnd Weide, Kardiologische Gemeinschaftspraxis, Hannover, Germany; Paolo Zecchi, Policlinico Gemelli, Roma, Italy.


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