Long-term therapy of heart failure with prazosin: a randomized double blind trial

Do adrenergic alpha-antagonists increase the risk of poor cardiovascular outcomes? A systematic review and meta-analysis

Due to concerns regarding neurohormonal activation and fluid retention, adrenergic alpha-1 receptor antagonists (A1Bs) are generally avoided in the setting of heart disease, namely, symptomatic heart failure (HF) with reduced ejection fraction (HFrEF). However, this contraindication is mainly supported by ancient studies, having recently been challenged by newer ones. We aim to perform a comprehensive meta-analysis aimed at ascertaining the extent to which A1Bs might influence cardiovascular (CV) outcomes. We systematically searched PubMed, Cochrane Central Register of Controlled Trials and Web of Science for both prospective and retrospective studies, published until 1 December 2020, addressing the impact of A1Bs on both clinical outcomes-namely, acute heart failure (AHF), acute coronary syndrome (ACS), CV and all-cause mortality-and on CV surrogate measures, specifically left ventricular ejection fraction (LVEF) and exercise tolerance, by means of exercise duration. Both randomized controlled trials (RCTs) and studies including only HF patients were further investigated separately. Study-specific odds ratios (ORs) and mean differences (MDs) were pooled using traditional meta-analytic techniques, under a random-effects model. A record was registered in PROSPERO database, with the code number CRD42020181804. Fifteen RCTs, three non-randomized prospective and two retrospective studies, encompassing 32 851, 19 287, and 71 600 patients, respectively, were deemed eligible; 62 256 patients were allocated to A1B, on the basis of multiple clinical indications: chronic HF itself [14 studies, with 72 558 patients, including seven studies with 850 HFrEF or HF with mildly reduced ejection fraction (HFmrEF) patients], arterial hypertension (four studies, with 44 184 patients) and low urinary tract symptoms (two studies, with 6996 patients). There were 25 998 AHF events, 1325 ACS episodes, 955 CV deaths and 33 567 all-cause deaths. When considering only RCTs, A1Bs were, indeed, found to increase AHF risk (OR 1.78, [1.46, 2.16] 95% CI, P < 0.00001, i2 2%), although displaying no significant effect on neither ACS nor CV or all-cause mortality rates (OR 1.02, [0.91, 1.15] 95% CI, i2 0%; OR 0.95, [0.47, 1.91] 95% CI, i2 17%; OR 1.1, [0.84, 1.43] 95% CI, i2 17%, respectively). Besides, when only HF patients were evaluated, A1Bs revealed themselves neutral towards not only ACS, CV, and all-cause mortality events (OR 0.49, [0.1, 2.47] 95% CI, i2 0%; OR 0.7, [0.21, 2.31] 95% CI, i2 21%; OR 1.09, [0.53, 2.23] 95% CI, i2 17%, respectively), but also AHF (OR 1.13, [0.66, 1.92] 95% CI, i2 0%). As for HFrEF and HFmrEF, A1Bs were found to exert a similarly inconsequential effect on AHF rates (OR 1.01, [0.5-2.05] 95% CI, i2 6%). Likewise, LVEF was not significantly influenced by A1Bs (MD 1.66, [-2.18, 5.50] 95% CI, i2 58%). Most strikingly, exercise tolerance was higher in those under this drug class (MD 139.16, [65.52, 212.8] 95% CI, P < 0.001, i2 26%). A1Bs do not seem to exert a negative influence on the prognosis of HF-and even of HFrEF-patients, thus contradicting currently held views. These drugs' impact on other major CV outcomes also appear trivial and they may even increment exercise tolerance.

Upregulation of Phospholipase C Gene Expression Due to Norepinephrine-Induced Hypertrophic Response

The activation of phospholipase C (PLC) is thought to have a key role in the cardiomyocyte response to several different hypertrophic agents such as norepinephrine, angiotensin II and endothelin-1. PLC activity results in the generation of diacylglycerol and inositol trisphosphate, which are downstream signal transducers for the expression of fetal genes, increased protein synthesis, and subsequent cardiomyocyte growth. In this article, we describe the signal transduction elements that regulate PLC gene expression. The discussion is focused on the norepinephrine- α₁-adrenoceptor signaling pathway and downstream signaling processes that mediate an upregulation of PLC isozyme gene expression. Evidence is also indicated to demonstrate that PLC activities self-regulate the expression of PLC isozymes with the suggestion that PLC activities may be part of a coordinated signaling process for the perpetuation of cardiac hypertrophy. Accordingly, from the information provided, it is plausible that specific PLC isozymes could be targeted for the mitigation of cardiac hypertrophy.

Role of Phospholipase C in Catecholamine-induced Increase in Myocardial Protein Synthesis

The activation of the α1-adrenoceptor-(α1-AR) by norepinephrine results in the G-protein (Gqα) mediated increase in the phosphoinositide-specific phospholipase C (PLC) activity. The byproducts of PLC hydrolytic activity, namely, 1,2-diacylglycerol and inositol-1,4,5-trisphosphate, are important downstream signal transducers for increased protein synthesis in the cardiomyocyte and the subsequent hypertrophic response. In this article, evidence is outlined to demonstrate the role of cardiomyocyte PLC isozymes in the catecholamine-induced increase in protein synthesis by using a blocker of α1-AR and an inhibitor of PLC. The discussion will be focused on the α1-AR-Gqα-PLC-mediated hypertrophic signaling pathway from the viewpoint that it may compliment the other β1-AR-Gs protein-adenylyl cyclase signal transduction mechanisms in the early stages of cardiac hypertrophy development, but may become more relevant at the late stage of cardiac hypertrophy. From the information provided here, it is suggested that some specific PLC isozymes may potentially serve as important targets for the attenuation of cardiac hypertrophy in the vulnerable patient population at-risk for heart failure.

Neurohormonal Connections with Mitochondria in Cardiomyopathy and Other Diseases

Neurohormonal signaling and mitochondrial dynamism are seemingly distinct processes that are almost ubiquitous among multicellular organisms. Both of these processes are regulated by GTPases, and disturbances in either can provoke disease. Here, inconspicuous pathophysiological connectivity between neurohormonal signaling and mitochondrial dynamism is reviewed in the context of cardiac and neurological syndromes. For both processes, greater understanding of basic mechanisms has evoked a reversal of conventional pathophysiological concepts. Thus, neurohormonal systems induced in, and previously thought to be critical for, cardiac functioning in heart failure are now pharmaceutically interrupted as modern standard of care. And, mitochondrial abnormalities in neuropathies that were originally attributed to an imbalance between mitochondrial fusion and fission are increasingly recognized as an interruption of axonal mitochondrial transport. The data are presented in a historical context to provided insight into how scientific thought has evolved and to foster an appreciation for how seemingly different areas of investigation can converge. Finally, some theoretical notions are presented to explain how different molecular and functional defects can evoke tissue-specific disease.

