Secondary Prevention Implantable Cardioverter Defibrillator Recipients Research Articles

Appropriate Implantable Cardioverter-Defibrillator Therapy in Patients with Ventricular Arrhythmia of Unclear Cause in Secondary Prevention of Sudden Cardiac Death.

In this study, we sought to investigate the occurrence of appropriate implantable cardioverter-defibrillator (ICD) therapies and inappropriate shocks in secondary prevention ICD recipients with ventricular arrhythmia of unclear cause and ventricular arrhythmia in the context of underlying heart disease. In this retrospective study, consecutive patients with an ICD implanted for secondary prevention in the University Medical Center Groningen (UMCG), the Netherlands between 1 January 2012 and 31 December 2018 were included. Patients were classified as having ventricular arrhythmia of unclear cause if no clear cause was found which could explain the index ventricular arrhythmia. The primary outcome was appropriate ICD therapy. The study population consisted of 257 patients. In 220 patients, an underlying heart disease could be identified as the cause of ventricular arrhythmia, while 37 patients had an unclear cause of ventricular arrhythmia. The median age was 64 years (interquartile range (IQR) 53-72 years). Forty-five (18%) patients were women. During a median duration of follow-up of 6.2 years (IQR 4.8-7.8 years), appropriate ICD therapy occurred in 95 (37%) patients. This number was 90 (41%) in the group with a clear etiology and 5 (14%) in the group with an unclear etiology. In multivariable analysis, index ventricular arrhythmia of unclear cause was associated with fewer appropriate ICD therapies (HR 0.37 [95% CI 0.14-0.99]; p = 0.048), as well as an increased risk of inappropriate ICD shocks (HR 3.71 [95% CI 1.17-11.80]; p = 0.026). Index ventricular arrhythmia of unclear cause was significantly associated with fewer appropriate ICD therapies.

Long-term Clinical Outcomes of Implantable Cardioverter Defibrillator Recipients in New Zealand

The long-term clinical outcomes of implantable cardioverter defibrillator (ICD) recipients across New Zealand are unknown. This study provides a detailed analysis of long-term clinical outcomes of ICD recipients in New Zealand over the past decade. All patients with an ICD implant between 2010 and 2019 were identified using the National Minimum Dataset, which collects all public hospital admissions in New Zealand using International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, Australian Modification (ICD10-AM) procedure coding. There were 4,261 patients with a mean follow-up of 4.85±2.76 years. There were 1,739 (40.8%) primary prevention and 2,522 (59.2%) secondary prevention ICD recipients. The median age was 62 years and 78.9% were male. There was no significant difference in all-cause mortality between primary prevention or secondary prevention ICD recipients (21.7% vs 21.9%, p=0.99). In the primary prevention ICD group, heart failure (HF) hospitalisation more frequently occurred (32.7% vs 26.1%, p<0.001) but hospitalisations with ventricular arrhythmia (VA) were less common (16.7% vs 27.1%, p<0.001). Compared with ICD recipients with non-ischaemic aetiology for HF, those with ischaemic HF had higher all-cause mortality (30.0% vs 16.1%, p<0.001), HF hospitalisation (38.0% vs 22.4%, p<0.001), and hospitalisation with VA (27.9% vs 19.4%, p<0.001). In New Zealand ICD recipients, there was no difference in all-cause mortality between primary prevention and secondary prevention ICD implants. However, ICD recipients with ischaemic aetiology for HF had significantly higher all-cause mortality, HF hospitalisation, and hospitalisation with VA.

