Relations between heart failure, ejection fraction, arrhythmia suppression and mortality: analysis of the Cardiac Arrhythmia Suppression Trial

Sacubitril/valsartan and arrhythmic burden in patients with heart failure and reduced ejection fraction: a systematic review and meta-analysis

The aim of this study was to assess whether angiotensin receptor/neprilysin inhibitor (ARNI) decreases ventricular arrhythmic burden compared to angiotensin-converting enzyme inhibitors or angiotensin receptor antagonist (ACE-I/ARB) treatment in chronic heart failure with reduced ejection fraction (HFrEF) patients. Further, we assessed if ARNI influenced the percentage of biventricular pacing. A systematic review of studies (both RCTs and observational studies) including HFrEF patients and those receiving ARNI after ACE-I/ARB treatment was conducted using Medline and Embase up to February 2023. Initial search found 617 articles. After duplicate removal and text check, 1 RCT and 3 non-RCTs with a total of 8837 patients were included in the final analysis. ARNI was associated with a significative reduction of ventricular arrhythmias both in RCT (RR 0.78 (95% CI 0.63-0.96); p = 0.02) and observational studies (RR 0.62; 95% CI 0.53-0.72; p < 0.001). Furthermore, in non-RCTs, ARNI also reduced sustained (RR 0.36 (95% CI 0.2-0.63); p < 0.001), non-sustained VT (RR 0.67 (95% CI 0.57-0.80; p = 0.007), ICD shock (RR 0.24 (95% CI 0.12-0.48; p < 0.001), and increased biventricular pacing (2.96% (95% CI 2.25-3.67), p < 0.001). In patients with chronic HFrEF, switching from ACE-I/ARB to ARNI treatment was associated with a consistent reduction of ventricular arrhythmic burden. This association could be related to a direct pharmacological effect of ARNI on cardiac remodeling.Trial registration: CRD42021257977.

Cardiac-Specific Overexpression of Caveolin-1 in Rats With Ischemic Cardiomyopathy Improves Arrhythmogenicity and Cardiac Remodelling

BACKGROUND

Ischemic cardiomyopathy (ICM) is associated with electrical and structural remodelling, leading to arrhythmias. Caveolin-1 (Cav1) is a membrane protein involved in the pathogenesis of ischemic injury. Cav1 deficiency has been associated with arrhythmogenicity. The current study aimed to determine how Cav1 overexpression inhibits arrhythmias and cardiac remodelling in ICM.

METHODS

ICM was modelled using left anterior descending (LAD) artery ligation for 4 weeks. Cardiac-specific Cav1 overexpression in ICM on arrhythmias, excitation-contraction coupling, and cardiac remodelling were investigated using the intramyocardial injection of an adeno-associated virus serotype 9 (AAV-9) system, carrying a specific sequence expressing Cav1 (AAV^Cav1) under the cardiac troponin T (cTnT) promoter.

RESULTS

Cav1 overexpression decreased susceptibility to arrhythmias by upregulating gap junction connexin 43 (CX43) and reducing spontaneous irregular proarrhythmogenic Ca²⁺ waves in ventricular cardiomyocytes. It also alleviated ischemic injury-induced contractility weakness by improving Ca²⁺ cycling through normalizing Ca²⁺-handling protein levels and improving Ca²⁺ homeostasis. Masson stain and immunoblotting revealed that the deposition of excessive fibrosis was attenuated by Cav1 overexpression, inhibiting the transforming growth factor-β (TGF-β)/Smad2 signalling pathway. Coimmunoprecipitation assays demonstrated that the interaction between Cav1 and cSrc modulated CX43 expression and Ca²⁺-handling protein levels.

CONCLUSIONS

Cardiac-specific overexpression of Cav1 attenuated ventricular arrhythmia, improved Ca²⁺ cycling, and attenuated cardiac remodelling. These effects were attributed to modulation of CX43, normalized Ca²⁺-handling protein levels, improved Ca²⁺ homeostasis, and attenuated cardiac fibrosis.

Effect of Sacubitril/Valsartan on Reducing the Risk of Arrhythmia: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background and Objective

Relevant data of PARADIGM-HF reveals sacubitril/valsartan (SV) therapy led to a greater reduction in the risks of arrhythmia, and sudden cardiac death than angiotensin converting enzyme inhibitor (ACEI)/angiotensin receptor inhibitor (ARB) therapy in HFrEF, however, inconsistent results were reported in subsequent studies. Here, we conduct a meta-analysis of related randomized controlled trials (RCTs) to evaluate the protective effect of SV on reducing the risk of arrhythmias.

Methods and Results

RCTs focused on the difference in therapeutic outcomes between SV and ACEI/ARB were searched from PUBMED, EMBASE, ClinicalTrials.gov, and Cochrane Library. The results were extracted from each individual study, expressed as binary risk, 95% confidence interval (CI) and relative risk (RR). Sixteen RCTs including 22, 563 patients met the study criteria. Compared with ACEI/ARB therapy, SV therapy did significantly reduce in the risks of severe arrhythmias among patients with heart failure with reduced ejection fraction (HFrEF) (RR 0.83, 95% CI 0.73–0.95, p = 0.006), ventricular tachycardia (VT) among patients with HFrEF (RR 0.69, 95% CI 0.51–0.92, p = 0.01), cardiac arrest among patients with heart failure (HF) (RR 0.52, 95% CI 0.37–0.73, p = 0.0002), cardiac arrest among patients with HFrEF (RR 0.49, 95% CI 0.32–0.76, p = 0.001), cardiac arrest or ventricular fibrillation (VF) among patients with HF (RR 0.63, 95% CI 0.48–0.83, p = 0.001), and cardiac arrest or VF among patients with HFrEF (RR 0.65, 95% CI 0.47–0.89, p = 0.008), but reduced the risks of arrhythmias (RR 0.87, 95% CI 0.74–1.01, p = 0.07), atrial arrhythmias (RR 0.98, 95% CI 0.83–1.16, p = 0.85), and atrial fibrillation (RR 0.98, 95% CI 0.82–1.17, p = 0.82) among all patients with no significant between-group difference. The merged result was robust after sensitivity analysis, and there was no publication bias.

Conclusion

Our meta-analysis provides evidence that, compared with ACEI/ARB, SV can additionally reduce the risks of most arrhythmias, just the significant differences are revealed in reducing the risks of VT, severe arrhythmias, and cardiac arrest in patients with HFrEF. Besides, the positive effect of SV on VF according to statistical result of combining VF with cardiac arrest in patients with HFrEF is credibility.

