Rates of upgrade of ICD recipients to CRT in clinical practice and the potential impact of the more liberal use of CRT at initial implant

Background: Many implantable cardioverter defibrillator (ICD) recipients may develop indications for cardiac resynchronization therapy (CRT) during follow‐up. However, the actual upgrade rate during follow‐up in clinical practice is not known. Methods: We performed a single center retrospective observational study of all new ICD implants over 5 years (2003–2007). The rate of CRT upgrade of patients initially implanted with a single‐/dual‐chamber ICD during follow‐up was assessed. The impact of using alternative criteria on the need for CRT in ICD recipients at initial implant was also evaluated. Results: During the study period, there were 549 new ICD implants. The initial implant was a single/dual‐chamber ICD in 73% (n = 399) and a CRT‐D in 27% (n = 150). During follow‐up (48±20 months) of the 399 ICD recipients, 70 (17.5%) died and 15 (3.8%) were upgraded to CRT, including eight cases where left ventricular lead implant had been initially unsuccessful. Upgrade rates at 1, 3, and 5 years were 0.03%, 2.4%, and 5.1%, respectively. Using alternative CRT criteria (left ventricular ejection fraction [LVEF]≤30%, QRS ≥130 ms, New York Heart Association I‐IV) 42.6% (n = 234) of ICD recipients met criteria for CRT at initial implant. Conclusion: In this retrospective single center study, rates of CRT upgrade in ICD recipients over the medium term were low, which may reflect underuse in otherwise appropriate candidates. The more liberal use of CRT at initial implant in patients with a reduced LVEF, a broad QRS, but only mild heart failure symptoms would require approximately 50% increase in CRT use in ICD recipients at initial implant, and may help address some of the suggested underutilization. (PACE 2012; 35:73–80)     

Analysis of Implantable Defibrillator Longevity Under Clinical Circumstances: Implications for Device Selection

Introduction: Information about implantable cardioverter‐defibrillator (ICD) longevity is mostly calculated from measurements under ideal laboratory conditions. However, little information about longevity under clinical circumstances is available. This survey gives an overview on ICD service times and generator replacements in a cohort of consecutive ICD patients. Methods: Indications for replacement were classified as a normal end‐of‐service (EOS), premature EOS, system malfunction, infection and device advisory, or recall actions. From the premature and normal EOS group, longevity from single‐chamber (SC), dual‐chamber (DC), and cardiac resynchronization therapy defibrillator (CRT‐D), rate‐responsive (RR) settings, high output (HO) stimulation, and indication for ICD therapy was compared. Differences between brands were compared as well. Results: In a total of 854 patients, 203 ICD replacements (165 patients) were recorded. Premature and normal EOS replacements consisted of 32 SC, 98 DC and 24 CRT‐D systems. Longevity was significantly longer in SC systems compared to DC and CRT‐D systems (54 ± 19 vs. 40 ± 17 and 42 ± 15 months; P = 0.008). Longevity between non‐RR (n = 143) and RR (n = 11) settings was not significantly different (43 ± 18 vs. 45 ± 13 months) as it also was not for HO versus non‐HO stimulation (43 ± 19 vs. 46 ± 17 months). Longevity of ICDs was not significantly different between primary and secondary prevention (42 ± 19 vs. 44 ± 18 months). The average longevity on account of a device‐based EOS message was 43 ± 18 months. Average longevity for Biotronik (BIO, n = 72) was 33 ± 10 months, for ELA Medical (ELA, n = 12) 44 ± 17 months, for Guidant (GDT, n = 36) 49 ± 12 months, for Medtronic (MDT, n = 29) 62 ± 22 months, and for St. Jude Medical (SJM, n = 5) 31 ± 9 months (P < 0.001). Conclusion: SC ICD generators had a longer service time compared to DC and CRT‐D systems. No influence of indication for ICD therapy and HO stimulation on generator longevity was observed in this study. MDT ICDs had the longest service time.     

