Exercise capacity, hemodynamic, and neurohumoral changes following acute and chronic administration of flosequinan in chronic congestive heart failure

Long-Term Effects of Flosequinan on the Morbidity and Mortality of Patients With Severe Chronic Heart Failure: Primary Results of the PROFILE Trial After 24 Years

OBJECTIVES

The purpose of this clinical trial was to evaluate the long-term effects of flosequinan on the morbidity and mortality of patients with severe chronic heart failure.

BACKGROUND

Flosequinan was the first oral vasodilator to be used in the clinic to augment the effects of digitalis, diuretics, and angiotensin-converting enzyme inhibitors in heart failure. However, the drug activated neurohormonal systems and exerted both positive inotropic and chronotropic effects, raising concerns about its safety during long-term use.

METHODS

Following a run-in period designed to minimize the risk of tachycardia, we randomly assigned 2,354 patients in New York Heart Association functional class III to IV heart failure and with an ejection fraction ≤35% to receive long-term treatment with placebo or flosequinan (75 or 100 mg/day) in addition to their usual therapy. The primary outcome was all-cause mortality.

RESULTS

The trial was terminated after a recommendation of the Data and Safety Monitoring Board, because during an average of 10 months of follow-up, 192 patients died in the placebo group and 255 patients died in the flosequinan group (hazard ratio: 1.39, 95% confidence interval: 1.15 to 1.67; p = 0.0006). Flosequinan also increased the risk of disease progression, which was paralleled by drug-related increases in heart rate and neurohormonal activation. However, during the first month, patients in the flosequinan group were more likely to report an improvement in well-being and less likely to experience worsening heart failure. Similarly, during the month following drug withdrawal at the end of the trial, patients withdrawn from flosequinan were more likely than those withdrawn from placebo to report symptoms of or to require treatment for worsening heart failure.

CONCLUSIONS

Although flosequinan produced meaningful symptomatic benefits during short- and long-term treatment, the drug increased the risk of death in patients with severe chronic heart failure.

Effects of balanced vasodilator, flosequinan, on aortic impedance in failing heart

An arteriovenous vasodilator, flosequinan, has been shown to be effective for the treatment of acute heart failure. However, little is known as to its effect on aortic impedance, which is known to be a proper and precise expression of left ventricular (LV) afterload. To evaluate the acute cardiovascular effect of flosequinan in failing heart, we administered flosequinan intravenously to seven dogs with cardiac failure produced by an infusion of carbon powder (20-50 microm in diameter) into left main trunks of coronary artery. The LV-pump function was severely impaired after intracoronary injection of carbon powder, as evidenced by the findings that cardiac output, circumferential shortening velocity (mean Vcf), and peak +dP/dt of LV pressure were all decreased, associated with a significant increase in LV end-diastolic pressure. Flosequinan (0.9 mg/kg, i.v.) increased cardiac output by 28%, mean Vcf by 44%, and peak +dP/dt by 24%, whereas it decreased total systemic resistance by 32%, time constant of LV pressure decay by 22%, and LV end-diastolic pressure by 18%. Moreover, flosequinan substantially decreased the pulsatile components of LV afterload (i.e., characteristic impedance by 11% and arterial wave reflection coefficient by 45%). Thus flosequinan exerted not only positive inotropic but also positive lusitropic effects, in association with a significant reduction of both pulsatile and steady components of LV afterload, contributing to an improvement of LV-pump function in acute cardiac failure.

Hemodynamic and neurohormonal effects of flosequinan in patients with heart failure

In a double-blind, placebo-controlled study, the central and peripheral hemodynamic effects of 100 mg oral flosequinan and the impact of this drug on neurohormonal activation were noninvasively evaluated in 18 patients with congestive heart failure, after the first administration and after 10 days of treatment. No significant hemodynamic and neurohormonal changes were observed after acute administration. After 10 days, flosequinan produced central and peripheral hemodynamic improvement characterized by an increase in left ventricular circumferential fiber shortening velocity (+12%), a decrease in total systemic resistance (-36%), and an increase in leg blood flow (+37%). No significant changes were observed in heart rate and arterial pressure in patients receiving flosequinan, though a slight increase in heart rate (+17%) was recorded. Despite these favorable hemodynamic effects, flosequinan significantly increased plasma norepinephrine (+38%) and plasma renin activity (+13%) after 10 days of treatment. Thus, the beneficial central and peripheral hemodynamic effects of flosequinan are accompanied by activation of the sympathetic and reninangiotensin systems. This might be related to the unfavorable effects of the drug on survival in patients with heart failure.

