Implantable cardioverter-defibrillators in patients with left ventricular noncompaction

Background: Left ventricular noncompaction (LVNC) is a rare, congenital cardiomyopathy and can be associated with heart failure, embolic events, arrhythmias, and sudden cardiac death. Implantation of implantable cardioverter-defibrillators in these patients is a treatment option, but data on long-term follow-up are limited. The aim of the study was to analyze the clinical outcome of patients with LVNC who were treated with an implantable cardioverter-defibrillator (ICD).
Methods: We conducted a retrospective study on 12 patients (mean age: 45 ± 13 years, range 20–60) with LVNC, who underwent ICD implantation for secondary (n = 8) and primary (n = 4) prevention.
Results: During a median follow-up of 36 months, five patients (42%) presented with appropriate ICD therapy: in four of the eight patients (50%) in whom the ICD was implanted as a secondary prevention and in one of the four patients (25%) for whom the ICD was implanted for primary prevention. In eight patients (66%) supraventricular tachyarrhythmias were documented. Improvement of left ventricular function could be observed in one of two patients with a biventricular ICD.
Conclusions: Potentially life-threatening ventricular tachyarrhythmias may occur in patients with LVNC. ICD therapy may be effective for primary and secondary prevention in these patients. Due to the high prevalence of supraventricular tachyarrhythmias devices with reliable detection enhancements should be considered.     

Low Referral Rate for Prophylactic Implantation of Cardioverter-Defibrillators in a Tertiary Care Medical Center

Background: Implantable cardioverter-defibrillators (ICDs) for primary prevention became standard of care after the publication of the second Multicenter Automatic Defibrillator Implantation Trial (MADIT-II) and Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT).
Objective: To determine the percentage of patients in a Veterans Affairs medical center appropriately referred for primary prophylaxis ICD and to further categorize the reasons patients are not being referred.
Methods : Echocardiograms obtained since the release of MADIT-II in 2002 were searched for a left ventricular ejection fraction (LVEF) ≤ 35% and ≤30%. We randomly selected 120 patients per year from 2002 to 2006, for a total of 600 patients in each group. Data were reviewed to determine the number of ICD recipients and the reasons patients were not referred.
Results: In the LVEF ≤ 35% group an ICD was implanted in 28% of 392 eligible patients. Nonreferral (58%) was the most common reason that eligible patients did not receive an ICD. Patients were not referred for ICD because of appropriate contraindications in 26% of cases. Overall mortality was 29% (15% with and 31% without ICD). In the LVEF ≤30% group an ICD was implanted in 33% of 388 eligible patients. Nonreferral (51%) was the most common reason that eligible patients did not receive an ICD. Patients were not referred for ICD because of appropriate contraindications in 24% of cases. Overall mortality was 28% (18% with and 32% without ICD).
Conclusions: After the publication of MADIT-II and SCD-HeFT, only 42% of eligible patients with LVEF ≤ 35% and 49% of patients with LVEF ≤30% were offered a potentially life-saving ICD between 2002 and 2006 in our medical center, sometimes with considerable delay.     

Left Ventricular Ejection Fraction as Criterion for Implantation of an Implantable Cardioverter-Defibrillator in Heart Failure Patients Undergoing Surgical Left Ventricular Reconstruction