Prognostic significance of atrial arrhythmias in a primary prevention ICD population

Introduction : We investigated whether primary prevention implantable cardioverter defibrillator (ICD) patients with atrial arrhythmias are at higher risk for ICD shocks and mortality compared to patients without atrial arrhythmias in a subanalysis of the PREPARE study. Methods and Results : Details of the PREPARE study design and results have been previously reported. We now included 537 of the 700 patients enrolled in PREPARE. These patients had a dual or biventricular device and at least one device follow‐up after implantation. Continuously collected device diagnostics data were used to classify patients into two groups during follow‐up: with (n = 133) or without (n = 404) atrial tachycardia/atrial fibrillation (AT/AF). The primary outcomes were ICD shocks and mortality. Subjects were followed for a mean of 333 ± 73 (range 5–365) days. During a follow‐up of 1 year, ICD shocks occurred in 44 (8%) patients. Significantly, more patients with AT/AF received a shock (13.0% vs 6.9%, P = 0.03), with inappropriate shocks accounting for the majority of the difference (6.9% vs 2.6%, P = 0.02). There was no difference in prevalence of shocks between patients with and without a history of AF. Mortality was similar in patients with and without AT/AF, whether detected during the study or prior to the study. In addition, the 34 subjects with high average ventricular rate (≥110 beats per minute) during AT/AF had a higher risk of an inappropriate shock (21.0% vs 2.1%, P < 0.01). Conclusion : Primary prevention ICD patients with AT/AF are more likely to receive shocks, especially inappropriate shocks. Mortality was not higher in AT/AF patients. (PACE 2011; 34:1070–1079)     

Safety and effectiveness of primary prevention cardioverter defibrillators in octogenarians

Background: Implantable cardioverter‐defibrillators (ICDs) reduce the rate of sudden cardiac death (SCD) in patients with cardiomyopathy and reduced left ventricular systolic function. It is unclear if this benefit extends to the very elderly patient population. Methods: Patients who underwent initial ICD implantation at age 80 or older between January 1995 and April 2010 for primary SCD prevention were identified. Clinical data were collected from the medical record, including periprocedural complications, device type, and therapies delivered. Results: Three‐hundred eighty patients were identified; 84 patients met eligibility criteria. The mean age was 82.68 years; mean follow‐up was 34 months. Mean left ventricular ejection fraction was 28.1%. Mortality during follow‐up was 17.9%. One‐ and 5‐year survival estimates were 100% and 60%, respectively. Periprocedural complications occurred in 9.4% of patients; serious complications occurred in 4.8% with no periprocedural deaths. Device therapies occurred in 11.9% (n = 10) of patients (9.5% appropriate, n = 8; 2.4% inappropriate, n = 2). Cardiac resynchronization therapy‐defibrillator (CRT‐D) implantation was associated with prolonged median survival and decreased risk of death (hazard ratio 0.212; 95% confidence interval 0.048?.942, P = 0.042) compared to ICD alone. Conclusions: Implantation of primary prevention ICDs in patients 80 years of age or older was associated with a low risk of serious complications and a 5‐year survival estimate of 60%. Inappropriate therapies after implantation were uncommon. CRT‐D implantation was associated with a decreased risk of death compared to ICD alone. These data suggest that, in selected patients in this age group, ICD implantation is safe and effective. (PACE 2011; 34:900–906)     

Response to Cardiac Resynchronization Therapy in Patients with Heart Failure and Renal Insufficiency

Background: Renal insufficiency (RI) adversely impacts prognosis in heart failure (HF) patients, partly because renal and cardiac dysfunction are intertwined, yet few cardiac resynchronization therapy (CRT) studies have examined patients with moderate‐to‐severe RI. Methods: We analyzed 787 CRT‐defibrillator (CRT‐D) recipients with a glomerular filtration rate (GFR) measured prior to implant. Patients were grouped by GFR (in mL/min/1.73 m²): ≥60 (n = 376), 30–59 (n = 347), and <30 (n = 64). Overall survival, changes in left ventricular (LV) ejection fraction and LV end‐systolic diameter, and GFR change at 3–6 months were compared among CRT‐D groups and with a control cohort (n = 88), also stratified by GFR, in whom LV lead implant was unsuccessful and a standard defibrillator (SD) was placed. All patients met clinical criteria for CRT‐D. Results: Among CRT‐D recipients, overall survival improved incrementally with higher baseline GFR (for each 10 mL/min/1.73 m² increase, corrected hazard ratio [HR] 1.21, 95% confidence interval [CI] 1.13–1.30, P < 0.0001). Survival among SD and CRT‐D patients within GFR < 30 and GFR ≥ 60 groups was similar, whereas CRT‐D recipients with GFR 30–59 had significantly better survival compared to SD counterparts (HR 2.23, 95% CI 1.34–3.70; P = 0.002). This survival benefit was associated with improved renal and cardiac function. CRT recipients with GFR ≥ 60 derived significant echocardiographic benefit but experienced a GFR decline, whereas those with GFR < 30 had no echocardiographic benefit but did improve GFR. Conclusions: CRT may provide the largest survival benefit in HF patients with moderate RI, perhaps by improving GFR and LV function. Severe baseline RI predicts poor survival and limited echocardiographic improvement despite a modest GFR increase, such that CRT may not benefit those with GFR < 30 mL/min/1.73 m². CRT recipients with normal renal function derive echocardiographic benefit but no overall survival advantage. (PACE 2010; 850–859)     