Ventricular tachycardia as presenting arrhythmia as a determinant of appropriate implantable cardioverter-defibrillator therapy in secondary prevention

Abstract Funding Acknowledgements Type of funding sources: None. Background Sudden cardiac death (SCD) is a leading cause of death. The implantable cardioverter-defibrillator (ICD) is an established therapy to prevent SCD in patients with prior ventricular tachycardia (VT) or ventricular fibrillation (VF). Determination of patient characteristics related to ICD therapies may provide targets for more intensive monitoring or management of ventricular arrhythmias. Therefore, we aimed to find determinants of appropriate ICD therapy. Methods In this retrospective, single-centre study, 223 consecutive secondary prevention ICD recipients were included. Data was obtained on medical history, laboratory measurements, electrocardiography and echocardiography. The primary outcome was appropriate ICD therapy, which included shock and antitachycardia pacing (ATP) given for VF or VT. Backward stepwise Cox regression analysis was performed to find determinants of appropriate therapy. Results The median age of the study population was 65.3 years (interquartile range (IQR) 55.4 – 72.0 years). 188 (84.3%) patients were male. 153 (68.6%) patients had ischemic heart disease. During a median follow-up duration of 6.00 years (interquartile range (IQR) 4.85 – 7.70 years), appropriate ICD therapy occurred in 89 (39.9%) patients, appropriate ICD shock in 65 (29.1%) patients, death in 55 (24.7%), inappropriate shock in 11 (4.9%) and device-related complications in 18 (8.1%). VT as index arrhythmia, QRS fragmentation and diminished right ventricular function were determinants of appropriate device therapy. Interestingly, whereas the majority of patients (141 (63.2%)) had an ICD implanted for initial presentation with VF, the first occurrence of appropriate therapy during follow-up was for monomorphic VT in the majority of patients (84 (94.4%)). Conclusion In patients with a secondary prevention ICD indication, VT as presenting arrhythmia is a determinant of appropriate ICD therapy during follow-up. Most ICD therapies during follow-up were applied for monomorphic VT.

Left ventricle remodeling predicts the recurrence of ventricular tachyarrhythmias in implantable cardioverter defibrillator recipients for secondary prevention.

BackgroundImplantable cardioverter defibrillator (ICD) is an effective treatment for secondary prevention of ventricular tachycardia/ventricular fibrillation (VT/VF). Left ventricular (LV) remodeling may develop before ICD implant and over time. However, it remains unclear how LV remodeling affects subsequent risk for recurrence VT/VF in ICD recipients under optimal medical therapy.MethodsFrom May of 2004 to June of 2015, 144 patients received ICD implantation for secondary prevention were enrolled in this study. All information interrogated from ICD devices during follow-up or ICD therapy history (anti-tachycardia pacing and shock therapy) were reviewed and validated the occurrences of VT/VF.ResultsAt a mean follow-up of 1110.5 ± 860.6 days, 53 patients (36.8%) had recurrence of VT/VF episodes and 91 patients had no recurrence of VT/VF episode after ICD implant. Left ventricular end-diastolic volume (LVEDV) > 163.5 mL had significant predictive value for VT/VF recurrence (area under the curve: 0.602, p = 0.041). Moreover, the percentage of patients with LVEDV >163.5 mL was significantly higher in patients with recurrent VT/VF than patients without recurrent VT/VF (62.3 vs 40.0%, p = 0.010). Left ventricular ejection fraction ≤ 30% (p = 0.031), LVEDV > 163.5 mL (p = 0.012) and QRS width > 125 msec (p = 0.049) were significant predictors for VT/VF recurrence by univariate Cox regression analysis. However, only LVEDV > 163.5 mL (hazard ratio: 2.549, 95% confidence interval: 1.249 ~ 5.201, p = 0.010) and QRS width > 125 msec (hazard ratio: 2.173, 95% confidence interval: 1.030 ~ 4.586, p = 0.042) were independent predictors for recurrence of VT/VF after multivariable adjustment.ConclusionLV remodeling and QRS width > 125 msec were independent predictors for VT/VF recurrence in secondary prevention ICD recipients under optimal medical therapy, independent of LV ejection fraction.