Heart Failure Spending Function: An Investment Framework for Sequencing and Intensification of Guideline-Directed Medical Therapies

Heart failure with reduced ejection fraction is managed with increasing numbers of guideline-directed medical therapies (GDMT). Benefits tend to be additive. Burdens can also be additive. We propose a heart failure spending function as a conceptual framework for tailored intensification of GDMT that maximizes therapeutic opportunity while limiting adverse events and patient burden. Each patient is conceptualized to have reserve in physiological and psychosocial domains, which can be spent for a future return on investment. Key domains are blood pressure, heart rate, serum creatinine, potassium, and out-of-pocket costs. For each patient, GDMT should be initiated and intensified in a sequence that prioritizes medications with the greatest expected cardiac benefit while drawing on areas where the patient has ample reserves. When reserve is underspent, patients fail to gain the full benefit of GDMT. Conversely, when a reserve is fully spent, addition of new drugs or higher doses that draw upon a domain will lead to patient harm. The benefit of multiple agents drawing upon varied physiological domains should be balanced against cost and complexity. Thresholds for overspending are explored, as are mechanisms for implementing these concepts into routine care, but further health care delivery research is needed to validate and refine clinical use of the spending function. The heart failure spending function also suggests how newer therapies may be considered in terms of relative value, prioritizing agents that draw on different spending domains from existing GDMT.

Muscle metaboreflex-induced coronary vasoconstriction limits ventricular contractility during dynamic exercise in heart failure

Muscle metaboreflex activation (MMA) during dynamic exercise increases cardiac work and myocardial O2 demand via increases in heart rate, ventricular contractility, and afterload. This increase in cardiac work should lead to metabolic coronary vasodilation; however, no change in coronary vascular conductance occurs. This indicates that the MMA-induced increase in sympathetic activity to the heart, which raises heart rate, ventricular contractility, and cardiac output, also elicits coronary vasoconstriction. In heart failure, cardiac output does not increase with MMA presumably due to impaired ability to improve left ventricular contractility. In this setting actual coronary vasoconstriction is observed. We tested whether this coronary vasoconstriction could explain, in part, the reduced ability to increase cardiac performance during MMA. In conscious, chronically instrumented dogs before and after pacing-induced heart failure, MMA responses during mild exercise were observed before and after α1-adrenergic blockade (prazosin 20-50 μg/kg). During MMA, the increases in coronary vascular conductance, coronary blood flow, maximal rate of left ventricular pressure change, and cardiac output were significantly greater after α1-adrenergic blockade. We conclude that in subjects with heart failure, coronary vasoconstriction during MMA limits the ability to increase left ventricular contractility.

Quantitative evaluation of drug or device effects on ventricular remodeling as predictors of therapeutic effects on mortality in patients with heart failure and reduced ejection fraction: a meta-analytic approach

OBJECTIVES

The purpose of this study was to quantitatively assess the relationship between therapy-induced changes in left ventricular (LV) remodeling and longer-term outcomes in patients with left ventricular dysfunction (LVD).

BACKGROUND

Whether therapy-induced changes in left ventricular ejection fraction (LVEF), end-diastolic volume (EDV), and end-systolic volume (ESV) are predictors of mortality in patients with LVD is not established.

METHODS

Searches for randomized controlled trials (RCTs) were conducted to identify drug or device therapies for which an effect on mortality in patients with LVD was studied in at least 1 RCT of > or = 500 patients (mortality trials). Then, all RCTs involving those therapies were identified in patients with LVD that described changes in LVEF and/or volumes over time (remodeling trials). We examined whether the magnitude of remodeling effects is associated with the odds ratios for death across all therapies or associated with whether the odds ratio for mortality was favorable, neutral, or adverse (i.e., statistically significantly decreased, nonsignificant, or statistically significantly increased odds for mortality, respectively).

RESULTS

Included were 30 mortality trials of 25 drug/device therapies (n = 69,766 patients; median follow-up 17 months) and 88 remodeling trials of the same therapies (n = 19,921 patients; median follow-up 6 months). The odds ratio for death in the mortality trials was correlated with drug/device effects on LVEF (r = -0.51, p < 0.001), EDV (r = 0.44, p = 0.002), and ESV (r = 0.48, p = 0.002). In (ordinal) logistic regressions, the odds for neutral or favorable effects in the mortality RCTs increased with mean increases in LVEF and with mean decreases in EDV and ESV in the remodeling trials.

CONCLUSIONS

In patients with LVD, short-term trial-level therapeutic effects of a drug or device on LV remodeling are associated with longer-term trial-level effects on mortality.

Impact of alpha 1-adrenergic antagonist use for benign prostatic hypertrophy on outcomes in patients with heart failure

Previous clinical trials have shown that alpha(1)-adrenergic antagonists are not effective in subjects with heart failure (HF) and might increase HF rates when used for hypertension. However, alpha(1)-adrenergic antagonists may be prescribed to subjects with HF who have symptomatic benign prostatic hyperplasia. We sought to determine any association between alpha(1)-adrenergic antagonist use, commonly prescribed for benign prostatic hyperplasia, and the clinical outcomes of subjects with HF receiving contemporary therapy. An existing database of 388 subjects with decompensated HF admissions from 2002 to 2004 at the Veterans Affairs Hospital was analyzed according to the use of alpha(1)-adrenergic antagonists at discharge. Covariate-adjusted Cox proportional hazard models were used to examine any association with future admissions for decompensated HF and total mortality. Alpha-1-adrenergic antagonist therapy was prescribed in 25% of our HF population, predominantly for benign prostatic hyperplasia, and was not associated with significant increases in the combined risk of all-cause mortality and rehospitalization for HF (hazard ratio 1.24, 95% confidence interval 0.93 to 1.65, p = 0.14), HF hospitalization (hazard ratio 1.20, 95% confidence interval 0.85 to 1.70, p = 0.31), or all-cause mortality (hazard ratio 1.10, 95% confidence interval 0.78 to 1.56, p = 0.57). In patients not receiving beta-blocker therapy, alpha(1)-adrenergic antagonist therapy was significantly associated with increased HF hospitalizations (hazard ratio 1.94, 95% confidence interval 1.14 to 3.32, p = 0.015). In conclusion, in patients with chronic HF, the use of alpha(1)-adrenergic antagonists was significantly associated with more HF hospitalizations when prescribed without concomitant beta blockade. Thus, background beta-blocker therapy appears to be protective against the potential harmful effects of alpha(1)-adrenergic antagonist therapy in patients with HF.