Use of a Wearable Automated Defibrillator in Children Compared to Young Adults

Background: A wearable automated external defibrillator has been shown to be efficacious in the prevention of sudden death in adults who had a history of cardiac arrest but who did not have a permanent internal cardioverter/defibrillator (ICD) placed. The use of a wearable defibrillator has not been established in the pediatric population. Methods: We retrospectively reviewed the clinical database for the wearable external defibrillator from ZOLL Lifecor Corporation (Pittsburgh, PA, USA). We compared the use of the wearable defibrillator in patients ≤18 years of age to those aged 19–21 years. Results: There were 81 patients ≤18 years of age (median age = 16.5 years [9–18] and 52% male). There were 103 patients aged 19–21 years (median age = 20 years [19–21] and 47% male). There was no difference between groups in average hours/day or in total number of days the patients wore the defibrillator. In patients ≤18 years of age, there was one inappropriate therapy and one withholding of therapy due to a device–device interaction. In patients aged 19–21 years, there were five appropriate discharges in two patients and one inappropriate discharge in a single patient. Conclusion: It is reasonable to consider the wearable automated external defibrillator as a therapy for pediatric patients who are at high risk of sudden cardiac arrest but who have contraindications to or would like to defer placement of a permanent ICD. As there were no appropriate shocks in our patients ≤18 years of age, this study cannot address efficacy of the therapy. (PACE 2010; 33:1119–1124)     

Effect of bioimpedance body composition analysis on function of implanted cardiac devices

Background: It is routinely recommended that patients with pacemakers, implantable cardioverter defibrillators (ICD), and cardiac resynchronization therapy‐defibrillators (CRT‐D) avoid bioelectrical impedance analysis (BIA)—a commonly used method to estimate body composition—because of the concern for the potential for BIA interference with pacemaker or ICD function. However, the prevalence of such interference is not known. Objective: Assess for incidence of interference between BIA and ICD or CRT‐D devices. Methods and Results: Twenty patients with heart failure and cardiac implanted electronic devices (50% ICD, 50% CRT‐D) underwent BIA during real‐time device interrogation to detect interference. Study patients were 90% male, with mean age 54 ±14 years, and mean LVEF 23 ± 11%. Devices from all four leading cardiac device manufacturers were included. Device therapies were temporarily disabled to prevent inappropriate shocks. During body composition testing using BIA, no evidence of interference with ICD function was seen in any patient, including no telemetry disruption, no oversensing on any lead, and no patient symptoms. Conclusions: Despite the manufacturers’ recommendation to avoid BIA in patients with ICDs, this study showed no evidence of any interference in 20 patients. Bioimpedance analysis might be safe in such patients, but further confirmatory studies are required. (PACE 2012; 35:681–684)     

Effect of cardiac resynchronization on gradient reduction in patients with obstructive hypertrophic cardiomyopathy: preliminary study