Background: Besides implantation of an implantable cardioverter-defibrillator (ICD), a proportion of patients with left ventricular (LV) dysfunction due to ischemic cardiomyopathy are potential candidates for surgical LV reconstruction (Dor procedure), which changes LV ejection fraction (LVEF) considerably. In these patients, LVEF as selection criterium for ICD implantation may be difficult. This study aimed to determine the value of LVEF as criterium for ICD implantation in heart failure patients undergoing surgical LV reconstruction.
Methods: Consecutive patients with end-stage heart failure who underwent ICD implantation and LV reconstruction were evaluated. During admission, two-dimensional (2D) echocardiography (LV volumes and LVEF) was performed before surgery and was repeated at 3 months after surgery. Over a median follow-up of 18 months, the incidence of ICD therapy was evaluated.
Results: The study population consisted of 37 patients (59 ± 11 years). At baseline, mean LVEF was 23 ± 5%. Mean left ventricular end-systolic volume (LVESV) and left ventricular end-diastolic volume (LVEDV) were 175 ± 73 mL and 225 ± 88 mL, respectively. At 3-month follow-up, mean LVEF was 41 ± 9% (P < 0.0001 vs. baseline), and mean LVESV and LVEDV were 108 ± 65 mL and 176 ± 73 mL, respectively (P < 0.0001 vs. baseline). During 18-month follow-up, 12 (32%) patients had ventricular arrhythmias, resulting in appropriate ICD therapy. No significant relations existed between baseline LVEF (P = 0.77), LVEF at 3-month follow-up (P = 0.34), change in LVEF from baseline to 3-month follow-up (P = 0.28), and the occurrence of ICD therapy during 18-month follow-up.
Conclusion: LVEF before and after surgical LV reconstruction is of limited use as criterium for ICD implantation in patients with end-stage heart failure.     

Outcomes of Elderly Recipients of Implantable Cardioverter Defibrillators

Aims of the Study: To examine the patterns of use, complication rates, and survival in elderly recipients of implantable cardioverter defibrillators (ICD).
Methods and Results: We followed 500 consecutive patients included in the Marburg Defibrillator database for 48 ± 39 months. There were 40 patients (8%) ≥75 and 460 (92%) <75 years of age at the time of implant. The 5-year Kaplan-Meier estimate for appropriate treatment of VT or VF by ICD was 49% among patients <75- versus 57% among patients ≥75-years-old (P = 0.17). The 5-year sudden death rate was similarly low in both groups of patients (2% versus 3%). The 5-year overall mortality rate was significantly higher in patients ≥75 than in patients <75 years of age (55% versus 21%, P = 0.001), due to a higher mortality from heart failure (HF). All procedure-related, lead-related, and pulse generator-related complications were similar in both patient groups (23% versus 25%).
Conclusions: ICD therapy was equally effective in patients ≥75 and patients <75 years of age in the prevention of sudden cardiac death. While the complication rates were similar in both age groups, the long-term mortality was considerably higher in elderly patients, due to a higher mortality from HF. The current ICD therapy guidelines appear applicable to elderly patients who are otherwise medically stable and without advanced HF.     

Clinical Predictors of Appropriate Implantable-Cardioverter Defibrillator Discharge

Background : The implantable cardioverter-defibrillator (ICD) is the mainstay of treatment for ventricular tachyarrhythmias due to its impact on mortality. ICD discharges may be appropriate or inappropriate, and identification of patients at risk for ICD discharge is essential. We sought to determine the predictors of appropriate ICD discharge.
Methods : We analyzed data from 591 ICD recipients (mean age 67.9 ± 13.0 years; 474 men; mean follow-up 10.9 ± 13.8 months). The association between ICD discharges and multiple clinical variables, including age, gender, hypertension, diabetes, coronary artery bypass graft (CABG) surgery, syncope, atrial fibrillation (AF), prior coronary intervention, left ventricular ejection fraction (LVEF), left ventricular end diastolic dimension, left ventricular end systolic dimension (LVESD), and ambient drug therapy was examined.
Results : The rates of appropriate or inappropriate discharges, delivered to 155 patients, were 0.49 per follow-up year (F/Y). The median time-to-first appropriate discharge was 3.4 years. Among the discharges delivered, 97(63%) were appropriate and 58(37%) were inappropriate. Risk factors associated with a trend toward earlier appropriate discharges included age ≤65 years, and diuretic and digitalis use. By multiple variable analysis, no history of CABG and an enlarged LVESD were independent predictors of earlier appropriate ICD discharge.
Conclusions: Patients who did not have CABG revascularization were 2.8-fold more likely than those who underwent CABG, and patients with enlarged LVESD were 2.5-fold more likely than those with normal LVESD to receive appropriate ICD discharges. These patients deserve special vigilance and management in order to prevent the occurrence of ventricular tachyarrhythmias triggering ICD discharges.     

