The effects of an angiotensin-converting inhibitor (enalapril) on patients with mild cardiac failure--evaluating cardiac function based on the relationship between daily walking pace and heart rate

BACKGROUND

Heart failure has been evaluated by several methods, the New York Heart Association (NYHA) classification of heart failure based on symptoms being used most frequently. However, the degree of heart failure assessed by these criteria does not always correlate with cardiac function in daily life.

HYPOTHESIS

The aim of the study was to evaluate cardiac function based on the walking pace/heart rate (HR) relationship to assess the effects of enalapril, an angiotensin-converting enzyme inhibitor, in patients with mild to moderate cardiac function.

METHODS

To evaluate cardiac function objectively, we developed a method using a pedometer to count the steps walked while simultaneously recording HR using a Holter electrocardiograph (ECG). Step-count walk rate (WR) was recorded on the magnetic tape of the Holter apparatus, and both HR and walking pace were calculated automatically by the Holter ECG analysis system. Data were determined every hour, and mean pace and HR were plotted along the x and y axes, respectively. The slope of HR x WR was calculated using the least squares method. The slope and the total number of steps were regarded as indicators of cardiac function and quality of life, respectively. We analyzed 36 subjects, consisting of 8 normal volunteers, 8 patients in New York Heart Association (NYHA) class I. 11 in class II, and 9 in class III chronic mild heart failure, during maximal exercise work load by bicycle ergometer; furthermore, fractional shortening of the left ventricle on echocardiogram was determined in 14 patients with chronic mild heart failure and was compared with the slope of HR x WR. Enalapril was administered at a daily dose of 2.5-10 mg for 1-24 months (mean 6 months) in 60 patients to evaluate the effects of this drug on these parameters.

RESULTS

There was a significant inverse relationship between maximal work load and the HR x WR slope, and also between the fractional shortening and the slope, suggesting that the slope may reflect the severity of cardiac dysfunction. Furthermore, the slope decreased significantly from 1.8 +/- 1.26 before enalapril to 1.0 +/- 0.94 (mean +/- standard deviation) after drug administration, while the total number of steps increased significantly from 4842 +/- 3581 to 7804 +/- 4793.

CONCLUSION

The slope of the graph relating step count and HR proved to be a good, objective indicator of cardiac function, and enalapril therapy improved this parameter.

The role of third-generation beta-blocking agents in chronic heart failure

Third-generation beta-blocking agents developed for the hypertension market are proving useful in the treatment of chronic heart failure (HF). These compounds share the ancillary property of vasodilation, which improves acute tolerability by unloading the failing left ventricle at a time when beta-adrenergic withdrawal produces myocardial depression. In the case of carvedilol and bucindolol, this allows for the administration of nonselective beta blockade. Because of blockade of both beta 1 and beta 2 adrenergic receptors as well as other properties, these compounds possess a more comprehensive antiadrenergic profile than second-generation, beta 1-selective compounds. For this and potentially other reasons, third-generation beta-blocking agents have theoretical efficacy advantages that have yet to be demonstrated in large-scale trials. Ongoing trials with either second- or third-generation compounds and one trial directly comparing a compound from each class will provide the answer as to whether third-generation compounds have an advantage in the treatment of chronic HF.

Effects of chronic application of propranolol on beta-adrenergic signal transduction in heart ventricles from myopathic BIO TO2 and control hamsters