Long-term vasodilator treatment with flosequinan does not lead to hemodynamic tolerance or neurohormonal activation in severe heart failure

Flosequinan is a balanced-type vasodilator with a prolonged mode of action due to an approximate 38-hour half-life of its active first metabolite, BTS 53554. As this may lead to tolerance and neurohormonal activation, the acute and long-term pharmacokinetic, hemodynamic, and neurohormonal profile of flosequinan was evaluated. On three consecutive days, 23 patients with heart failure (New York Heart Association classes II-IV), despite digitalis and diuretics, underwent invasive hemodynamic studies after receiving 100 mg oral flosequinan (day 1), placebo (day 2), and 100 mg flosequinan (day 3), followed by repeat invasive evaluation after long-term flosequinan (100 mg daily) for 17 +/- 2 weeks. On each study day, plasma flosequinan levels increased to 1.9 +/- 0.2 mg/L after 1 hour, but returned to baseline levels at 24 hours. In contrast, BTS 53554 increased progressively, reaching relatively high plateau levels (6 mg/L) during chronic therapy. First-dose flosequinan decreased the pulmonary wedge, right atrial pressure, and systemic resistance by 50, 60, and 22%, respectively, whereas the cardiac index was increased by 40%; these effects lasted for 48 hours. During long-term treatment, baseline values of the pulmonary wedge and right atrial pressure were comparable to prestudy values, whereas systemic resistance had decreased by 22%, and the cardiac index and heart rate had increased by 22 and 14%, respectively. Readministration of flosequinan did not further affect hemodynamics, apart from a moderate reduction in the pulmonary wedge and right atrial pressure. Neurohumoral activation did not occur during acute or long-term therapy. Thus, although changes in left and right heart filling pressures are attenuated during long-term treatment, flosequinan induces sustained arterial dilatation and improves cardiac pump function without activation of circulating neurohormones.

Acute and chronic effects of flosequinan on resting and exercise haemodynamics in congestive heart failure

1 The acute and chronic (8 weeks) haemodynamic responses to oral flosequinan have been investigated in 12 male patients of mean age 58.9 years with congestive heart failure of N.Y.H.A. classes II and III. 2 Flosequinan 125 mg orally significantly reduced right atrial pressure, pulmonary artery pressure and pulmonary wedge pressure prior to and following 8 weeks chronic treatment (125 mg daily). A significant decrease in systemic pressure and an increase in heart rate were also observed with acute flosequinan prior to chronic treatment. A reduction in systemic vascular resistance and an increase in cardiac index reached significance in response to flosequinan 125 mg orally following 8 weeks of therapy. 3 In the erect position, flosequinan reduced pulmonary wedge pressure and tended to reduce systemic vascular resistance, without decreasing mean arterial pressure. 4 Following chronic treatment, there was a trend towards a reduction in pulmonary wedge pressure and an increase in cardiac index, otherwise resting and exercise haemodynamics were unchanged. 5 The response to flosequinan was similar at week 1 and after 8 weeks of treatment for all of the haemodynamic parameters. 6 Flosequinan increased bicycle exercise times and attenuated exercise-induced increases in pulmonary arterial and systemic pressures. There was a trend towards an increase in treadmill exercise time. 7 Sublingual glyceryl trinitrate (0.5 mg) and oral flosequinan (125 mg) had similar effects on right atrial pressure, pulmonary arterial and pulmonary wedge pressures at 5 min and 2 h respectively post-dosing. A small additive effect on pulmonary arterial and wedge pressures was observed.

Sustained hemodynamic response to flosequinan in patients with heart failure receiving angiotensin-converting enzyme inhibitors

OBJECTIVES

We evaluated the short- and long-term effects of flosequinan in 47 patients with severe heart failure despite ongoing captopril treatment.

BACKGROUND

There have been no previous evaluations of the long-term hemodynamic effects of any direct-acting vasodilator in patients with heart failure receiving an angiotensin-converting enzyme inhibitor. Flosequinan is an arterial and venous vasodilator with actions similar to those of the hydralazine-isosorbide dinitrate combination.

METHODS

After baseline hemodynamic measurements using balloon-tipped pulmonary artery and radial arterial catheters, patients were randomized to receive 50, 100 or 150 mg of flosequinan daily. Hemodynamic variables were measured immediately before and after short-term flosequinan administration and after 8 weeks of therapy.

RESULTS

With short-term flosequinan administration, mean arterial, right atrial and left ventricular filling pressures decreased by 6.4 +/- 1.1, 3.8 +/- 0.5 and 7.3 +/- 0.7 mm Hg, respectively (all p < 0.001). Cardiac index increased by 0.5 +/- 0.1 liters/min per m2, systemic vascular resistance decreased by 616 +/- 105 dynes.s.cm-5 and heart rate increased by 4 +/- 1 beats/min (all p < 0.001). After 8 weeks of long-term flosequinan administration, the vasodilator effect of a dose of flosequinan persisted. Compared with pretreatment baseline values, mean arterial, right atrial and left ventricular filling pressures at the peak effect of flosequinan were decreased by 3.5 +/- 1.3, 2.8 +/- 0.7 and 5.1 +/- 1.3 mm Hg, respectively (all p < 0.01). Systemic vascular resistance had decreased by 585 +/- 95 dynes.s.cm-5, cardiac index had increased by 0.5 +/- 0.1 liters/min per m2 and heart rate had increased by 10 +/- 2 beats/min (all p < 0.001).