Aspects on "traditional" vasodilators in the treatment of chronic heart failure

Vasodilator therapy of heart failure has through the last 5-10 years become a well established treatment. Traditionally these drugs have been classified after their primary site of action on the vascular beds. Thus drugs primarily acting on the arteriolar bed are called afterload-reducing agents and are exemplified by hydralazine. Drugs primarily acting on the venous bed have been called preload-reducing reducing agents and the typical example is nitroglycerin. Other drugs, like prazosin, act on both the arteriolar and venous vascular beds. The classification is, however, not as sharp as originally believed since preload- and afterload-reducing activities mix with each other. Treatment with vasodilators for chronic heart failure has mainly been advocated in patients with valvular regurgitation, ischemic heart disease and various types of dilated cardiomyopathies. It seems appropriate today to put some questions concerning vasodilator therapy for heart failure. Among such questions are: When in the natural history of congestive heart failure should vasodilator therapy be commenced? How effective is long-term administration of vasodilating drugs? May vasodilator therapy decrease mortality in congestive heart failure? What about the efficacy of new vasodilating drugs compared to more traditional ones? In the review of vasodilating drugs besides ACE inhibitors, these questions will be addressed.

Effects of red rest and prazosin in congestive heart failure

Twelve patients with congestive heart failure were monitored with invasive and noninvasive techniques to evaluate the effect of vasodilator treatment. During the 18 hours of strict bed rest before administration of prazosin, the hemodynamics improved substantially while only small and transient heModynamic changes were observed after introduction of prazosin. At 6 weeks' control the effect of vasodilator treatment with prazosin, 3 mg x 4, was lost. The beneficial results often credited to vasodilators in studies on congestive heart failure might in part be due to the concomitant bed rest introduced during the monitoring of the patients.

Acute hemodynamic and long-term clinical effects of prazosin in the treatment of chronic congestive heart failure

The effect of prazosin in congestive heart failure was assessed in 10 patients (age 39--69) years) with ischemic heart disease or cardiomyopathy in functional class II-IV (NYHA). All patients were treated with digitalis and diuretics in optimal doses. Mean (+/- S.E.M.) cardiac index (CI) was 2.2 +/- 0.2 l/min/m2 before and 2.3 +/- 0.1 one hour after oral administration of 2--4 mg prazosin (given as tablets) (p less than 0.10). Mean pulmonary capillary wedge pressure (PWP) fell from 24 +/- 4 to 20 +/- 4 mmHg (p greater than 0.10). Prazosin seemed to have a more beneficial effect on patients with markedly elevated PWP or reduced CI before prazosin administration. The effect of prazosin on heart rate and systolic blood pressure was insignificant. During a follow-up period of 1--20 months (mean 7.3), 2 of 7 patients treated with prazosin (2--4 mg daily) improved their clinical condition, one patient was unchanged and 4 patients died in progressive cardiac failure. The results indicate that some patients with severe heart failure may benefit from prazosin when conventional treatment has failed.

Effect of alpha1-adrenergic receptors in cardiac pathophysiology

Compelling evidence now exists that proves adrenergic blockade is at the center of neurohormonal antagonism in heart failure (HF). Catecholamines are well known to act through both beta- and alpha-adrenergic receptors (ARs), which mediate their effects through distinct receptor pathways. Beta-AR blockers are commonly used in the treatment of HF and have distinct receptor affinity profiles. The recent COMET trial comparing 2 important beta-blocking drugs showed a distinct advantage for carvedilol in decreasing the risk of mortality from HF. The mechanism of action for carvedilol differs from metoprolol tartrate in its ability to block both alpha- and beta-ARs, leading to renewed interest in the potential role of alpha-ARs in the progression of HF. In contrast, however, the ALLHAT study discontinued use of doxazosin, an alpha1-receptor blocker because of an increase in cardiovascular events among patients using this drug. The results of these studies appear to be in contrast with respect to the role of alpha-ARs in regards to cardiovascular pathophysiology. Further study of the alpha-receptor and understanding the role of alpha-ARs in HF is necessary to understand the therapeutic effect of alpha-blockade. This article reviews our understanding of the alpha-AR in HF.

BNP in hormone-guided treatment of heart failure

The pharmacotherapy of heart failure has become complex. Angiotensin-converting enzyme inhibitors (or angiotensin II receptor blockers), beta-blockers, spironolactone, diuretics and digoxin can be prescribed concurrently. Endothelin antagonists and combined inhibitors of converting enzyme and neutral endopeptidase are under investigation. Optimal dosing will become increasingly difficult to judge. Plasma brain natriuretic peptide (BNP) indicates the severity of left ventricular dysfunction. The C-terminal bioactive peptide and N-terminal BNP (N-BNP) circulate at concentrations related to cardiac status. We proposed that plasma levels of N-BNP would provide an index to guide drug treatment in established heart failure. Sixty-nine patients were randomized to treatment adjusted according to clinical criteria or plasma N-BNP. Hormone-guided therapy resulted in fewer clinical end points than did clinical management. This encourages further exploration of hormone guidance of anti-heart failure therapy, which could be extended to patients with preserved ejection fraction, in addition to those with established systolic dysfunction.

Brain natriuretic peptide-guided therapy for heart failure

The drug treatment of heart failure, once simple, has become complex. Apart from a loop diuretic and digoxin, most patients should now be receiving an angiotensin-converting enzyme inhibitor (or angiotensin II receptor blocker), a beta-blocker and spironolactone. Newer drugs, such as endothelin-receptor antagonists and combined blockers of converting-enzyme and neutral endopeptidase, might soon become available. When to introduce these drugs and what dose is optimal for any individual, are questions that currently vex clinicians. We proposed that plasma levels of the cardiac hormone brain natriuretic peptide (BNP, or better, its 1-76 amino-acid N-terminal fragment, N-BNP), would provide an objective index for guiding drug treatment in patients with established, stable cardiac failure. In a pilot study, 69 patients were randomized to drug treatment based on clinical criteria, or based on plasma levels of N-BNP. After a median follow-up of 9.6 months, those in the N-BNP group had fewer clinical end-points than those in the group managed by clinical criteria alone (19 vs 54; P= 0.02). These preliminary data encourage the concept that the increasingly complex pharmacotherapy for heart failure, both chronic (as in this trial) and acute, might best be guided by an objective measure such as plasma levels of BNP or N-BNP.

Effects of afterload-reducing drugs on pathogenesis of antioxidant changes and congestive heart failure in rats

OBJECTIVES

The present study sought to evaluate the effects of the afterload-reducing drugs captopril and prazosin on changes in antioxidants as well as oxidative stress in relation to hemodynamic function in congestive heart failure (CHF) subsequent to myocardial infarction (MI).

