Preimplantation B-type natriuretic peptide concentration is an independent predictor of future appropriate implantable defibrillator therapies

N-terminal pro-B-type natriuretic peptide for prediction of ventricular arrhythmias: Data from the SMASH study

BACKGROUND

Elevated N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentrations predict heart failure (HF) and mortality, but whether NT-proBNP predicts ventricular arrhythmias (VA) is not clear.

HYPOTHESIS

We hypothesize that high NT-proBNP concentrations associate with the risk of incident VA, defined as adjudicated ventricular fibrillation or sustained ventricular tachycardia.

METHODS

In a prospective, observational study of patients treated with implantable cardioverter defibrillator (ICD), we analyzed NT-proBNP concentrations at baseline and after mean 1.4 years in association to incident VA.

RESULTS

We included 490 patients (age 66 ± 12 years, 83% men) out of whom 51% had a primary prevention ICD indication. The median NT-proBNP concentration was 567 (25-75 percentile 203-1480) ng/L and patients with higher concentrations were older with more HF and ICD for primary prevention. During mean 3.1 ± 0.7 years, 137 patients (28%) had ≥1 VA. Baseline NT-proBNP concentrations were associated with the risk of incident VA (hazard ratio [HR]: 1.39, 95% confidence interval [95% CI]: 1.22-1.58, p < .001), HF hospitalizations (HR: 3.11, 95% CI: 2.53-3.82, p < .001), and all-cause mortality (HR: 2.49, 95% CI: 2.04-3.03, p < .001), which persisted after adjusting for age, sex, body mass index, coronary artery disease, HF, renal function, and left ventricular ejection fraction. The association with VA was stronger in secondary versus primary prevention ICD indication: HR: 1.59 (95% CI: 1.34-1.88 C-statistics 0.71) versus HR: 1.24, 95% CI: 1.02-1.51, C-statistics 0.55), p-for-interaction = 0.06. Changes in NT-proBNP during the first 1.4 years did not associate with subsequent VA.

CONCLUSIONS

NT-proBNP concentrations are associated with the risk of incident VA after adjustment for established risk factors, with the strongest association in patients with a secondary prevention ICD indication.

Primary Prevention Implantable Cardioverter-Defibrillator Therapy in Heart Failure with Recovered Ejection Fraction

Given recent advances in both pharmacologic and nonpharmacologic strategies for improving outcomes related to chronic systolic heart failure, heart failure with recovered ejection fraction (HFrecEF) is now recognized as a distinct clinical entity with increasing prevalence. In many patients who once had an indication for active implantable cardioverter-defibrillator (ICD) therapy, questions remain regarding the usefulness of this primary prevention strategy to protect against syncope and cardiac arrest after they have achieved myocardial recovery. Early, small studies provide convincing evidence for continued guideline-directed medical therapy (GDMT) in segments of the HFrecEF population to promote persistent left ventricular myocardial recovery. Retrospective data suggest that the risk of sudden cardiac death is lower, but still present, in HFrecEF as compared with HF with reduced ejection fraction, with reports of up to 5 appropriate ICD therapies delivered per 100 patient-years. The usefulness of continued ICD therapy is weighed against the unfavorable effects of this strategy, which include a cumulative risk of infection, inappropriate discharge, and patient-level anxiety. Historically, many surrogate measures for risk stratification have been explored, but few have demonstrated efficacy and widespread availability. We found that the available data to inform decisions surrounding the continued use of active ICD therapies in this population are incomplete, and more advanced tools such as genetic testing, evaluation of high-risk structural cardiomyopathies (such as noncompaction), and cardiac magnetic resonance imaging have emerged as vital in risk stratification. Clinicians and patients should engage in shared decision-making to evaluate the appropriateness of active ICD therapy for any given individual. In this article, we explore the definition of HFrecEF, data underlying continuation of guideline-directed medical therapy in patients who have achieved left ventricular ejection fraction recovery, the benefits and risks of active ICD therapy, and surrogate measures that may have a role in risk stratification.

N-terminal pro-B-type natriuretic peptide is a specific predictor of appropriate device therapies in patients with primary prevention implantable cardioverter-defibrillators

BACKGROUND

Sudden death risk stratification of patients with left ventricular systolic dysfunction remains challenging. Retrospective studies have suggested N-terminal pro-B-type natriuretic peptide (NT-proBNP) may be a useful risk stratification tool.

OBJECTIVE

The purpose of this study was to ascertain the utility of NT-proBNP as a predictor of appropriate implantable cardioverter-defibrillator (ICD) therapies in primary prevention ICD recipients.

METHODS

This was a prospective study of 342 stable patients with left ventricular ejection fraction ≤40% who received a primary prevention ICD. NT-proBNP assay was performed at the time of device implant and used as a dichotomized variable (1st-3rd NT-proBNP quartiles vs 4th NT-proBNP quartile) to predict primary (appropriate ICD therapies) and secondary (death, ICD-deactivation, chronic inotropic support, transplant) outcomes.