1. In human congestive heart failure beta-adrenoceptor antagonists improve exercise tolerance and cardiac contractility. These beneficial effects are thought to reflect an up-regulation of cardiac beta-adrenoceptors, involving mainly the beta1-subtype. In the present study we evaluated the functional contribution of beta-adrenoceptor subtypes to stimulation of adenylyl cyclase in an animal model of dilated cardiomyopathy, and compared the effects of treatment with propranolol on cardiac beta-adrenergic signal transduction in myopathic and control hamsters. 2. Cardiomyopathic BIO TO2 hamsters and BIO F1B controls aged 270 days were used. In the treatment study, hamsters received drinking water with or without propranolol 40 mg kg(-1) d(-1) for 4 weeks prior to sacrifice. Density and subtype distribution of beta-adrenoceptors were determined in radioligand binding studies. Functional contributions of beta-adrenoceptors were evaluated by subtype-selective stimulation of adenylyl cyclase. Cardiac G-protein content was determined by immunoblotting. 3. Compared to BIO F1B controls, myopathic hamsters showed increases in cardiac total beta- and beta2-adrenoceptor density, G(s alpha) and G(i alpha) content. In BIO TO2 ventricles, beta1-adrenoceptors were almost completely uncoupled from adenylyl cyclase stimulation despite an unchanged density. Treatment of hamsters with propranolol resulted in increased density of beta1-adrenoceptors in both strains, but had no effect on their functional efficacy. Moreover, beta2-adrenergic stimulation of adenylyl cyclase was even reduced in propranolol-treated animals, which could not be explained by changes in cardiac G-protein content. 4. Cardiomyopathic BIO TO2 hamsters showed functional uncoupling of cardiac beta1-adrenoceptors, which could not be normalized by propranolol and, therefore, is unlikely to be solely due to agonist-dependent desensitization. The paradoxical reduction in beta2-adrenergic efficiency in propranolol-treated myopathic and control hamsters deserves further investigation.

Ferrous sulphate interacts with captopril

AIMS

To determine if iron binds strongly to captopril and reduces captopril absorption.

METHODS

A variety of in vitro experiments was conducted to examine iron binding to captopril and a randomized, double-blind, placebo controlled, cross-over study design was used to assess the in vivo interaction. Captopril (25 mg) was coingested with either ferrous sulphate (300 mg) or placebo by seven healthy adult volunteers. Subjects were phlebotomized and had blood pressure measured at 0, 0.25, 0.5, 1, 2, 4, 6, 8, and 12 h post ingestion. A 1 week washout period was used.

RESULTS

The coingestion of ferrous sulphate and captopril was associated with a 37% (134 ng ml(-1) h, 95% CI 41-228 ng ml(-1) h, P = 0.03) decrease in area under the curve (AUC) for unconjugated plasma captopril. There were no substantial changes in Cmax (mean difference; -32; 95% CI -124-62 ng ml(-1) (P = 0.57)) or in tmax (mean difference; 0; 95% CI -18-18 min (P = 0.65)) for unconjugated captopril when captopril was ingested with iron. There was a statistically insignificant increase in AUC for total plasma captopril of 43% (1312 ng ml(-1) h, 95% CI -827-3451 ng ml(-1) h P = 0.27) when captopril was ingested with iron. The addition of ferric chloride to captopril resulted in the initial rapid formation of a soluble blue complex which rapidly disappeared to be replaced by a white precipitant. The white precipitate was identified as captopril disulphide dimer. There were no significant differences in systolic and diastolic blood pressures between the treatment and placebo groups.

CONCLUSIONS

Co-administration of ferrous sulphate and iron results in decreased unconjugated captopril levels likely due to a chemical interaction between ferric ion and captopril in the gastrointestinal tract. Care is required when coprescribing captopril and iron salts.

Left ventricular structure and function in children infected with human immunodeficiency virus: the prospective P2C2 HIV Multicenter Study. Pediatric Pulmonary and Cardiac Complications of Vertically Transmitted HIV Infection (P2C2 HIV) Study Group

BACKGROUND

The frequency of, course of, and factors associated with cardiovascular abnormalities in pediatric HIV are incompletely understood.

METHODS AND RESULTS

A baseline echocardiogram (median age, 2.1 years) and 2 years of follow-up every 4 months were obtained as part of a prospective study on 196 vertically HIV-infected children. Age- or body surface area-adjusted z scores were calculated by use of data from normal control subjects. Although 88% had symptomatic HIV infection, only 2 had CHF at enrollment, with a 2-year cumulative incidence of 4.7% (95% CI, 1.5% to 7.9%). All mean cardiac measurements were abnormal at baseline (decreased left ventricular fractional shortening [LV FS] and contractility and increased heart rate and LV dimension, mass, and wall stresses). Most of the abnormal baseline cardiac measurements correlated with depressed CD4 cell count z scores and the presence of HIV encephalopathy. Heart rate and LV mass showed significantly progressive abnormalities, whereas FS and contractility tended to decline. No association was seen between longitudinal changes in FS and CD4 cell count z score. Children who developed encephalopathy during follow-up had depressed initial FS, and FS continued to decline during follow-up.

