Ambulatory ventricular arrhythmias in patients with heart failure do not specifically predict an increased risk of sudden death. PROMISE (Prospective Randomized Milrinone Survival Evaluation) Investigators

The worsening of left ventricular hypertrophy is the strongest predictor of sudden cardiac death in haemodialysis patients: a 10 year survey

BACKGROUND

Although the incidence of sudden cardiac death (SCD) is high among haemodialysis (HD) patients, there are few papers available on this topic. The aim of this study on a single-centre HD population observed over a 10 year period was to identify patient- and HD-related specific factors that might be associated with a higher risk of SCD.

METHODS

The study included 123 patients (76 men; age 29-79 years) undergoing renal replacement therapy at our dialysis unit for at least 6 months. For each patient, routine laboratory tests were performed monthly, blood pressure was measured both at the start and the end of each dialysis session, haemoglobin and pre-dialysis serum K(+) were determined weekly, serum iPTH was assessed thrice yearly, and an echocardiographic study was performed annually to determine the left ventricular mass index (LVMi). The prevalence of cardiovascular (CV) co-morbidities, and the incidence of new events were also recorded.

RESULTS

During the 10 years, 85 patients died-16 from SCD, 30 from cardiac causes (CC) other than SCD, and 39 from other causes (OC); 38 patients were still alive (AL) at the end of the observation period. Comparative analysis of SCD, CC, OC and AL, reveals that the male prevalence (13/3) was higher in SCD than in AL, while AL were younger than the deceased patients regardless of the cause of death (P<0.0001; ANOVA), the duration of arterial hypertension was higher in SCD (129+/-104 months; P = 0.0005; ANOVA), despite similar antihypertensive therapies, and the difference between LVMi at end-point and at inception (deltaLVMi) was significantly higher in SCD [+56+/-38 g/m(2) body surface area] compared with OC (-5+/-35), AL (-17+/-25) and even CC (7+/-30) (P<0.0001; ANOVA); finally, the prevalence of patients with ischaemic heart disease (IHD) was higher in the SCD group (11/5; P<0.0001, chi(2)). Univariate Cox regression analysis demonstrated that the factors increasing the risk of SCD were IHD (P = 0.002), the worsening of left ventricular hypertrophy (LVH) (P<0.0001), and the presence of long-lasting arterial hypertension (P = 0.001). An increase in LVH was the sole risk factor for SCD when comparing SCD with CC patients (P = 0.003). By multivariate Cox regression analysis deltaLVMi was identified as the strongest predictor of SCD (P<0.0001).

CONCLUSION

While confirming the role of common CV risk factors for SCD in dialysis patients such as IHD and arterial hypertension, this study is the first to demonstrate that the worsening of LVH is the strongest predictor of sudden death.

Noninvasive risk stratification in postinfarction patients with severe left ventricular dysfunction and methodology of the MADIT II noninvasive electrocardiology substudy

Sudden cardiac death occurs as a result of a complex interplay of changes in myocardial substrate, imbalance of autonomic regulation of the heart, and myocardial vulnerability. Noninvasive electrocardiology serves as a comprehensive tool for investigating factors representing mechanistic pathways leading to cardiac events. Heart rate variability, nonlinear dynamics of heart rate, and heart rate turbulence provide insight into autonomic control of the heart. Prognostic value of these parameters in postinfarction patients is well established for predicting cardiac death, but there is less evidence for their association with sudden death or arrhythmic events. Electrical manifestation of changes in myocardial substrate include QRS and QTc prolongation, presence of conduction disturbances, presence of late potentials, abnormalities of repolarization morphology, and presence of nonsinus rhythm, namely atrial fibrillation. Electrocardiogram (ECG) measures reflecting myocardial vulnerability to arrhythmias include frequent ventricular premature beats, T wave alternans, or QT variability. Prognostic significance of these parameters is documented in studies focused mostly on them as individual markers of risk. The noninvasive electrocardiology substudy of the Multicenter Automatic Defibrillator Implantation Trial II (MADIT II) allows for simultaneous analysis of several of the above ECG markers of risk and will provide insight about relative contribution of mechanistic pathways leading to cardiac death in postinfarction patients with severe left ventricular dysfunction. Combination of a standard 12-lead ECG and 10-minute high-resolution Holter recordings serves to evaluate the prognostic significance of noninvasive electrocardiology parameters for mortality in patients randomized to conventional treatment and for arrhythmic events in patients randomized to implantable cardioverter defibrillator therapy.