RESULTS

Median follow-up was 35.0 months (interquartile range 15.2-55.3). In unadjusted analyses, NT-proBNP predicted both primary (hazard ratio [HR] 1.89; 95% confidence interval [CI] 1.00-3.56); P = .049) and secondary outcomes (HR 2.13; 95% CI 1.18-3.85; P =.012). Multivariable analysis reaffirmed NT-proBNP as a primary outcome predictor (HR 4.31; 95% CI 1.92-9.70; P <.001) but not as a secondary outcome predictor (HR 1.23; 95% CI 0.61-2.50; P = .564). Instead, secondary outcome was predicted by patient age and renal function. In an unadjusted subanalysis limited to patients with blood urea nitrogen <30 mg/dL, NT-proBNP remained a primary endpoint predictor (HR 2.51; 95% CI 1.25-5.05; P = .010) but not a secondary endpoint predictor (HR 1.34; 95% CI 0.52-3.44; P = .541). Receiver operating analyses at 2- and 3-year follow-up timepoints confirmed that NT-proBNP significantly improved the performance of multivariable models designed to predict future appropriate ICD therapies.

CONCLUSION

In multivariable analysis, NT-proBNP is a reasonable and specific predictor of future appropriate device therapies in primary prevention ICD recipients. In contrast, adjusted NT-proBNP does not predict all-cause mortality.

Classic and Novel Biomarkers as Potential Predictors of Ventricular Arrhythmias and Sudden Cardiac Death

Sudden cardiac death (SCD), most often induced by ventricular arrhythmias, is one of the main reasons for cardiovascular-related mortality. While coronary artery disease remains the leading cause of SCD, other pathologies like cardiomyopathies and, especially in the younger population, genetic disorders, are linked to arrhythmia-related mortality. Despite many efforts to enhance the efficiency of risk-stratification strategies, effective tools for risk assessment are still missing. Biomarkers have a major impact on clinical practice in various cardiac pathologies. While classic biomarkers like brain natriuretic peptide (BNP) and troponins are integrated into daily clinical practice, inflammatory biomarkers may also be helpful for risk assessment. Indeed, several trials investigated their application for the prediction of arrhythmic events indicating promising results. Furthermore, in recent years, active research efforts have brought forward an increasingly large number of “novel and alternative” candidate markers of various pathophysiological origins. Investigations of these promising biological compounds have revealed encouraging results when evaluating the prediction of arrhythmic events. To elucidate this issue, we review current literature dealing with this topic. We highlight the potential of “classic” but also “novel” biomarkers as promising tools for arrhythmia prediction, which in the future might be integrated into clinical practice.

Predictors of cardiac arrhythmic events in non coronary artery disease patients

Arrhythmic sudden cardiac death (SCD) represents a major worldwide public health problem accounting for 15–20% of deaths. Risk stratification to identify patients at risk of SCD is crucial in order to implement preventive measures in the general population. Several biomarkers have been tested exploring different pathophysiological mechanisms of cardiac conditions. Conflicting results have been described limiting so far their use in clinical practice. The use of new biomarkers such as microRNAs and sex hormones and the emerging role of genetic on risk prediction of SCD is a current research topic showing promising results.

This review outlines the role of plasma biomarkers to predict ventricular arrhythmias and SCD in non coronary artery disease with a special focus on their relationship with the genetic biomarkers.

Therapy for ventricular arrhythmias in structural heart disease: a multifaceted challenge

The unpredictable nature and potentially catastrophic consequences of ventricular arrhythmias (VAs) have obligated physicians to search for therapies to prevent sudden cardiac death (SCD). At present, a low left ventricular ejection fraction (LVEF) has been used as a risk factor to predict SCD in patients with structural heart disease and has been consistently adopted as the predominant, and sometimes sole, indication for implantable cardioverter defibrillator (ICD) therapy. Although the ICD remains the mainstay life-saving therapy for SCD, it does not modify the underlying arrhythmic substrate and may be associated with adverse effects from perioperative and long-term complications. Preventative pharmacological therapy has been associated with limited benefits, but anti-arrhythmic medications have significant side effects profiles. Catheter ablation of VAs has greatly evolved over the last few decades. Substrate mapping in sinus rhythm has allowed haemodynamically unstable VAs to be successfully treated. Both LVEF as an indication for ICD therapy and electro-anatomical mapping for substrate modification identify static components of underlying myocardial arrhythmogenicity. They do not take into account dynamic factors, such as the mechanisms of arrhythmia initiation and development of new anatomical or functional lines of block, leading to the initiation and maintenance of VAs. Dynamic factors are difficult to evaluate and consequently are not routinely used in clinical practice to guide treatment. However, progress in the treatment of VAs should consider and integrate dynamic factors with static components to fully characterize the myocardial arrhythmic substrate.