Long-term outcome of implantable cardioverter–defibrillator implantation in secondary prevention of sudden cardiac death

Little is known about the long-term outcomes of patients who receive an implantable cardioverter-defibrillator (ICD) for purely secondary prevention indications. To assess the rates and predictors of appropriate therapies over a very long-term follow-up period in this population. Between June 2003 and August 2006, 239 consecutive patients with structural left ventricular disease and a secondary prophylaxis indication for ICD therapy (survivors of life-threatening ventricular tachyarrhythmias) were prospectively enrolled. An extended follow-up of these patients was carried out. The primary endpoint was the occurrence of appropriate device therapy. Secondary endpoints were all-cause death, electrical storm and inappropriate therapy. The study population consisted of 239 patients (90% men; mean age 64±12 years; 72% ischaemic cardiomyopathy; left ventricular ejection fraction 37±12%). During a median follow-up of 7.8 (3.5-9.3) years, appropriate device therapy occurred in 139 (58.2%) patients. Death occurred in 141 patients (59%), electrical storm in 73 (30.5%) and inappropriate therapy in 42 (17.6%). Multivariable analysis identified patients whose presenting arrhythmia was ventricular fibrillation as being less likely to require appropriate device therapy than those whose presenting arrhythmia was ventricular tachycardia (sub-hazard ratio 0.62, 95% confidence interval 0.40-0.97; P=0.04). Independent predictors of all-cause death were age at implantation (P<0.0001), wide QRS complexes (P=0.024), creatinine concentration (P=0.0002) and B-type natriuretic peptide at implantation (P=0.0001). Secondary prevention ICD recipients exhibit a high risk of appropriate device therapy and death over prolonged follow-up. Patients who presented initially with ventricular fibrillation were less likely to require the delivery of appropriate device therapy.

Prediction of ventricular arrhythmia events in ischemic heart disease patients with implantable cardioverter-defibrillators.

The aim of the study was to exam the prediction of ventricular arrhythmia events in ischemic heart disease patients with implantable cardioverter-defibrillators (ICD). A total of 123 consecutive patients confirmed ischemia heart disease with ICD were examined. After device implantation, the occurrence of appropriate ICD therapy was noted. Patients were divided into two groups according to the ventricular arrhythmia occurrence. Patients with ventricular arrhythmia occurrence had a significantly great incidence of atrial fibrillation history compare to the no-ventricular arrhythmia occurrence group (8 vs. 39%, P = 0.02). The level of high-sensitive C-reactive protein (hsCRP) baseline was also significantly higher in the ventricular arrhythmia group than in the no ventricular arrhythmia (3.78 ± 1.1 vs. 0.94 ± 0.7, P < 0.01). The taking of β blocker is not common in ventricular arrhythmia group patients than no ventricular arrhythmia group (5 vs. 29%, P = 0.03). By univariate comparison, male sex, the history of atrial fibrillation, and a high level of hsCRP were significant predictors for ventricular arrhythmia occurrence. By multivariate analysis, the atrial fibrillation burden, and had a high level of hsCRP were significant for incidence of ventricular arrhythmia occurrence in ischemic heart disease patients. β-block were more likely to be free from ventricular arrhythmia occurrence. The high level of hsCRP, and the atrial fibrillation burden were strong predictor of ventricular arrhythmia occurrence in secondary prevention ICD recipients with ischemic heart disease. Taking β-blockers was free from ventricular arrhythmia occurrence.

QTc duration and QRS fragmentation on baseline ECG relate to sustained ventricular tachyarrhythmia and sudden cardiac death in hypertrophic cardiomyopathy