BACKGROUND

Afterload reduction therapy has been shown to reduce morbidity and mortality in patients with MI. CHF subsequent to MI in rats is associated with a decrease in myocardial endogenous antioxidants and an increase in oxidative stress.

METHODS

The left anterior descending coronary artery in male Sprague-Dawley rats was ligated. Sham and experimental (post-MI [PMI]) animals were assessed for hemodynamic function as well as lung and liver weights at 1, 4 and 16 weeks after operation. At 4 weeks, some rats were also treated with captopril (2 g/liter in drinking water daily) or prazosin (0.2 mg/kg body weight subcutaneously daily) and assessed at 16 weeks. Hearts were isolated to study the activity of superoxide dismutase (SOD), glutathione peroxidase (GSHPx) and catalase as well as for thiobarbituric acid reactive substances (TBARS).

RESULTS

CHF at 4 and 16 weeks in the infarcted rats was indicated by an increase in left ventricular end-diastolic pressure and wet/dry weight lung and liver ratios and depressed left ventricular systolic pressure and dyspnea. All these changes were attenuated in both the captopril- and prazosin-treated groups. SOD, GSHPx and catalase activity in the untreated PMI groups was decreased at 4 and 16 weeks. However, treatment with captopril resulted in a significant improvement in SOD, GSHPx and catalase activity in the 16-week PMI group. With prazosin, only SOD activity was improved in the treated 16-week PMI group. Lipid peroxidation as indicated by TBARS was significantly increased in the 16-week PMI group, and both captopril and prazosin modulated this increase.

CONCLUSIONS

Occurrence of an antioxidant deficit and an increase in oxidative stress in the myocardium may play a role in the pathogenesis of CHF subsequent to MI. Attenuation of these changes in antioxidant activity with vasodilator (or antioxidant?) therapy mitigates the process of heart failure.

Long-term strategies in the management of heart failure: looking beyond ventricular function and symptoms

Therapeutic approaches to the management of heart failure have traditionally focused on shortterm hemodynamic and symptomatic goals, but present evidence suggests that most therapeutic decisions have long-term consequences. Treatment may change the rate of disease progression, modify the need for additional therapy, influence the number of hospitalizations, and alter the risk of death. However, there may be little relation between a drug's short-term effect on cardiac function or cardiovascular symptoms and its long-term effect on survival. Some therapeutic interventions favorably influence the outcome of patients with heart failure, even though they exert negative inotropic effects; others adversely affect the outcome of patients, even though they markedly improve cardiac performance. This discordance might be explained if the most important predictor of response to a therapeutic intervention in heart failure were the effect of the pharmacologic agent on neurohormonal systems rather than on hemodynamic variables. In general, drugs that decrease the effects of the sympathetic nervous system (digitalis glycosides) and the renin-angiotensin system (angiotensin-converting enzyme [ACE] inhibitors) reduce the risk of worsening heart failure. Conversely, drugs that potentiate the effects, or increase the activity, of the sympathetic nervous system (phosphodiesterase inhibitors) or the renin-angiotensin system (calcium antagonists) increase cardiovascular morbidity and mortality. These observations suggest that physicians should no longer focus on short-term hemodynamic or symptomatic goals in the treatment of heart failure but, instead, should manage patients to improve both the quality and quantity of life.

Vasodilators. A re-evaluation of their role in heart failure

Over the past 25 years, the concept of circulation in heart failure has evolved from that of a simple circuit with a weak pump and high pressures to a complex integrated system of cellular modification, cardiac compensation and systemic neurohumoral responses. The original model of cardiac afterload as the systemic vascular resistance has been refined to reflect the interdependence of preload and afterload and the central role of atrioventricular valve regurgitation. It is becoming increasingly apparent that the impact of vasodilator therapy far exceeds the direct haemodynamic effects on preload and afterload, and depends on the mechanism by which vasodilation is achieved, with increasing emphasis on those agents which oppose neurohumoral activation. The potential goals of therapy have broadened to include not only haemodynamic stabilisation through tailored therapy for patients referred with advanced heart failure, but also the prevention of disease progression for patients with asymptomatic ventricular dilation. As the different profiles of heart failure have come to be recognised, the purpose and design of vasodilator treatment must now be considered individually for each patient.

Effect of medical therapy on survival of patients with dilated cardiomyopathy

Few studies have been conducted that focus on survival as the end point of medical therapy of CHF. No vigorous studies have been conducted in dogs. It is generally accepted that diuretic therapy is an essential component of the therapy of CHF in cardiomyopathic dogs. Significant symptomatic improvement is afforded by diuretics, and acute death may be prevented. In this context diuretics can be said to improve survival. However, diuretics do not alter the natural progression of cardiomyopathy and in this context do not favorably influence long-term survival. Digitalis glycosides have been shown in humans to improve various parameters of CHF in a subset of patients with either atrial fibrillation or third heart sounds. In dogs, these gallop heart rhythms due to third heart sounds are usually associated with myocardial failure due to dilated cardiomyopathy. In spite of symptomatic improvement, no study has demonstrated an unequivocal favorable effect of digoxin on survival of patients with dilated cardiomyopathy. Likewise, there is no convincing evidence of an adverse effect on survival. Newer, powerful inotropes, such as milrinone, often demonstrate impressive short-term improvements in left ventricular function, clinical signs, and exercise tolerance in patients with CHF. However, their long-term benefits are much less impressive, they are arrhythmogenic, and they have not been shown to prolong survival. In fact, long-term milrinone therapy in humans has had an unfavorable influence on mortality. Vasodilators offer the potential advantage of increasing left ventricular performance without an associated increase in myocardial oxygen demand and cardiac rhythm disturbances. The only vigorous survival study that unequivocally demonstrated improved survival of patients with advanced CHF due to myocardial failure, including dilated cardiomyopathy, was the Consensus Trial. Survival of patients receiving enalapril was significantly better than those receiving placebo. In fact, the trial was stopped prematurely by the ethical review committee when it became obvious that the results favored the enalapril group. Although the use of beta-adrenergic blocking drugs in cardiomyopathic patients with CHF is controversial and associated with a risk of short-term deterioration of left ventricular function, their use in human medicine is gaining acceptance. Although hemodynamic and clinical evidence of improvement has been demonstrated along with withdrawal-associated deterioration, the only study purporting a beneficial effect on survival used retrospective controls.(ABSTRACT TRUNCATED AT 400 WORDS)

Treatment considerations for the hypertensive patient over age 55

The prevalence of hypertension increases with age. The majority of the hypertensive population is over age 55. Although the treatment of systolic hypertension remains incompletely understood, the reduction of diastolic hypertension with pharmacotherapy has been shown to reduce complications from hypertension in persons over age 55. The older hypertensive patient is at risk for the same complications as the younger patient: angina, myocardial infarction, arteriosclerosis obliterans, stroke, myocardial hypertrophy, congestive heart failure, and renal failure; the risk of sudden death and multi-infarct dementia in the older patient may be somewhat higher. The older hypertensive individual may have reduced plasma volume and defective salt and water conservation, reduced renal function, impairment of baroreceptor reflexes and sympathetic reactivity, and altered drug pharmacokinetics, or may have arteriosclerosis leading to pseudohypertension. Many circumstances interfere with adequate compliance with therapeutic regimens among the elderly. Concomitant medical conditions increase the possibility of drug interactions and require that the practitioner be able to adjust the antihypertensive program to the patient.

