Pearls and perils of an implantable defibrillator trial using a common control: implications for the design of future studies

Abstract Aims Implantable defibrillators are considered life-saving therapy in heart failure (CHF) patients. Surprisingly, the recent Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) reached an opposing conclusion from that of numerous other trials about their survival benefit in patients with advanced CHF. A critical analysis of common control trial design may explain this paradoxical finding, with important implications for future studies. Methods and Results Common control trials compare several intervention groups to a single rather than separate control groups. Though potentially requiring fewer patients than trials using separate controls, variation in the common control group will influence all comparisons and creates correlations between findings. During subgroup analyses, this dependency of outcomes may increase belief in the presence of a real subgroup effect when, in fact, it should increase skepticism. For example, a high (r = 0.92), statistically unlikely (p = 0.052) correlation between comparisons was observed across the subgroups reported in SCD-HeFT. Such concordance between amiodarone and a defibrillator across subgroups was unexpected, given how much the effects of these treatments significantly differed from one another in the main study. This suggests the study's subgroup findings (specifically the absence of benefit from defibrillators in advanced CHF) were not necessarily a consequence of treatment; more likely, they resulted from variation in what the treatments were compared against, the common control. Conclusion Common control trials can be more efficient than other designs, but induce dependence between treatment comparisons and require cautious interpretation.</p

Controversies in the Use of Beta Blockers in Heart Failure

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94510/1/j.1527-5299.2003.00294.x.pd

Rationale and study design of a cross sectional study documenting the prevalence of Heart Failure amongst the minority ethnic communities in the UK: the E-ECHOES Study (Ethnic - Echocardiographic Heart of England Screening Study)

Background: Heart failure is an important cause of cardiovascular morbidity and mortality. Studies to date have not established the prevalence heart failure amongst the minority ethnic community in the UK. The aim of the E-ECHOES (Ethnic - Echocardiographic Heart of England Screening Study) is to establish, for the first time, the community prevalence and severity of left ventricular systolic dysfunction (LVSD) and heart failure amongst the South Asian and Black African-Caribbean ethnic groups in the UK.Methods/Design: This is a community based cross-sectional population survey of a sample of South Asian (i.e. those originating from India, Pakistan, Bangladesh) and Black African-Caribbean male and female subjects aged 45 years and over. Data collection undertaken using a standardised protocol comprising a questionnaire incorporating targeted clinical history taking, physical examination, and investigations with resting electrocardiography and echocardiography; and blood sampling with consent. This is the largest study on heart failure amongst these ethnic groups. Full data collection started in September 2006 and will be completed by August 2009.Discussion: The E-ECHOES study will enable the planning and delivery of clinically and cost-effective treatment of this common and debilitating condition within these communities. In addition it will increase knowledge of the aetiology and management of heart failure within minority ethnic communities

Present and future pharmacotherapeutic agents in heart failure: an evolving paradigm

Many conditions culminate in heart failure (HF), a multi-organ systemic syndrome with an intrinsically poor prognosis. Pharmacotherapeutic agents that correct neurohormonal dysregulation and haemodynamic instability have occupied the forefront of developments within the treatment of HF in the past. Indeed, multiple trials aimed to validate these agents in the 1980s and early 1990s, resulting in a large and robust evidence-base supporting their use clinically. An established treatment paradigm now exists for the treatment of HF with reduced ejection fraction (HFrEF), but there have been very few notable developments in recent years. HF remains a significant health concern with an increasing incidence as the population ages. We may indeed be entering the surgical era for HF treatment, but these therapies remain expensive and inaccessible to many. Newer pharmacotherapeutic agents are slowly emerging, many targeting alternative therapeutic pathways, but with mixed results. Metabolic modulation and manipulation of the nitrate/nitrite/nitric oxide pathway have shown promise and could provide the answers to fill the therapeutic gap between medical interventions and surgery, but further definitive trials are warranted. We review the significant evidence base behind the current medical treatments for HFrEF, the physiology of metabolic impairment in HF, and discuss two promising novel agents, perhexiline and nitrite

Titration to target dose of bisoprolol vs. carvedilol in elderly patients with heart failure: the CIBIS-ELD trial

AIMS: Various beta-blockers with distinct pharmacological profiles are approved in heart failure, yet they remain underused and underdosed. Although potentially of major public health importance, whether one agent is superior in terms of tolerability and optimal dosing has not been investigated. The aim of this study was therefore to compare the tolerability and clinical effects of two proven beta-blockers in elderly patients with heart failure. METHODS AND RESULTS: We performed a double-blind superiority trial of bisoprolol vs. carvedilol in 883 elderly heart failure patients with reduced or preserved left ventricular ejection fraction in 41 European centres. The primary endpoint was tolerability, defined as reaching and maintaining guideline-recommended target doses after 12 weeks treatment. Adverse events and clinical parameters of patient status were secondary endpoints. None of the beta-blockers was superior with regards to tolerability: 24% [95% confidence interval (CI) 20-28] of patients in the bisoprolol arm and 25% (95% CI 21-29) of patients in the carvedilol arm achieved the primary endpoint (P= 0.64). The use of bisoprolol resulted in greater reduction of heart rate (adjusted mean difference 2.1 b.p.m., 95% CI 0.5-3.6, P= 0.008) and more, dose-limiting, bradycardic adverse events (16 vs. 11%; P= 0.02). The use of carvedilol led to a reduction of forced expiratory volume (adjusted mean difference 50 mL, 95% CI 4-95, P= 0.03) and more, non-dose-limiting, pulmonary adverse events (10 vs. 4%; P < 0.001). CONCLUSION: Overall tolerability to target doses was comparable. The pattern of intolerance, however, was different: bradycardia occurred more often in the bisoprolol group, whereas pulmonary adverse events occurred more often in the carvedilol group. This study is registered with controlled-trials.com, number ISRCTN34827306