Risk Stratification and Primary Prevention of Sudden Cardiac Death

The initial challenge in primary prevention of sudden cardiac death (SCD) lies in identifying those at greatest risk, before the index event. Ventricular fibrillation is the leading cause of SCD; however, many clinical conditions predispose fatal ventricular dysrhythmias. In patients with structural heart disease, left ventricular dysfunction is the strongest predictor of SCD. Noninvasive markers such as nonsustained ventricular tachycardia, delayed potentials, decreased heart rate variability and baroreflex sensitivity, and repolarization alternans are further observed to assess risk in ischemic cardiomyopathy; however, most of these markers have poor positive predictive value and lack specificity. The electrophysiologic study has strong positive predictive value, but remains a costly and invasive method for risk stratification. In patients with normal hearts, genetic predisposition may identify patients at risk but clinical markers are not readily recognized. The implantable loop recorder is a useful tool in detecting dysrhythmic causes of syncope and identifying patients at risk for SCD.

Prevention and management of chronic heart failure with electrical therapy

Sudden cardiac death is responsible for >40% of patients with heart failure losing their lives. Thus, the prevention of life-threatening cardiac arrhythmias is a major goal in the management of heart failure. In several randomized clinical trials, electrical therapy with the implantable cardioverter defibrillator (ICD) has proved superior to medical antiarrhythmic therapy in both the secondary and primary prevention of sudden cardiac death in patients with reduced left ventricular function. In addition to the severity of left ventricular dysfunction, the etiology of the cardiomyopathy appears to be a determinant in the benefit derived from this form of electrical therapy. Whereas patients with ischemic cardiomyopathy clearly show improved survival with ICD therapy, outcome data in patients with nonischemic cardiomyopathy are less convincing. The major challenge lies in the risk stratification of patients with heart failure for arrhythmic death. Catheter ablation is another form of electrical therapy that can help in the treatment of patients with heart failure. In patients with a tachycardia-mediated cardiomyopathy because of drug-refractory atrial fibrillation with rapid ventricular response, catheter ablation of the atrioventricular node and pacemaker implantation can effectively restore a physiologic heart rate, often with dramatic regression of left ventricular dysfunction. In patients with frequent ICD therapies because of frequent recurrences of ventricular tachyarrhythmias, catheter ablation of ventricular tachycardia can be an effective adjunctive therapy. New catheter ablation techniques and new atrial pacing algorithms can also significantly reduce the atrial fibrillation burden in patients with heart failure who are particularly susceptible to decompensation because of atrial fibrillation. Pacing for hemodynamic benefit in heart failure has evolved from dual-chamber pacing modes with optimized atrioventricular delay to biventricular pacing resulting in cardiac resynchronization. This new treatment modality for advanced heart failure has been shown to result in significant symptomatic and hemodynamic improvement.

Cardiovascular risk factors, monitoring, and therapy for HIV-infected patients

Cardiovascular complications are important contributors to morbidity and mortality in HIV-infected patients. These complications can usually be detected at subclinical levels with monitoring, which can help guide targeted interventions. This article reviews available data on types and frequency of cardiovascular manifestations in HIV-infected patients and proposes monitoring strategies aimed at early subclinical detection. In particular, we recommend routine echocardiography for HIV-infected patients, even those with no evidence of cardiovascular disease. We also review preventive and therapeutic cardiovascular interventions. For procedures that have not been studied in HIV-infected patients, we extrapolate from evidence-based guidelines for the general population.