Prazosin in chronic congestive heart failure due to ischemic heart disease

Oral prazosin hydrochloride (2-20 mg/day) was administered to 38 patients with chronic congestive heart failure due to ischemic heart disease for 6-18 months. Half (19) of the patients were hypertensive and half (19) nonhypertensive. All were receiving furosemide (80 mg/day, orally) and 19 were receiving digoxin (0.25-0.5 mg/day, orally) in addition to prazosin. Clinical radiological, mechanocardiographic, echocardiographic, and biochemical observations were made initially, at peak response, and at the end of 6 months. Prazosin improved left ventricular function indexes at rest, relieved symptoms and signs of congestion, and remained effective for 6-18 months with little or no increase in dose. There was no reflex tachycardia, tension-time indexes fell in all patients, angina was relieved in 8 patients who complained of it, and dyskinesia of left ventricular wall was corrected in 8 of 13 patients. The New York Heart Association functional class improved in all patients, but to a greater extent in hypertensive patients and in those not receiving concomitant digoxin. Mild, transient side effects occurred in 6 patients.

First dose hypotension with enalapril and prazosin in congestive heart failure

Since the introduction of angiotensin converting enzyme inhibitors into the adjunctive treatment of patients with congestive heart failure, cases of severe hypotension, especially on the first day of treatment, have occasionally been reported. To assess the safety of the angiotensin converting enzyme inhibitor enalapril a multicenter, open, randomized, prazosin-controlled trial was designed comparing the incidence and severity of symptomatic hypotension on the first day of treatment. Trial medication was 2.5 mg enalapril or 0.5 mg prazosin. Subjects were 1210 inpatients with New York Heart Association functional class (I)/II and III who were not adequately compensated with digitalis and/or diuretics. In the group receiving enalapril, 3 patients (0.5%) experienced severe hypotension on day 1 and 28 patients (4.7%) moderate hypotension. In those given prazosin, 15 patients (2.6%) experienced severe hypotension and 60 patients (10.3%) moderate hypotension. The difference is statistically significant (P less than or equal to 0.000012). All patients recovered. It was concluded that treatment of patients suffering from congestive heart failure New York Heart Association functional class (I)/II or III with enalapril is comparably well tolerated.

Prazosin's effect in high renin hypertension complicating pheochromocytoma

During three consecutive days of prazosin treatment in a patient with pheochromocytoma, urinary catecholamine metabolite levels were correlated with plasma renin activity. Suppression of renin plasma activity resulted in sustained hemodynamic and clinical improvement, while no remarkable changes were observed in urinary catecholamine metabolite levels. This suggests that prazosin may interrupt the vicious cycle of worsening hypertension provoked by further activation of the renin-angiotensin system mediated by excessive circulating catecholamines.

Which vasodilator drug in patients with chronic heart failure? A randomised comparison of captopril and hydralazine

1. Fifty patients with symptoms due to chronic heart failure despite diuretic therapy were randomised to receive additional treatment with either hydralazine or captopril. The dose was titrated; 24 received hydralazine and 26 captopril up to a maximum daily dosage of 225 mg and 75 mg respectively. Forty-three patients had coronary heart disease and seven dilated cardiomyopathy. 2. Dyspnoea and tiredness were assessed using a visual analogue scale (0-100) before and during 12 weeks' treatment. Captopril produced a significantly greater reduction in breathlessness (F = 31.6, P less than 0.001) and tiredness (F = 65.8, P less than 0.001) compared with hydralazine. 3. There was an increase in treadmill exercise time during treatment with both hydralazine (from 5.5 (3.47-7.53) min to 6.9 (4.87-8.93) min), and captopril (from 5.0 (3.05-6.95) min to 7.8 (5.85-9.75) min), but the degree of improvement was significantly greater in the patients treated with captopril (F = 7.4, P less than 0.001). 4. There was no significant change in right ventricular ejection fraction (from 27.9 (19.3-36.5)% to 28.7 (20.1-37.3)%) or left ventricular ejection fraction (from 22.2 (14.2-30.2)% to 23.9 (15.9-31.9)%) during treatment with hydralazine. However, both right and left ventricular ejection fraction increased significantly during treatment with captopril (from 27.1 (18.9-35.3)% to 32.0 (23.8-40.2)%, P less than 0.05; and from 25.0 (17.2-32.8)% to 29.6 (21.8-37.4)%, P less than 0.05 respectively). 5. These results suggest that in patients with symptoms due to chronic heart failure despite diuretic therapy, treatment with captopril produces a greater symptomatic and haemodynamic improvement than treatment with hydralazine.

Doxazosin for the treatment of chronic congestive heart failure: results of a randomized double-blind and placebo-controlled study

In this study we evaluated the effects of once-daily administration of oral doxazosin in patients with chronic congestive heart failure (CHF). After a stabilization period of at least 2 weeks with digitalis and diuretics, 73 patients with chronic CHF were randomized to receive additionally either doxazosin or placebo in double-blind fashion. Patients underwent weekly dose adjustments with increasing doses of doxazosin (1, 2, 4, 8, and 16 mg daily) or placebo for 5 weeks, and 67 were evaluated for 12 additional weeks on maximally tolerated doses of blinded study drugs. Treatment groups were evaluated with respect to symptoms of heart failure, indexes of quality of life and left ventricular function, frequency and type of arrhythmia, adverse events, and mortality rates. Doxazosin (11.9 +/- 0.9 mg) given once daily produced a favorable trend in the investigators' and patients' assessments of symptomatic change. Doxazosin was associated with a significantly higher level of voluntary submaximal exercise and a favorable trend on left ventricular ejection fraction (increase of 9.8% of the baseline value vs 2.7% with placebo; p = NS). During the 3-month steady-dosing period, patients treated with doxazosin had a significant (p less than 0.004) reduction in ventricular arrhythmias and significantly fewer morbid and mortal cardiac events (including episodes of worsening heart failure severe enough to prompt discontinuation of the study, myocardial infarction, and death). Doxazosin was well tolerated, producing no major side effects and only a slightly higher frequency of minor treatment-related side effects compared with placebo (p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Medical management of chronic heart failure: inotropic, vasodilator, or inodilator drugs?