Background: The purpose of this study was to assess the effectiveness of cardiac resynchronization therapy (CRT) in terms of outflow tract gradient reduction and functional improvement in symptomatic patients with hypertrophic obstructive cardiomyopathy (HOCM) requiring implantable cardioverter‐defibrillator (ICD) implantation. Methods: Eleven consecutive symptomatic HOCM patients with a significant (≥40 mmHg) gradient and indications for ICD, but without indications for resynchronization, underwent CRT‐D implantation. Nine of them (four female, median age of 50 years) in whom the procedure succeeded were screened for New York Heart Association (NYHA) class, outflow gradient, mechanical dyssynchrony, QRS‐width change, and 6‐minute walking distance (6MWD) and peak oxygen consumption (VO₂peak) improvement after 6 months and remotely. Results: After 6 months of pacing, NYHA class decreased (median 1 vs 2, respectively); peak (33 vs 84 mmHg) and mean (13 vs 38 mmHg) outflow tract gradients were reduced; and QRS width (143 vs 105 ms), intraventricular dyssynchrony (35 vs 55 ms), and VO₂peak (19.5 vs 14.2 mL/kg/min) increased significantly (all P < 0.05) compared to baseline. In six of nine patients (67%), the peak gradient was reduced >50% and reached <40 mmHg. After a median of 36 months, the outflow gradient decreased even more (8 mmHg) and was significantly (P < 0.05) lower than after 6 months of CRT. Conclusions: These preliminary data suggest that CRT seems to be an effective method of reducing the outflow tract gradient and improving the functional status of symptomatic HOCM patients requiring ICD implantation. Our findings need to be confirmed by more extensive studies. (PACE 2011; 34:1544–1552)     

Utilization of Defibrillators and Resynchronization Therapy at the Time of Evaluation at a Heart Failure and Cardiac Transplantation Center

Background: Internal cardioverter defibrillators (ICDs) and cardiac resynchronization therapy (CRT) reduce mortality, but are underutilized in routine clinical practice. The use of these devices in patients at the time of an initial evaluation at an advanced heart failure and cardiac transplantation center is unknown. Methods: We retrospectively analyzed consecutive patients who were enrolled in a database examining parameters of cardiopulmonary exercise testing in chronic heart failure (CHF) patients at the time of an initial outpatient evaluation at a tertiary care center. Rates of ICD and CRT use in eligible patients were determined. Results: Two hundred two patients had an average age of 54 ± 13 years and an average peak oxygen consumption (pVO₂) of 12.5 ± 4.5 mL/kg/min. Of 97 patients eligible for an ICD only, 57% had an ICD at the time of evaluation. Sixty‐four percent of ICD‐eligible male patients had an ICD compared to 36% of ICD‐eligible female patients (P = 0.015). Of 105 patients meeting criteria for CRT, 54% had a CRT device. There was no difference between CRT use in eligible male and female patients. Conclusions: ICDs and CRT are underutilized in patients with severe CHF at the time of evaluation at a tertiary care center despite young age, objective functional limitation, and active consideration for advanced CHF therapies. Female patients have lower rates of ICD use than male patients. (PACE 2010; 988–993)     

Monitoring device acceptance in implantable cardioverter defibrillator patients using the Florida Patient Acceptance Survey

Background: Patient device acceptance might be essential in identifying patients at risk for adverse patient‐reported outcomes following implantation of an implantable cardioverter defibrillator (ICD). We examined the validity and reliability of the Florida Patient Acceptance Scale (FPAS) and identified correlates of device acceptance in a Dutch cohort of ICD patients. Methods: Patients with a first‐time ICD (N = 272, mean age = 59.2 ± 11.9, 82% men) recruited from the Erasmus Medical Center, Rotterdam, or the Medisch Spectrum Twente, Enschede, The Netherlands completed the FPAS, the Type D Scale, and the Hospital Anxiety and Depression Scale. Results: Exploratory and confirmatory factor analyses indicated that eliminating three items from the FPAS, leaving 12 items contributing to three factors, is equivalent to the original four‐factor version of the FPAS. The abbreviated FPAS had a high internal consistency both for the total scale and all subscales, with Cronbach's alphas ranging from 0.76 to 0.82. Anxiety (odds ratio [OR]: 9.75; 95% confidence interval [CI]: 2.38–39.87; P = 0.002), depression (OR: 2.96; 95% CI: 0.98–8.93; P = 0.05), and the distressed (Type D) personality (OR: 5.04; 95% CI: 1.50–16.92; P = 0.01), but not demographic and clinical factors including shocks, were significant independent correlates of poor device acceptance. Conclusion: A shortened 12‐item, three‐factor version of the FPAS was shown to be a valid and internally consistent instrument to assess device acceptance in Dutch ICD patients. Psychological but not clinical factors were the primary correlates of device acceptance, which underlines the importance of taking into account the patient's psychological profile when seeking to identify patients at risk for adjustment difficulties after ICD implantation. (PACE 2011;XX:1–10)     