Device therapy for heart failure

Although pharmacologic therapy has made impressive advances in the past decade and is the mainstay of therapy for heart failure (HF), there is still a large unmet need, because morbidity and mortality remain unacceptably high. Implanted medical devices are gaining increasing utility in this group of patients and have the potential to revolutionize the treatment of HF. The majority of devices in clinical use or under active investigation in HF can be grouped into 1 of 4 categories: devices to monitor the HF condition, devices to treat rhythm disturbances, devices to improve the mechanical efficiency of the heart, and devices to replace part or all of the heart's function. There are several devices either approved or under development to monitor the HF condition, ranging from interactive weight scales to implantable continuous pressure monitors. The challenge is to demonstrate that this technology can improve patient outcomes. Pacemakers and implantable cardioverter defibrillators (ICDs) are used to treat heart rhythms in a broad range of patients with heart disease, but they now have a special place in HF management with the prophylactic use of ICDs in patients who have advanced systolic dysfunction. The Multicenter Automatic Defibrillator Implantation Trial (MADIT) II study demonstrated a 29% reduction in all-cause mortality with ICDs in patients with a history of a myocardial infarction and a left ventricular (LV) ejection fraction <0.30. LV and multisite pacing are means of improving the mechanical efficiency of the heart. The concept is to create a more coordinated contraction of the ventricles to overcome the inefficiency associated with conduction system delays, which are common in HF. The acute hemodynamic effect can be impressive and is immediate. Several studies of intermediate duration (3 to 6 months) have consistently demonstrated that biventricular pacing improves symptoms and exercise capacity. Mechanical methods of remodeling the heart into a more efficient shape have been under scrutiny for several years. New methods of restraining the heart with prosthetic material are under investigation in humans, with encouraging pilot results. Heart replacement has been evaluated clinically with LV assist devices for several decades. The Randomized Evaluation of Mechanical Assistance Therapy as an Alternative in Congestive Heart Failure (REMATCH) study has demonstrated a proof of concept for the use of mechanical blood pumps to improve survival, functional capacity, and symptoms. Several assist devices with such features as total implantability, improved durability, and smaller size are now under study; these may further improve the outcomes of patients. One year ago, the world witnessed the first clinical use of a totally implantable total artificial heart. Although the long-term outcomes were limited, the device demonstrated an impressive ability to improve organ function and extend survival in the population facing imminent death. Further development in this field is expected. The use of devices in HF now has a strong foothold, and the potential exists for substantially greater use of a broad range of devices in the near future.

Management of arrhythmias in heart failure

Arrhythmias continue to contribute significantly to morbidity and mortality in heart failure. Implantable defibrillators have assumed an increasingly important role in preventing sudden death and are recommended for patients who have been resuscitated from cardiac arrest, have unexplained syncope, or exhibit inducible ventricular tachycardia in the setting of prior myocardial infarction. The extension of survival conferred by implantable defibrillators is likely to be limited in patients with advanced heart failure. Ongoing trials will help define the use of these devices in heart failure populations, in whom atrial fibrillation is common and rate control and anticoagulation are of major importance. Among pharmaceutical options, amiodarone and dofetilide are the major agents for maintenance of sinus rhythm. The complexity of coexistent heart failure and arrhythmia management warrants close collaboration between heart failure and arrhythmia specialists.

Predicting death due to progressive heart failure in patients with mild-to-moderate chronic heart failure

OBJECTIVES

The aim of this study was to explore the value of noninvasive predictors of death/mode of death in ambulant outpatients with chronic heart failure (HF).

BACKGROUND

Mortality in chronic HF remains high, with a significant number of patients dying of progressive disease. Identification of these patients is important.

METHODS

We recruited 553 ambulant outpatients age 63 +/- 10 years with symptoms of chronic HF (New York Heart Association functional class, 2.3 +/- 0.5) and objective evidence of left ventricular dysfunction (ejection fraction <45%, cardiothoracic ratio >0.55, or pulmonary edema on chest radiograph). After 2,365 patient-years of follow-up, 201 patients had died, with 76 events due to progressive HF.