Is Low Heart Rate Variability Associated with Emotional Dysregulation, Psychopathological Dimensions, and Prefrontal Dysfunctions? An Integrative View

Several studies have suggested a correlation between heart rate variability (HRV), emotion regulation (ER), psychopathological conditions, and cognitive functions in the past two decades. Specifically, recent data seem to support the hypothesis that low-frequency heart rate variability (LF-HRV), an index of sympathetic cardiac control, correlates with worse executive performances, worse ER, and specific psychopathological dimensions. The present work aims to review the previous findings on these topics and integrate them from two main cornerstones of this perspective: Porges' Polyvagal Theory and Thayer and Lane's Neurovisceral Integration Model, which are necessary to understand these associations better. For this reason, based on these two approaches, we point out that low HRV is associated with emotional dysregulation, worse cognitive performance, and transversal psychopathological conditions. We report studies that underline the importance of considering the heart-brain relation in order to shed light on the necessity to implement psychophysiology into a broader perspective on emotions, mental health, and good cognitive functioning. This integration is beneficial not only as a theoretical ground from which to start for further research studies but as a starting point for new theoretical perspectives useful in clinical practice.

Clinical Predictors of Recurrent Ventricular Arrhythmias in Secondary Prevention Implantable Cardioverter Defibrillator Recipients With Coronary Artery Disease - Lower Left Ventricular Ejection Fraction and Incomplete Revascularization

BACKGROUND

The implantable cardioverter defibrillator (ICD) is a standard prevention therapy for patients at high risk for sudden cardiac death (SCD) due to life-threatening ventricular arrhythmia (VA), that is, ventricular fibrillation and ventricular tachycardia. However, clinical predictors of recurrent VA in secondary prevention ICD recipients with coronary artery disease (CAD) remain unknown. Methods and Results: We followed up 96 consecutive patients with CAD undergoing ICD implantation for secondary prevention of SCD. Long-term rates and clinical predictors of appropriate ICD therapy (ICD-Tx) for VA were analyzed. Appropriate ICD-Tx occurred in 41 (42.7%) patients during a median follow-up of 2.4 years (interquartile range, 0.9-6.1). These patients had significantly greater left ventricular end-diastolic diameter (62.3±1.3 vs. 54.6±1.1 mm, P<0.001), lower left ventricular ejection fraction (LVEF; 36.3±2.0% vs. 45.7±1.8%, P<0.001), and more incomplete revascularization (ICR; 70.7% vs. 45.5%, P=0.014) than those without appropriate ICD-Tx. Multivariable analysis showed that LVEF (hazards ratio [HR], 0.950; 95% CI: 0.925-0.975; P<0.001) and ICR (HR, 2.293; 95% CI: 1.133-4.637; P=0.021) were significant predictors of appropriate ICD-Tx for VA.

CONCLUSIONS

Lower LVEF and ICR were independent predictors of recurrent VA in secondary prevention ICD recipients with CAD.

MODELING HEART TISSUE AS A MICROMORPHIC MEDIUM: A NUMERICAL INVESTIGATION

Recent years have seen a renewed interest in the theories of extended continuum mechanics. These allow for a finer and relatively simple modeling of physical phenomena occurring on the microscopic level. The Eringen’s micromorphic medium belongs to this class and allows accounting for the material microstructure. A subclass of this model was applied to model the mechanical behavior of cardiac tissue. With the aid of a specifically developed numerical tool, the validity of the approach is demonstrated using different myocardial infarct scenario.

Personalized Computer Simulation of Diastolic Function in Heart Failure

The search for a parameter representing left ventricular relaxation from non-invasive and invasive diagnostic tools has been extensive, since heart failure (HF) with preserved ejection fraction (HF-pEF) is a global health problem. We explore here the feasibility using patient-specific cardiac computer modeling to capture diastolic parameters in patients suffering from different degrees of systolic HF. Fifty eight patients with idiopathic dilated cardiomyopathy have undergone thorough clinical evaluation, including cardiac magnetic resonance imaging (MRI), heart catheterization, echocardiography, and cardiac biomarker assessment. A previously-introduced framework for creating multi-scale patient-specific cardiac models has been applied on all these patients. Novel parameters, such as global stiffness factor and maximum left ventricular active stress, representing cardiac active and passive tissue properties have been computed for all patients. Invasive pressure measurements from heart catheterization were then used to evaluate ventricular relaxation using the time constant of isovolumic relaxation Tau (τ). Parameters from heart catheterization and the multi-scale model have been evaluated and compared to patient clinical presentation. The model parameter global stiffness factor, representing diastolic passive tissue properties, is correlated significantly across the patient population with τ. This study shows that multi-modal cardiac models can successfully capture diastolic (dys) function, a prerequisite for future clinical trials on HF-pEF.

Aldosterone and cardiovascular remodelling: focus on myocardial failure

Heart failure is a clinical syndrome that may result from different disease states or conditions that injure the myocardium. The activation of circulating neurohormones, particularly aldosterone, may play a pivotal role in left ventricular (LV) remodelling. The Randomized Aldactone Evaluation Study and Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival trial have emphasised the clinical importance of aldosterone. This review addresses some of the proposed mechanisms of LV remodelling in heart failure.

Mechanical Dyssynchrony by Tissue Doppler Cross-Correlation is Associated with Risk for Complex Ventricular Arrhythmias after Cardiac Resynchronization Therapy

BACKGROUND

Tissue Doppler cross-correlation analysis has been shown to be associated with long-term survival after cardiac resynchronization defibrillator therapy (CRT-D). Its association with ventricular arrhythmia (VA) is unknown.

METHODS

From two centers 151 CRT-D patients (New York Heart Association functional classes II-IV, ejection fraction ≤ 35%, and QRS duration ≥ 120 msec) were prospectively included. Tissue Doppler cross-correlation analysis of myocardial acceleration curves from the basal segments in the apical views both at baseline and 6 months after CRT-D implantation was performed. Patients were divided into four subgroups on the basis of dyssynchrony at baseline and follow-up after CRT-D. Outcome events were predefined as appropriate antitachycardia pacing, shock, or death over 2 years.