Clustering of Poor Device Acceptance and Type D Personality is Associated with Increased Distress in Danish Cardioverter-Defibrillator Patients

Background: Psychosocial risk factors tend to cluster together within individuals, likely enhancing the risk of adverse health outcomes. We examined (1) the influence of clustering of poor device acceptance and Type D personality on anxiety and depressive symptoms, and (2) the demographic and clinical determinants of patients with clustering, in a large cohort of Danish implantable cardioverter defibrillator (ICD) patients. Methods: Patients (N = 557; 81.9% male; mean age = 61.9 ± 14.3 years) implanted with an ICD between 1989 and 2006 were asked to complete a set of standardized and validated questionnaires and were divided into four risk groups: (1) No risk factors (neither poor device acceptance nor Type D), (2) Poor device acceptance only, (3) Type D only, (4) Clustering (both poor device acceptance and Type D). Results: The prevalence of anxiety was significantly higher in patients with clustering of risk factors (54.2%) compared to patients with poor device acceptance (30.0%), Type D personality (26.5%), or no risk factors (7.6%) (χ²= 88.472; df = 3; P < 0.001). Similarly, the prevalence of depression was higher in the clustering group (47.2%) compared to patients with poor device acceptance (19.1%), Type D personality (23.5%), or no risk factors (1.8%) (Fisher's exact = 112.874; df = 3; P < 0.001). Patients with the clustering of poor device acceptance and Type D had the highest mean scores of anxiety (P < 0.001) and depression (<0.001), also when adjusting for demographic and clinical baseline characteristics including shocks. Shocks (P = 0.006) were associated with increased anxiety but not with depression (P = 0.31). Conclusion: Patients with poor device acceptance and Type D personality should be identified and monitored in clinical practice, as they may benefit from adjunctive intervention in order to experience the same quality of life benefits following implantation as other patients. Given the cross‐sectional nature of the study, these findings should be confirmed using a prospective study design.     

Prognostic impact of hs‐CRP and IL‐6 in patients with persistent atrial fibrillation treated with electrical cardioversion

Objective. The aim of this study was to assess the role of inflammatory processes in the development of atrial fibrillation (AF) and the prognostic impact of inflammatory markers in predicting long‐term risk of AF recurrence after electrical cardioversion (CV). Methods. High‐sensitivity C‐reactive protein (hs‐CRP) and interleukin‐6 (IL‐6) were measured in 56 patients with persistent AF (lasting mean 128 days (range 14–960), mean age 65 years (34–84)), 19 healthy volunteers and 19 patients with permanent AF. Patients with persistent AF underwent CV. Blood samples were taken prior to CV and after 1, 30 and 180 days. Results. The immediate success rate of CV was 88?%, while the total recurrence rate after 180 days was 68?%. Patients with permanent AF had significantly higher levels of hs‐CRP and IL‐6 than patients with persistent AF (p = 0.0011, p<0.001). Patients in sinus rhythm (SR) after 180 days had significantly lower baseline hs‐CRP (1.25?mg/L (0.5–2.4) versus 2.0?mg/L (0.9–3.3), p<0.001) and IL‐6 (1.96?pg/mL (1.35–2.7) versus 2.75?pg/mL (1.55–3.62), p<0.001) than patients with recurrent AF. Baseline IL‐6 was the only independent predictor of recurrent AF (p = 0.04) in a multivariate Cox analysis. Patients in the lowest hs‐CRP quartile (<0.8?mg/L) had significantly lower AF recurrence rates after 180 days (50?% versus 74?% in the other three quartiles combined; p = 0.0069). Conclusion. Patients with AF had elevated levels of inflammatory markers. Low hs‐CRP and IL‐6 prior to CV are associated with a lower risk of AF recurrence after CV.     