Left Ventricular Ejection Fraction and Absence of ACE Inhibitor/Angiotensin II Receptor Blocker Predicts Appropriate Defibrillator Therapy in the Primary Prevention Population

Introduction: Implantable cardioverter defibrillators (ICD) significantly reduce mortality in patients with left ventricular (LV) dysfunction. However, little is known of the predictors of appropriate device activation in the primary prevention population. The aim of the present study was to determine predictors of appropriate device therapy in patients receiving ICDs for primary prevention. Methods & Results: One hundred twenty‐six patients with a left ventricular ejection fraction (LVEF) of < 35% and no prior documented ventricular arrhythmias underwent ICD implantation. The ICD implanted was single chamber in 60 (48%), dual chamber in 10 (8%), and biventricular in 56 (44%) patients and programmed with a single ventricular fibrillation (VF) zone at >180 beats per minute. Mean age was 58 ± 13 years and mean LVEF was 23 ± 7%. Fifty‐two percent had ischemic cardiomyopathy and 66% were New York Heart Association heart failure class II/III. During a mean follow‐up period of 589 ± 353 days, 17 (13%) patients received appropriate device therapy and three (4%) received inappropriate shocks. Appropriate ICD therapy was associated with reduced LVEF (mean 19.9% vs 23.7%, P = 0.02) and the patients were less likely to have received angiotensin‐converting enzyme inhibitor (ACEI) or angiotensin II receptor blockers (AIIRB) (65% vs 90%, P = 0.04). Multivariate analysis revealed lack of ACEI/AIIRB (odds ratio [OR]= 0.06, 95% confidence interval [CI]= 0.01–0.37, P = <0.01) and lower LVEF (OR = 0.88, 95% CI 0.79–0.98, P = 0.02) predicted appropriate device activation. There was no difference in transplant‐free survival between the appropriate therapy and no/inappropriate therapy groups, LVEF <20% and LVEF >20% group, and lack of ACEI/AIIRB and ACEI/AIIRB group. Conclusion: Appropriate device activation occurred in 13% of patients in a primary prevention population. LVEF and absence of ACEI/AIIRB predicted appropriate ICD therapy. (PACE 2010; 33:696–704)     

Sleep-Disordered Breathing in Recipients of Implantable Defibrillators

Study Objectives: To examine the prevalence and clinical significance of sleep-disordered breathing in patients with implantable cardioverter defibrillators (ICD).
Methods and Results: Overnight sleep studies were performed in 129 ICD recipients who had no history of sleep apnea. The mean left ventricular ejection fraction (LVEF) was 29 ± 11%. Mild, moderate, and severe sleep apnea was diagnosed in the presence of an apnea/hypopnea index (AHI) of 5–15/h, 15.1–30/h, and >30/h, respectively. No sleep apnea was present in 49 patients (38%), 57 (44%) had central sleep apnea (CSA), and 23 patients (18%) had obstructive sleep apnea (OSA). Mild, moderate, and severe sleep apnea were present in 25%, 31%, and 44% of patients with CSA, compared with 52%, 22%, and 26% of patients with OSA (P < 0.05). LVEF was similar in patients with versus without OSA or CSA. Patients with CSA were significantly older and had a higher prevalence of ischemic cardiomyopathy than patients without sleep apnea.
Conclusions: Previously undiagnosed CSA is common in ICD recipients. Severely disordered breathing during sleep was more prevalent among patients with CSA than patients with OSA. This prospective, observational study will examine the long-term clinical significance of sleep-disordered breathing in ICD recipients.     

Elevated serum creatinine at baseline predicts poor outcome in patients receiving cardiac resynchronization therapy

