How should we judge the efficacy of drug therapy in patients with chronic congestive heart failure? The insights of six blind men

The Role of Sodium-Glucose Cotransporter-2 Inhibitors in Heart Failure Management: The Continuing Challenge of Clinical Outcome Endpoints in Heart Failure Trials

The introduction of sodium-glucose cotransporter-2 (SGLT2) inhibitors in the management of heart failure with preserved ejection fraction (HFpEF) may be regarded as the first effective treatment in these patients. However, this proposition must be evaluated from the perspective of the complexity of clinical outcome endpoints in heart failure. The major goals of heart failure treatment have been categorized as: (1) reduction in (cardiovascular) mortality, (2) prevention of recurrent hospitalizations due to worsening heart failure, and (3) improvement in clinical status, functional capacity, and quality of life. The use of the composite primary endpoint of cardiovascular death and hospitalization for heart failure in SGLT2 inhibitor HFpEF trials flowed from the assumption that hospitalization for heart failure is a proxy for subsequent cardiovascular death. The use of this composite endpoint was not justified since the effect of the intervention on both components was clearly distinct. Moreover, the lack of convincing and clinically meaningful effects of SGLT2 inhibitors on metrics of heart failure-related health status indicates that the effect of this class of drugs in HFpEF patients is essentially restricted to an effect on hospitalization for heart failure. In conclusion, SGLT2 inhibitors do not represent a substantial breakthrough in the management of HFpEF.

Conceptual framework for health-related quality of life assessment in acute gastroenteritis

BACKGROUND AND OBJECTIVES

To date, most trials in pediatric acute gastroenteritis have evaluated short-term clinical disease activity (eg, duration of diarrhea or vomiting, level of dehydration), laboratory outcomes (eg, rotavirus, norovirus), or a composite of these outcomes. Measuring health-related quality of life may also be important in evaluating the effect of interventions for acute gastroenteritis in children. The objectives of this study were to conduct individual interviews and, when possible, focus group discussions, with parents of children with acute gastroenteritis; to determine how parent and child quality of life is negatively affected by acute gastroenteritis; and, from the perspective of parents and children, to develop a conceptual framework for quality of life instrument specific to pediatric acute gastroenteritis.

METHODS

We conducted interviews and focus groups with parents of children (3 months-5 years of age) given a diagnosis of gastroenteritis in a hospital emergency department. Interviews and focus groups were conducted to determine the effect of gastroenteritis on quality of life in parents and children (as perceived by the parents).

RESULTS

Interviews and focus groups involving 25 parents suggested a conceptual framework that, for children, includes 2 domains (physical and emotional function) and 14 subdomains. For parents, our framework includes 3 domains (physical, emotional, and social function) with physical function including 4 subdomains, emotional function including 7 subdomains, and social function including 2 subdomains. The framework has been used to develop a preliminary quality of life questionnaire for parents and children.

CONCLUSIONS

Acute gastroenteritis has an important adverse effect on health-related quality in both children and parents involving physical symptoms and restrictions in physical function and disturbed emotional function. Upon further research on the psychometric properties of the proposed questionnaires, future trials of effectiveness should consider measuring patient important outcomes such as health-related quality of life.

Selection of endpoints for heart failure clinical trials

In assessing the efficacy and the safety of a new drug, randomized clinical trials represent the standard scientific method. The selection of the best response variables in a clinical trial of a treatment in congestive heart failure patients is often not straightforward; the primary end point of a trial should be clinically relevant, directly related to the primary goal of the trial, and with favorable distributional properties. All-cause mortality is undoubtedly the most unbiased endpoint, but there is interest both in assessing cause-specific mortality and hospitalization rate and in evaluating 'soft' endpoints (functional status, exercise tolerance); the latter, in fact, are clinically relevant and potentially more useful in mild heart failure patients. Physiopathologic variables (e.g. left ventricular function) could provide information on drug action mechanism. In this paper, several recent large clinical trials are reviewed and the advantages and drawbacks of the response variables used, are analyzed.