RESULTS

Mechanical dyssynchrony was present in 97 patients (64%) at baseline. At follow-up, 42 of these 97 patients (43%) had persistent dyssynchrony. Furthermore, among 54 patients with no dyssynchrony at baseline, 15 (28%) had onset of new dyssynchrony after CRT-D. In comparison with the group with reduced dyssynchrony, patients with persistent dyssynchrony after CRT-D were associated with a substantially increased risk for VA (hazard ratio [HR], 4.4; 95% CI, 1.2-16.3; P = .03) and VA or death (HR, 4.0; 95% CI, 1.7-9.6; P = .002) after adjusting for other covariates. Similarly, patients with new dyssynchrony had increased risk for VA (HR, 10.6; 95% CI, 2.8-40.4; P = .001) and VA or death (HR, 5.0; 95% CI, 1.8-13.5; P = .002).

CONCLUSIONS

Persistent and new mechanical dyssynchrony after CRT-D was associated with subsequent complex VA. Dyssynchrony after CRT-D is a marker of poor prognosis.

Outpatient management of chronic heart failure

INTRODUCTION

Heart failure (HF) treatment attracts a share of intensive research because of its poor HF prognosis. In the past decades, the prognosis of HF has improved considerably, mainly as a consequence of the progress that has been made in the pharmacological management of HF.

AREAS COVERED

This article reviews the outpatient pharmacological management of chronic HF due to left ventricular systolic dysfunction and offers recommendations on the use of various drugs. In addition, the present article attempts to provide practical therapeutic algorithms based on current clinical strategies.

EXPERT OPINION

Continued research directed toward identifying factors associated with high pharmacotherapy guideline adherence and understanding of variants that influence response to drugs will hopefully halt or reverse the major pathophysiological mechanisms involved in this syndrome.

Adjuvant antiarrhythmic therapy in patients with implantable cardioverter defibrillators

The risk of sudden cardiac death from ventricular fibrillation or ventricular tachycardia in patients with cardiomyopathy related to structural heart disease has been favorably impacted by the wide adaptation of implantable cardioverter defibrillators (ICDs) for both primary and secondary prevention. Unfortunately, after ICD implantation both appropriate and inappropriate ICD therapies are common. ICD shocks in particular can have significant effects on quality of life and disease-related morbidity and mortality. While not indicated for primary prevention of ICD therapies, beta-blockers and antiarrhythmic drugs are a cornerstone for secondary prevention of them. This review will summarize our current understanding of adjuvant antiarrhythmic drug therapy in ICD patients. The review will also discuss the roles of nonantiarrhythmic drug approaches that are used in isolation and in combination with antiarrhythmic drugs to reduce subsequent risk of ICD shocks.

Peripheral artery disease is an independent predictor of mortality after implantable cardioverter-defibrillator implantation in patients with severe left ventricular dysfunction

The impact of peripheral artery disease (PAD) on survival in implantable cardioverter defibrillator (ICD) patients is poorly understood. Thus, we assessed the risk of PAD in our adult ICD patients with left ventricular dysfunction (ejection fraction [EF] ≤35%). Survival was estimated with Kaplan-Meier method and compared by the log-rank test; a Cox proportional hazards model assessed the effects of clinical variables on survival. Average age and EF of 1399 patients were 67.0 ± 12.1 years and 23.8% ± 7.2%, respectively. The ICD patients with PAD had significantly worse survival than those without (unadjusted P < .0001). The multivariate predictors of survival at implant were (hazard ratio, HR [95% confidence interval]) age (HR 1.05 [1.04-1.07] P < .0001), PAD (HR 2.07 [1.53-2.80] P < .0001), class III/IV heart failure (HR 1.36 [1.06-1.76] P = .016), creatinine 1.4-2.0 mg/dL (HR 1.36 [1.05-1.76] P = .019), and creatinine ≥2.0 mg/dL (HR 2.01 [1.42-2.85] P < .0001). The PAD is an independent predictor of mortality and should be considered in the preimplant risk assessment.

Role of selected parameters and integral indices of treadmill test in the assessment of complication risk among patients with chronic coronary heart disease

Aim. To identify the value of selected parameters and integral indices of treadmill test (TT), such as Duke Treadmill Score (DTS), Centre for Preventive Medicine index (CPMI), and modified CPMI, in the assessment of cardiovascular complication (CVC) risk among patients with chronic coronary heart disease (CCHD). Material and methods. The study included all consecutive patients with the admission diagnosis of CCHD (n=260), who underwent coronary angiography (CAG) and TT in the period from January 1st 2004 to December 31st 2007, and were permanent residents of Moscow City or Moscow Region. Primary end-point was death from all causes; non-fatal CVC included acute myocardial infarction, acute cerebrovascular accident, and revascularization (percutaneous coronary intervention or coronary artery bypass graft surgery). Results. The mean time to the development of primary end-point was 3,2 years; it total, it was registered in 71 patients (32,0 %). The incidence of primary end-point was higher in patients with ST segment depression ≥1 mm at TT, positive TT result, or chest pain development during the test. Achievement of target heart rate and TT time ≥12 minutes was associated with a better prognosis. In patients with high and intermediate risk by DTS and CPMI, the incidence of primary end-point was higher than in patients with low risk. Modified CPMI demonstrated high correlation with the primary end-point. Conclusion. The highest prognostic value in the assessment of the risk of CCHD complications was demonstrated by TT result, ST segment depression ≥1 mm, TT time, and chronotropic TT response. The role of CPMI and modified CPMI as predictors of CVC risk in CCHD patients was assessed.

Chronic Suppression of Ventricular Tachyarrhythmias in Patients with ICDs

In this review, we examine the data evaluating the role of adjuvant therapy with antiarrthymic drugs (AADs) in chronic suppression of ventricular tachyarrhythmias in the patient with an ICD. It must be noted that all uses of AADs for this indication represent "off-label" prescription. No AAD is approved by the Food and Drug Administration (FDA) specifically as a therapy to reduce ICD shocks.