CONCLUSIONS

The arterial and venous vasodilator flosequinan exerts both short- and long-term sustained hemodynamic effects in patients with heart failure receiving angiotensin-converting enzyme inhibitors.

Can further benefit be achieved by adding flosequinan to patients with congestive heart failure who remain symptomatic on diuretic, digoxin, and an angiotensin converting enzyme inhibitor? Results of the flosequinan-ACE inhibitor trial (FACET)

BACKGROUND

Angiotensin converting enzyme inhibitors, diuretics, and digoxin are each effective in treating congestive heart failure, but many patients remain symptom-limited on all three medications. This trial was designed to determine whether the addition of oral flosequinan, a new direct-acting arterial and venous vasodilator with possible dose-dependent positive inotropic effects, improves exercise tolerance and quality of life in such patients.

METHODS AND RESULTS

In a randomized, double-blind multicenter trial, 322 patients with predominantly New York Heart Association class II or III congestive heart failure and left ventricular ejection fractions of 35% or less, who were stabilized on a diuretic, angiotensin converting enzyme inhibitor, and digoxin, were treated with 100 mg flosequinan once daily, 75 mg flosequinan twice daily, or matching placebo. Efficacy was evaluated with serial measurements of treadmill exercise time, responses to the Minnesota Living With Heart Failure Questionnaire (LWHF), and clinical assessments during a baseline phase and a 16-week treatment period. After 16 weeks, 100 mg flosequinan once daily produced a significant increment in median exercise time (64 seconds at 16 weeks) compared with placebo (5 seconds), whereas the higher-dose flosequinan group did not show a statistically significant increase. Flosequinan (100 mg once daily) also improved the overall LWHF score significantly compared with placebo; both active therapies decreased the physical component, but 75 mg flosequinan twice daily was associated with a trend toward worsening of the emotional component. Most clinical assessments tended to improve on active therapy.

CONCLUSIONS

These results indicate that additional symptomatic benefit can be attained by adding flosequinan to a therapeutic regimen already including a converting enzyme inhibitor. Because in the future most patients will fall into this category, flosequinan is a potential adjunctive agent in the management of severe congestive heart failure. However, because recent evidence indicates that the flosequinan dose studied in the present trial has an adverse effect on survival, the benefit-to-risk ratio must be assessed in individual patients.

Relationship between inotropic activity and phosphodiesterase inhibition for flosequinan and milrinone

The goal of this study was to assess the relationship between the positive inotropic response to high concentrations of the vasodilators flosequinan and BTS 53 554 (the sulfone metabolite of flosequinan) and the effect of both compounds on different forms of cyclic nucleotide phosphodiesterase. In addition, the relationship between inotropic activity and phosphodiesterase inhibition for the cardiotonic milrinone was also evaluated. All three agents exerted a positive inotropic effect on human cardiac muscle fibers. The concentration of milrinone required to increase cardiac contractility was comparable to the concentration required to inhibit the milrinone-sensitive subclass of cyclic AMP-specific phosphodiesterase (type III phosphodiesterase). However, no such relationship was observed for flosequinan and BTS 53 554. These results suggest that the cardiac response to high concentrations of flosequinan and BTS 53 554 is not mediated by inhibition of type III phosphodiesterase.

Positive inotropic and lusitropic effects of intravenous flosequinan in patients with heart failure

OBJECTIVES

This study was designed to assess the direct effects of flosequinan on myocardial function.

BACKGROUND

Flosequinan has been shown to improve symptoms and exercise tolerance in patients with heart failure. Although previous studies have established that flosequinan is a vasodilator, it is not known to what extent direct actions of the drug on myocardial contractility or diastolic properties contribute to its beneficial hemodynamic effects.

METHODS

Nitroprusside and intravenous flosequinan were administered sequentially to 18 patients with severe heart failure (New York Heart Association functional class III or IV, left ventricular ejection fraction 0.14 +/- 0.02). Micromanometer left ventricular pressure and radionuclide volume data were combined to construct pressure-volume loops during 1) a baseline period, 2) nitroprusside infusion, 3) a second baseline period, and 4) flosequinan infusion.

RESULTS

The peak rate of left ventricular pressure development increased from 899 +/- 84 to 1,070 +/- 94 mm Hg/s (p less than 0.05) with flosequinan. The baseline left ventricular end-systolic pressure-volume relation was constructed in 15 patients from the two baseline pressure-volume loops and from that obtained during afterload manipulation with nitroprusside. During flosequinan administration, the relation between end-systolic pressure and volume was shifted upward and leftward, indicating enhanced contractility, in 14 of 15 patients (p less than 0.001). The maximal rate of decrease in left ventricular pressure during isovolumetric relaxation increased in magnitude with flosequinan from 882 +/- 63 to 1,026 +/- 68 mm Hg/s (p less than 0.05).

CONCLUSIONS

These results indicate that intravenous flosequinan has positive inotropic and lusitropic effects in patients with heart failure. Further studies are needed to assess the direct myocardial effects of oral flosequinan.