Background: Renal insufficiency is recognized as a predictor of mortality and poor outcome in heart failure patients. We sought to study the impact of baseline serum creatinine on subsequent outcome in cardiac resynchronization therapy ( CRT) recipients.
Methods: We retrospectively reviewed hospital records of all CRT recipients at Pittsburgh Veterans Affairs (VA) Healthcare System (2003–2005) and University of Pittsburgh Medical Center (2004) . We recorded clinical characteristics at the time of implantation including demographics, New York Heart Association (NYHA) functional class, ejection fraction, QRS duration, cardiomyopathy etiology, medical history, medication use, and serum creatinine. Mortality alone and mortality combined with heart failure hospitalization were the study endpoints.
Results: Out of the 330 patients studied, a total of 66 (20.0%) patients died over a mean follow-up duration of 19.7 ± 9.0 months (range 1–44). The cohort was studied by three creatinine tertiles (0.6–1.0, 1.1–1.3, 1.4–3.0 mg/dL). Both study endpoints were observed more frequently in patients in the highest creatinine tertile compared to others (28.7% vs 14.0%, P = 0.008 for death and 41.6% vs 21.5%, P = 0.001 for the combined endpoint). High creatinine remained an independent predictor of mortality (hazard ratio [HR] 1.89, 95% confidence interval [CI] 1.06–3.39, P = 0.032) and the combined endpoint (HR 1.94, 95% CI 1.20–3.13, P = 0.007) in multivariate adjusted models. Studied as a continuous variable, increase in creatinine level by 0.1 mg/dL was associated with an 11% increase in mortality risk and a 7% increase in the combined endpoint.
Conclusion: In an unselected cohort of CRT recipients, the baseline creatinine was found to predict worse survival and poor outcome over a modest follow-up duration.     

Effect of end-stage renal failure and hemodialysis on mortality rates in implantable cardioverter-defibrillator recipients

BACKGROUND: Most defibrillator (ICD) trials have excluded patients on hemodialysis (HD). It is therefore not known whether the ICD, when indicated, confers the same mortality benefit to HD and non-HD patients. METHOD: HD patients implanted with an ICD from July 2001 to June 2004 were matched by age, gender, left ventricular ejection fraction (LVEF), and class of heart failure to non-HD ICD recipients. RESULTS: Forty-six (16 on HD) patients (age = 65 +/- 15 yrs, LVEF = 30 +/- 14%, 44% in class III-IV HF) were followed for a mean of 30 +/- 16 months (range, 4-61 months) after ICD implantation. During this period, 12/16 HD versus 9/30 non-HD patients died (P = 0.006). The two-year mortality rates were 54% and 29% in the HD and non-HD groups, respectively (P = 0.01). After correcting for age, gender, race, LVEF, class of HF, and ICD indication (primary vs. secondary prevention) in a Cox regression model, HD remained a significant predictor of the time to death (HR = 2.9, adjusted P = 0.023). CONCLUSION: Despite having an ICD, HD patients have approximately a three-fold increase in total mortality and may therefore not extract the same survival benefits from the ICD as their non-HD counterparts. If duplicated in larger randomized trials, these results may demonstrate the futility of implanting defibrillators in HD patients.     

Mortality, Morbidity, and Complications in 3,344 Patients with Implantable Cardioverter Defibrillators:

ICDs are the therapy of choice in patients with life-threatening ventricular arrhythmias. Mortality, morbidity, and complication rates including appropriate and inappropriate therapies are unknown when ICDs are used in routine medical care and not in well-defined patients included in multicenter trials. Therefore, the data of 3,344 patients (   61.1 ± 12.1  years   ; 80.2% men; CAD 64.6%, dilated cardiomyopathy 18.9%; NYHA Class I–III: 19.1%, 54.3%, 20.1%, respectively;   LVEF > 0.50   : 0.234, LVEF 0.30–0.50: 0.472,   LVEF < 0.30   : 0.293, respectively) implanted in 62 German hospitals between January 1998 and October 2000 were prospectively collected and analyzed as a part of the European Registry of Implantable Defibrillators (EURID Germany). The 1-year survival rate was 93.5%. Patients in NYHA Class III and a   LVEF < 0.30   had a lower survival rate than patients in NYHA Class I and a preserved LVEF (0.852 vs 0.975,   P = 0.0001   ). Including the 1-year follow-up, 49.5% of patients had an intervention by the ICD, 39.8% had appropriate ICD therapies, 16.2% had inappropriate therapies. Overall, 1,691 hospital readmissions were recorded. The main causes for hospital readmissions were ventricular arrhythmias (61.3%) and congestive heart failure symptoms (12.9%). Thus, demographic data and mortality of patients treated with an ICD in conditions of standard medical care seems to be comparable and based on, or congruent with, the large secondary preventions trials. When ICDs are used in standard medical care, the 1-year survival rate is high, especially in patients with NYHA Class I and preserved LVEF. However, nearly half of all patients suffer from ICD intervention. (PACE 2003; 26[Pt. I]:1511–1518)     