Osteopontin and galectin-3 predict the risk of ventricular tachycardia and fibrillation in heart failure patients with implantable defibrillators

BACKGROUND

Myocardial extracellular matrix remodelling provides electrical heterogeneity entailing ventricular tachycardia/fibrillation (VT/VF) in heart failure (HF) patients. Osteopontin (OPN) and Galectin-3 (Gal-3) are fibrosis markers and may reflect the extension of the arrhythmogenic substrate. We assessed whether plasma OPN and Gal-3 predict the risk of sustained VT/VF in a cohort of HF patients with implantable cardioverter-defibrillator (ICD).

METHODS

A total of 75 HF patients underwent pre-ICD implantation clinical evaluation and assessment of plasma OPN and Gal-3. The primary endpoint was the time to the occurrence of the first sustained VT/VF. Hazard ratios (HR) were derived from Cox proportional-hazards analysis.

RESULTS

Patients with coronary artery disease (CAD) had higher plasma OPN (79.8 ± 44.0 ng/mL vs. 66.0 ± 31.8 ng/mL; P = 0.04). Both Gal-3 (r = -0.38; P = 0.01) and OPN (r = -0.27; p = 0.01) were negatively related to estimated glomerular filtration rate. After 29 ± 17 months, 20 patients (27%) reached the primary endpoint. Patients with VT/VF had higher plasma OPN and Gal-3 (97.4 ± 51.7 ng/mL vs. 65.9 ± 31.3 ng/mL; P = 0.002 and 19.7 ± 8.5 ng/mL vs. 16.2 ± 6.2 ng/mL; P = 0.05). In univariate analysis, OPN (log-OPN, HR: 32.4; 95%CI: 3.9-264.7; P = 0.001) and Gal-3 (HR: 1.05; 95%CI: 1.00-1.11; P = 0.04) predicted sustained VT/VF. In multivariable analysis, both OPN (HR: 41.4; 95%CI: 3.8-441.9; P = 0.002) and Gal-3 (HR: 1.06; 95%CI: 1.00-1.12; P = 0.03) retained their prognostic power after correction for age, sex, history of MI, EF, NYHA class, eGFR, use of ACE-I, and amiodarone.

CONCLUSIONS

Plasma OPN and Gal-3 predict sustained VT/VF in HF patients at high risk for SCD. Larger prospective studies should outline the role of these biomarkers in predicting SCD on top of conventional risk stratification.

Changes in BNP and QTc for prediction of sudden death in heart failure

Evaluation of: Vrtovec B, Knezevic I, Poglajen G, Sebesjen M, Okrajsek R, Haddad F. Relation of B-type natriuretic peptide level in heart failure to sudden cardiac death in patients with and without QT interval prolongation. Am. J. Cardiol. 111(6), 886–890 (2013). Guidelines recommend an implantable cardioverter defibrillator (ICD) for patients with chronic heart failure (HF) and left ventricular ejection fraction (LVEF) <35%, and New York Heart Association (NYHA) class II/III, despite optimal medical treatment. However, by this mode of patient selection, many patients receive an ICD but never use it. Therefore, additional clinical and laboratory parameters, including estimated glomerular filtration rate and B-type natriuretic petide (BNP), and ECG parameters such as the corrected QT-interval (QTc), have been suggested for a more refined assessment of the risk of sudden cardiac death (SCD). However, changes in these parameters over time may be even more informative for SCD prediction than single measures, but this had not been investigated so far. In the present paper, the authors assessed the association between changes in BNP and QTc during a 3-month period in 398 patients with advanced chronic HF (NYHA III/IV) and LVEF <40%. After a follow-up of 1 year, 20 patients had suffered SCD. Patients with a significant (≥10%) increase in BNP were more likely to have a significant (≥10%) increase in QTc and had a longer QTc at 3 months than those without. The risk of SCD did not differ between patients with and without a significant increase in BNP, but was higher in patients with a significant increase in QTc compared with those without. Among patients with an increase in BNP of ≥10%, those with an increase in QTc of ≥10% were several-fold more likely to experience SCD compared with those without, whereas there was no such association between the change in QTc and SCD among patients without an increase in BNP of ≥10%. Thus, this study showed that changes in QTc better predicted SCD than changes in BNP, and that a strategy using both a marker of heart failure severity and a marker of the propensity of the left ventricle for arrhythmia better predicted SCD than a single-marker strategy. Further studies are required to evaluate whether novel markers besides LVEF and NYHA class alone (e.g., biomarkers and cardiac MRI) will allow a more accurate selection of patients with chronic HF who need an ICD.

Review on natriuretic peptides: where we are, where we are going

BACKGROUND

Tremendous advances have been made in our understanding of the pathophysiology and treatment of congestive heart failure. However, diagnosis of the disease still remains difficult, even with a comprehensive physical examination. Symptoms such as dyspnea are nonspecific and insensitive indicators for heart failure, which can go largely undetected. Several studies have suggested the need for new diagnostic capabilities, especially with the increasing prevalence of heart failure in the US. The discovery of natriuretic peptides as diagnostic biomarkers has been one of the most critical advances for the management of heart failure. Both B-type natriuretic peptide and N-terminal pro-B-type natriuretic peptide have the potential to diagnose heart failure, assess prognostic risk of rehospitalization and mortality, and even help guide treatment. Their relative cost-effectiveness and availability have also facilitated their acceptance into many emergency departments, clinics and in-patient units as standard care when evaluating patients with suspected heart failure. Our understanding of the natriuretic peptide system is still in its infancy, but natriuretic peptides have emerged as important diagnostic and prognostic tools that have generated interest in finding broader applications for their use.