Cardiac resynchronization therapy with or without anatomical reverse remodeling does not affect defibrillation threshold

Background: Recent clinical trials have documented beneficial reverse‐remodeling effects with cardiac resynchronization therapy (CRT). The aim of this study was to investigate the effect of CRT with or without reverse anatomical remodeling of the left ventricle on defibrillation threshold (DFT) levels in a prospective and consecutive group of patients with class II‐IV systolic heart failure. Methods: Study population consisted of 29 patients (14 women and 15 men; mean age 61 ± 11 years old). All patients underwent baseline (within 24‐hours of cardiac resynchronization therapy‐defibrillator [CRT‐D] implantation) and 6‐month follow‐up DFT testing. Reverse anatomical remodeling of the left ventricle was defined as ≥15% reduction in left ventricular end‐systolic volume at the end of 6 months of follow‐up compared to baseline. Results: Baseline, average DFT was 8.8 ± 5.9 J. Left ventricular end‐diastolic volume was the only predictor of baseline DFT level (P = 0.02) among the baseline demographics. Safety margin of at least 10 J was achieved in all patients. Average DFT at the end of 6 months of biventricular pacing was 9.2 ± 6.9 J. One patient (3.4%) failed to have a safety margin of 10 J. Reverse anatomical remodeling was observed in 14 (48%) patients and did not have any effect on DFT level. There were no complications related to DFT testings. Conclusions: Baseline average DFT in patients undergoing CRT‐D was ≤10 J in our study. CRT‐D with or without anatomical reverse remodeling does not affect DFT at the end of 6 months of follow‐up. High DFT level at the end of 6 months of follow‐up is rare (3.4%) among patients with current CRT‐D devices. PACE 2012; 35:416–421)     

Lower incidence of inappropriate shock therapy in patients with combined cardiac resynchronisation therapy defibrillators (CRT‐D) compared with patients with non‐CRT defibrillators (ICDs)

Introduction: A significant number of patients experience inappropriate shock therapy (IST) from implantable cardioverter‐defibrillators (ICD). An increasing number of patients with advanced heart failure receive combined ICD and cardiac resynchronisation therapy devices (CRT‐D). The incidence of IST in this group is less well described. We aimed to assess the incidence and predictors of IST in CRT‐D patients. Methods: A retrospective cohort study of prospectively collected data on patients who received an ICD and CRT‐D between October 2007 and January 2009 at our institution were studied. The primary outcome measures were the IST event rate and all‐cause mortality. Results: A total of 185 patients with ICD/CRT‐D (100/85) were included in the analysis. Eighteen patients experienced 35 episodes of IST during the follow‐up (21 ± 13 months). There was a significantly lower IST cumulative event rate in the CRT‐D vs. ICD group, 5% (CI: 1–13%) vs. 19% (95% CI: 11–30%) by 24 months, (p = 0.017). The majority of the IST was caused by atrial arrhythmias with atrial fibrillation accounting for 28 episodes of IST in nine patients. Multivariate analysis using Cox hazard model including baseline characteristics and coexisting appropriate shock therapy showed that a history of atrial fibrillation/flutter was the strongest independent predictor of IST with a hazard ratio of 3.53 (p = 0.019). Conclusion: Patients with CRT‐D had a significantly lower incidence of IST compared with patients receiving an ICD. Given that atrial arrhythmia remained the commonest trigger for IST, our finding lends support to the hypothesis that CRT may reduce atrial fibrillation burden in patients receiving CRT‐D.     

Right Ventricular Dysfunction and the Incidence of Implantable Cardioverter‐Defibrillator Therapies

Introduction: Implantable cardioverter‐defibrillator (ICD) therapy is well established in preventing sudden cardiac death in patients with left ventricular dysfunction. The influence of right ventricular (RV) function on ICD therapy for sudden cardiac death (SCD) is not known. Methods: We retrospectively studied 222 patients receiving an ICD for primary prevention of SCD. Baseline clinical and echocardiographic data were gathered. RV systolic function was qualitatively assessed as normal or abnormal (described as mildly, moderately, or severely reduced). Primary endpoint was combined ICD therapy or death and secondary endpoint was ICD therapy alone. Results: The mean follow‐up was 940 ± 522 days. The mean left ventricular ejection fraction was 0.23 ± 0.07. By Kaplan‐Meier analysis, RV dysfunction was predictive of combined ICD therapy or death when comparing between normal and abnormal RV function (P = 0.008) and among qualitative ranges of RV function (P = 0.012). RV dysfunction was not predictive of ICD therapy alone with either type of classification. After adjusting for clinical covariates, severe RV dysfunction was predictive of the combined endpoint of ICD therapy or death (HR 2.02, 95% CI 1.04–3.92, P = 0.037). Conclusion: Severe RV dysfunction appears to be an independent predictor of the combined endpoint of ICD therapy or death. RV dysfunction does not reliably predict the incidence of ICD therapy alone.     