Long-Term Outcomes of CRT-PM Versus CRT-D Recipients

Objective: To compare the rates of all-cause mortality in recipients of cardiac resynchronization therapy devices without (CRT-PM) versus with defibrillator (CRT-D).
Methods: Between February 1999 and July 2004, 233 patients (mean age = 69 ± 8 years, 180 men) underwent implantation of CRT-PM or CRT-D devices. New York Heart Association (NYHA) heart failure functional class II was present in 11%, class III in 69%, and class IV in 20% of patients; mean left ventricle ejection fraction (LVEF) was 26.5 ± 6.5 %, 48% presented with idiopathic dilated cardiomyopathy and 49% with ischemic heart disease. Cox multiple variable regression analysis was performed in search of predictors of death.
Results: The clinical characteristics of the 117 CRT-PM and 116 CRT-D recipients were similar, except for LVEF (28.2 ± 6.2% vs 25.0 ± 6.5%, respectively; P < 0.001), and ischemic versus nonischemic etiology of heart failure (41% vs 56%, respectively P = 0.02). Over a mean follow-up of 58 ± 15 months, no significance difference in overall mortality rate was observed between the two study groups. Male sex, NYHA functional class IV, and atrial fibrillation at implant were significant predictors of death.
Conclusions: There was no difference in long-term survival rate among patients with CRT-D versus CRT-PM, although CRT-D more effectively lowered the sudden death rate. Male sex, NYHA functional class IV, and atrial fibrillation predicted the worst prognosis.     

Ventricular Proarrhythmic Effects of Atrial Fibrillation are Modulated by Depolarization and Repolarization Anomalies in Patients with Left Ventricular Dysfunction

Background: Atrial fibrillation (AF) may have a ventricular proarrhythmic effect, particularly in the setting of heart failure. We assessed whether AF predicts appropriate implantable cardioverter-defibrillator (ICD) shocks in patients with left ventricular dysfunction and explored modulators of risk.
Methods and Results: A retrospective cohort study was conducted on 215 consecutive patients with ICDs for primary prevention having a left ventricular ejection fraction ≤ 35%. Mean age at ICD implantation was 61.0 ± 9.7 years and 17% were women. Overall, 22 patients (10.2%) experienced appropriate ICD shocks over a follow-up of 1.3 ± 0.7 years, corresponding to an actuarial event-rate of 5.8% per year. In univariate analysis, AF was associated with a 3.6-fold increased risk of appropriate shocks (P = 0.0037). Annual rates of appropriate ICD shocks in patients with and without AF were 12.9% and 3.5%, respectively (P = 0.0200). In multivariate stepwise Cox regression analyses controlling for baseline imbalances, demographic parameters, underlying heart disease, and therapy, history of AF independently predicted appropriate shocks (hazard ratio 2.7, P = 0.0278). Prolonged QRS duration (>130 ms) and QTc (>440 ms) modulated the effect of AF on appropriate shocks. Patients with both AF and QRS > 130 ms were more than five times more likely to receive an appropriate ICD shock (hazard ratio 5.4, P = 0.0396). Patients with AF and QTc > 440 ms experienced a greater than 12-fold increased risk of appropriate shocks (hazard ratio 12.7, P = 0.0177).
Conclusion: In prophylactic ICD recipients with left ventricular dysfunction, AF is associated with increased risk for ventricular tachyarrhythmias, particularly when combined with conduction and/or repolarization abnormalities.     