OBJECTIVE

The purpose of this review is to discuss the clinical approaches and future applications of natriuretic peptides in diagnosing and managing treatment of congestive heart failure.

METHOD

A comprehensive review of studies to assess the utility of natriuretic peptides for diagnosis and prognosis of heart failure and other conditions.

CONCLUSION

Natriuretic peptides are powerful tools to aid the physician in the diagnosis, prognosis and management of heart failure in both in-patient and out-patient settings. However, natriuretic peptides should be used as an adjunct test as many circumstances can also influence changes in natriuretic peptide levels.

Circulating heart-type fatty acid binding protein levels predict the occurrence of appropriate shocks and cardiac death in patients with implantable cardioverter-defibrillators

BACKGROUND

The association between ongoing myocardial damage and outcomes in patients who have received an implantable cardioverter-defibrillator (ICD) is unclear.

METHODS AND RESULTS

Consecutive patients with cardiomyopathy, who had received an ICD (n = 107, mean age 65 ± 11 years), were prospectively enrolled. Myocardial membrane injury (heart-type fatty acid binding protein [H-FABP] >4.3 ng/mL) and myofibrillar injury (troponin T >0.01 ng/mL) were defined using receiver operating characteristic curves. Patients were followed for a median of 33.6 months, to an end point of appropriate ICD shock or cardiac death. Myocardial membrane injury (45%) and myofibrillar injury (41%) were equally prevalent among patients with cardiomyopathy who had received ICDs. Appropriate ICD shocks or cardiac death occurred in 31% and 15% of patients, respectively. Multivariate Cox regression analysis showed that serum H-FABP levels >4.3 ng/mL, but not troponin T levels, were a significant independent prognostic factor for cardiac events (hazard ratio 5.502, 95% confidence interval 1.705-17.75, P = .004). Subgroup analysis revealed that measuring H-FABP levels was valuable for anticipating event-free survival among patients with ICDs who were receiving amiodarone. High H-FABP levels also predicted subsequent outcomes in patients who had received ICDs for primary or secondary prevention.

CONCLUSION

Evaluating myocardial damage using H-FABP may be a promising tool for predicting outcomes in patients with cardiomyopathy who have received ICDs.

Prognostic role of high-sensitivity C-reactive protein and B-type natriuretic peptide in implantable cardioverter-defibrillator patients

BACKGROUND

High-sensitivity C-reactive protein (hs-CRP) and B-type natriuretic peptide (BNP) are useful biomarkers for cardiovascular risk stratification. Little data are available regarding the prognostic value of hs-CRP and BNP serum levels and future ventricular arrhythmic events triggering implantable cardioverter defibrillator (ICD) therapy.

METHODS

A total of 100 patients eligible for ICD implantation were enrolled in a prospective cohort study. Serum levels of hs-CRP and BNP were obtained the day before ICD implantation and at scheduled follow-up visits. For risk analysis, the study cohort was dichotomized based on serum level of hs-CRP using a cut-off value of 3 mg/L. The endpoint was appropriate ICD therapy triggered by ventricular arrhythmias during a follow-up of 24 months.

RESULTS

Appropriate ICD therapy was delivered in 20% of patients. Median baseline serum level of hs-CRP was significantly higher in patients with appropriate ICD therapy than in those without appropriate ICD therapy (5.33 mg/L vs 2.19 mg/L; P = 0.002). The same was true for median serum levels of hs-CRP and BNP during follow-up (5.43 mg/L vs 2.61 mg/L, P = 0.001 and 261.0 pg/mL vs 80.1 pg/mL, P = 0.01, respectively). Multivariate analysis demonstrated that baseline hs-CRP level > 3 mg/L was independently associated with appropriate ICD therapy (odds ratio 4.0, 95% 1.1-14.2; P = 0.03).

CONCLUSION

Elevated preimplantation hs-CRP serum level is independently associated with increased risk for appropriate ICD therapy. Monitoring for elevated BNP levels during follow-up adds to the assessment of risk for future arrhythmias.

Characterization and financial impact of implantable cardioverter-defibrillator patients without interventions 5 years after implantation

BACKGROUND

Implantable cardioverter defibrillators (ICD's) are increasingly used for primary and secondary prevention of sudden cardiac death. However, data on how many ICD patients indeed receive appropriate ICD therapy during long-term follow-up is scarce.

AIM

The aim of our study was to determine the number of patients without appropriate ICD therapy 5 years after ICD implantation, to identify predicting factors, to assess the occurrence of late first ICD therapy and to quantify the financial impact of ICD therapy in a real-world setting.

DESIGN

Prospective observational study.