CONCLUSIONS

Subclinical cardiac abnormalities in HIV-infected children are common, persistent, and often progressive. Dilated cardiomyopathy (depressed contractility and dilatation) and inappropriate LV hypertrophy (elevated LV mass in the setting of decreased height and weight) were noted. Depressed LV function correlated with immune dysfunction at baseline but not longitudinally, suggesting that the CD4 cell count may not be a useful surrogate marker of HIV-associated LV dysfunction. However, the development of encephalopathy may signal a decline in FS.

Hypocalcemic heart failure: a reversible form of heart muscle disease

This paper reports the case of a 53-year-old woman with hypocalcemia-induced reversible cardiomyopathy. Laboratory tests showed hypocalcemia caused by idiopathic hypoparathyroidism. Her left ventricular dysfunction persisted for a long period even after normalization of the serum calcium level. Observations suggest that physicians should be aware that hypocalcemia can be a reversible cause of cardiomyopathy and congestive heart failure.

Prediction of indications for valve replacement among asymptomatic or minimally symptomatic patients with chronic aortic regurgitation and normal left ventricular performance

BACKGROUND

Optimal criteria for valve replacement are unclear in asymptomatic/minimally symptomatic patients with aortic regurgitation (AR) and normal left ventricular (LV) performance at rest. Moreover, previous studies have not assessed the prognostic capacity of load-adjusted LV performance ("contractility") variables, which may be fundamentally related to clinical state. Therefore, 18 years ago, we set out to test prospectively the hypothesis that objective noninvasive measures of LV size and performance and, specifically, of load-adjusted variables, assessed at rest and during exercise (ex), could predict the development of currently accepted indications for operation for AR.

METHODS AND RESULTS

Clinical variables and measures of LV size, performance, and end-systolic wall stress (ESS) were assessed annually in 104 patients by radionuclide cineangiography at rest and maximal ex and by echocardiography at rest; ESS was derived during ex. During an average 7.3-year follow-up among patients who had not been operated on, 39 of 104 patients either died suddenly (n = 4) or developed operable symptoms only (n = 22) or subnormal LV performance with or without symptoms (n = 13) (progression rate=6.2%/y). By multivariate Cox model analysis, change (delta) in LV ejection fraction (EF) from rest to ex, normalized for deltaESS from rest to ex (deltaLVEF-deltaESS index), was the strongest predictor of progression to any end point or to sudden cardiac death alone. Unadjusted deltaLVEF was almost as efficient. Symptom status modified prediction on the basis of the deltaLVEF-deltaESS index. The population tercile at highest risk by deltaLVEF-deltaESS progressed to end points at a rate of 13.3%/y, and the lowest-risk tercile progressed at 1.8%/y.

CONCLUSIONS

Currently accepted symptom and LV performance indications for valve replacement, as well as sudden cardiac death, can be predicted in asymptomatic/minimally symptomatic patients with AR by load-adjusted deltaLVEF-deltaESS index, which includes data obtained during exercise.

Effects of long-term treatment with trandolapril on sarcoplasmic reticulum function of cardiac muscle in rats with chronic heart failure following myocardial infarction

1 Calcium transport activity of isolated cardiac sarcoplasmic reticulum (SR) including Ca2+ uptake and release is decreased in animals with chronic heart failure (CHF) following myocardial infarction. The present study was undertaken to determine whether an angiotensin converting enzyme (ACE) inhibitor, trandolapril, improves cardiac sarcoplasmic reticular function in animals with CHF following myocardial infarction. 2 CHF was induced by left coronary artery ligation in rats, which resulted in an infarction of approximately 45% of the left ventricle. Aortic flow and cardiac output index were decreased, and left ventricular end-diastolic pressure was increased 8 weeks after the operation, suggesting the development of CHF. 3 The developed force transients of cardiac skinned fibres of the rats with CHF were decreased when the skinned fibre was preloaded for 0.25-1 min with 10(-5) M Ca2+ (48-88%) and when preloaded with 10(-6) M Ca2+ and then exposed to 0.1-1 mM caffeine (45-93%). 4 The [3H]-ryanodine-binding activity in SR-enriched fractions was reduced by 23% in the CHF group. These results suggest that the amount of Ca2+ released from SR is decreased due to a reduced rate of SR Ca2+ uptake and a downregulation of the SR Ca2+-release channel. 5 Rats were treated orally with 3 mg kg(-1) day(-1) trandolapril from the 2nd to the 8th week after the coronary artery ligation. Treatment with trandolapril attenuated the reduction in aortic flow and cardiac output index and the increase in left ventricular end-diastolic pressure, and improved the developed force transients of the skinned fibre of the animal with CHF without causing a reduction of infarct size. Treatment with trandolapril also attenuated the reduction in ryanodine receptor density in the viable left ventricle of the rat with CHF. 6 It is concluded that long-term treatment with trandolapril attenuates cardiac SR dysfunction in rats with CHF and that the mechanism underlying this effect is, at least in part, attributed to prevention of downregulation of Ca2+ release channel.