Quantitative evaluation of the amount of delayed myocardial enhancement as a predictor of systolic dysfunction

30 patients with delayed contrast enhancement in patterns suggestive of myocardial infarctions were reviewed. Infarct mass was quantitatively measured using short axis images obtained in the delayed phase of gadopentetate administration. Left ventricular mass and ejection fraction were measured using short axis, steady state free precession images. A relationship is drawn between increased mass of infarction and decreased left ventricular ejection fraction. For each gram of infarct, there is a 0.5 % reduction in ejection fraction (EF = 50 - (0.48 x gm infarcted myocardium); r²= 0.49). For each % increase of infarcted myocardium, there is a 0.67 % reduction in ejection fraction (EF = 50 - (0.67 x percent of infarcted myocardium); r²= 0.39). Left ventricular ejection fraction correlates inversely with the mass of myocardium with delayed enhancement on cardiac MRI.

Clinical and demographic determinants of heart rate variability in patients post myocardial infarction: insights from the cardiac arrhythmia suppression trial (CAST)

BACKGROUND

Clinical and demographic determinants of heart rate variability (HRV), an almost universal predictor of increased mortality, have not been systematically investigated in patients post myocardial infarction (MI).

HYPOTHESIS

The study was undertaken to evaluate the relationship between pretreatment clinical and demographic variables and HRV in the Cardiac Arrhythmia Suppression Trial (CAST).

METHODS

CAST patients were post MI and had > or =6 ventricular premature complexes/h on pretreatment recording. Patients in this substudy (n = 769) had usable pretreatment and suppression tapes and were successfully randomized on the first antiarrhythmic treatment. Tapes were rescanned; only time domain HRV was reported because many tapes lacked the calibrated timing signal needed for accurate frequency domain analysis. Independent predictors of HRV were determined by stepwise selection.

RESULTS

Coronary artery bypass graft surgery (CABG) after the qualifying MI was the strongest determinant of HRV. The markedly decreased HRV associated with CABG was not associated with increased mortality. Ejection fraction and diabetes were also independent predictors of HRV. Other predictors for some indices of HRV included beta-blocker use, gender, time from MI to Holter, history of CABG before the qualifying MI, and systolic blood pressure. Decreased HRV did not predict mortality for the entire group. For patients without CABG or diabetes, decreased standard deviation of all NN intervals (SDANN) predicted mortality. Clinical and demographic factors accounted for 31% of the variance in the average of normal-to-normal intervals (AVGNN) and 13-26% of the variance in other HRV indices.

CONCLUSIONS

Heart rate variability post MI is largely independent of clinical and demographic factors. Antecedent CABG dramatically reduces HRV. Recognition of this is necessary to prevent misclassification of risk in patients post infarct.

Management of atrial fibrillation in patients with heart failure

BACKGROUND

There is a well-documented relationship and a complex interaction between atrial fibrillation (AF) and heart failure. The coexistence of these 2 clinical entities renders their management even more challenging.

METHODS AND RESULTS

We searched current literature to review the management of AF in patients with heart failure. The cornerstones of AF treatment are rate control, cardioversion, and maintenance of sinus rhythm (SR), and prevention of thromboembolism. The issue of rhythm versus rate control remains unresolved. Nonpharmacologic therapies such as radiofrequency catheter ablation of the atrioventricular node with permanent pacemaker implantation, curative catheter ablation of AF, and cardiac resynchronization therapy are emerging and may alter the management of these patients.

CONCLUSION

Treatment of atrial fibrillation in the setting of heart failure encompasses a variety of approaches including drugs, devices, and ablation. Larger randomized trials are required to clarify the management of such patients.

Development of more erratic heart rate patterns is associated with mortality post-myocardial infarction

Cardiac patients often have sinus arrhythmia of nonrespiratory origin (erratic sinus rhythm [ESR]). ESR was quantified using hourly Poincaré and power spectral heart rate variability plots from normal-to-normal interbeat intervals and hourly values of the short-term fractal scaling exponent and correlations of normal-to-normal intervals in n = 60 nonsurvivors and n = 66 randomly selected survivors in the Cardiac Arrhythmia Suppression Trial. Hours were coded (ABN) as normal (0), borderline (0.5), or ESR (1). t Tests compared ABN for n = 2413 paired hours at baseline and on therapy. ABN was higher in nonsurvivors (0.38 +/- 0.44 vs 0.28 +/- 0.40, baseline, and 0.51 +/- 0.45 vs 0.34 +/- 0.43, on therapy, P < .001). Increased ABN with treatment were greater in nonsurvivors. Normal hours at baseline (relative risk = 0.77; 095% confidence interval, 0.62-0.96, P = .018) and on treatment (relative risk = 0.47; 95% confidence interval, 0.39-0.58) were significantly associated with decreased mortality compared with ESR. Quantification of ESR may identify more vulnerable patients or help monitor the effects of pharmacologic treatment.

Spironolactone Reduced Arrhythmia and Maintained Magnesium Homeostasis in Patients With Congestive Heart Failure

BACKGROUND

Patients with congestive heart failure (CHF) often have increased aldosterone activity that leads to hypomagnesemia. Hypomagnesemia can induce arrhythmias, an important cause of death in patients with CHF. We determined whether the aldosterone receptor antagonist spironolactone improved magnesium homeostasis and reduced arrhythmias in patients with CHF.

METHODS AND RESULTS

We randomized 116 consecutive patients with CHF into placebo control group (n = 58) and spironolactone group (20 mg daily, n = 58) in addition to conventional therapy. Plasma magnesium concentration (PMC), erythrocyte magnesium concentration (EMC), and erythrocyte magnesium efflux were not different between the 2 groups of patients before treatment. Compared with control patients, patients treated with spironolactone for 6 months had increased PMC and EMC and decreased erythrocyte magnesium efflux. Patients on spironolactone therapy also had a marked decrease of 24-hour mean heart rate, ventricular and atrial premature beats, and the risk of atrial fibrillation/flutter. Pooled data from the 116 patients showed that patients with a higher EMC or a lower sodium-dependent erythrocyte magnesium efflux had a slower heart rate, fewer ventricular premature beats, and a lower risk of atrial fibrillation/flutter.

CONCLUSIONS

Our results suggest that reducing cellular magnesium efflux and loss may contribute to the spironolactone-reduced arrhythmias in patients with CHF.

Predicting the recurrence of ventricular tachyarrhythmias from T-wave alternans assessed on antiarrhythmic pharmacotherapy: a prospective study in patients with dilated cardiomyopathy

BACKGROUND

Microvolt T-wave alternans (TWA) has been proposed as a useful index to identify patients at risk of ventricular tachyarrhythmias. Recent studies have demonstrated that antiarrhythmic drugs, such as amiodarone and procainamide, decrease the prevalence of TWA. In this study, we tested whether TWA in patients on antiarrhythmic pharmacotherapy significantly predicts the recurrence of ventricular tachyarrhythmias in patients with dilated cardiomyopathy.