Application of the Seattle Heart Failure Model in patients on cardiac resynchronization therapy

Background: The Seattle Heart Failure Model (SHFM) is a multimarker risk assessment tool able to predict outcome in heart failure (HF) patients. Aim: To assess whether the SHFM can be used to risk‐stratify HF patients who underwent cardiac resynchronization therapy with (CRT‐D) or without (CRT) an implantable defibrillator. Methods and Results: The SHFM was applied to 342 New York Heart Association class III‐IV patients who received a CRT (23%) or CRT‐D (77%) device. Discrimination and calibration of SHFM were evaluated through c‐statistics and Hosmer‐Lemeshow (H‐L) goodness‐of‐fit test. Primary endpoint was a composite of death from any cause/cardiac transplantation. During a median follow‐up of 24 months (25th–75th percentile [pct]: 12–37 months), 78 of 342 (22.8%) patients died; seven patients underwent urgent transplantation. Median SHFM score for patients with endpoint was 5.8 years (25th–75th pct: 4.25–8.7 years) versus 8.9 years (25th–75th pct: 6.6–11.8 years) for those without (P < 0.001). Discrimination of SHFM was adequate for the endpoint (c‐statistic always ranged around 0.7). The SHFM was a good fit of death from any cause/cardiac transplantation, without significant differences between observed and SHFM‐predicted survival. Conclusion: The SHFM successfully stratifies HF patients on CRT/CRT‐D and can be reliably applied to help clinicians in predicting survival in this clinical setting. (PACE 2012; 35:88–94)     

Significance of Supraventricular Tachyarrhythmias in Patients with Implanted Pacing Cardioverter Defibrillators

Eighty-six patients were treated with an implantable cardioverter defibrillator (ICD) because of sustained ventricalar tachycardia (VT) or ventricular fibrillation (VF). In 27 patients an epicardial system was used, in 59 patients a transvenous system with a subcutaneous patch electrode was implanted. During a mean follow-up time of 17 ± 9 months, inappropriate activations of the ICD due to supraventricular tachycardia were documented by Holter monitoring in 14 patients (16%). In 8 patients paroxysmal atrial fibrillation (AF), in 2 patients chronic AF, in 1 patient atrial flutter, and in 3 patients sinus tachycardia triggered antitachycardia pacing functions (12 patients) or internal defibrillation (2 patients). In 3 patients (5%) VT was induced by inappropriate antitachycardia pacing. In an additional 18 patients (21%) inappropriate activation of antitachycardia functions due to atrial tachyarrhythmias were suspected based on telemetry readouts or the patient's history. Inappropriate activation of ICD therapy triggered by intermittent supraventricular tachyarrhythmias is common. Further improvements of detection algorithms for supraventricular tachycardia are required in future device generations.     

Mood disorders and outcome in patients receiving cardiac resynchronization therapy