Positive inotropic effect of exogenous and endogenous NO in hypertrophic rat hearts

1. Recent evidence suggests that nitric oxide (NO) modulates the contractile force of isolated cardiomyocytes in a biphasic manner. We sought to examine whether myocardial hypertrophy induced by long-term hypertension changes the effects of NO on myocardial contractility. 2. We used constant flow perfused non-paced Langendorff preparations of hearts of 3 months old Wistar rats (WIS, n = 23) and of stroke-prone spontaneously hypertensive rats (SHR) at the age of 10 months (SHR10, n = 16) and 15 months (SHR15, n = 8). Changes of left ventricular peak pressure (LVP), +dP/dt(max), -dP/dt(max), coronary perfusion pressure (CPP) and heart rate (HR) were recorded after infusion of noradrenaline (NA, 0.1 micromol l(-1)), glyceryl trinitrate (GTN, 1-100 micromol l(-1)), S-nitroso-N-acetyl-D,L-penicillamine (SNAP, 1-10 micromol l(-1)) and N(omega)-nitro-L-arginine (L-NOARG, 0.1-1 mmol l(-1)). 3. Long-term hypertension induced myocardial hypertrophy and an abnormal response to NA. The relative heart weight (in mg kg(-1)) increased from 2.95 +/- 0.04 (WIS) to 6.67 +/- 0.34 (SHR15), while the increase in +dP/dt(max) induced by NA was absent in SHR15. Hearts of SHR10 showed an intermediate response. 4. Both SNAP and GTN significantly increased LVP, +dP/dt(max) and -dP/dt(max) in hearts of WIS and of SHR. In WIS but not in SHR10, SNAP also increased HR. In SHR10 the lowest concentration of SNAP (1 micromol l(-1)) showed no effect on contractility but a significantly diminished reduction of CPP suggesting inactivation of extracellularly released NO in the coronary circulation of SHR. 5. L-NOARG significantly reduced contractility in hearts of WIS and of SHR to a similar extent. At a concentration of 1 mmol l(-1) L-NOARG also reduced HR. 6. These results suggests that positive inotropic effects of exogenous and endogenous NO are not changed in hypertension induced myocardial hypertrophy.

Nitric oxide and cardiac failure

Cardiac myocytes express two types of nitric oxide (NO) synthase, eNOS and iNOS. eNOS activity is regulated by the contractile state of the heart, while iNOS expression is induced by cytokines. Nitric oxide induced by cytokines causes negative inotropic and lethal effects on cardiac myocytes. Expression of iNOS in the myocardium is increased in patients with dilated cardiomyopathy with clinical evidence of heart failure. Several neurohumoral factors activated in chronic heart failure augment cardiac iNOS expression and could cause cardiac dysfunction and cell damage.

Catecholamine modulatory effects of nepicastat (RS-25560-197), a novel, potent and selective inhibitor of dopamine-beta-hydroxylase