Purpose: The presence of prolonged QTc and QRS fragmentation (fQRS) on baseline ECG was studied in patients with hypertrophic cardiomyopathy (HCM) and related with occurrence of ventricular tachyarrhythmias or sudden cardiac death (VTA/SCD). Methods: A total of 195 clinical HCM patients was studied (52±13 years, 61% male). On a standard 12-lead ECG, QTc duration was calculated by Bazett's formula; fQRS was defined as presence of various RSR' patterns, R or S notching and/or >1 additional R wave in any non-aVR lead in patients without pacing or typical (in)complete bundle branch block. Study endpoint comprised SCD or sustained VTA (tachycardia or fibrillation) documented on ECG or, in baseline implantable cardioverter defibrillator (ICD) recipients [n=58 (30%)], by appropriate ICD therapies (shock/ATP) for VTA. QT prolonging drug recipients were excluded. Results: After a median follow up of 5.7 years (IQR 2.7-9.1), 26 (13%) patients experienced VTA (n=22) or SCD (n=4). Kaplan-Meier time to survival free of VTA/SCD showed worse survival in patients with QTc≥440 ms (p=0.017) or fQRS in ≥3 territories (inferior, lateral, septal and/or anterior) (p=0.004) (Figure). Multivariate regression analysis showed that both QTc ≥440 ms (β=2.4, p=0.034, 95% CI 1.07-5.58) and fQRS in ≥3 territories (β=3.4, p=0.007 95% CI 1.54-14.9) were independently associated with VTA/SCD. Excluding secondary prevention ICD recipients (n=13), likelihood ratio test indicated that assessment of QTc and fQRS on top of conventional SCD risk factors provided incremental value to predict occurrence of VTA/SCD (p=0.034). ![Figure][1] Kaplan Meier survival curve. Conclusion: QTc duration and presence of fQRS relate to occurrence of VTA/SCD in HCM patients, independently of conventional SCD risk factors, and therefore may have an impact on preventive treatment strategies. [1]: pending:yes

Circulation: Clinical Summaries

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Survival After Implantable Cardioverter-Defibrillator Implantation in the Elderly

The benefit of implantable cardioverter-defibrillators (ICDs) among elderly patients is controversial and may be attenuated by nonarrhythmic death. We examined the impact of age on device-delivered therapies and outcomes after primary or secondary prevention ICD. In a prospective, inclusive registry of 5399 ICD recipients in Ontario, Canada (February 2007 to September 2010), device-delivered therapies and complications were determined at routine clinic visits. Among primary prevention ICD recipients aged 18 to 49 (n=317), 50 to 59 (n=769), 60 to 69 (n=1336), 70 to 79 (n=1242), and ≥80 (n=275) years, mortality increased with age, as follows: 2.1, 3.0, 5.4, 6.9, and 10.2 deaths per 100 person-years, respectively (P<0.001). Secondary prevention ICD recipients aged 18 to 49 (n=114), 50 to 59 (n=244), 60 to 69 (n=481), 70 to 79 (n=462), and ≥80 (n=159) years also exhibited increasing mortality, as follows: 2.2, 3.8, 6.1, 8.7, and 15.5 deaths per 100 person-years, respectively (P<0.001). However, rates of appropriate shock were similar across age groups: from 6.7 (18-49 years) to 4.2 (≥80 years) per 100 person-years after primary prevention ICDs (P=0.139) and from 11.4 (18-49 years) to 11.9 (≥80 years) per 100 person-years after secondary prevention ICDs (P=0.993). Covariate-adjusted competing risk analysis demonstrated higher risk of death (Ptrend<0.001 for both primary and secondary prevention) but no significant decline in appropriate shocks with older age after primary (P=0.130) or secondary (P=0.810) prevention ICD implantation. Whereas elderly patients exhibited increased mortality after ICD implantation, rates of appropriate device shocks were similar across age groups. Decisions regarding ICD candidacy should not be based on age alone but should consider factors that predispose to mortality despite defibrillator implantation.

Electrophysiology Studies in Patients Undergoing ICD Implantation: Findings from the NCDR®

Electrophysiology studies (EPS) have historically played a role in sudden death risk stratification. More recent studies point to the left ventricular ejection fraction (EF) as a guide to implantable cardioverter defibrillators (ICD) implantation. The extent of EPS use in patients undergoing ICD implantation in the current era remains unknown. Patients undergoing de novo ICD implantation in the ICD Registry between September 2006 and March 2009 who also underwent EPS within 30 days before implant were compared to the remaining cohort to identify clinical characteristics that correlated with EPS performance. Multivariate models were generated using hierarchical logistic regression analysis. EPS were performed in 33,786 of 275,273 patients. Those undergoing EPS were more likely to have had a history of syncope, family history of sudden death, lack of congestive heart failure, narrower QRS intervals, and higher EF. Overall, 63.9% of EPS were performed in patients receiving primary prevention ICDs. Ventricular tachyarrhythmias were induced in 46.1% of primary prevention and 54.2% of secondary prevention ICD recipients. Monomorphic ventricular tachycardia was the most common type of arrhythmia induced in both groups. Complication rates were not higher in those undergoing EPS. EPS were performed predominantly in patients with borderline or less well-defined risk factors for sudden death. Ventricular arrhythmias induced from EPS were not uncommon and may help identify individuals at higher risk for future ICD therapies. Efforts to better define the role of EPS in patients undergoing ICD implantation should be considered.