METHODS

To evaluate the ability to predict the recurrence of ventricular tachyarrhythmias, determinate TWA and left ventricular ejection fraction (LVEF) were prospectively assessed in 49 patients with ischemic or nonischemic dilated cardiomyopathy on antiarrhythmic pharmacotherapy for sustained ventricular tachycardia (VT) or ventricular fibrillation (VF). The pharmacotherapy consisted of class I (17 patients), III (29 patients), and IV (3 patients) antiarrhythmic drugs. The study endpoint was the first recurrence of sustained VT or VF on treatment during the follow-up period.

RESULTS

TWA was positive on antiarrhythmic pharmacotherapy in 30 patients (61%). During a follow-up of 13 +/- 11 months, the sustained VT or VF recurred in 21 of the 41 patients (51%) with available follow-up data. The sensitivity of TWA and LVEF for predicting recurrence of ventricular tachyarrhythmias was 76 and 38%, specificity was 60 and 70%, positive predictive value was 67 and 57%, and negative predictive value was 71 and 52%. Kaplan-Meier event-free analysis revealed that TWA was a significant risk stratifier (P = 0.02), whereas LVEF was not.

CONCLUSIONS

This prospective study suggests that TWA significantly predicts the recurrence of ventricular tachyarrhythmias, even on antiarrhythmic pharmacotherapy, in patients with dilated cardiomyopathy. TWA may also be a useful marker for evaluating the efficacy of antiarrhythmic drugs for ventricular tachyarrhythmias.

Atrial Fibrillation and Congestive Heart Failure: Risk Factors, Mechanisms, and Treatment

Atrial fibrillation (AF) and congestive heart failure (CHF) are commonly encountered together, and either condition predisposes to the other. Risk factors for AF and CHF include age, hypertension, valve disease, and myocardial infarction, as well as a variety of medical conditions and genetic variants. Congestive heart failure and AF share common mechanisms, including myocardial fibrosis and dysregulation of intracellular calcium and neuroendocrine function. Pharmacological treatments including beta-blockers, digoxin, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers can be useful in treating both of these conditions. Antiarrhythmic medications intended to achieve and maintain sinus rhythm may be beneficial in some patients with AF and CHF. Advances in pacemaker and defibrillator therapy, including cardiac resynchronization therapy, may also benefit patients with AF and CHF. Surgical and catheter-based ablation therapy can restore sinus rhythm in patients with AF, with proven benefit in patients with concommitant CHF. Investigational biologic therapy, including cell and gene based therapy, offers promise for the future of reversing the pathophysiological mechanisms that underlie AF and CHF.

Out-patient management of chronic heart failure

Chronic heart failure is a clinical syndrome associated with an ominous long-term prognosis and major economic consequences for Western societies. In recent years, considerable progress has been made in the pharmacological management of heart failure, and several treatments have been confirmed to confer survival and symptomatic benefits. However, pharmaceuticals remain underutilised, and the combination of several different drugs present challenges for their optimal prescription, requiring a thorough knowledge of potential side effects and complex interactions. This article reviews in detail the evidence pertaining to the out-patient pharmacological management of chronic heart failure, and offers recommendations on the use of various drugs in complex clinical conditions, or in areas of ongoing controversy.

Electrophysiologic Effects of Carvedilol: Is Carvedilol an Antiarrhythmic Agent?

The cardiovascular drug carvedilol is characterized by multiple pharmacological actions, which translate into a wide-spectrum therapeutic potential. Its major molecular targets are membrane adrenoceptors, ion channels, and reactive oxygen species. Carvedilol's favorable hemodynamic effects are due to the fact that the drug competitively blocks beta(1)-, beta(2)-, and alpha(1)- adrenoceptors. Several additional properties have been documented and may be clinically important, including antioxidant, antiproliferative/antiatherogenic, anti-ischemic, and antihypertrophic effects. The antiarrhythmic action of carvedilol may be related to a combination of its beta-blocking effects with its modulating effects on a variety of ion channels and currents. Several studies suggest that the drug may be useful in reducing cardiac death in high-risk patients with prior myocardial infarction and/or heart failure, as well as for primary and secondary prevention of atrial fibrillation. This article will review experimental data available on the electrophysiologic properties of carvedilol, with a focus on their clinical relevance.

Can Amiodarone Prevent Sudden Cardiac Death in Patients with Hemodynamically Tolerated Sustained Ventricular Tachycardia and Coronary Artery Disease?

One of the most important challenges in today's cardiology is prevention of sudden cardiac death in high risk patients with coronary artery disease (CAD). Sustained hemodynamically tolerated ventricular tachycardia (HTVT) comprises up to 30% of all cases of monomorphic ventricular tachycardia in patients with CAD. While there is a consensus on treatment of hemodynamically unstable sustained ventricular tachycardia in patients with CAD, some controversies regarding the proper treatment of HTVT exist. We re-examined existing clinical evidence, controversies and current guidelines on the treatment of HTVT in patients with CAD and demonstrated that compared to implantable cardioverter-defibrillator, amiodarone is not an acceptable therapeutic option in patients with ischemic heart disease who suffer from HTVT.

Hypothermia is a bedside predictor of imminent death in patients with congestive heart failure

BACKGROUND

Most studies on predictors of mortality for patients with congestive heart failure (CHF) have described predictors that are either difficult to measure in routine practice or are only modestly sensitive and specific. Having observed 3 patients whose body temperature decreased shortly before death, we hypothesized that hypothermia may predict inhospital mortality.

METHODS

The medical records of 291 patients with a primary discharge diagnosis of CHF were selected from 423 admissions to Memorial Hermann Hospital, Houston, Tex, 1998, after excluding patients with comorbidities that confound body temperature, deaths for causes other than progressive pump failure, and readmissions except the last. Three groups were defined on the basis of admission body temperature (T adm): hypothermia groups T adm (95.5 degrees F-96.5 degrees F) and T adm < 95.5 degrees F, and reference group T adm > or = 96.6 degrees F. Several other known CHF risk factors were studied for confounding, and adjusted hazard ratios were calculated using Cox regression.