1. Inhibitory modulation of sympathetic nerve function may have a favourable impact on the progression of congestive heart failure. Nepicastat is a novel inhibitor of dopamine-beta-hydroxylase, the enzyme which catalyses the conversion of dopamine to noradrenaline in sympathetic nerves. The in vitro pharmacology and in vivo catecholamine modulatory effects of nepicastat were investigated in the present study. 2. Nepicastat produced concentration-dependent inhibition of bovine (IC50 = 8.5 +/- 0.8 nM) and human (IC50 = 9.0 +/- 0.8 nM) dopamine-beta-hydroxylase. The corresponding R-enantiomer (RS-25560-198) was approximately 2-3 fold less potent than nepicastat. Nepicastat had negligible affinity (> 10 microM) for twelve other enzymes and thirteen neurotransmitter receptors. 3. Administration of nepicastat to spontaneously hypertensive rats (SHRs) (three consecutive doses of either 3, 10, 30 or 100 mg kg-1, p.o.; 12 h apart) or beagle dogs (0.05, 0.5, 1.5 or 5 mg kg-1, p.o.; b.i.d., for 5 days) produced dose-dependent decreases in noradrenaline content, increases in dopamine content and increases in dopamine/noradrenaline ratio in the artery (mesenteric or renal), left ventricle and cerebral cortex. At the highest dose studied, the decreases in tissue noadrenaline were 47%, 35% and 42% (in SHRs) and 88%, 91% and 96% (in dogs) in the artery, left ventricle and cerebral cortex, respectively. When tested at 30 mg kg-1, p.o., in SHRs, nepicastat produced significantly greater changes in noradrenaline and dopamine content, as compared to the R-enantiomer (RS-25560-198), in the mesenteric artery and left ventricle. 4. Administration of nepicastat (2 mg kg-1, b.i.d, p.o.) to beagle dogs for 15 days produced significant decreases in plasma concentrations of noradrenaline and increases in plasma concentrations of dopamine and dopamine/noradrenaline ratio. The peak reduction (52%) in plasma concentration of noradrenaline and the peak increase (646%) in plasma concentration of dopamine were observed on day-6 and day-7 of dosing, respectively. 5. The findings of this study suggest that nepicastat is a potent, selective and orally active inhibitor of dopamine-beta-hydroxylase which produces gradual modulation of the sympathetic nervous system by inhibiting the biosynthesis of noradrenaline. This drug may, therefore, be of value in the treatment of cardiovascular disorders associated with over-activation of the sympathetic nervous system, such as congestive heart failure.

Amiodarone: the expanding antiarrhythmic role and how to follow a patient on chronic therapy

Amiodarone was introduced as an antiarrhythmic compound in the early 1970s and was approved in the U.S. for the treatment of refractory ventricular arrhythmias in late 1984. Since that time the drug has become the most widely studied antiarrhythmic compound with expanding potential indications, including maintaining stability of sinus rhythm, secondary prevention in the survivors of myocardial infarction, and prolongation of survival in certain subsets of patients with congestive heart failure. Intravenous amiodarone was introduced in the U.S. in 1995 for the control of recurrent destabilizing ventricular tachycardia or ventricular fibrillation resistant to conventional therapy. The level of comfort in its use has risen considerably in the recent past. This has stemmed from the reasonably decisive evidence that class I agents increase mortality in patients with structural heart disease. In contrast, amiodarone either reduces mortality or its effect is neutral; this is consistent with its low to negligible proarrhythmic actions. The drug does not aggravate heart failure and it may even increase left ventricular ejection fraction and improve exercise capacity. Above all, it is becoming increasingly evident from wider experience and from controlled clinical trials that the side-effect profile of the drug is not as compelling an issue as it appeared to be when first used in much higher doses. Therefore, the overall objective of amiodarone therapy is to use the lowest dose that produces a defined therapeutic end point without causing serious side effects. Careful clinical surveillance in conjunction with monitoring of certain laboratory parameters and indices of efficacy at regular intervals permits the drug to be used effectively in a large number of patients who fail to respond to, or are intolerant of other antiarrhythmic compounds. Many experienced clinicians have begun to consider the use of amiodarone as first-line therapy in certain disorders of rhythm, especially in patients with severely compromised ventricular function.

The design of the Mortality Assessment in Congestive Heart Failure Trial (MACH-1, mibefradil)

BACKGROUND

Despite the advances in therapy for heart failure with the use of angiotensin-converting enzyme inhibitors, heart failure remains a major medical problem, impacting on well-being and survival.

HYPOTHESIS

Mibefradil is a member of new class of agents that, due to its unique mechanism of action and pharmacologic and physiologic profile, may offer a significant advance in the treatment of heart failure. Mibefradil is a nonvoltage-regulated T-channel calcium blocker that differs from all the other currently available L-channel calcium blockers. The drug is a potent peripheral and coronary vasodilator, with no clinical negative inotropic activity. Furthermore, because of its long half-life, it can be given once a day and appears to be free of the common side effects seen with other calcium-channel blockers. The trial was designed to investigate whether the addition of mibefradil to standard therapy for heart failure will reduce mortality in patients with symptomatic heart failure.