Can we predict, prevent, and minimize defibrillator shocks? Lessons learned from “remote monitoring”

s I o f 9 f Beyond their principal role of successfully detecting and treating ventricular tachycardia (VT) and ventricular fibrillation (VF) with overdrive antitachycardia pacing and defibrillation shocks, modern implantable cardioverter-defibrillators (ICDs) are capable of providing sophisticated pacing and resynchronization therapy. They store enormous amounts of technical and patient-related data, such as arrhythmia burden and heart failure status. Device manufacturers recently introduced “remote monitoring” technology, which allows home transmitters to interrogate devices and to download and transmit collected and stored data via the Internet to a protected network. Remote monitoring not only has rapidly shifted the paradigm in device follow-up but has heightened interest in exploring the wealth of available information to better understand device functionality and disease substrates. Irrespective of the indications for ICD placement, given the associated risk factors and comorbidities, the majority of recipients also would be prone, if they have not already experienced, to develop atrial fibrillation (AF). The presence of AF, with its 5% to 30% incidence in the ICD population, is not merely a “nuisance” because it has many detrimental effects. Paroxysmal, persistent, and permanent AF have hazard ratios (HRs) (95% confidence interval] of 1.3 (0.7–2.5), 1.2 (0.6–2.2), and 1.7 (1.0–2.7), respectively, for mortality and 1.2 (0.6–2.2), 1.1 (0.5–2.4), and 2.4 (1.5–4.0), respectively, for appropriate ICD shocks. A ewly detected AF within the first 3 months of ICD placeent carries a significant risk for death with HR of 2.86 1.02–8.05). In patients with left ventricular dysfunction, persistent AF has been shown to cause appropriate ICD shocks and deterioration of heart failure. Furthermore, AF ay be proarrhythmic. In the Jewel AF trial, 8.6% of all T/VF episodes were found to have AF as a preceding or oncomitant rhythm. Interestingly, for consecutive episodes of VT/VF, time to next episode of VT/VF was longer when AF terminated than when it persisted.

Informed Consent in Cardiac Resynchronization Therapy

Cardiac resynchronization therapy (CRT) for the treatment of heart failure (HF) raises complex problems for informed consent. CRT with and without defibrillator backup has been demonstrated in clinical trials to improve symptoms from HF and decrease mortality.1–4 A CRT pacemaker (CRT-P) may improve symptoms and reduce mortality in selected patients, even without offering the specific protection from malignant arrhythmias afforded by a CRT defibrillator (CRT-D). Further, CRT-P may prevent disease progression even in earlier stages of HF.4,5 Implantable cardioverter-defibrillators (ICDs) alone are effective in preventing sudden cardiac death (SCD) in selected patients.6,7 Although most patients eligible for CRT-P will similarly meet guidelines for an ICD, the decision to include ICD backup with a CRT implant may not be straightforward.8 The decision for CRT-P or CRT-D implantation includes not only the medical facts, but also the important considerations based on values and principles. Patients and physicians may wrestle with fundamental questions about quality and quantity of life and struggle to come together toward a truly informed consent process. There are no formal guidelines or standards that argue for specific content to be included in the informed consent process for CRT. This article examines 4 categories of questions regarding CRT based on an understanding of autonomy and shared decision-making as elements of informed consent: (1) control over the manner of death, (2) quality versus quantity of life, (3) therapeutic flexibility, and (4) clinical uncertainty. This article may help to guide clinicians and patients by clarifying the clinical and moral considerations and the principles behind particular treatment decisions. Autonomy refers to an understanding and knowledge of available options and the ability to choose between them through rational deliberation.9,10 Respect for patient autonomy is the foundation of modern bioethics and, in …