RESULTS

Independent predictors of all-cause mortality assessed with the Cox proportional hazards model were as follows: a low standard deviation of all normal-to-normal RR intervals (SDNN); lower serum sodium and higher creatinine levels; higher cardiothoracic ratio; nonsustained ventricular tachycardia; higher left ventricular end-systolic diameter; left ventricular hypertrophy; and increasing age. Independent predictors of death specific to progressive HF were SDNN, serum sodium and creatinine levels. The hazard ratio of progressive HF death for a 10% decrease in SDNN was 1.06 (95% confidence interval [CI], 1.01 to 1.12); for a 2 mmol/l decrease in serum sodium, 1.22 (95% CI, 1.08 to 1.38); and for a 10 micromol/l increase in serum creatinine, 1.14 (95% CI, 1.09 to 1.19) (all p < 0.01).

CONCLUSIONS

In ambulant outpatients with chronic HF, low serum sodium and SDNN and high serum creatinine identify patients at increased risk of death due to progressive HF.

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.

Left bundle-branch block is associated with increased 1-year sudden and total mortality rate in 5517 outpatients with congestive heart failure: a report from the Italian network on congestive heart failure

BACKGROUND

A deleterious effect of complete left bundle-branch block (LBBB) on left ventricular function has been established. Nevertheless, the independent effect of a widened QRS on mortality rate in congestive heart failure (CHF) is still controversial. Therefore, we carried out this analysis to determine whether LBBB is an independent predictor of mortality in CHF.

METHODS AND RESULTS

We analyzed the large Italian Network on CHF Registry of unselected outpatients with CHF of different causes. The registry was established by the Italian Association of Hospital Cardiologists in 1995. Complete 1-year follow-up data were available for 5517 patients. The main underlying cardiac diagnosis was ischemic heart disease in 2512 patients (45.6%), dilated cardiomyopathy in 1988 patients (36.0%), and hypertensive heart disease in 714 patients (12.9%). Other causes were recorded in the remaining 303 cases (5.5%). LBBB was present in 1391 patients (25.2%) and was associated with an increased 1-year mortality rate from any cause (hazard ratio, 1.70; 95% confidence interval, 1.41 to 2.05) and sudden death (hazard ratio, 1.58; 95% confidence interval, 1.21 to 2.06). Multivariate analysis showed that such an increased risk was still significant after adjusting for age, underlying cardiac disease, indicators of CHF severity, and prescription of angiotensin-converting enzyme inhibitors and beta-blockers.

CONCLUSION

LBBB is an unfavorable prognostic marker in patients with CHF. The negative effect is independent of age, CHF severity, and drug prescriptions. These data may support the rationale of randomized trials to verify the effects on mortality rate of ventricular resynchronization with multisite cardiac pacing in patients with CHF and LBBB.

Management of arrhythmias in heart failure

Arrhythmias often complicate the management of heart failure and contribute to mortality and morbidity. Implantable cardioverter defibrillators are the best protection from death caused by ventricular arrhythmias, but their benefit will probably be less in heart failure populations than has been observed in trials that have not focused on heart failure populations. Implantable cardioverter defibrillators are first-line therapy for high-risk patients who have been resuscitated from sustained ventricular tachycardia or ventricular fibrillation, who have inducible ventricular tachycardia in the setting of previous myocardial infarction, or who have unexplained syncope. Amiodarone is the major pharmacologic option for treatment of symptomatic arrhythmias. In selecting therapy, the severity of heart failure and cause of heart failure are important considerations. Atrial fibrillation occurs with increasing frequency as the severity of heart failure increases. Anticoagulation and rate control are important. Attempted maintenance of sinus rhythm with amiodarone or dofetilide is a reasonable consideration for selected patients, although the benefit of treatment strategies that seek to maintain sinus rhythm has not been demonstrated. Ongoing trials will provide further guidance for arrhythmia management.