METHODS

This manuscript describes the design, organization, and status of MACH-1 (Mortality Assessment in Congestive Heart Failure), a double-blind, placebo-controlled study. It is to be a 2,400-patient international trial assessing the ability of mibefradil to impact upon survival and symptoms of heart failure in patients who are in NYHA classes II-IV and who were already treated with standard therapy.

Effects of nitrates on mortality in acute myocardial infarction and in heart failure

1. Seven randomized controlled trials of intravenous nitroglycerin in a total of about 850 patients have been reported. Overall, there were 51 deaths (12.5%) in the nitroglycerin group and 87 (20%) in the control group. This indicates a 48% reduction in the odds of death (P less than 0.001, 95% confidence limits (25% to 64%)). 2. There are five randomized trials of oral nitrates after acute myocardial infarction. In these trials, 11.8% of the patients in the nitrate group compared with 13.3% in the control group died. This indicates a nonsignificant 12% reduction in the odds of death but the 95% confidence interval overlaps widely with the i.v. trials. If all trials of i.v. or oral nitrates are considered the reduction in the odds of death is 32% (P less than 0.01). 3. Nitrates have a beneficial effect on haemodynamics in heart failure but the data on mortality effects are sparse. In combination with hydralazine, however, long-term mortality was reduced in the V-HEFT trial of chronic heart failure.

Mitigation of beta 1- and/or beta 2-adrenoceptor function in human heart failure

1. Patients with congestive heart failure (CHF) have an elevated activity of the sympatho-adrenal system. We have investigated several aspects of beta-adrenoceptor desensitization in such patients. 2. The positive inotropic response to isoprenaline was attenuated in CHF patients, and the pD2-values for isoprenaline's positive inotropic effect gradually decreased in more severe forms of the disease. Stimulation of adenylate cyclase by isoprenaline was also mitigated in cardiac membranes from patients with CHF. 3. We then studied the density of cardiac beta 1- and beta 2-adrenoceptors in order to understand the mechanism of beta-adrenoceptor desensitization in these patients. Our data show that cardiac beta 1-adrenoceptors are down-regulated in all forms of severe CHF, but that cardiac beta 2-adrenoceptor density decreases only in some forms of CHF including ischaemic cardiomyopathy and mitral valve disease. 4. In circulating mononuclear leucocytes (MNL) obtained from CHF patients at rest, isoprenaline- and prostaglandin E1-stimulated cAMP generation as well as cholera toxin and pertussis toxin catalyzed ADP ribosylation were similar to those in MNL from control patients. However, pretreatment of intact MNL with pertussis toxin enhanced cAMP generation in CHF patients but not in healthy control subjects, suggesting a tonic inhibitory effect of Gi in such patients. 5. We conclude that alterations of adrenoceptors and of their signal transduction might contribute to the desensitization of beta-adrenergic responses in CHF.

Beta-adrenoceptor control of immune function in congestive heart failure

1. We have determined the number of beta-adrenoceptors and the isoprenaline-stimulated cAMP generation in lymphocyte subsets. The in vitro beta-adrenergic sensitivity was greatest in Tsuppressor/cytotoxic- and natural killer cells and smallest in Thelper- and B-cells. B lymphocytes appear to have a poor receptor coupling to adenylate cyclase as they have many beta-adrenoceptors but generate only little cAMP in response to isoprenaline. 2. A 7 day treatment of healthy volunteers with terbutaline decreased the number of circulating cells in those lymphocyte subsets with a high in vitro sensitivity to beta-adrenoceptor stimulation (i.e. Tsuppressor/cytotoxic- and natural killer cells) but not in those with a poor in vitro sensitivity (i.e. Thelper- and B-lymphocytes). 3. Similar alterations of circulating lymphocyte subsets were found in patients with congestive heart failure (CHF). These alterations were not related to the aetiology of CHF but to its severity and could be correlated with plasma catecholamine levels. 4. We conclude that prolonged exposure to beta-adrenoceptor agonists or enhanced sympathetic activity can decrease the number of circulating lymphocytes with an increase in the Thelper-/Tsuppressor/cytotoxic-cell ratio.

