Clinical outcome in patients with implantable cardioverter-defibrillator and cancer: a nationwide study.

AIMS: Patients with cancer are insufficiently represented in randomized clinical trials investigating efficacy of implantable cardioverter-defibrillators (ICDs). We aimed to describe outcomes in patients with a pre-existing diagnosis of cancer at time of ICD implantation. METHODS AND RESULTS: We utilized Danish nationwide registries to identify primary and secondary prevention ICD implantations from 2007 to 2012. Multivariable Cox models were used to assess the risk of appropriate ICD therapy and mortality in patients with and without cancer at time of implantation. During a median follow-up of 2.1 years, 2935 primary prevention ICD and 2730 secondary prevention ICD implantations were identified. Out of these [289 (5.1%)] had pre-existing cancer [primary 140 (4.8%), secondary 149 (5.5%)]. No differential risk for appropriate ICD therapy was found between patients with or without cancer, [primary cancer: 19/140, no cancer: 380/2795, hazard ratio (HR) = 1.07 (0.67-1.69)] and [secondary cancer: 42/149, no cancer: 699/2581, HR = 1.28 (0.93-1.75)]. In primary patients, cancer was not associated with higher risk of 1-year [cancer: 10/140, no cancer: 133/2795, HR = 1.20 (0.84-2.28)] or all-time mortality [cancer: 22/140, no cancer: 339/2795, HR = 1.13 (0.74-1.75)]. In secondary patients, cancer was associated with a higher 1-year [cancer: 19/149, no cancer: 108/2581, HR = 2.62 (1.60-4.29)] and all-time mortality [cancer: 44/149, no cancer: 315/2581, HR = 2.36 (1.71-3.24)]. CONCLUSION: Implantable cardioverter-defibrillators were implanted in a minority of cancer patients. No difference in risk of appropriate therapy was observed between cancer and non-cancer patients, regardless of implant indication. Cancer was associated with increased mortality in secondary prevention ICD patients, but not in primary prevention ICD patients. In secondary prevention ICD patients, the majority of deaths were attributable to cancer.

Shortening of paced QRS duration after electrocardiographic optimization of left ventricular pacing vector in patients treated with Cardiac Resynchronization Therapy.

Background: Choice of left ventricular pacing vector (LVPV) affects the QRS-duration (QRSd) in patients with Cardiac Resynchronization Therapy (CRT). It is not known whether testing all LVPVs reduces QRSd compared to device-based "standard-programming". Methods: In patients implanted with CRT several ECGs were recorded for each usable LVPV (no phrenic nerve stimulation and threshold <3.5 V) and during "standard-programming" after device-based optimization of AV/VV delays. Results: 22 consecutive patients were included. Average QRSd reduction after CRT + "standard-programming" was 27.3 ±â€¯22 ms. Additional QRSd-reduction was possible in 4 patients by changing the LVPV, and in 5 other patients after optimization of AV- and VV delays without changing LVPV. Conclusions: Shortening of QRSd compared to "standard-programming" was possible approximately 40% of these patients treated with CRT by testing all LVPVs and re-optimizing AV/VV delays during follow-up. Studies of clinical effects are needed.

Is modification of the VVI backup mode in implantable cardioverter-defibrillators from St Jude medical required due to increased risk of inappropriate shocks?

Inappropriate implantable cardioverter-defibrillator (ICD) shock therapy is painful, stressful, and typically occurs unexpected in conscious patients and may be related to a less favourable prognosis. In our institution, we have observed four cases of multiple inappropriate ICD shocks during reset to VVI backup mode. All four patients were implanted with a St Jude Medical ICD since 2010. The reset to VVI backup mode happens as a 'safety' response when the ICD encounters errors in the software or hardware often due to electromagnetic interference. The ICD then operates in a simple mode, with only a ventricular fibrillation (VF) zone starting at 146 b.p.m., with shock therapy only and changes in sensitivity settings making the ICD more sensitive. In all cases, the reason for the multiple inappropriate shocks was that the VF zone was reached due to exercise-induced sinus tachycardia or due to oversensing during sinus rhythm. The VVI backup mode has to balance between protection from failure of ICD therapy during life-threatening ventricular arrhythmias and from inappropriate shocks. It seems the non-programmable parameters in VVI backup mode of St Jude Medical ICDs carry an unacceptable high risk of inappropriate shocks during normal rhythm as illustrated by our four cases. A higher VF zone comparable with the zones chosen by the other manufacturer would give a better balance, since it is very unlikely that a patient will need shock therapy urgently for slow ventricular tachycardia.

Precision of automated QRS duration measurement in patients treated with cardiac resynchronization therapy.

PURPOSE: Shortening of the QRS duration (QRSd) is often used to guide device optimization and reprogramming in patients with cardiac resynchronization therapy (CRT). Detecting the small changes expected during reprogramming requires that the QRSd can be measured with high precision, but this has never been studied in patients with CRT. In this study, we wanted to assess the precision of automated QRSd measurement in patients treated with CRT using two commonly available electrocardiographs. METHODS: Patients treated with CRT were recruited during routine follow-up in our pacemaker clinic. In all participants, a number of immediate successive ECGs were recorded with the GE MAC 5500 (Mac55) and the GE MAC 1600 (Mac16). Data were analyzed with a linear mixed model. RESULTS: A total of 785 12-lead ECGs were recorded in 36 patients with an average of 11.2 and 10.6 ECGs per patient with the Mac55 and Mac16, respectively. The Mac55 measured the QRSd longer by 10.3 milliseconds (ms) (95% CI 7.1-13.5 ms, p < 0.001) and with significantly smaller standard deviation for repeated measurements (6.3 vs. 10.4 ms, p < 0.001). Limits of agreement were ± 17.5 and ± 28.8 ms for the Mac55 and Mac16, respectively. CONCLUSIONS: Automated measurement of QRSd in patients with CRT shows low precision with limits of agreement of ± 17.5 and ± 28.8 ms for repeated measurements in two commercially available electrocardiographs. Device programming solely by QRSd changes should be done with caution, and clinical effects should be demonstrated in future trials. Device programming based on QRSd changes should be done with caution until the ability of this measure to predict clinical outcome can be demonstrated in prospective study.