Proposal for a new clinical end point to evaluate the efficacy of drugs and devices in the treatment of chronic heart failure

Clinical trials designed to evaluate the effect of drugs and devices on the symptoms and clinical status in chronic heart failure have frequently produced conflicting, inconclusive, or misleading results. These difficulties can be explained by the fact that previous studies have relied on efficacy measures that have inherent limitations and have been analyzed using statistical approaches that ignored episodes of clinical deterioration. Recognition of these pitfalls has led to the development of a new clinical composite score, which combines changes in the New York Heart Association class and the global assessment together with the information provided from the occurrence of major clinical events. Use of this score would have correctly distinguished active therapy from placebo in earlier trials and thus would have avoided some of their misleading conclusions. The new clinical composite score has been prospectively incorporated into the design of studies evaluating the efficacy of endothelin antagonists, cytokine antagonists, vasopressin antagonists, and cardiac resynchronization in the treatment of chronic heart failure. In the trials that have been completed to date, the clinical composite score has been more sensitive than conventional approaches in discerning the presence or absence of a true treatment effect.

Responses to constant work rate bicycle ergometry exercise in primary pulmonary hypertension: the effect of inhaled nitric oxide

OBJECTIVES

The purpose of this study was to investigate the responses of patients with primary pulmonary hypertension (PPH) to constant work rate exercise and to examine the effect of nitric oxide (NO) inhalation.

BACKGROUND

Maximal exercise tolerance is reduced in PPH, but gas exchange responses to constant work rate exercise have not been defined. We hypothesized that increased pulmonary vascular resistance in PPH would reduce the rate of rise of minute oxygen consumption in response to a given work rate. Because NO may lower pulmonary vascular pressures in PPH, we also postulated that inhaled NO might ameliorate gas exchange abnormalities.

METHODS

Nine PPH patients and nine matched normal subjects performed 6-min duration constant work rate cycle ergometry exercise (33.9+/-13.4 W). Patients performed two experiments: breathing air and breathing air with NO (20 ppm). Preexercise right ventricular systolic pressure was assessed by Doppler echocardiography. Normal subjects performed the air experiment only. Gas exchange and heart rate responses were characterized by fitting monoexponential curves.

RESULTS

In PPH patients, resting right ventricular systolic pressure fell after NO inhalation (from 83.8+/-16.9 to 73.9+/-21.6 mm Hg, p<0.01, analysis of variance with Tukey correction), but not after breathing air alone (from 88.0+/-20.8 to 86.7+/-20.6 mm Hg, p = NS). Nitric oxide did not affect any of the gas exchange responses. Minute oxygen consumption was similar by the end of exercise in patients and normals, but increased more slowly in patients (mean response time [MRT]: air, 63.17+/-14.99 s; NO, 61.60+/-15.45 s) than normals (MRT, 32.73+/-14.79, p<0.01, analysis of variance, Tukey test). Minute oxygen consumption kinetics during recovery were slower in patients (MRT air: 82.50+/-29.94 s; NO, 73.36+/-15.87 s) than in normals (MRT, 34.59+/-7.11 s, p<0.01). Heart rate kinetics during exercise and recovery were significantly slower in patients than in normals.

CONCLUSIONS

The cardiac output response is impaired in PPH. Nitric oxide lowered pulmonary artery pressure at rest, but failed to improve exercise gas exchange responses.

The effect of specific inspiratory muscle training on the sensation of dyspnea and exercise tolerance in patients with congestive heart failure

BACKGROUND

It has been previously shown that the inspiratory muscles of patients with congestive heart failure (CHF) are weaker than those of normal persons. This weakness may contribute to the dyspnea and limit exercise capacity in these patients. The respiratory muscles can be trained for both strength and endurance.

HYPOTHESIS

The present study was designed to evaluate the effect of specific inspiratory muscle training (SIMT) on inspiratory muscle performance, lung function, dyspnea, and exercise capacity in patients with moderate heart failure.