Long-term studies with xamoterol in heart failure

1. Xamoterol (Corwin, Carwin, Corwil, Xamtol, ICI 118,587) is a beta 1-adrenoceptor partial agonist which, unlike full beta-adrenoceptor agonists, does not down-regulate beta-adrenoceptors in the rat ventricle during chronic administration. 2. Improvements in myocardial performance have been demonstrated following acute administration of xamoterol to patients with mild or moderate heart failure, and these are sustained during at least 1 year of continued treatment. 3. Exercise duration is increased by xamoterol in patients with left ventricular dysfunction and benefit is still apparent after at least 1 year of therapy. 4. Despite sustained cardiac stimulation, xamoterol does not appear to affect adversely mortality in patients with mild or moderate heart failure. 5. Few adverse events directly attributable to xamoterol were reported during 3 month efficacy studies in more than 600 patients, and the laboratory safety profile over 1 year of treatment is good. 6. Xamoterol is a promising, well-tolerated addition to established therapies for chronic mild or moderate heart failure.

ACE inhibitors in acute and chronic ischaemia: current status and future promise

1. Myocyte loss, reactive hypertrophy, dynamic ischaemia with 'stunning', and ventricular wall remodelling are all involved in the initiation and progression of myocardial failure which is ischaemic in origin. 2. The effects of ACE inhibitors to reduce preload and afterload has potentially salutary effects in these settings. Moreover, sulphyl containing ACE inhibitors may have further actions in reducing free radicals and their damage in the acute phases of these events. 3. These promising initial studies warrant further exploration.

Xamoterol, a beta 1-adrenoceptor partial agonist: review of the clinical efficacy in heart failure

1. Xamoterol (Corwin, Carwin, Corwil, Xamtol, ICI 118,587), a beta 1-adrenoceptor partial agonist, improves both systolic and diastolic function in heart failure patients. 2. Double-blind, randomised studies comparing xamoterol with placebo showed that the beneficial haemodynamic effects of xamoterol produced significant improvements in exercise capacity and symptoms in patients with mild to moderate heart failure. These studies formed the basis for a large European multicentre study programme which recruited over 1000 patients, randomised to xamoterol (200 mg twice daily, n = 617), digoxin (0.125 mg twice daily, n = 135) or placebo (n = 300) for 3 months. 3. Efficacy was assessed by measuring exercise capacity and symptoms. The xamoterol group improved exercise capacity by 37% compared with an 18% improvement in the placebo group. Differences in the symptom scores measured by visual analogue scales and Likert scores indicated significant improvements by xamoterol in the cardinal symptoms of heart failure, dyspnoea and fatigue. 4. Analyses of data from subsets of patients in the study showed that elderly patients, patients on no other heart failure therapy and patients with cardiomegaly all had similar improvements in exercise and symptoms to those seen in the whole study population. In the subset which included digoxin treatment, xamoterol produced significantly greater improvements in exercise capacity than digoxin (33% vs 17%, P less than 0.05) and was associated with fewer side-effects. 5. Xamoterol is therefore a promising addition to heart failure therapies currently available.

Focus on diastolic dysfunction: a new approach to heart failure therapy

1. Although heart failure is commonly associated with depressed systolic function, there is increasing evidence that impaired diastolic performance is also universally present and might be a key determinant of symptoms, physical capacity and even survival in some subsets of patients. 2. Reduced diastolic distensibility increases cardiac filling pressure not only at rest, but even more during exercise when diastolic filling time is reduced. The increases in filling pressure and diastolic wall stress lead to pulmonary congestion and subendocardial ischaemia, it also triggers myocardial hypertrophy and a detrimental remodelling of the ventricular cavity. Perhaps even more importantly, impaired ventricular distensibility limits the use of the Frank-Starling mechanism, impairing systolic pump function and cardiac output adaptation during exercise. Therapies able to improve the distensibility of the ventricle are, therefore, desirable in heart failure. 3. Nitrates, angiotensin converting enzyme (ACE) inhibitors and diuretics may indirectly increase left ventricular chamber compliance by their effects on the right side of the heart. Cardiac glycosides do not improve myocardial relaxation and may even cause diastolic contracture at toxic doses. The new beta 1-adrenoceptor partial agonist, xamoterol, on the other hand, consistently lowers left ventricular filling pressure at rest and during exercise, and produces an increase in left ventricular dynamic compliance through the direct lusitropic effect of beta 1-adrenoceptor stimulation. These beneficial effects are maintained during prolonged therapy and also appear sufficient to slow the remodelling of the ventricular cavity. The improvement in symptoms and in exercise tolerance observed during xamoterol (Corwin, Carwin, Corwil, Xamtol, ICI 118,587) therapy might, therefore, be related to the improvement in left ventricular diastolic distensibility induced by this drug.