RESULTS

Of the 291 patients (mean age 73 years, 47% men), 17 (6%) had hypothermia on admission. Mean hospital stay was 5 days. Of the 17 (6%) patients who died of pump failure, 5 had been hypothermic on admission. Hypothermia was significantly associated with survival, and after adjusting for New York Heart Association functional class, hazard ratio for T adm < 95.5 degrees F was 4.46 (95% confidence interval 1.38-14.3) (P trend = .0283).

CONCLUSIONS

Hypothermia predicted inhospital death in these patients with CHF. If confirmed by future studies, this finding could prove useful, because temperature can be measured continuously, rapidly, and inexpensively, in or out of the hospital.

Traditional and nonlinear heart rate variability are each independently associated with mortality after myocardial infarction

INTRODUCTION

Decreased heart rate variability (HRV) and abnormal nonlinear HRV shortly after myocardial infarction (MI) are risk factors for mortality. Traditional HRV predicts mortality in patients with a range of times post-MI, but the association of nonlinear HRV and outcome in this population is unknown.

METHODS AND RESULTS

HRV was determined from 740 tapes recorded before antiarrhythmic therapy in Cardiac Arrhythmia Suppression Trial patients with ventricular premature contractions (VPCs) suppressed on the first randomized treatment. Patients were 70 +/- 121 days post-MI. Follow up was 362 +/- 241 days (70 deaths). The association between traditional time and frequency-domain HRV and mortality and nonlinear HRV and mortality were compared for the entire population (ALL), those without coronary artery bypass graft post-MI (no CABG), and those without CABG or diabetes (no CABG, no DIAB) using univariate and multivariate Cox regression analysis. Strength of association was compared by P values and Wald Chi-square values. Nonlinear HRV included short-term fractal scaling exponent, power law slope, and SD12 (Poincare dimension). For ALL and for no CABG, increased daytime SD12 had the strongest association with mortality (P=0.002 ALL and P <0.001 no CABG). For no CABG, no DIAB increased 24-hour SD12 hours had the strongest association (P <0.001) with mortality. Upon multivariate analysis, increased SD12, decreased ln ULF (ultra low frequency), and history of prior MI and history of congestive heart failure each remained in the model.

CONCLUSION

Nonlinear HRV is associated with mortality post-MI. However, as with traditional HRV, this is diluted by CABG surgery post-MI and by diabetes. Results suggest that decreased long-term HRV and increased randomness of heart rate are each independent risk factors for mortality post-MI.

Including patients with diabetes mellitus or coronary artery bypass grafting decreases the association between heart rate variability and mortality after myocardial infarction

BACKGROUND

Decreased heart rate variability (HRV) is often assumed to be associated with mortality in all patients after myocardial infarction (MI), independent of clinical factors or time after MI.

METHOD

HRV was determined from Holter tapes in the Cardiac Arrhythmia Suppression Trial (CAST). Patients were 71 +/- 120 days after MI. A total of 735 pre-therapy tapes were analyzed in patients who had ventricular premature contractions (VPCs) suppressed on the first treatment. The period of follow-up was 362 +/- 243 days (69 deaths). The association of clinical and demographic factors and 24-hour, daytime, and nighttime HRV to mortality in all patients, patients without coronary artery bypass graft (CABG) surgery between the qualifying MI and the Holter monitoring, and patients with neither CABG nor diabetes mellitus was determined with univariate Cox regression analysis.

RESULTS

For the entire group and the subgroup without CABG, the strongest association was with increased daytime normalized high frequency power (NHF day). Further excluding patients with diabetes mellitus strengthened the association of HRV with mortality rate. Decreased natural logarithm (ln) 24-hour total and ultra low frequency (ULF) power were the strongest predictors of mortality. The best cutoff point for ln ULF for separating survivors and non-survivors was determined. After including a history of MI, congestive heart failure, or both as co-factors, ln ULF < or =7.85 identified patients at approximately 4-times the relative risk of mortality, but did not risk-stratify patients without prior MI or history of congestive heart failure.

CONCLUSIONS

HRV predicts mortality rate in a broad range of times after MI. Excluding patients with CABG after MI or with diabetes mellitus significantly strengthens the association of HRV with mortality. HRV measures beyond the peri-infarction period, with clinical factors, can identify subgroups at an elevated risk of mortality.

The association of left ventricular ejection fraction, mortality, and cause of death in stable outpatients with heart failure

OBJECTIVES

The aim of this study was to assess the prognostic importance of left ventricular ejection fraction (LVEF) in stable outpatients with heart failure (HF).

BACKGROUND

Although LVEF is an accepted prognostic indicator of prognosis in HF patients, the relationship of LVEF and mortality across the full spectrum of LVEF is incompletely understood.

METHODS

We examined the association of LVEF and outcomes among 7,788 stable HF patients enrolled in the Digitalis Investigation Group trial.

RESULTS

During mean follow-up of 37 months, mortality was substantial in all LVEF groups (range, LVEF <or= 15%, 51.7%, LVEF > 55%, 23.5%). Among patients with LVEF <or= 45%, mortality decreased in a near linear fashion across successively higher LVEF groups (LVEF < 15%, 51.7%; LVEF 36% to 45%, 25.6%; p < 0.0001). This association was present after multivariable adjustment, although the magnitude of this associated risk was reduced (LVEF <or= 15%: hazard ratio [HR] 1.77, 95% confidence interval [CI] 1.48 to 2.11; LVEF 16% to 25%: HR 1.44, 95% CI 1.28 to 1.61; LVEF 26% to 35%: HR 1.10, 95% CI 0.98 to 1.28; LVEF 36% to 45%: referent). In contrast, mortality rates were comparable among patients with LVEF > 45% both before (LVEF 46% to 55%: 23.3%; LVEF > 55%: 23.5%; p = 0.25), and after multivariable adjustment (LVEF 46% to 55%: HR 0.92, 95% CI 0.77 to 1.10; LVEF > 55%: HR 0.88, 95% CI 0.71 to 1.09; LVEF 36% to 45%: referent). Patients with lower LVEF were at increased absolute risk of death due to arrhythmia and worsening HF, but these were leading causes of death in all LVEF groups.

CONCLUSIONS

Among HF patients in sinus rhythm, higher LVEFs were associated with a linear decrease in mortality up to an LVEF of 45%. However, increases above 45% were not associated with further reductions in mortality.