ECG Quantification of Myocardial Scar Does Not Differ between Primary and Secondary Prevention ICD Recipients with Ischemic Heart Disease

Myocardial scar is an anatomic substrate for potentially lethal arrhythmias. Recent study showed that higher QRS-estimated scar size using the Selvester QRS score was associated with increased arrhythmogenesis during electrophysiologic testing. Therefore, QRS scoring might play a potential role in risk stratification before implantable cardioverter defibrillator (ICD) implantation. In this study, we tested the hypothesis that QRS scores among ICD recipients for secondary prevention are higher than QRS scores in primary prevention patients. From the hospital database, 100 consecutive patients with ischemic heart disease and prior ICD implantation were selected. Twelve-lead electrocardiograms (ECGs) had been obtained before implantation. ECGs were scored following the 32-points Selvester QRS scoring system and corrected for underlying conduction defects and/or hypertrophy. Ninety-three ECGs were suitable for scoring; seven ECGs were rejected because of noise, missing leads, excessive ventricular extrasystoles, or ventricular pacing. No statistically significant difference in QRS score was found between the primary [6.90 (standard deviation [SD] 3.94), n = 63] and secondary prevention group [6.17 (SD 4.50) (P = 0.260), n = 30]. Left ventricular ejection fraction (LVEF) was significantly higher in the secondary prevention group [31% (SD 13.5) vs 24% (SD 11.7) (P = 0.015)]. When patients with LVEF > or =35% were excluded, QRS scores were still comparable, namely 7.02 (SD 4.04) in the primary prevention group (n = 52) and 6.28 (SD 4.24) in the secondary (P = 0.510) (n = 18). We found no significant difference in QRS score between the ischemic primary and secondary prevention groups. Therefore, a role of the Selvester QRS score as a risk stratifier remains unlikely.

Recurrence of ventricular arrhythmias in ischaemic secondary prevention implantable cardioverter defibrillator recipients: long-term follow-up of the Leiden out-of-hospital cardiac arrest study (LOHCAT)

To assess the long-term rate of mortality and the recurrence of potentially life-threatening ventricular arrhythmias in secondary prevention implantable cardioverter defibrillator (ICD) patients and to construct a model for baseline risk stratification. Since 1996, all patients with ischaemic heart disease, receiving ICD therapy for secondary prevention of sudden death, were included in the current study. Patients were evaluated at implantation and during long-term follow-up. A total of 456 patients were included in the analysis and followed for 54 +/- 35 months. During follow-up, 100 (22%) patients died and ICD therapy was noted in 216 (47%) patients, of which 138 (30%) for fast, potentially life-threatening ventricular arrhythmia. Multivariate analysis revealed a history of atrial fibrillation or flutter (AF), ventricular tachycardia as presenting arrhythmia, and wide QRS and poor left ventricular ejection fraction as independent predictors of life-threatening ventricular arrhythmias. The strongest predictor was AF with a hazard ratio of 2.1 (95% confidence interval 1.3-3.2). On the basis of the available clinical data, it was not possible to identify a group which exhibited no risk on recurrence of potentially life-threatening ventricular arrhythmias. Ischaemic secondary prevention ICD recipients exhibit a high recurrence rate of potentially life-threatening ventricular arrhythmias. Factors that increase risk can be identified but, even with these factors, it was not possible to distinguish a recurrence-free group.

Quality of Life Among Implantable Cardioverter‐Defibrillator Recipients in the Primary Prevention Therapeutic Era