METHODS

Twenty patients with CHF (NYHA functional class II-III) were recruited for the study. The subjects were randomized into two groups: 10 patients were included in the study group and received SIMT and 10 patients were assigned to the control group and received sham training. Subjects in both groups trained daily, 6 times/week, for one-half h, for 3 months. The subjects started breathing at a resistance equal to 15% of their PImax for 1 week and the resistance was then increased incrementally to 60%. Spirometry, inspiratory muscle strength (assessed by measuring the PImax at residual volume), and endurance (expressed by the relationship between PmPeak and PImax), the 12-min walk test, and peak VO2 were performed before the beginning and at the end of the training period.

RESULTS

All patients in the training group showed an increase in the inspiratory muscle strength [mean (+/- standard error of the mean) PImax increased from 46.5 +/- 4.7 to 63.6 +/- 4.0 cm H2O, p < 0.005], and endurance (mean PmPeak/PImax from 47.8 +/- 3.6 to 67.7 +/- 1.7%, p < 0.05), while they remained unchanged in the control group. This was associated in the training group with a small but significant increase in forced vital capacity, a significant increase in the distance walked (458 +/- 29 to 562 +/- 32 m, p < 0.01), and an improvement in the dyspnea index score. No statistically significant change in the mean peak VO2 was noted in either group.

CONCLUSIONS

Specific inspiratory muscle training resulted in increased inspiratory muscle strength and endurance. This increase was associated with decreased dyspnea, increase in submaximal exercise capacity, and no change in maximal exercise capacity. This training may probe to be a complementary therapy in patients with congestive heart failure.

Extraction of human alpha atrial natriuretic peptide and its physiological validation

A very sensitive and specific radioimmunoassay for human alpha atrial natriuretic peptide (hANP) and a novel extraction method for hANP, have been developed. Antiserum to hANP showed no cross-reactivity with related analogues (e.g., brain natriuretic peptide). The radioimmunoassay can detect 1.2 fmol ANP/assay tube. Using a commercially available tracer, the antiserum binds 0.7 fmol of radioligand at a final dilution of 1:96,000. Production of ANP tracer, using 125I, Iodogen and reversed-phase HPLC separation, produces two products. The first has identical properties to the commercial reagent resulting in an identical antibody titre. The second, however, is more reactive with the antiserum which can be employed at a final dilution of 1:192K. These products represent oxidised and reduced peptides, respectively, inferring that the commercial tracer is oxidised. The recovery of synthetic hANP from plasma over the range of 0-1000 ng/l through Sep-Pak C18 cartridges, using an extraction method of acetic acid-acetonitrile (4:96) was 89%. Inter- and intra-assay coefficients of variation were 9.5% and 8.2%, respectively. The radioimmunoassay was validated in man by measuring plasma ANP (ng/l) following change of posture and exercise in normal man. Plasma ANP rose from 13.2 (1.0; S.D.) to 20.1 (1.6) from supine to sitting position. Plasma ANP increased to 20.1 (1.6) at rest (sitting) to 34 (2.7) ng/l at peak of exercise, but decreased from 31.2 (2.5) to 21.4 (0.1) ng/l at 3 and 6 min after exercise, respectively. These results confirm that the assay is capable of differentiating changes of concentrations within the physiological range.

Improvement in the mechanical efficiency of walking: an explanation for the "placebo effect" seen during repeated exercise testing of patients with heart failure. Duke University Clinical Cardiology Studies (DUCCS) Exercise Group