Atrial fibrillation in patients with congestive heart failure

CHF and AF are common problems that are frequently encountered together. These two disease states interact in a way that can result in a viscous cycle. This brief review will attempt to address the interaction between AF and CHF, atrial pathology and abnormal electrophysiology, clinical consequences, prognostic importance, and therapy.

Neurohumoral activation and ventricular arrhythmias in patients with decompensated congestive heart failure: role of endothelin

Patients with congestive heart failure (CHF) have a high incidence of ventricular arrhythmias and sudden arrhythmic death. CHF entails profound and complex abnormalities in humoral responses that are thought to promote arrhythmic events. However, it is unknown which of the many endogenous mediators that accumulate as part of neurohormonal activation is important in arrhythmogenesis in the setting of CHF. The study included 83 patients admitted to the hospital for treatment of decompensated CHF. Neurohormonal and cytokine activation was assessed by measuring plasma renin activity, aldosterone, norepinephrine, endothelin-1, tumor necrosis factor-alpha, and interleukin-6 levels. Atrial and ventricular arrhythmic events were assessed by 24-hour Holter monitoring. In a univariate analysis, a highly significant, positive relationship was found between plasma endothelin-1 levels and the average hourly total premature ventricular beats (P = 0.003), the frequency of ventricular pairs (P = 0.0003), and the frequency of ventricular tachycardia episodes (P = 0.001). After inclusion of clinical variables, drug therapies, neurohormones, and cytokine levels in a multivariate analysis, the positive relationship between plasma endothelin-1 level and the average hourly total premature ventricular beats (P = 0.008), the frequency of ventricular pairs (P = 0.007), and ventricular tachycardia episodes (P = 0.009) remained independent. No association between other neurohormones or cytokines and arrhythmic events was demonstrated. The results of the present study suggest that increased endothelin-1 concentrations may be involved in promoting the occurrence of ventricular ectopy in patients with decompensated CHF. Proarrhythmic effects may account, in part, for the poor outcome associated with increased endothelin-1 levels in patients with decompensated CHF.

Relation of ejection fraction and inducible ventricular tachycardia to mode of death in patients with coronary artery disease: an analysis of patients enrolled in the multicenter unsustained tachycardia trial

BACKGROUND

Fifty percent of deaths in patients with coronary disease occur suddenly. Although many factors correlate with increased mortality, there is little information regarding the influence of these factors on mode of death. As such, optimum methods to determine patients most likely to benefit from implantable defibrillator therapy are unclear.

METHODS AND RESULTS

We analyzed the relation of ejection fraction and inducible ventricular tachyarrhythmias to mode of death in all 1791 patients enrolled in the Multicenter Unsustained Tachycardia Trial who did not receive antiarrhythmic therapy. Total mortality and arrhythmic deaths/cardiac arrests occurred more frequently in patients with ejection fraction <30% than in those with ejection fraction of 30% to 40%. The percentage of deaths classified as arrhythmic was similar in patients with ejection fraction <30% or > or =30%. The relative contribution of arrhythmic events to total mortality was significantly higher in patients with inducible tachyarrhythmia (58% of deaths in inducible patients versus 46% in noninducible patients, P=0.004). The higher percentage of events that were arrhythmic among patients with inducible tachyarrhythmia appeared more distinct among patients with an ejection fraction > or =30% (61% of events were arrhythmic among inducible patients with ejection fraction > or =30% and only 42% among noninducible patients, P=0.002).

CONCLUSIONS

Both low ejection fraction and inducible tachyarrhythmias identify patients with coronary disease at increased mortality risk. Ejection fraction does not discriminate between modes of death, whereas inducible tachyarrhythmia identifies patients for whom death, if it occurs, is significantly more likely to be arrhythmic, especially if ejection fraction is > or =30%.

Prevalence and incidence of arrhythmias and sudden death in heart failure

Patients with heart failure are prone to a variety of arrhythmias, symptomatic and asymptomatic, that are prognostically significant and have an important bearing on the management of these patients. However there are some inherent problems in assessing the frequency of these arrhythmias within a large patient population, due to a lack of uniformity in defining heart failure and the transient nature of these rhythms. Patients with heart failure commonly die suddenly. The causes of these deaths are difficult to ascertain accurately and are often presumed arrhythmic. With the advent of effective interventions to prevent sudden death, accurately defining the causal relationship between the arrhythmias and sudden death has assumed great importance to appropriately target therapy. Several attempts have been made to predict such deaths on the basis of non-invasive and invasive diagnostic investigations with variable success. In this article we review the incidence and prevalence of atrial and ventricular arrhythmias and sudden deaths in epidemiological studies, surveys and randomised control trials of patients with heart failure. We discuss the prognostic significance of these arrhythmias, the inherent problems in their diagnosis and whether their presence predicts the risk of sudden deaths and the mode of such deaths in the heart failure population. The role of various investigations in risk stratification of sudden death has also been discussed.

Concomitant beta-blocker therapy is associated with a lower occurrence of ventricular arrhythmias in patients with decompensated heart failure

BACKGROUND

Ventricular arrhythmias are nearly universally present in patients with advanced congestive heart failure (CHF) and represent an important cause of mortality in these patients. One of the putative mechanisms for the salutary effects of beta-blockers on sudden death mortality in heart failure is their ability to suppress ventricular arrhythmias. However, supporting data in patients with CHF are sparse, especially in the setting of excessive neurohumoral activation associated with symptomatic decompensated heart failure.

METHODS AND RESULTS

We studied 236 patients (159 men; mean age, 61 +/- 14 years) admitted for decompensated CHF. Fifty patients were receiving beta-blockers at the time of the study. The severity of ventricular arrhythmia was assessed by 24-hour Holter recordings by using several prospectively defined measures of ventricular ectopy. All measures of ventricular ectopy were lower in patients receiving beta-blockers. The average hourly total premature ventricular beats (PVCs), hourly ventricular couplets, repetitive PVCs, and frequency of ventricular tachycardia episodes were 15% (P =.02), 75% (P <.05), 72% (P <.05), and 87% (P =.01) lower in patient receiving beta-blockers, respectively. In a multivariate regression analysis, the negative relationship between beta-blockers and the average hourly PVCs (P =.03), the frequency of ventricular pairs (P =.03), repetitive PVCs (P <.05), and ventricular tachycardia episodes (P =.01) remained significant and independent.