Outcome studies with device therapy in patients with heart failure

Heart failure is a common debilitating condition for which pharmacologic therapy thus far has provided only partial relief. Despite, and sometimes because of, medical therapy, the overall prognosis remains poor, with high rates of sudden death and death from progressive heart failure. Device-based therapies offer considerable promise for relief of symptoms and for improving prognosis. It is clear that implantable defibrillators should be considered for patients with heart failure who have been resuscitated from ventricular fibrillation or sustained ventricular tachycardia. Several large studies currently are investigating the effects of implantable defibrillators on total mortality in patients with major left ventricular systolic dysfunction but without other risk factors for sudden death. Cardiac resynchronization is a promising new therapy that may relieve the symptoms of heart failure in appropriately selected patients resistant to optimal pharmacologic therapy. Two large trials (CARE-HF and COMPANION) currently are investigating the effects of cardiac resynchronization therapy (CRT) on morbidity and mortality. It is important that those involved in these trials enroll patients quickly and minimize device implantation into patients who have not been assigned this therapy (cross-overs). Overenthusiasm for the benefits that doctors believe devices might bring could destroy the future basis for our clinical practice, denying future generations of patients and the doctors themselves access to what they believe to be effective treatments.

Cardiovascular monitoring and therapy for HIV-infected patients

Cardiovascular complications are important contributors to morbidity and mortality in HIV-infected patients. These complications can usually be detected at subclinical levels with monitoring, which can help guide targeted interventions. This article reviews available data on types and frequency of cardiovascular manifestations in HIV+ patients and proposes monitoring strategies aimed at early subclinical detection. In particular, we recommend routine echocardiography for HIV+ patients, even those with no evidence of cardiovascular disease. We also review preventive and therapeutic cardiovascular interventions. For procedures that have not been studied in HIV+ patients, we extrapolate from evidence-based guidelines for the general population.

Implantable cardioverter defibrillators in heart failure

Implantable cardioverter defibrillators provide effective and reliable treatment of spontaneous VT and VF. These devices can be expected to decrease the risk for arrhythmic death in patients with heart failure but do not improve overall survival when death from severe pump dysfunction is imminent. Appropriate patient selection is a major aspect of arrhythmia management. Future devices will incorporate features that have the potential to reduce atrial arrhythmias, improve ventricular function, monitor hemodynamics, and prevent sudden arrhythmic death.

The use of surrogate endpoints in clinical trials: focus on clinical trials in cardiovascular diseases

Surrogate endpoints include a wide range of laboratory or physical measurements used in clinical trials as a substitute for meaningful clinical endpoints that directly assess effects of the intervention(s) tested on mortality and/or morbidity. These surrogate endpoints are frequently employed in clinical trials and when used judiciously, can accelerate and focus the study of new therapies and can greatly enhance our understanding of their mechanisms of action. The current review provides a definition of surrogate endpoints, proposes practical criteria for establishing their validity, outlines some of the advantages, disadvantages and specific statistical considerations associated with their use in clinical trials and attempts also to highlight drug approval issues associated with the use of these endpoints. A number of examples are also provided related to the use of surrogate endpoints in clinical trials with special emphasis on their use in cardiovascular medicine.

Survival benefit with an implanted defibrillator in relation to mortality risk in chronic coronary heart disease