Value of Heart Rate Variability to Predict Ventricular Arrhythmias in Recipients of Prophylactic Defibrillators with Idiopathic Dilated Cardiomyopathy

GRIMM, W., et al. : Value of Heart Rate Variability to Predict Ventricular Arrhythmias in Recipients of Prophylactic Defibrillators with Idiopathic Dilated Cardiomyopathy. This study investigated the relation between heart rate variability (HRV) measured as standard deviation of normal to normal RR intervals (SDNN) on baseline 24-hour ambulatory electrocardiogram (ECG) and subsequent appropriate implantable cardioverter defibrillator (ICD) interventions in 70 patients with idiopathic dilated cardiomyopathy (IDC) in whom ICDs were implanted prophylactically in the presence of a low left ventricular ejection fraction (LVEF). During   43 ± 26   months of follow-up, 26 of 70 (37%) study patients with IDC received one or more appropriate ICD interventions for sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) documented by electrograms stored in the ICD. Mean SDNN at ICD implant was   94 ± 33 ms   . No difference was found between patients with   (90 ± 25 ms)   versus without   (96 ± 37 ms)   appropriate ICD interventions for VT or VF during follow-up. Multivariate Cox regression analysis of baseline clinical characteristics including age, gender, LVEF, NYHA functional class, nonsustained VT on Holter, history of syncope, left bundle branch block, baseline medication and HRV revealed LVEF as the only significant predictor of arrhythmia. These findings do not support the use of HRV measured as SDNN on 24-hour ambulatory ECG to select patients with IDC for prophylactic ICD therapy. (PACE 2003; 26[Pt. II]:411–415)     

Implantable Cardioverter Defibrillator Therapy for Primary Prevention of Sudden Cardiac Death after Myocardial Infarction:

Study Objective: To estimate the proportion of patients eligible for implantable cardioverter defibrillator (ICD) therapy for the primary prevention of sudden cardiac death after a myocardial infarction (MI), according to the current guidelines.
Methods: Eligibility was assessed retrospectively at 6 weeks in 513 post-MI survivors (age 66 ± 13 years, left ventricular ejection fraction 48.2 ± 17%) on the basis of an electrocardiogram and an echocardiogram.
Results: LVEF was ≤ 40% in 37% and ≤ 35% in 30%, and QRS duration was <120 ms in 89% and ≥120 ms in 11% of patients. The proportion of post-MI patients meeting the criteria set by guidelines were 37% for 2006 American College of Cardiology/American Heart Association/European Society of Cardiology (ACC/AHA/ESC) 26.5% for 2008 ACC/AHA/Canadian Heart Rhythm Society 16.3% for 2005 US Centers for Medicare and Medicaid Services (CMS), and 5.8% for the 2006 United Kingdom (UK) National Institute of Clinical Excellence (NICE). According to 2005 CMS and 2006 UK-NICE guidelines, Holter monitoring was required in 7% and 18%, respectively. For the United States (700,000 MI in 2006), the 2006 ACC/AHA/ESC guidelines equate to 216,783 ICD implantations/year. For UK (60,499 MI in 2006), the 2006 NICE guidelines equate to 2,941 ICD implantations, 10,488 Holter studies, and 1,065 VT induction tests/year.
Conclusions: Current ICD therapy guidelines for primary prevention of SCD post-MI demand a substantial increase in service provision worldwide.     

Incidence and Characteristics of Appropriate and Inappropriate Therapies in Recipients of ICD Implanted for Primary Prevention of Sudden Cardiac Death

Background: We evaluated the number of appropriate and inappropriate therapies for ventricular tachyarrhythmias and trigger mechanisms in 55 MADIT II (MII)-like (group 1) and 86 SCD-HeFT-like (group 2) patients.
Methods and Results: We analyzed 399 appropriate episodes in 31 patients with implantable cardioverter defibrillators (ICD) implanted according to the MII trial indications, and 502 appropriate episodes in 47 patients matching the SCD-HeFT trial criteria (mean follow-up in both groups = 33 ± 19 months). In group 1, 39 treated episodes were inappropriate (9% of all episodes), while in group 2, 76 episodes were treated inappropriately (15% of all episodes). At least one episode of inappropriate ICD therapy was recorded in 18% of patients in group 1 (n = 10) and in 22% of patients in group 2 (n = 19).
Conclusions: Our study supports the implantation of ICD as primary prevention in patients who are at risk of sudden cardiac death, although the proportion of inappropriate ICD interventions remains high.     