METHODS

We prospectively enrolled 322 consecutive ICD patients. Baseline data were collected at implantation and patients were followed for a median of 7.3 years (IQR 5.8-9.2 years). Time to first appropriate ICD therapy (either antitachycardia pacing or cardioversion) was documented.

RESULTS

Five years after implantation, 139 patients (43%) had not received appropriate ICD therapy. In multivariable analysis, a primary prevention indication and negative electrophysiological studies prior to ICD implantation were independent predictors of freedom from ICD therapy. Of the patients without ICD therapy, 5 years after implantation, 25% had experienced inappropriate ICD shocks. Two hundred and seven devices (1.5 devices per patient) were needed for the 139 patients without ICD intervention within 5 years, accounting for € 31,784 per patient. During an additional follow-up of 3 years, 12% of the patients with unused ICD received a late first appropriate ICD therapy.

CONCLUSION

About half of the ICD patients receive appropriate ICD therapy within 5 years after implantation. Furthermore, there is a significant proportion of patients receiving late first shocks after five initially uneventful years.

Comparison of detection of arrhythmias in patients with chronic heart failure secondary to non-ischemic versus ischemic cardiomyopathy by 1 versus 7-day holter monitoring

The purpose of this study was to compare the diagnostic sensitivity of 1-day Holter monitoring versus 7-day Holter monitoring (7DH) to detect atrial and ventricular arrhythmias in a population of stable patients with chronic heart failure and left ventricular dysfunction. Sixty-three consecutive stable patients with chronic heart failure with left ventricular ejection fractions < or =50% were included. Blood samples were obtained, the Minnesota Living With Heart Failure Questionnaire was administered, and echocardiography, 6-minute walk tests, and 7DH were performed at enrollment. The mean ejection fraction was 35.8 +/- 9.8%, and the mean age was 55.5 +/- 13.9 years. Seven-day Holter monitoring did not significantly increase the detection of nonsustained atrial tachycardia or atrial fibrillation. In contrast, the incidence of nonsustained ventricular tachycardia increased in nonischemic patients from 35.1% on day 1 to 54.1% on day 7 (p = 0.01). In ischemic patients, the sensitivity increased from 11.5% to 46.2% (p = 0.004). Two patients without nonsustained ventricular tachycardia on day 1 had episodes of 13 and 16 beats on days 3 and 6 of monitoring. In patients with left ventricular ejection fractions >35% and N-terminal-pro-brain natriuretic peptide levels <1,000 pg/ml, no episodes of nonsustained ventricular tachycardia were detected on day 1 in nonischemic and ischemic patients, but 7DH detected 3 new patients in each group. In conclusion, 7DH clearly improves the detection and allows a better characterization of ventricular arrhythmic episodes but seems to be less useful for supraventricular events.

Heart failure: the challenge of selecting patients for implantable cardioverter defibrillator therapy

Patients with heart failure die predominantly of progressive pump failure or sudden cardiac death. Therefore, it is attractive to believe that an implantable cardioverter defibrillator (ICD) will dramatically reduce mortality by reducing sudden death. However, unfortunately it is not that simple; sudden death is not the same as ICD-preventable death. While ICD prophylaxis always reduces arrhythmic death, it does not always reduce all-cause mortality due to competing risks. Importantly, an arrhythmia may be a marker for heart failure decompensation, with patients at increased risk of heart failure death following shock therapy. Randomized trials have now demonstrated the potential benefits of ICDs in selected patients with left ventricular dysfunction, yet they have also failed to demonstrate benefit in populations where one might have expected to see benefit (e.g., early post-myocardial infarction). Device therapy can offer heart failure patients much more than just a simple shock box. The addition of a left ventricular lead to allow biventricular pacing (cardiac resynchronization therapy) improves symptoms and prolongs life in selected patients with QRS prolongation. Newer technologies allow remote monitoring through the device, which offers the potential to recognize heart failure decompensation or arrhythmias early so that appropriate treatment can be instituted. However, deciding which patient should receive an ICD remains one of the most challenging questions in cardiovascular medicine.

Role of proinflammatory markers and NT-proBNP in patients with an implantable cardioverter-defibrillator and an electrical storm

BACKGROUND

Several studies have attempted to identify risk factors for the development of an electrical storm (ES), which is defined as 3 separate ventricular tachyarrhythmic (VT/VF) events, but in the majority of studies no triggers have been found. However, little is known about the role of inflammation and NT-proBNP in patients with ES. The aim of this study was therefore to assess the relationship of Interleukin-6 (IL-6), high-sensitivity C-reactive protein (hs-CRP) and NT-proBNP serum concentrations in ICD-patients with or without single spontaneous ventricular tachyarrhythmic events (VT/VF) and in ES.

METHODS

Markers were determined in 51 patients without ICD-intervention, in 15 ICD-patients with single VT/VF-episodes during 9-months follow-up and in 20 ICD-patients with ES (blood sampling performed within 60min after fulfilling ES criteria). VT/VF-episodes were analysed by stored ICD-electrograms.