Background: Mood disorders (MD) have been demonstrated to influence outcome in cardiac disease in general and specifically in chronic heart failure (HF). Little is known about their possible effect on response to cardiac resynchronization therapy (CRT). Objective: To evaluate the influence of MD on CRT response. Methods: We conducted a retrospective chart review of all cardiac CRT‐D (CRT defibrillator) recipients (N = 153) at the Veterans Affairs Pittsburgh Healthcare System from beginning of 2004 through end of 2006. All‐cause death and HF‐related hospitalizations (HFH), individually and combined, were sought through 2009. Results: During a mean follow‐up time of 31.4 ± 14.7 months, there were 48 (31.4%) deaths and 55 (35.9%) HFHs in HF patients having New York Heart Association class of 2.9 ± 0.3, left ventricular ejection fraction (LVEF) of 25.8 ± 9.1%, left ventricular end‐diastolic diameter (LVEDD) of 61.6 ± 11.6 mm, and QRS of 152 ± 30.5 ms . A total of 65 (42.5%) patients had MD (depression, anxiety, or posttraumatic stress disorder). Compared to others, patients in the MD group were at a significantly higher risk of HFH alone (47.7% vs 27.3%, P = 0.009) or when combined with death (58.5% vs 39.8%, P = 0.022) but not death alone (35.4% vs 28.4%, P = 0.36). The significant predictive effect of MD on HFH alone and when combined with death shown in univariate analysis was not attenuated after adjustment for age, ejection fraction, etiology of cardiomyopathy, cumulative number of any shocks, smoking, and evidence of postimplantation echocardiographic improvement. Conclusions: MD in patients with advanced but stable HF receiving CRT‐D therapy was a predictor of HFH alone or when combined with death but not mortality alone. (PACE 2011;1–9)     

Termination of ventricular tachycardia by far-field stimulation in humans: a feasibility study

Background: Although a low‐energy cardioversion (LEC) shock from an implantable cardioverter‐defibrillator (ICD) can terminate ventricular tachycardia (VT), it frequently triggers ventricular fibrillation (VF) and is therefore not used in clinical practice. We tested whether a modified LEC shock with a very short duration (0.12–0.36 ms), termed “field stimulus,” can terminate VT without triggering VF. Methods: In 13 sedated patients with implanted ICDs, we attempted to induce VT and to terminate the arrhythmias by field stimuli during hospital predischarge tests. Results: In eight patients, 27 VT episodes were induced and treated with a total of 46 high‐voltage (25–200 V) field stimuli, which terminated 11 VT episodes (41% efficacy) and never accelerated VT into VF. VT episodes slower than 230 beats per minute (bpm) (median rate) were terminated more successfully than faster arrhythmia episodes (69% vs 15%, P < 0.01). The strength of the field stimulus had no major influence on the effectiveness. We therefore postulate that suboptimal timing of field stimuli (delivered simultaneously with a sensed event in the right ventricular apex) was the main reason for failed VT terminations. Conclusion: A short (0.12–0.36 ms), high‐voltage (50–100 V) field stimulus delivered from the shock coil of an implanted ICD system can safely terminate VT, especially for VT rates below 230 bpm. We believe that it would be reasonable to test the effectiveness of automatic field‐stimulus therapy from implanted ICDs in VT episodes up to 230 bpm that are not susceptible to termination by antitachycardia pacing. (PACE 2010; 33:1540–1547)     

Implantable Cardioverter Defibrillator Therapy for Prevention of Sudden Cardiac Death in Children in The Netherlands

Introduction: Implantable cardioverter defibrillator (ICD) therapy is increasingly used in children. The purpose of this multicenter study is to evaluate mid‐term clinical outcome and to identify predictors for device discharge in pediatric ICD recipients. Methods and Results: From 1995 to 2006, 45 patients in The Netherlands under the age of 18 years received an ICD. Mean age at implantation was 10.8 ± 5.2 years. Primary prevention (N = 22) and secondary prevention (N = 23) were equally distributed. Underlying cardiac disorders were primary electrical disease (55%), cardiomyopathy (20%), and congenital heart disease (17%). The follow‐up was 44 ± 32.9 months. Three patients (7%) died and one patient (2%) underwent heart transplantation. ICD‐related complications occurred in eight patients (17%), seven of whom had lead‐related complications. Fourteen patients (31%) received appropriate ICD shocks; 12 patients (27%) received inappropriate ICD shocks. Fifty‐five percent of 22 ICD recipients under the age of 12 years received appropriate shocks, which was higher as compared with 9% of 23 older ICD recipients (P = 0.003). Although the incidence of appropriate shocks in the present study was larger in secondary prevention (9/23; 39%) as compared with primary prevention (5/22; 23%), this difference did not reach significance. Conclusions: In our population of patients, children <12 years of age had more appropriate shocks than patients 13–18 years. The complication rate is low, and is mainly lead related. (PACE 2010; 33:179–185)