Although improved patient survival has been reported in several randomized trials with the implanted cardioverter-defibrillator, <15% of patients treated with defibrillators during trials receive life-saving benefit from this therapy. We evaluated the survival benefit from defibrillator therapy in relation to the severity of the mortality risk in patients with coronary heart disease. Using data from the Multicenter Automatic Defibrillator Implantation Trial, we partitioned the study population into high- and low-risk subsets for each of 3 physiologically meaningful risk factors (ejection fraction, QRS duration, and history of heart failure requiring therapy). Risk of death was evaluated by Cox proportional-hazards regression analyses in patients with single and multiple risk factors. The defibrillator was associated with a significant (p = 0.002) reduction in mortality only in high-risk subsets with ejection fraction <0.26, QRS duration > or =0.12 second, and history of heart failure requiring treatment. The Cox hazard ratio for the risk of death progressively increased >1.0 as a function of the number of risk factors present. Defibrillator therapy was associated with a progressive reduction in the hazard ratio <1.0 (improved survival) at each increased level of mortality risk. Patients at the highest mortality risk (all 3 risk factors; hazard ratio 4.33) achieved the largest mortality reduction (hazard ratio 0.20) from defibrillator therapy. In patients with chronic coronary heart disease, the magnitude of the survival benefit from the implanted defibrillator is directly related to the severity of cardiac dysfunction and its associated mortality risk.

Long-term follow-up of right ventricular monomorphic extrasystoles

OBJECTIVES

The purpose of this study was to verify in a long-term follow-up whether frequent monomorphic right ventricle extrasystoles may progress to arrhythmogenic right ventricular dysplasia (ARVD).

BACKGROUND

Frequent monomorphic right ventricle extrasystoles are generally considered benign. However, in patients with this pattern, cardiac magnetic resonance (MR) has recently shown anatomical and functional abnormalities of the right ventricle.

METHODS

Sixty-one patients who had been classified by noninvasive examinations as having frequent idiopathic right ventricle ectopy were contacted after 15 +/- 2 years (12 to 20) and submitted to clinical examination, electrocardiogram (ECG), Holter monitoring, stress test, signal averaged ECG, echocardiography and, in 11 patients, cardiac MR. The primary end point was to ascertain the presence of cases of sudden death or progression to ARVD.

RESULTS

At the end of the follow-up, 55 patients were alive; six died, none of sudden death; eight stated to be well but refused further examinations. The 47 patients examined had normal ECG; in 24 patients (51%), extrasystoles were no longer present at Holter monitoring; late potentials were present in up to 15% of the patients; the right ventricle was normal at echocardiography. In 8 of 11 patients (73%), cardiac MR showed focal fatty replacement and other abnormalities of the right ventricle.

CONCLUSIONS

In this long-term follow-up study, no patient died of sudden death nor developed ARVD; two-thirds of the patients were asymptomatic, and, in half of the patients, ectopy had disappeared. Focal fatty replacement in the right ventricle was present in most.

Therapeutic options in patients with reduced ejection fraction and nonsustained ventricular tachycardia

The patient with a reduced ejection fraction and nonsustained ventricular tachycardia represents a common management problem for the physician. This article reviews the supporting evidence for the therapeutic options available for these patients according to the etiology of the reduced ejection fraction. In postinfarction patients, electrophysiology-guided implantable cardioverter defibrillator therapy improves survival more than antiarrhythmic therapy. In patients with nonischemic cardiomyopathy, the best therapy is yet undetermined. Ongoing clinical trials will hopefully direct future therapy.

Nonsustained ventricular tachycardia. A guide to the clinical significance and management

The patient with nonsustained ventricular tachycardia represents a common management problem for the cardiologists and internists. Treatment is sometimes needed for the suppression of symptoms. More commonly, nonsustained ventricular tachycardia is asymptomatic, and the clinician must determine the prognostic importance. The prognostic implications, the role of electrophysiologic study, and the potential role of pharmacologic and defibrillator intervention depend on the underlying cardiac substrate present in the individual patient.