RESULTS

All patients had idiopathic dilated cardiomyopathy (n=23) or coronary artery disease (n=63). Patients with ES revealed significantly higher mean serum concentrations of all markers (IL-6 15.19+/-10.34 pg/mL, hs-CRP 20.12+/-14.4 mg/L, NT-proBNP 4799+/-4596 pg/mL) compared to baseline values of patients with single VT/VF-events during follow-up (IL-6 8.37+/-5.8 pg/mL (p=0.03), hs-CRP 4.7+/-5.3 mg/dL (p<0.001), NT-proBNP 1913+/-2665pg/mL (p=0.04)) and compared to baseline values of ICD-patients without device intervention (IL-6 4.62+/-3.66 pg/mL (p<0.001), hs-CRP 4.1+/-3.4 mg/L (p<0.001), NT-proBNP 1461+/-2281pg/mL (p<0.001)). In 9/20 patients presenting with ES (45%) baseline values were available. All markers were significantly higher during ES compared to event-free determination (IL-6 14.54+/-10.43 vs. 7.03+/-2.83 pg/mL (p=0.04), hs-CRP 19.07+/-16.07 vs. 6.5+/-3.9 mg/L (p=0.02), NT-proBNP 4218+/-2561 vs. 2099+/-1279 pg/mL (p=0.03)).

CONCLUSIONS

Electrical storm is associated with significantly elevated IL-6, hs-CRP and NT-proBNP serum concentrations in ICD-patients with structural heart disease. Thus, ES may be triggered by proinflammatory activity. Combined intraindividual elevation of determined markers might help to identify patients at risk of impending electrical storm.

Predictors of implantable cardioverter defibrillator shocks during the first year

The purpose of this study was to predict implantable cardioverter defibrillator (ICD) shocks using demographic and clinical characteristics in the first year after implantation for secondary prevention of cardiac arrest. A prospective design was used to follow 168 first-time ICD recipients over 12 months. Demographic and clinical data were obtained from medical records at the time of ICD insertion. Implantable cardioverter defibrillator shock data were obtained from ICD interrogation reports at hospital discharge, 3, 6, and 12 months. Logistic regression was used to predict ever receiving an ICD shock using background characteristics. Patients received an ICD for secondary prevention of sudden cardiac arrest, they were 64.1 years old, 89% were white, 77% were male, with a mean (SD) ejection fraction of 33.7% (14.1%). The cumulative percentage of ever receiving an ICD shock was 33.3% over 1 year. Three variables predicted shocks in the first year: history of chronic obstructive pulmonary disease (COPD) (odds ratio [OR], 4.42; 95% confidence interval [CI], 1.2-16.4; P = .03), history of congestive heart failure (OR, 3.55; 95% CI, 1.4-9.3; P = .01), and documented ventricular tachycardia (VT) at the time of ICD implant (OR, 10.05; 95% Cl, 1.8-55.4; P = .01). High levels of anxiety approached significance (OR = 2.82; P = .09). The presence of COPD, congestive heart failure, or VT at ICD implant was a significant predictor of receiving an ICD shock in the first year after ICD implantation. Because ICD shocks are distressing, painful, and associated with greater mortality, healthcare providers should focus attention on prevention of shocks by controlling VT, careful management of HF symptoms, reduction of the use of short acting beta agonist medications in COPD, and perhaps recognizing and treating high levels of anxiety.

B-type natruiretic peptide levels stratify the risk for arrhythmia among implantable cardioverter defibrillator patients

BACKGROUND

We sought to study the association between brain natriuretic peptide (BNP) levels and the occurrence of ventricular arrhythmias in patients with left ventricular dysfunction (LVD) and an implantable cardioverter defibrillator (ICD).

METHODS

This was a prospective study of consecutive, stable, ambulatory patients with moderate and severe ischemic LVD and an ICD. A plasma BNP level was obtained at recruitment. Patients were evaluated every 3-6 mo for a minimum of 1 y. The primary end point was the occurrence of malignant ventricular arrhythmia or sudden cardiac death (SCD).

RESULTS

The cohort consisted of 94 subjects (6 women) with a mean +/- standard deviation (SD) age of 69 +/- 10 y. The ICD implantation indication was primary and secondary prevention of SCD in 49% and 51% of subjects, respectively. A primary end point occurred in 27 patients (29%), and was more frequent in symptomatic heart failure patients and those implanted for secondary prevention of SCD. The median BNP level was significantly higher among patients who experienced an end point (191 pg/ml versus 142 pg/ml, p = 0.03). After controlling for New York Heart Association heart failure class and ICD implantation indication, the odds ratio (OR) for experiencing an adverse outcome among the upper BNP quartile versus all others was 3.5 (95% confidence interval [CI]: 1.2-10.2). Among patients implanted for primary prevention of SCD, none of the patients in the lower BNP quartile (BNP < 91 pg/ml) experienced an adverse outcome.