CONCLUSIONS

Concomitant beta-blocker therapy during heart failure decompensation is associated with a marked reduction in complex ventricular ectopy and episodes of ventricular tachycardia. This effect of beta-blockers may play an important protective role by preventing serious ventricular arrhythmias during transient increases in sympathetic activity.

Effect of spironolactone on ventricular arrhythmias in congestive heart failure secondary to idiopathic dilated or to ischemic cardiomyopathy

Epidemiologic studies have shown an important increase in the high mortality of patients with congestive heart failure (CHF) despite optimal medical management. Ventricular arrhythmia was recognized as the most common cause of death in this population. Electrolyte imbalance, myocardial fibrosis, left ventricular dysfunction, and inappropriate neurohumoral activation are presumed responsible for sudden cardiac death. In this study, we focused on the deleterious effects of the overproduction of aldosterone that occurs in patients with CHF. Secondary hyperaldersteronism can be part of several factors thought to be responsible for sudden cardiac death. We randomized 35 patients (32 men, aged 48 +/- 9 years) with systolic dysfunction (ejection fraction 33 +/- 5%) and New York Heart Association class III CHF secondary to dilated or ischemic cardiomyopathy into 2 groups. The treatment group received spironolactone, an aldosterone receptor antagonist, along with standard medical management using furosemide, angiotensin-converting enzyme inhibitors, and digoxin. The control group received only the standard medical treatment. Holter monitoring was used to assess the severity of ventricular arrhythmia. After 20 weeks, patients who received spironolactone had a reduced hourly frequency of ventricular premature complexes (VPCs) (65 +/- 18 VPCs/hour at week 0 and 17 +/- 9 VPCs/hour at week 16) and episodes of nonsustained ventricular tachycardia (VT) (3.0 +/- 0.8 episodes of VT/24-hour period at week 0, and 0.6 +/- 0.3 VT/24-hour period at week 16). During monitored treadmill exercise, a significant improvement in ventricular arrhythmia was found in the group receiving spironolactone (39 +/- 10 VPCs at week 0, and 6 +/- 2 VPCs at week 16). These findings suggest that aldosterone may contribute to the incidence of ventricular arrhythmia in patients with CHF, and spironolactone helps reduce this complication.

Prognostic value of congestive heart failure history in patients undergoing percutaneous coronary interventions

OBJECTIVES

We sought to determine the prognostic significance of a history of congestive heart failure above that provided by baseline ejection fraction in patients undergoing percutaneous coronary interventions.

BACKGROUND

Left ventricular function is a known predictor of survival in patients with coronary artery disease, as is a history of congestive heart failure. The contribution of heart failure history independent of left ventricular function is unknown.

METHODS

Data were pooled from four interventional trials and the Duke University database. The combined dataset included 5,260 patients undergoing percutaneous interventions, 334 with and 4,926 without a history of heart failure. Patients were defined by the treating physician as having a clinical history of heart failure at the time of enrollment.

RESULTS

The 30-day and 6-month mortality were higher in patients with a clinical history of congestive heart failure than in those without such a history (2% vs. <1%, p=0.002 at 30 days, 5% vs. 1%, p=0.001 at 6 months). Heart failure history did not influence the incidence of myocardial infarction, use of angioplasty or the use of bypass surgery during follow-up. Multivariable analysis revealed that heart failure history added significantly to ejection fraction in predicting intermediate-term (6-month) mortality (p=0.01). Stepwise logistic regression also revealed heart failure history to be an independent predictor of 6-month mortality (odds risk 1.9, 95% confidence interval 1.1 to 3.5).

CONCLUSIONS

A clinical history of congestive heart failure is associated with increased early and intermediate-term mortality in patients undergoing percutaneous revascularization. Congestive heart failure history appears to provide prognostic information independent of that available from a patient's left ventricular function. These findings suggest that patients with a clinical history of congestive heart failure who undergo a percutaneous intervention should be closely monitored, especially those with the lowest ejection fractions.

Mortality in the Survival With ORal D-sotalol (SWORD) trial: why did patients die?

The Survival With ORal D-sotalol (SWORD) trial tested the hypothesis that the prophylactic administration of oral d-sotalol would reduce total mortality in patients surviving myocardial infarction (MI) with a left ventricular ejection fraction (LVEF) of < or = 40%. Two index MI groups were included: recent (6 to 42 days) and remote (> 42 days) with clinical heart failure (n = 915 and 2,206, respectively). The trial was discontinued when the statistical boundary for harm was crossed (RR = 1.65; p = 0.006). All baseline variables known to be associated with mortality risk (e.g., LVEF, heart failure class, age) as well as variables related to torsades de pointes (e.g., time from beginning of therapy, QTc, gender, potassium, renal function, dose of d-sotalol) were assessed for interaction of each variable with treatment assignment, computing RR and 95% confidence interval (CI) from Cox regression models. The d-sotalol-associated mortality was greatest in the group with remote MI and LVEFs of 31% to 40% (RR = 7.9; 95% CI 2.4 to 26.2). Most variables known to be associated with torsades de pointes were not differentially predictive of d-sotalol-associated risk, except female gender (RR = 4.7; 95% CI 1.4 to 16.5). These findings suggest that (1) most of the d-sotalol-associated risk was in patients remote from MI with a LVEF of 31% to 40%; comparable placebo patients had a very low mortality (0.5%); and (2) very little objective data supports torsades de pointes or any specific proarrhythmic mechanism as an explanation for d-sotalol-associated mortality risk.

Mechanisms of arrhythmias in heart failure

The diagnosis of heart failure infers a bad prognosis. Mortality is high and many patients die suddenly. Ventricular arrhythmias, commonly observed in patients with heart failure, are thought to underlie at least some of these sudden deaths. The mechanism of arrhythmias occurring in the setting of heart failure is still unclear. Experimental evidence points to a higher tendency for failing myocardium to develop delayed and early afterdepolarization-induced triggered activity and automaticity. Conditions favoring reentry also have been described in failing hearts. Modulating factors such as sympathetic activation, electrolyte disturbances, and chronic stretch are present in the setting of heart failure and may favor all of the mentioned mechanisms of arrhythmias. Clinical evaluation of arrhythmias in patients and animals with heart failure and the effects of pharmacologic treatment of ventricular arrhythmias in patients with depressed left ventricular function further accentuate that more than one mechanism of arrhythmia may be operating in heart failure and underscore the importance of modulating factors such as sympathetic activation and stretch.