On the basis of pathophysiologic mechanisms, the medical therapy of today for chronic heart failure is reviewed. The advantages and disadvantages of the vasodilator drugs and the inotropic drugs are presented. Finally, the therapeutic value of the inodilator drugs, which combine the central myocardial effects of positive inotropic agents with those of peripheral vasodilators, is discussed. In particular, the orally available dopaminergic agents, such as ibopamine, which interact with beta-receptors in the heart (mediating a positive inotropic effect) as well as with dopaminergic receptors in the peripheral vessels (mediating a systemic vasodilator effect) and in the kidneys (potentiating the natriuretic effect of diuresis), seem to be an advancement in the modern medical therapy of chronic heart failure. Data are shown during long-term treatment with ibopamine, in which the sustained clinical benefit in heart failure was not diminished, despite a decrease of the adrenergic receptors in blood cells. Dopamine plasma concentration was permanently normalized during long-term treatment. The discrepancy between clinical improvement and the measured adrenergic downregulation may be due to the interference of the inodilator with neurohormonal systems at multiple sites and is probably independent of receptor activation. It is suggested that the biosynthesis of noradrenaline is improved by increasing intracellular dopamine transport.

Vasodilator therapy without converting-enzyme inhibition in congestive heart failure--usefulness and limitations

Despite a well-established rationale for pharmacologically induced arterial and venous vasodilatation in congestive heart failure, the clinical usefulness of long-term vasodilator therapy without concomitant converting-enzyme inhibition generally has been disappointing. With the exception of nitrates and, possibly, the combination of nitrates and hydralazine, the use of converting-enzyme inhibitors in many aspects appears preferable in the majority of patients. This article reviews the pathophysiology of inappropriate vasoconstriction in heart failure, the cellular mode of action of the various vasodilators, hemodynamic effects with respect to the peripheral site of action, clinical usefulness and limitations of different vasodilators, and the various determinants of clinical efficacy. Finally, an attempt is made to assess when and how to introduce vasodilator treatment with and without concomitant ACE inhibition.

Effect of flosequinan on exercise capacity and symptoms in severe heart failure

Twenty patients with severe chronic cardiac failure caused by ischaemic heart disease were treated with flosequinan 100 mg daily or placebo in addition to their existing treatment with diuretics and, in some, digoxin in a randomised double blind trial. After eight weeks of treatment, flosequinan significantly improved treadmill exercise time, increased peak achieved oxygen consumption, and improved the New York Heart Association symptom grade when compared with placebo. One patient in the placebo group died and another was withdrawn because heart failure worsened. One patient in the flosequinan group was lost to follow up but there were no other withdrawals. Flosequinan was well tolerated with few adverse effects, and it may prove to be a useful addition to diuretics and digoxin in the treatment of chronic cardiac failure.

Vasodilator and inotropic drugs for the treatment of chronic heart failure: distinguishing hype from hope

During the past 10 years, more than 80 orally active vasodilator and inotropic agents have been tested in the clinical setting to evaluate their potential utility in the treatment of chronic heart failure. Although the initial reports of all of these drugs suggested that each represented a major therapeutic advance, only three agents--digoxin, captopril and enalapril--have produced consistent long-term hemodynamic and clinical benefits in these severely ill patients. Most of the other drugs that have been tested have not (to date) distinguished themselves from placebo therapy in large-scale, controlled trials, even though these agents produce hemodynamic effects that closely resemble those seen with digitalis and the converting-enzyme inhibitors. These observations suggest that the hemodynamic derangements that characteristically accompany the development of left ventricular dysfunction cannot be considered to be the most important pathophysiologic abnormality in chronic heart failure. Although cardiac contractility is usually depressed in this disease, positive inotropic agents do not consistently improve the clinical status of these patients. Similarly, although the systemic vessels are usually markedly constricted, drugs that ameliorate this vasoconstriction do not consistently relieve symptoms, enhance exercise capacity or prolong life. Hence, correction of the central hemodynamic abnormalities seen in heart failure may not necessarily provide a rational basis for drug development, and future advances in therapy are likely to evolve only by attempting to understand and modify the basic physiologic derangements in this disorder.

Effect of drug therapy on survival in chronic congestive heart failure

A review of the current evidence on the effects of various agents on survival among patients with congestive heart failure (CHF) suggests that angiotensin-converting enzyme inhibitors probably offer the greatest potential for benefit. Trials undertaken before the Cooperative North Scandinavian Enalapril Survival Study (CONSENSUS) revealed favorable trends among patients in New York Heart Association functional classes II to IV who received angiotensin-converting enzyme inhibitors. Data from CONSENSUS clearly demonstrate that enalapril reduces mortality rates among patients in New York Heart Association class IV, but conclusions regarding effects in patients with mild or moderate CHF must await the results of future studies. In contrast, the large data base on alpha-adrenergic blockers suggests that these drugs are not likely to improve survival. Information on inotropic agents is sparse, but it is possible that these drugs may not improve survival and, in fact, may have a harmful effect. Mortality data on CHF patients treated with beta blockers and calcium channel blockers are likewise limited; conclusions concerning effects on survival must be postponed until further studies are conducted. Many of the investigations undertaken thus far to examine survival in patients with CHF have been small and of short duration, so any comparisons of the effects of various drugs must be interpreted with caution.

The hypertensive patient with concomitant cardiovascular disease

Many drugs for the treatment of hypertension are available in the United States today. Of the various factors that determine the appropriate treatment for a particular patient, the presence of concomitant heart disease requires specific tailoring of the antihypertensive therapy. Coronary artery disease, aortic insufficiency, congestive heart failure, left ventricular hypertrophy, premature ventricular contractions, supraventricular arrhythmias, mitral valve prolapse, orthostatic hypotension, and aortic dissection are some of the conditions that influence the choice of treatment. Diabetes places hypertensive patients at increased risk of heart disease, and exercise and sexual function are other considerations that govern the selection of treatment for the hypertensive person. For all of these conditions, more than one drug choice is often possible, but usually hypertensive patients can be treated with a beta-blocker or a calcium channel blocker in these special circumstances.

Alpha-adrenergic blockers

alpha-Adrenergic blockers are important drugs in the treatment of hypertension and other cardiovascular and noncardiovascular disorders. The ability to selectively block alpha-receptor subtypes provides a greater margin of safety and efficacy for these drugs.