CONCLUSIONS

These results suggest that abnormally high BNP levels not only predict cardiac death, but also arrhythmic death in this patient population, and a low BNP level can serve to identify low risk patients. (c)

Primary prevention of sudden cardiac death using implantable cardioverter defibrillators

Despite substantial advances in prevention and treatment of cardiovascular diseases, sudden cardiac death (SCD) remains a leading cause of death in industrialized countries. Implantable cardioverter defibrillator (ICD) has been demonstrated to be an attractive option for primary prevention of SCD in high-risk patients. This review discusses the progress in the risk stratification for selecting high-risk patients, highlights the clinical trials of primary prevention for SCD, outlines the efficacy of combined use of cardiac resynchronization therapy with ICD, and analyses the cost-effectiveness issue of this device.

The prediction of ICD therapy in multicenter automatic defibrillator implantation trial (MADIT) II like patients: a retrospective analysis

OBJECTIVES

MADIT II like patients have not been compared to patients without an electrophysiological study, patients in whom ventricular tachycardia or fibrillation were induced in an electrophysiological study (EPS) and patients without an inducibility in EPS in one study.

BACKGROUND

The multicenter automatic defibrillator implantation trial (MADIT) II showed a benefit of ICD implantation in patients with ischemic heart disease.

METHODS

We performed a retrospective analysis in 93 patients with an ischemic heart disease and an ejection fraction </=30% who had an ICD implanted with a follow-up at least an 18 months. Patients were divided into 3 groups according to the primary indication for ICD implantation: without EPS (group I), patients in whom ventricular tachycardia or fibrillation were inducible in EPS (group II) or patients without an inducibility in EPS (group III).

RESULTS

During the mean follow-up of 32.9 +/- 16.1 months 289 appropriate ICD therapies and 10 deaths occurred. The incidence of appropriate ICD therapies did not differ significantly between the groups (group I 40%, group II 54% and group III 48% of patients). We found in group II a higher risk of appropriate ICD therapies with occurrence of a specific constellation of EPS values. These patients showed a 15-fold risk (P = 0.005) of an appropriate ICD therapy. Furthermore a brain natriuretic peptide value of 265 pg/ml also predicted an appropriate ICD therapy with a 3.5-fold risk (P = 0.017).

CONCLUSION

In the present retrospective study the results of MADIT II were affirmed in the case of incidence of ventricular arrhythmias in patients with an EF < 30% and coronary heart disease. The prediction of an appropriate ICD therapy with EPS was only achieved in patients with inducibility in the EPS.

Inflammatory biomarkers are not predictive of intermediate-term risk of ventricular tachyarrhythmias in stable CHF patients

BACKGROUND

Elevated levels of inflammatory biomarkers and brain natriuretic peptide (BNP) are associated with increased mortality in patients with heart failure (HF).

HYPOTHESIS

: The aim of the current study was to assess the correlation between circulating biomarkers and ventricular tachyarrhythmias among patients with HF.

METHODS

Blood samples from 50 stable ambulatory HF patients with moderate to severe systolic left ventricular (LV) dysfunction and an implantable cardioverter defibrillator (ICD) were analyzed for interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), high-sensitivity C-reactive protein (hsCRP) and BNP. Thereafter, the patients were followed for a mean period of 152 +/- 44 days, during which ventricular tachyarrhythmias were recorded by the ICDs.

RESULTS

Follow-up data were obtained from 47 patients. Of them, 45 (96%) had ischemic cardiomyopathy, 38 (81%) had New York Heart Association class I-II, 43 (91%) were males, and the mean age was 68.6 +/- 11.1 years. During follow-up, 5 patients (11%) had nonsustained ventricular tachycardia (NSVT), 6 patients (13%) had sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) and 36 patients (76%) had no events. The circulating biomarkers' levels upon enrollment were not significantly different between patients who subsequently had NSVT or VT/VF and patients who were free of events.

CONCLUSIONS

No correlation was found between plasma levels of IL-6, TNF-alpha, hsCRP and BNP and ventricular arrhythmic events among stable HF patients during an intermediate term follow-up of 5.1 months. Further studies are still required to assess the association between these biomarkers and long-term risk of ventricular tachyarrhythmia.

Natriuretic peptides

Natriuretic peptides (NPs) are released from the heart in response to pressure and volume overload. B-type natriuretic peptide (BNP) and N-terminal-proBNP have become important diagnostic tools for assessing patients who present acutely with dyspnea. The NP level reflects a compilation of systolic and diastolic function as well as right ventricular and valvular function. Studies suggest that using NPs in the emergency department can reduce the consumption of hospital resources and can lower costs by either eliminating the need for other, more expensive tests or by establishing an alternative diagnosis that does not require hospital stay. Caveats such as body mass index and renal function must be taken into account when analyzing NP levels. Natriuretic peptide levels have important prognostic value in multiple clinical settings, including in patients with stable coronary artery disease and with acute coronary syndromes. In patients with decompensated heart failure due to volume overload, a treatment-induced drop in wedge pressure is often accompanied by a rapid drop in NP levels. Knowing a patient's NP levels might thus assist with hemodynamic assessment and subsequent treatment titration. Monitoring NP levels in the outpatient setting might also improve patient care and outcomes.