Primary Prevention Implantation of Cardioverter Defibrillator without Defibrillation Threshold Testing: 2-Year Follow-up

Background: Even though the intraoperative threshold testing of the implantable cardioverter defibrillator ( ICD ) may cause hemodynamic impairment or be unfeasible, it is still considered required standard practice at the time of implantation. We compared the outcome of ICD recipients who underwent defibrillation threshold testing (DFT) with that of patients in whom no testing was performed.
Methods: A total of 291 subjects with ischemic dilated cardiomyopathy received transvenous ICDs between January 2000 and December 2004 in five Italian cardiology centers. In two centers, DFT was routinely performed in 137 patients (81% men; mean age 69 ± 9 years; mean ejection fraction 26 ± 4%) (DFT group), while three centers never performed DFT in 154 patients (90% men; mean age 69 ± 9 years; mean ejection fraction 27 ± 5%) (no-DFT group).
Results: We compared total mortality, total cardiovascular mortality, sudden cardiac death (SCD), and spontaneous episodes of ventricular arrhythmia (sustained ventricular tachycardia, VT, and ventricular fibrillation, VF) between these groups 2 years after implantation (median 23 months, 25th–75th percentile, 12–44 months). On comparing the DFT and no-DFT groups, we found an overall mortality rate of 20% versus 16%, cardiovascular mortality of 13% versus 10%, SCD of 3% versus 0.6%, VT incidence of 8% versus 10%, and VF incidence of 6% versus 4% (no significant difference in any comparison).
Conclusions: No significant differences in the incidence of clinical outcomes considered emerged between no-DFT and DFT groups. These results should be confirmed in larger prospective studies.     

Long-Term Effects of Dynamic Atrial Overdrive Pacing on Sleep-Related Breathing Disorders in Pacemaker or Cardioverter Defibrillator Recipients

Introduction: Sleep-related breathing disorders occur in 20–30% of Europeans and North Americans, including 10% of sleep apnea syndrome (SAS). A preliminary study suggested that atrial overdrive pacing with a fixed heart rate might alleviate SAS. However, it is not known whether dynamic atrial overdrive pacing alleviates SAS.
Methods: Patients with indications for a dual chamber pacemaker or implantable cardioverter-defibrillator (ICD) were screened for SAS using the Pittsburgh Sleep Quality Index (PSQI) questionnaire. If PSQI was >5, cardio-respiratory polygraphy was performed before and 4 and 7 months after device implantation. Patients were randomized to algorithm ON–OFF (group A) or OFF–ON (group B) and the apnea-hypopnea index (AHI) was measured.
Results: Out of 105 consecutive patients, 46 (44%) had a positive PSQI. This analysis included 12 patients (mean age = 61 ± 10 years, body mass index 28.9 ± 6.5 kg/m², left ventricular ejection fraction = 38.3 ± 13.6%; 10 men). All patients suffered from obstructive or mixed SAS. There were no significant differences in PSQI or AHI between baseline and follow-up or between the two study groups. Therefore, the study was terminated ahead of schedule.
Conclusions: The prevalence of obstructive or mixed SAS was high in pacemaker or ICD recipients and reduced left ventricular ejection fraction. In these patients, long-term dynamic atrial overdrive pacing using did not improve PSQI or SAS. Therefore, patients with relevant obstructive or mixed SAS should not be offered atrial pacing therapy.     

Prevention of Inappropriate Shocks in ICD Recipients: A Review of 10,000 Tachycardia Episodes

