Pharmacological reasons that may explain why randomized clinical trials have failed in acute heart failure syndromes

Why has positive inotropy failed in chronic heart failure? Lessons from prior inotrope trials

Current pharmacological therapies for heart failure with reduced ejection fraction are largely either repurposed anti‐hypertensives that blunt overactivation of the neurohormonal system or diuretics that decrease congestion. However, they do not address the symptoms of heart failure that result from reductions in cardiac output and reserve. Over the last few decades, numerous attempts have been made to develop and test positive cardiac inotropes that improve cardiac haemodynamics. However, definitive clinical trials have failed to show a survival benefit. As a result, no positive inotrope is currently approved for long‐term use in heart failure. The focus of this state‐of‐the‐art review is to revisit prior clinical trials and to understand the causes for their findings. Using the learnings from those experiences, we propose a framework for future trials of such agents that maximizes their potential for success. This includes enriching the trials with patients who are most likely to derive benefit, using biomarkers and imaging in trial design and execution, evaluating efficacy based on a wider range of intermediate phenotypes, and collecting detailed data on functional status and quality of life. With a rapidly growing population of patients with advanced heart failure, the epidemiologic insignificance of heart transplantation as a therapeutic intervention, and both the cost and morbidity associated with ventricular assist devices, there is an enormous potential for positive inotropic therapies to impact the outcomes that matter most to patients.

A mouse model of heart failure exhibiting pulmonary edema and pleural effusion: Useful for testing new drugs

INTRODUCTION

Mouse models of chronic heart failure (HF) have been widely used in HF research. However, the current HF models most often use the C57BL/6 mouse strain and do not show the clinically relevant characteristics of pulmonary congestion. In this study, we developed a robust mouse model of HF in the BALB/c mouse strain, exhibiting pulmonary edema and pleural effusion, and we validated the model using the standard pharmacological therapies in patients with chronic HF and reduced ejection fraction (HFrEF) or acute decompensated HF.

METHODS

After induction of myocardial infarction (MI) by permanent ligation of the left coronary artery in BALB/c mice, the cardiac function, pulmonary congestion, disease biomarkers, and survival were evaluated using the angiotensin converting enzyme inhibitor enalapril or the loop diuretic furosemide. Enalapril was administered 4 weeks post-MI for 6 weeks or furosemide was given 10 weeks post-MI for 4 days, when pulmonary congestion was evident.

RESULTS

Compared to sham controls, MI mice developed systolic dysfunction, exhibited lung weight increase at 4 weeks, and progressively developed pleural effusion (60% of the animals) at 10 weeks. Compared to the vehicle, enalapril significantly reduced the lung weight and pleural effusion, preserved systolic function, and improved survival. Furthermore, furosemide completely abolished the pleural effusion. Enalapril or furosemide also reduced the plasma brain natriuretic peptide concentration.

DISCUSSION

The post-MI HF in BALB/c mice shows reproducible and robust pulmonary congestion and may be a clinically relevant model for novel drug testing for treatment in patients with HFrEF or acute decompensated HF.

Patterns of dyspnoea onset in patients with acute heart failure: clinical and prognostic implications

Aims

Despite attempts to improve the management of patients with acute heart failure (HF), virtually all therapeutic agents investigated in large clinical trials failed to show any consistent reduction in mortality and morbidity. Complexity of the clinical syndrome of acute HF seems to be likely an underlying explanation. Traditionally, clinical trials studied mixed patient populations with acute HF, and only recently, better clinical characterization of patients has been proposed. Dyspnoea is the most common presenting symptom related to hospital admission for acute HF. Whether in patients with acute HF, the pattern of symptoms onset preceding hospital admission is associated with clinical characteristics, and the outcomes have not yet been established.

Methods and results

We investigated 137 patients (mean age: 65 ± 13 years; 80% men) hospitalized due to acute HF with dyspnoea as major reported symptom, who were divided according to the time of its onset into those with acute (n = 98) vs. subacute (n = 39) onset (i.e. within 7 days vs. >7 days preceding hospital admission, respectively). On admission, the former group presented higher blood pressure (138 ± 33 vs. 121 ± 32 mmHg), more often moderate–severe pulmonary congestion (33 vs. 8%), and lower bilirubin level [1.07 (0.72–1.60) vs. 1.27 (0.87–2.06); P < 0.05 in all comparisons]. There were no other differences in baseline clinical characteristics and laboratory indices. Higher percentage of patients with an acute dyspnoea onset reported marked/moderate dyspnoea relief after 6 (18% vs. 7%), 24 (59% vs. 24%), and 48 h (80% vs. 46% assessed as an improvement of at least 5 points in self‐reported 10‐point Likert scale; P < 0.05 in all time points). In patients with an acute onset of dyspnoea after 48 h, a decrease of N‐terminal pro BNP was more frequently observed (83% vs. 65%), and the levels of endothelin‐1 were more reduced [−1.1 (−2.9–0.03) vs 0.4 (−2.2–1.4); all P < 0.05]. Patients with acute onset experienced less in‐hospital HF worsening (13% vs. 40%, P = 0.001), and 1 year cardiovascular mortality was significantly lower (20% vs. 41%, P = 0.01). On the multivariable analysis, subacute pattern of dyspnoea was independent predictor of 12 month cardiovascular mortality in patients with acute HF after adjusting for other prognostic factors: systolic blood pressure, urea, and HF de novo [hazard ratio (95% confidence interval): 2.32 (1.13–4.75), P = 0.02].

Conclusions

In patients with acute HF, the pattern of symptoms onset is associated with baseline differences in clinical characteristics, biomarker profile, response to standard treatment, and the long‐term outcomes. This is relevant information for planning future clinical trials.

Mode of presentation and mortality amongst patients hospitalized with heart failure? A report from the First Euro Heart Failure Survey

BACKGROUND

Heart failure is heterogeneous in aetiology, pathophysiology, and presentation. Despite this diversity, clinical trials of patients hospitalized for HF deal with this problem as a single entity, which may be one reason for repeated failures.

METHODS

The first EuroHeart Failure Survey screened consecutive deaths and discharges of patients with suspected heart failure during 2000-2001. Patients were sorted into seven mutually exclusive hierarchical presentations: (1) with cardiac arrest/ventricular arrhythmia; (2) with acute coronary syndrome; (3) with rapid atrial fibrillation; (4) with acute breathlessness; (5) with other symptoms/signs such as peripheral oedema; (6) with stable symptoms; and (7) others in whom the contribution of HF to admission was not clear.

RESULTS

The 10,701 patients enrolled were classified into the above seven presentations as follows: 260 (2%), 560 (5%), 799 (8%), 2479 (24%), 1040 (10%), 703 (7%), and 4691 (45%) for which index-admission mortality was 26%, 20%, 10%, 8%, 6%, 6%, and 4%, respectively. Compared to those in group 7, the hazard ratios for death during the index admission were 4.9 (p ≤ 0.001), 4.0 (p < 0.001), 2.2 (p < 0.001), 2.1 (p < 0.001), 1.4 (p < 0.04) and 1.4 (p = 0.04), respectively. These differences were no longer statistically significant by 12 weeks.

CONCLUSION

There is great diversity in the presentation of heart failure that is associated with very different short-term outcomes. Only a minority of hospitalizations associated with suspected heart failure are associated with acute breathlessness. This should be taken into account in the design of future clinical trials.