Changes and predictive value of dispersion of repolarization parameters for appropriate therapy in patients with biventricular implantable cardioverter-defibrillators

BACKGROUND

The impact of cardiac resynchronization therapy (CRT) on dispersion of repolarization is controversial. The benefit of CRT on sudden cardiac death has been demonstrated only after 3 years follow-up.

OBJECTIVE

The purpose of this study was to explore the immediate effect of CRT on dispersion of repolarization and to define the value of dispersion of repolarization parameters as predictors of appropriate implantable cardioverter-defibrillator (ICD) therapy.

METHODS

Data from 100 patients who underwent CRT-ICD placement were analyzed retrospectively. Patients had symptoms of New York Heart Association functional class III or IV heart failure, left ventricular ejection fraction < or =35%, and QRS duration >130 ms or QRS < or =130 ms with left intraventricular dyssynchrony. ECG indices of dispersion of repolarization before and immediately after CRT implantation (QT dispersion, Tpeak-Tend [Tp-e], and Tp-e dispersion) were measured.

RESULTS

In patients who were upgraded to a biventricular system, Tp-e did not increase significantly after CRT. However, Tp-e increased significantly after CRT in patients with left bundle branch block or narrow QRS at baseline. After 12-month follow-up, 22 patients had received appropriate ICD therapy. ICD therapy and no ICD therapy groups had similar baseline characteristics, such as secondary prevention and ischemic cardiomyopathy. Postimplantation Tp-e was the only independent predictor of future ICD therapy (P = .02).

CONCLUSION

Immediately after CRT, Tp-e did not increase in patients who received a biventricular upgrade; however, Tp-e did increase in patients with preimplantation left bundle branch block or narrow QRS. Postimplantation Tp-e was the only independent predictor of appropriate ICD therapy.

Comparison of N-terminal pro-brain natriuretic peptide versus electrophysiologic study for predicting future outcomes in patients with an implantable cardioverter defibrillator after myocardial infarction

The aim of the study was to examine the predictive value of N-terminal pro-brain natriuretic peptide (NT-pro-BNP) versus electrophysiologic study in patients with implantable cardioverter-defibrillators (ICDs) after myocardial infarction (MI). We prospectively studied 99 consecutive patients with a history of MI who underwent ICD implantation for primary or secondary prevention of sudden cardiac death. An electrophysiologic study was performed in all patients. Venous blood samples for NT-pro-BNP measurement were obtained at the beginning of the study. The primary end point was ventricular tachycardia or ventricular fibrillation (VT/VF) and the secondary end point was a composite of death, hospitalization for heart failure, or MI. On multivariate Cox regression analysis, NT-pro-BNP level at or greater than median (497 ng/L) was the only significant predictor for VT/VF occurrence (p = 0.047). Along with amiodarone use (p = 0.001), NT-pro-BNP levels higher than median were also associated with a higher risk of composite clinical events (p = 0.036). Kaplan-Meier analysis showed that patients with NT-pro-BNP level at or greater than median had a higher risk of experiencing VT/VF and composite clinical events than patients with NT-pro-BNP levels less than median (log-rank p <0.05). In conclusion, assay of NT-pro-BNP, which is easy to perform and widely available, is superior to electrophysiologic study for prediction of future outcomes in predominantly secondary prophylactic ICD recipients after MI. In the era of primary prophylactic ICD implantation without preimplantation electrophysiologic study, higher NT-pro-BNP levels might help to improve risk-adjusted concomitant antiarrhythmic therapy and device selection.

Better identification of patients who benefit from implantable cardioverter defibrillators by genotyping the G protein β3 subunit (GNB3) C825T polymorphism

AIMS

There is a need for better identification of patients at high risk for malignant arrhythmias who would benefit from implantable cardioverter defibrillators (ICD). The purpose of this study was to assess whether the C825T polymorphism in the G-protein beta3 subunit gene, GNB3, might serve as a genetic marker for recurrent ventricular arrhythmias.

METHODS AND RESULTS

Genotyping was performed in 82 patients with ischemic heart disease treated with an ICD for primary and secondary prevention of cardiac arrhythmias. The Kaplan-Meier method was used to estimate the probability of remaining free from VT/VF with cycle length (CL) < 330 ms that required treatment by the ICD. Genotyping yielded 7 individuals homozygous for the 825T allele (TT), 36 homozygous for the C825 allele (CC), and 39 heterozygotes (CT). Multivariate analysis revealed that the C825T polymorphism (P = 0.004), left ventricular ejection fraction (P = 0.009), and QRS-duration (P = 0.039) were independent determinants of severe ventricular arrhythmias. Homozygous carriers of the C825 allele had a 3.9-fold risk for severe ventricular arrhythmias.

CONCLUSION

The results from this pilot study suggest that the C825T polymorphism may have a modifying effect on the propensity towards life-threatening arrhythmias. Genotyping the C825T polymorphism may help to better identify individuals at high risk for life-threatening arrhythmias who benefit from ICD therapy.