Hemodynamic correlates of left ventricular versus right ventricular radionuclide volumetric responses to vasodilator therapy in congestive heart failure secondary to ischemic or dilated cardiomyopathy

Previous studies have failed to demonstrate the clinical relevance of radionuclide functional measurements during treatment of congestive heart failure (CHF). In the present study, data derived before and during nitroprusside infusion were analyzed in 16 patients with CHF to compare correlations of changes in left (LV) and right ventricular (RV) radionuclide measurements with simultaneous changes in 8 hemodynamic variables. Nitroprusside infusion decreased systemic artery pressure, pulmonary arterial wedge pressure, pulmonary artery pressure, right atrial pressure, and pulmonary and systemic vascular resistance, and increased cardiac output. Nitroprusside decreased LV and RV end-diastolic and end-systolic volumes and increased LV and RV ejection fraction and stroke volume. Changes in RV volumes exceeded changes in LV volumes. LV radionuclide measurements did not correlate significantly with any hemodynamic measurement except for a weak correlation between changes in LV end-systolic volume and right atrial pressure (r = 0.51). In contrast, the combination of changes in RV end-systolic volume and stroke volume predicted changes in pulmonary artery peak systolic (r = 0.90) and mean (r = 0.89) pressures. Changes in pulmonary arterial wedge pressure correlated with changes in RV end-diastolic (r = 0.78) and end-systolic (r = 0.71) volumes. In conclusion, LV radionuclide measurements are of limited value in predicting hemodynamic responses to vasodilator therapy in CHF, whereas RV volumes are strongly influenced by load changes. Their responses to nitroprusside correlate well with changes in pulmonary artery and pulmonary arterial wedge pressures.

Contribution of the renin-angiotensin-aldosterone system to development of tolerance and fluid retention in chronic congestive heart failure during prazosin treatment

To determine the effects of the renin-angiotensin-aldosterone system on development of tolerance and fluid retention in patients with chronic congestive heart failure during long-term prazosin treatment, plasma renin concentration, aldosterone, norepinephrine and maximal exercise tolerance were measured during chronic therapy with digitalis and diuretics, to which prazosin, captopril or a combination of both drugs was added. Plasma renin concentration and aldosterone level decreased slightly during prazosin therapy and norepinephrine level increased significantly. When captopril was given, plasma renin concentration increased as expected, aldosterone level normalized and norepinephrine level decreased significantly. When prazosin was added to captopril therapy, norepinephrine level increased and plasma renin concentration and aldosterone level did not change. Exercise capacity did not increase during prazosin treatment, but was increased with captopril treatment. Prazosin treatment was associated with an increase in body weight even though the dose of furosemide was increased. Inhibition of the renin-angiotensin system did not prevent fluid retention induced by prazosin during combination therapy. These findings suggest that the renin-angiotensin-aldosterone system is not substantially involved in development of tolerance and fluid retention during prazosin therapy; stimulation of plasma norepinephrine may be of decisive importance.

Contribution of reduced mitral regurgitant volume to vasodilator effect in severe left ventricular failure secondary to coronary artery disease or idiopathic dilated cardiomyopathy

Although vasodilators improve cardiac output in severe left ventricular (LV) failure, the degree to which reduction in mitral regurgitation (MR) contributes to this response is unknown. In the present study, nitroprusside-induced changes in forward cardiac output were compared with simultaneous radionuclide LV output in 14 patients with severe LV systolic dysfunction in the absence of known primary valvular disease. Regurgitant output was estimated as LV output minus forward output and regurgitant fraction was calculated as regurgitant output/LV output. At rest, LV ejection fraction averaged 0.16 +/- 0.04 (mean +/- standard deviation). Patients were classified into 2 groups based on regurgitant fraction at rest. Group I (n = 5) had little or no detectable valvular regurgitation, with regurgitant fraction less than 0.10; group II (n = 9) had evidence of MR with regurgitant fraction greater than 0.30. Nitroprusside increased forward cardiac output in all patients in both groups, but this effect was significantly greater in group II (64 +/- 34%) than in group I (31 +/- 17%) (p less than 0.01). Nitroprusside decreased regurgitant fraction in all group II patients, with mean regurgitant fraction decreasing from 0.44 +/- 0.12 to 0.26 +/- 0.15 (p less than 0.005). Thus, a large percentage of patients with severe LV systolic dysfunction have clinically relevant MR, defined as a regurgitant fraction greater than 0.30. Nitroprusside has a greater effect on forward cardiac output in patients with LV failure and MR than in patients with comparable ventricular dysfunction in the absence of detectable MR.(ABSTRACT TRUNCATED AT 250 WORDS)

Congestive heart failure

A review of the epidemiology, pathophysiology, and treatment of congestive heart failure is presented, with particular attention given to newer modalities of therapy.

Effect of vasodilator therapy on mortality in chronic congestive heart failure. Results of a Veterans Administration Cooperative Study

To evaluate the effects of vasodilator therapy on mortality among patients with chronic congestive heart failure, we randomly assigned 642 men with impaired cardiac function and reduced exercise tolerance who were taking digoxin and a diuretic to receive additional double-blind treatment with placebo, prazosin (20 mg per day), or the combination of hydralazine (300 mg per day) and isosorbide dinitrate (160 mg per day). Follow-up averaged 2.3 years (range, 6 months to 5.7 years). Mortality over the entire follow-up period was lower in the group that received hydralazine and isosorbide dinitrate than in the placebo group. This difference was of borderline statistical significance. For mortality by two years, a major end point specified in the protocol, the risk reduction among patients treated with both hydralazine and isosorbide dinitrate was 34 percent (P less than 0.028). The cumulative mortality rates at two years were 25.6 percent in the hydralazine--isosorbide dinitrate group and 34.3 percent in the placebo group; at three years, the mortality rate was 36.2 percent versus 46.9 percent. The mortality-risk reduction in the group treated with hydralazine and isosorbide dinitrate was 36 percent by three years. The mortality in the prazosin group was similar to that in the placebo group. Left ventricular ejection fraction (measured sequentially) rose significantly at eight weeks and at one year in the group treated with hydralazine and isosorbide dinitrate but not in the placebo or prazosin groups. Our data suggest that the addition of hydralazine and isosorbide dinitrate to the therapeutic regimen of digoxin and diuretics in patients with chronic congestive heart failure can have a favorable effect on left ventricular function and mortality.