Single-coil and dual-coil defibrillator leads and association with clinical outcomes in a complete Danish nationwide ICD cohort.

BACKGROUND: The best choice of defibrillator lead in patients with routine implantable cardioverter-defibrillator (ICD) is not settled. Traditionally, most physicians prefer dual-coil leads but the use of single-coil leads is increasing. OBJECTIVE: The purpose of this study was to compare clinical outcomes in patients with single- and dual-coil leads. METHODS: All 4769 Danish patients 18 years or older with first-time ICD implants from 2007 to 2011 were included from the Danish Pacemaker and ICD Register. Defibrillator leads were 38.9% single-coil leads and 61.1% dual-coil leads. The primary end point was all-cause mortality. Secondary end points were lowest successful energy at implant defibrillation testing, first shock failure in spontaneous arrhythmias, structural lead failure, and lead extraction outcomes. RESULTS: Single-coil leads were associated with lower all-cause mortality with an adjusted hazard ratio of 0.85 (95% confidence interval 0.73-0.99; P = .04). This finding was robust in a supplementary propensity score-matched analysis. However, dual-coil leads were used in patients with slightly higher preimplant morbidity, making residual confounding by indication the most likely explanation for the observed association between lead type and mortality. The lowest successful defibrillation energy was higher using single-coil leads (23.2 ± 4.3 J vs 22.1 ± 3.9 J; P < .001). No significant differences were observed for other secondary end points showing high shock efficacies and low rates of lead failures and extraction complications. CONCLUSION: Shock efficacy is high for modern ICD systems. The choice between single-coil and dual-coil defibrillator leads is unlikely to have a clinically significant impact on patient outcomes in routine ICD implants.

The patient perspective on the Riata defibrillator lead advisory: a Danish nationwide study.

BACKGROUND: The St Jude Medical Riata lead advisory was issued owing to insulation failures. The impact of this advisory on patients' well-being is unknown. OBJECTIVES: The objectives of this study were to describe the acute impact of the Riata advisory on patients' well-being and psychological functioning and to examine changes over time. METHODS: Patients with active Riata leads completed standardized and validated patient-reported outcomes (PROs) in connection with a nationwide fluoroscopic screening with 12-month follow-up. They were matched (1:1) on age, sex, and implant indication with nonadvisory controls for baseline comparisons. Cohen's effect size d was used to determine the clinical relevance of the estimated adjusted mean differences (small, d = 0.20; moderate, d = 0.50; large, d ≥ 0.80). RESULTS: Of all Riata patients, 86% (256 of 299) completed baseline PROs and 70% (210 of 299) follow-up PROs. Riata patients reported poorer device acceptance (d = -0.28; P = .001) and increased device-related concerns (d = 0.29; P < .001) as compared with matched nonadvisory controls. There were no differences in symptoms of depression (d = 0.13; P = .13). Female sex was an independent predictor of a high advisory impact on general well-being as assessed with a purpose-designed question (odds ratio 2.24; P = .04). Device-related concerns decreased over time (d = -0.17; P = .002), but no changes were seen for other PROs. CONCLUSION: The Riata advisory is associated with a persistent small reduction in device acceptance and a small increase in device-related concerns with minimal improvement over time. Female sex is a predictor of a high negative advisory impact on general well-being. A need for counseling may arise in vulnerable subsets of patients.

Prospective nationwide fluoroscopic and electrical longitudinal follow-up of recalled Riata defibrillator leads in Denmark.

BACKGROUND: Recalled St. Jude Medical Riata defibrillator leads are prone to insulation failures with externalized conductors (ECs). Longitudinal studies are needed to guide lead management. OBJECTIVE: The purpose of this study was to describe the dynamic nature of EC and the association with electrical abnormalities and lead extraction outcomes. METHODS: A nationwide cohort established in 2012 of 295 patients with recalled Riata leads with dwell time 5.1 ± 1.1 years, 34 ECs, and 19 electrical abnormalities were followed until death, lead discontinuation with fluoroscopy, or a new 2013 screening with fluoroscopy and device interrogation. RESULTS: Fluoroscopic follow-up of 239 patients with normal baseline fluoroscopy revealed incident overt EC in 8 leads and borderline EC in 2 leads after 1.1 ± 0.2 years, with an incidence rate of 3.7 per 100 person-years (95% confidence interval 2.0-6.9). Fluoroscopic follow-up in 27 patients with baseline EC showed an increase in EC length of 4 ± 1 mm (P <.001) after 1.1 ± 0.3 years. Electrical follow-up in 276 patients with normal baseline electrical function demonstrated 20 incident electrical abnormalities after 1.0 ± 0.3 years, with an incidence rate of 7.1 per 100 person-years (95% confidence interval 4.6-11.0). This rate was significantly higher in leads with baseline EC, with an adjusted incidence rate ratio of 4.4 (95% confidence interval 1.7-11.5, P = .002). In 15 extractions, all leads were removed, with 2 major complications. CONCLUSION: The development of EC is a dynamic process despite long lead dwell time. ECs are associated with a higher risk of electrical abnormalities. Therefore, lead replacement should be considered, especially in patients with a long life expectancy.