Xamoterol in mild to moderate heart failure: a subgroup analysis of patients with cardiomegaly but no concomitant angina pectoris

Xamoterol has been shown in large, double-blind studies to produce benefit in patients with heart failure. Ischaemic heart disease is the commonest cause of heart failure in the Western World and many patients with heart failure also have angina pectoris (Califf et al., 1982). In view of the known anti-ischaemic effects of xamoterol, we analysed the results of a subgroup of 269 patients with heart failure but without chest pain as a limiting factor on exercise to compare the efficacy of xamoterol in such patients with that of the total group. There were no differences in exercise heart rate, exercise tolerance and symptoms in patients without chest pain compared with the total group. Xamoterol is probably, therefore, acting through myocardial mechanisms other than an anti-ischaemic effect.

The efficacy and safety of chronic oral administration of xamoterol to patients with severe heart failure treated with ACE inhibitors

Xamoterol 200 mg twice daily was given for 2 months to nine patients with severe heart failure already being treated with angiotensin converting enzyme (ACE) inhibitors. Left ventricular end-diastolic pressure fell from 28 to 13 mmHg and end-systolic volume fell from 115 to 106 ml m-2; indices of contractility improved and ejection fraction rose from 33 to 38%. The time constant of ventricular relaxation, T1, improved from 62 to 44 ms. Exercise tolerance improved. Thus, in this group of patients with severe heart failure, xamoterol produced benefits in systolic and diastolic function. There were no adverse effects.

Long-term efficacy of xamoterol (a beta 1-adrenoceptor partial agonist) in patients with mild to moderate heart failure

This study was designed to assess the efficacy of xamoterol in 14 patients with mild to moderate heart failure over a period of 18 months. A beneficial effect on exercise capacity and a lowering of heart rate on exercise was sustained, and ejection fraction did not change, although some deterioration may be expected over this length of time in patients with heart failure. Xamoterol is safe and effective, and its benefits are maintained over at least 18 months.

The management of heart failure and the scope for new therapies: what role for xamoterol?

1. Current therapy of heart failure leaves much to be desired. Not all patients respond, and many agents lose their effects with time. 2. Newer agents may be effective but toxic, and some which have a beneficial action when given intravenously have proved disappointing when used orally. 3. The value of digoxin in patients in sinus rhythm is open to debate, and diuretics, although useful acutely in reducing fluid overload, do not appear to improve prognosis. 4. Vasodilators increase effort capacity and reduce symptoms, possibly conferring some long-term benefit, and angiotensin converting enzyme (ACE) inhibitors improve symptoms and decrease mortality in a wide range of patients. 5. Positive inotropes may be effective in the short term, but they increase myocardial oxygen demand and show tachyphylaxis with no prognostic benefit. 6. Xamoterol (Corwin, Carwin, Corwil, Xamtol, ICI 118,587) is a partial sympathetic agonist with approximately 50% of the activity of a pure agonist, which provides inotropic support at rest, and protection against excess sympathetic activity on exercise. 7. It is compatible with other therapies and has shown no serious toxicity. 8. It should be considered at present as an adjunct to diuretic and/or ACE inhibitor therapy, although it may be useful alone; its role will become clearer as its effects on mortality are established.

The effects of age, sex and treatment with xamoterol on exercise capacity in patients with heart failure

The influence of age, sex and xamoterol treatment on exercise capacity has been investigated in 705 heart failure patients who took part in a multicentre, placebo-controlled study. Regression analysis suggests that although less than 20% of the total variation in exercise capacity between patients is explained by these factors, useful information may be gained by taking them into account. Exercise capacity declines with age, more rapidly in males than in females; the benefits of xamoterol are independent of age and sex. This approach demonstrates that exercise testing is a sensitive indicator of physical performance and allows the effects of treatment to be seen in context.