Background: The efficacy of dual-chamber ICD arrhythmia classification algorithms is crucial to prevent inappropriate shocks. We report our experience from a meta-analysis of five prospective clinical studies with inclusion phases ranging between 1997 and 2003.
Methods: Dual-chamber ICD using standard dual-chamber arrhythmia classification algorithms were implanted in 802 patients (mean age = 64 ± 11 years, 88% men) in 74 medical centers. The ICD indication was secondary prevention in 95% of patients. Supraventricular tachyarrhythmias (SVT) were previously documented in 26% of patients. All spontaneous tachyarrhythmic events documented by the device memories were analyzed by a adjudicating committee. The episodes lasting >12 seconds and/or treated by the ICD were analyzed.
Results: Over a mean follow-up of 302 ± 113 days, 9,690 events were reported. Mean heart rate at the time of events was 131 ± 45 bpm (100–430). Events were classified as oversensing in 1.4%, sinus tachycardia (ST) in 66%, SVT in 13%, slow (<150 bpm) ventricular tachycardia (VT) in 8.7%, and VT or ventricular fibrillation (VF) in 10.3%. The sensitivity of slow VT detection was 94%, and of VT/VF detection 99.3%. The specificity of sinus rhythm/ST/SVT recognition was 94%, positive predictive value 79.3%, and negative predictive value 99.2%. A total of 1,918 episodes were treated in 330 patients: 1,472 appropriately in 213, and 446 inappropriately in 117 (15% of the overall population) patients. Only 62 episodes were inappropriately treated by shocks in 40 patients, representing 5% of the overall population.
Conclusions: In this conventional ICD population, the overall specificity of standard dual-chamber arrhythmia detection settings reached 94%. This feature allows efficient detection of fast as well as slow VT events with a very low rate of inappropriate shocks.     

Early Benefit of Implantable Cardioverter Defibrillator Therapy in Patients Waiting for Cardiac Transplantation

The ICD can effectively recognize and treat ventricular arrhythmias that can lead to sudden death. Sudden death is a major problem in patients awaiting heart transplantation. We reviewed our experience with the ICD in patients with malignant ventricular arrhythmias waiting for cardiac transplantation. Nineteen patients were included. Seventeen were men, mean age was 54 ±11 years (range 17–66) and the left ventricular ejection fraction was 22%± 10% (range 9%–46%). After a mean follow–up of 6 ± 5 months (range 1–20 months), 17 patients reached heart transplantation. One patient died and the other is waiting for a transplant. Before transplantation 71 % of patients received an appropriate discharge. The mean time to the first appropriate discharge was 2 ± 2 months (range < 1–6 months), which was significantly shorter than the mean time to first discharge in the other patients (n = 182) receiving a defibrillator in our center (11 ±10 months; range 1–58 months) (P < 0.0004). In conclusion, cardiac transplantation candidates with life–threatening ventricular arrhythmias can effectively be protected against sudden arrhythmic death by ICD. These patients have a high incidence of appropriate shocks occurring very early after implantation.     

Remote, Wireless, Ambulatory Monitoring of Implantable Pacemakers, Cardioverter Defibrillators, and Cardiac Resynchronization Therapy Systems: Analysis of a Worldwide Database

Study Objective: To describe the daily routine application of a new telemonitoring system in a large population of cardiac device recipients.
Methods: Data transmitted daily and automatically by a remote, wireless Home Monitoring™ system (HM) were analyzed. The average time gained in the detection of events using HM versus standard practice and the impact of HM on physician workload were examined. The mean interval between device interrogations was used to compare the rates of follow-up visits versus that recommended in guidelines.
Results: 3,004,763 transmissions were made by 11,624 recipients of pacemakers (n = 4,631), defibrillators (ICD; n = 6,548), and combined ICD + cardiac resynchronization therapy (CRT-D) systems (n = 445) worldwide. The duration of monitoring/patient ranged from 1 to 49 months, representing 10,057 years. The vast majority (86%) of events were disease-related. The mean interval between last follow-up and occurrence of events notified by HM was 26 days, representing a putative temporal gain of 154 and 64 days in patients usually followed at 6- and 3-month intervals, respectively. The mean numbers of events per patient per month reported to the caregivers for the overall population was 0.6. On average, 47.6% of the patients were event-free. The mean interval between follow-up visits in patients with pacemakers, single-chamber ICDs, dual chamber ICDs, and CRT-D systems were 5.9 ± 2.1, 3.6 ± 3.3, 3.3 ± 3.5, and 1.9 ± 2.9 months, respectively.
Conclusions: This broad clinical application of a new monitoring system strongly supports its capability to improve the care of cardiac device recipients, enhance their safety, and optimize the allocation of health resources.