Although patients receiving implantable cardioverter-defibrillators (ICDs) for primary prevention of sudden cardiac death are the fastest growing segment of the ICD recipient population, the quality-of-life (QOL) effects of the ICD among primary prevention patients are not well understood. The purpose of this study was to measure and compare the health-related QOL among primary and secondary prevention ICD recipients, and to determine predictive factors for high or low QOL in each group. Forty-five primary prevention and 75 secondary prevention ICD recipients receiving routine care in electrophysiology clinics within the University of Pennsylvania Health System were assessed using several well-validated general and ICD-specific QOL instruments. Between primary and secondary prevention patients, there were no significant differences in EuroQol 5D (medians: 0.84 vs 0.84, P = 0.71), Health Utilities Index (medians: 0.88 vs 0.85, P = 0.95), Short Form-12 aggregate physical summary (means: 45 vs 46, P = 0.64), and Short Form-12 aggregate mental summary (means: 46 vs 47, P = 0.93) scores. Both primary and secondary prevention patients viewed their devices favorably according to the Florida Patient Acceptance Survey scale, with no significant differences between group means (80 vs 83, P = 0.71). However, substantial fractions of both primary and secondary prevention recipients had particular concerns about lifting (40%), sexual activity (19%), and driving (14%). QOL does not significantly differ between primary prevention and secondary prevention ICD recipients. Device recipients had comparable QOL to published, nationwide QOL estimates among non-ICD patients of similar age. The ICD was highly acceptable to most primary and secondary prevention patients.

Atrial Tachyarrhythmias in Primary and Secondary Prevention ICD Recipients: Clinical and Prognostic Data

Atrial fibrillation (AF) is the most common sustained arrhythmia encountered in clinical practice. The natural history of this disturbance and its effect on survival is still not known in patients with implantable cardioverter defibrillators (ICDs). Several controlled trials for both secondary and primary prevention of sudden death using ICDs have been published in literature, and meta-analysis of them provided useful clinical information on the outcome during the follow-up of this population. AF occurs in about 25% of the patients with secondary prevention indication for ICD implantation. The prevalence of AF in patients with primary prevention indication for ICD implantation is much more difficult to define; it seems to be higher in patients with left ventricular dysfunction due to nonischemic etiology (ranging from 15% to 25%), and is lower in patients with ischemic etiology (about 5-10%). However, data from clinical registries, which are expected to better reflect clinical practice than randomized trials, seem to show a substantial difference as compared to the latter ones. A history of AF episodes in patients with an ICD indication for both primary and secondary prevention is probably associated with a higher risk of death. This is particularly evident in secondary prevention in ICD recipients, while it is still controversial in patients who received an ICD for primary prevention, particularly when patients with nonischemic etiology of their left ventricular dysfunction are considered. In a population of patients implanted with an ICD, there are several other clinical factors (ejection fraction, New York Heart Association functional class, age) that can interfere with the risk of death much more than AF itself. Further large-scale registries are needed to further characterize the population receiving ICD implantation, assessing the course of risk of death with regard to clinical variables and to evaluate the degree of acceptance of trials in clinical practice.

Native QRS duration predicts the occurrence of arrhythmic events in ICD recipients

Identification of implantable cardioverter/defibrillator (ICD) recipients at higher risk of future therapies may assist in pre-empting future shocks. Native QRS duration is an established predictor of overall mortality, but the role of this parameter as a clinical predictor of arrhythmic events warrants further investigation. In an analysis of a single-centre, 13-year ICD implantation experience (1990-2002), multiple clinical parameters including QRS duration were analysed using a multiple logistic regression model. Of 562 patients followed for at least 1 year, 98 (17%) did not receive ICD therapies (event-free, group A). Comparisons were made with a randomly selected sample of 123 patients who received ICD therapies (arrhythmic events, group B). There were no significant differences in age, gender, frequency of coronary artery disease, and degree of left ventricular dysfunction. However, QRS duration was a significant determinant of arrhythmic events (> or =100 vs. <100 ms: adjusted OR 2.75, 95% CI 1.37-5.51; > or =120 vs. <120 ms: adjusted OR 1.77, 95% CI 0.97-3.23). QRS duration was also a predictor of overall mortality in the logistic regression models (> or =100 ms: adjusted OR 3.72, 95% CI 1.17-11.9; > or =120 ms: adjusted OR 3.09, 95% CI 1.39-6.85). In this ICD population, consisting largely of secondary prevention ICD recipients, longer QRS duration predicted higher likelihood of arrhythmic events. Extent of QRS prolongation could guide the decision to initiate prophylactic anti-arrhythmic therapy in ICD patients.