Spontaneous ventricular arrhythmias following partial left ventriculectomy for nonischemic dilated cardiomyopathy: relation to hemodynamics and survival

The study assessed the value of ambulatory electrocardiogram (AECG) monitoring for identification of patients who are at increased risk for cardiac death or arrhythmic event following partial left ventriculectomy (PLV). Furthermore, the impact of PLV and its hemodynamics on the occurrence of spontaneous ventricular arrhythmias was assessed in long-term survivors. In 32 idiopathic dilated cardiomyopathy patients who underwent PLV, ambulatory ECG (AECG) was performed preoperatively, early postoperatively, and 6 months and 12 months after surgery. In 17 of 19 patients who survived > 12 months after the procedure, left ventricular (LV) angiography was performed at the same time points and was used to calculate LV ejection fraction, and end-diastolic and end-systolic wall stress. During a mean follow-up of 478 +/- 405 days, 11 cardiac events occurred. Cox univariate regression revealed frequency of premature ventricular contractions > 30/hour at baseline (p = 0.0213) and duration of heart failure symptoms (p = 0.0226) as predictors of cardiac death or arrhythmic event after PLV. In a multivariate analysis, only frequency of premature ventricular contractions > 30/hour was a significant predictor. There was no change in the frequency or severity of ventricular arrhythmias after PLV. However, frequency of premature ventricular contractions correlated with LV end-diastolic stress (r = 0.35, p = 0.013), and ejection fraction (r = -0.34, p = 0.016). Preoperative AECG monitoring may help stratification of PLV patients. Serial AECG did not show that PLV influence the incidence or the complexity of spontaneous ventricular arrhythmias. In contrast, it appears that a hemodynamically "successful" procedure may decrease the incidence of ventricular arrhythmias.

Should stimulation therapy for congestive heart failure be combined with defibrillation backup?

Biventricular pacing has been proposed to resynchronize ventricular contraction in patients with congestive heart failure (CHF) and interventricular conduction delay. However, the sudden death rate is still high despite the improvement in cardiac performance. Devices combining biventricular pacing with implantable cardioverter defibrillator (ICD) backup are now under clinical investigation to demonstrate whether they can decrease sudden death. From the first implant of an ICD with biventricular transvenous pacing on August 1998 to April 2000, 96 patients underwent such implants: 67 (70%) received pacemakers alone and 29 (30%), who had class I ICD indications, received combined pacemaker/ICD systems. During a mean follow-up of 283 +/- 170 days, 13 (14%) patients died: 5 of 29 (17%) in the ICD group and 8 of 67 (12%) in the pacemaker group. A total of 15 patients (52%) had ICD shocks and 6 patients (21%) had 113 episodes of ventricular tachyarrhythmias, of which 96 (85%) were converted to sinus rhythm with antitachypacing. The echocardiograms showed a narrowing of the delay between the onset of right and left ventricular outflow from 40 +/- 37 msec to 17 +/- 16 msec (p = 0.03) and a reduction of the mitral regurgitation area from 7 +/- 3.8 cm2 to 5 +/- 4 cm2 (p = 0.04) at 3 months. Functional class improved from 2.8 +/- 0.7 to 1.6 +/- 0.5 (p <0.001) 3 months after implant. Thus, ischemic patients with reduced left ventricular ejection fraction and ventricular tachyarrhythmias seem good candidates for biventricular pacing with ICD backup. The sudden death risk for those with idiopathic dilated cardiomyopathy, however, is difficult to stratify, and the choice of ICD backup has to be considered on the basis of patient safety, as well as of costs.

Beta-adrenergic blocker mortality trials in congestive heart failure

Many of the current discussions of beta-adrenergic blocker therapy in patients with congestive heart failure have used fairy tales to describe the evolution of this treatment from contraindication to standard of care. This article reviews the early studies that initiated this revolution in heart failure therapy and discusses the major mortality trials that have demonstrated that these agents improve survival and limit the progression of congestive heart failure. These major trials have used 1 of 4 beta blockers (metoprolol, bisoprolol, carvedilol, or bucindolol) in varying study designs with different patient populations. Each trial had different objectives and limitations, and these are described in the context of their impact on proving a survival benefit. In addition, the specific effect of beta-blocker therapy on sudden death in patients with heart failure is briefly discussed. The weight of these trials suggests that beta-adrenergic blocker therapy can save 1 life of every 35 patients treated in patients with mild-to-moderate heart failure. The data are compelling and the techniques for "starting low and going slow" with titrations have been well documented.