Comparative hemodynamic and clinical effects of long-term treatment with prazosin and captopril for severe chronic congestive heart failure secondary to coronary artery disease or idiopathic dilated cardiomyopathy

Short- and long-term hemodynamic and clinical responses to sequential therapy with prazosin (15 mg/day for 3 to 12 weeks) and captopril (75 to 300 mg/day for 2 to 15 weeks) were compared in 22 patients with severe chronic congestive heart failure. First doses of prazosin produced marked increases in cardiac index and stroke volume index (p less than 0.01), but these effects were lost during long-term treatment. First doses of captopril produced only modest increases in both variables, but these persisted without attenuation during prolonged therapy. Both drugs produced immediate decreases in left ventricular filling pressure, mean arterial pressure, mean right atrial pressure and systemic vascular resistance; these changes became significantly attenuated (p less than 0.01) with prazosin but not with captopril. At the end of treatment, stroke volume index was significantly higher and right and left ventricular filling pressures were significantly lower with captopril than with prazosin (p less than 0.05 to 0.01). Only 8 of the 22 patients (36%) treated with prazosin benefited clinically, whereas 14 of 19 patients (74%) treated with captopril felt that they had improved (p less than 0.05). These differences could not have been predicted by comparing responses to first doses of the 2 drugs. These findings indicate that the choice of 1 vasodilator drug over another in patients with congestive heart failure should be based on studies that compare their long-term rather than short-term hemodynamic and clinical effects.

Chronic afterload reduction in infants and children with primary myocardial disease

The purpose of this study was to determine the long-term effects of chronic afterload reduction with oral hydralazine therapy in patients with primary myocardial disease (PMD). Twenty-six children aged 3 to 48 months with the diagnosis confirmed by M-mode and two-dimensional echocardiograms and angiograms were given digitalis and diuretics. Fourteen of these patients also received hydralazine orally in doses up to 4.0 mg/kg/day in four divided doses. Echocardiograms were initially repeated at 1- to 3-month intervals and subsequently at 6-month intervals. Long-term follow-up data were available in 10 patients given hydralazine and eight control patients; the follow-up interval ranged from 3 to 48 months. In the hydralazine group the shortening fraction rose from 14.5 +/- 4.9 to 23.2 +/- 7.5 (P less than 0.01), and the ratio of pre-ejection period to ejection time (0.52 +/- 0.05 to 0.35 +/- 0.06, P less than 0.001) and left ventricular size, normalized to body surface area (116 +/- 7 to 87 +/- 21, P less than 0.01), decreased. Significant improvement was demonstrated by echocardiography after 12 months of hydralazine therapy. There was no significant change in any of these values in the control group. We conclude that hydralazine therapy is a useful adjunct in the management of primary myocardial disease in infancy and childhood.

Role of the renin-angiotensin system in the development of hemodynamic and clinical tolerance to long-term prazosin therapy in patients with severe chronic heart failure

Right heart catheterization was performed before and during long-term therapy with prazosin in 27 patients with severe chronic heart failure who underwent serial hemodynamic studies during 3 to 12 weeks of treatment with the drug. Doses of digoxin and furosemide remained constant during the trial; in addition, 11 of the 27 patients were assigned to concomitant therapy with spironolactone, while the remaining 16 patients did not receive the aldosterone antagonist. First doses of prazosin produced marked increases in cardiac index and marked decreases in mean arterial pressure, left ventricular filling pressure and systemic vascular resistance in both groups of patients (all p less than 0.01), but these effects became rapidly attenuated (p less than 0.01) in both groups after 48 hours and remained attenuated during long-term therapy. After 3 to 12 weeks, values for cardiac index returned to pretreatment levels and did not decrease when the drug was withdrawn; values for mean arterial pressure, left ventricular filling pressure and systemic vascular resistance remained significantly decreased (although attenuated) after 3 to 12 weeks (p less than 0.01) and increased to pretreatment values when the drug was withdrawn. The magnitude and time course of these responses were not altered by concomitant therapy with spironolactone. Complete loss of hemodynamic efficacy (prazosin tolerance) was noted in 14 (58%) of the 24 patients who underwent long-term hemodynamic study and was not accompanied by long-term changes in plasma renin activity or body weight. These data indicate that prazosin produces long-term hemodynamic and clinical benefits in only 30 to 40% of patients with severe chronic heart failure and do not support a role for the renin-angiotensin system in the development of tolerance to alpha-adrenergic blockade. This low response rate explains why most randomized double-blind trials of prazosin in heart failure have not been able to demonstrate a significant difference between patients treated with placebo and those receiving active drug.

Differential long-term intrarenal and neurohormonal effects of captopril and prazosin in patients with chronic congestive heart failure: importance of initial plasma renin activity

Fifty patients with congestive heart failure received, by infusion, 15 ml/kg body weight water load, and systemic hemodynamic, renal function, and neurohumoral parameters values were measured before, 2 days, and 1 month after randomly allocating patients to prazosin or captopril therapy. Both prazosin and captopril caused similar and persistent hemodynamic changes, but important differences existed between their renal and neurohumoral effects. After 1 month of continuous therapy, captopril increased creatinine clearance from 71 to 84 ml/min/1.73(2) (p less than .05), increased the water load excreted in 5 hr from 50% to 71% (p less than .005), and increased 5 hr sodium excreted from 6.8 to 14.7 meq (p less than .005), Captopril also caused a decrease in plasma norepinephrine from 568 to 448 pg/ml (p less than .005), in plasma epinephrine from 94 to 73 pg/ml (p less than .05), and in plasma aldosterone from 57 to 28 ng/dl (p less than .005), without changing plasma vasopressin. These beneficial effects were greater after 1 month of therapy than after 2 days. The only beneficial effect of prazosin was to increase water excretion from 49% to 59% (p less than .05). The long-term response to captopril was similar in patients with higher (greater than 2.5 ng/ml/hr) and lower renin levels. However, in patients with lower renin levels, prazosin decreased pulmonary capillary wedge pressure (24.8 to 21.8 mm Hg, p less than .05), decreased plasma arginine vasopressin (1.16 to 0.75 pg/ml, p less than .05), increased water excretion (62% to 85%, p less than .005), and decreased plasma epinephrine (81 to 46 pg/ml, p less than .05), while in patients with higher renin levels none of these beneficial effects were noted. We conclude that captopril produces long-term beneficial renal and neurohumoral effects that prazosin does not despite similar hemodynamic changes with the two drugs, that these effects are at least partially dependent on the initial neurohumoral and hemodynamic status of the patient, and that through hemodynamic improvement vasodilators may chronically interrupt vasopressin overstimulation.

Vasodilator therapy

Vasodilators are a group of drugs with various degrees of arteriolar or venous dilatation used in the treatment of congestive heart failure when symptoms persist after digoxin and diuretic therapy. Nitrates and captopril provide the most consistent improvement in symptoms. Reduced mortality rates in congestive heart failure with vasodilator therapy has not been demonstrated, and prediction of clinical response to therapy is difficult.