To determine the mechanism responsible for the "placebo effect" seen during serial exercise testing of patients with heart failure, we examined metabolic variables for 81 patients who underwent five baseline exercise tests as part of a multicenter drug trial. The patients were 50 men and 31 women with a mean ejection fraction of 30.1% and a mean age of 69 years. From test 1 to 2, the exercise time increased from 419 +/- 140 to 462 +/- 130 seconds before it reached a plateau over the next three tests. Metabolic measurements at test 1 and test 3 revealed no change in peak oxygen consumption ( 1119 +/- 376 to 1105 +/- 346 ml/min). Maximum heart rate, systolic blood pressure, ventilation, and respiratory exchange ratio also were unchanged. The onset of the anaerobic threshold was delayed from 211 +/- 81 to 238 +/- 93 seconds, but there was no change in oxygen consumption at the anaerobic threshold (810 +/- 222 to 795 +/- 220 ml/min). At a predetermined submaximal level, oxygen consumption, ventilation, and respiratory exchange ratio all decreased to a statistically significant degree. These results indicate that a rapid increase in the mechanical efficiency of walking contributes to the placebo effect among patients with heart failure during serial exercise testing and is independent of changes in conditioning or motivation.

Plasma N-terminal atrial natriuretic factor: a predictor of survival in patients with congestive heart failure

BACKGROUND

Congestive heart failure results in biatrial stretch, which stimulates myocyte release of atrial natriuretic factor (1-126). The N-terminal fragment, proatrial natriuretic factor(1-98), (proANF), is released on an equimolar basis with the C-terminal (99-126) active hormone and may be assayed simply because of prolonged in vitro stability. Proatrial natriuretic factor has been shown to be predictive of clinical status in patients with congestive heart failure. This retrospective analysis was undertaken to evaluate the relationship between N-terminal atrial natriuretic factor(1-98) and survival in patients with stable congestive heart failure.

METHODS AND RESULTS

Proatrial natriuretic factor was sampled from 316 patients (mean age, 68 (+/-) 11 years; 71% men) recruited from an outpatient heart failure clinic. The mean ejection fraction was 34 (+/-) 13%. Seventy-three deaths were registered during the period of data collection (42 months). Deaths per proANF quartile (n = 79) were as follows: 2 (2.5%) in quartile I. 13 (16.5%) in quartile II, 21 (26.6%) in quartile III, and 37 (46.8%) in quartile IV. The odds ratio estimates for death adjusted for age and sex were 7.6, 13.9, and 33.9 for the second, third, and fourth quartiles, respectively. Survival curves constructed according to proANF quartiles demonstrate significant differences in mortality rates. The correlation with death was greater for proANF as compared with left ventricular end-diastolic diameter (P < .001), systolic pulmonary artery pressure (P < .005), or ejection fraction (P < .05).

CONCLUSION

These data indicate that the concentration of proANF is related to prognosis in patients with heart failure and that moderate elevation is associated with markedly decreased survival. Analysis should be of practical value in the assessment of prognosis in this heterogeneous population.

Outcomes for older men and women with congestive heart failure

OBJECTIVES

To describe and compare outcomes for men and women discharged alive following a hospitalization for congestive heart failure (CHF).

DESIGN

Prospective cohort study.

PARTICIPANTS

A total of 519 patients, aged > or = 65, who were discharged alive after a hospitalization for CHF (DRG = 127).

MEASUREMENTS

Outcomes (Activities of Daily Living (ADLs), shortness of breath when walking, perceived health, living situation, rehospitalization, and mortality) were measured at 3 times (6 weeks, 6 months, and 1 year) post-discharge.

RESULTS

The 205 men were, on average, younger (77 +/- 7 vs 80 +/- 8, P < .001), wealthier (46% vs 21% earned > or = $10,000, P < .001), and more often married (50% vs 19%, P < .001). Men were more likely than women to have a previous history of CHF (71% vs 63%, P = .052). Men also had higher 1-year mortality than women (48% vs 35%, P = .009), even after adjusting for age, comorbidity, physiological severity (APACHE II APS and RAND discharge instability), radiological evidence of CHF, prior ADLs, walking ability, living situation, and perceived health. Men and women survivors at 1-year had similar and substantial impairment for all non-fatal outcomes considered (all P values > or = .489). Their adjusted mean ADL scores were consistent with complete dependence on one essential activity (range 0-6 dependencies); 35% were short of breath walking less than 1 block; 62% had fair or poor perceived health; 32% received some formal care; and 46% were rehospitalized within 1 year of discharge.

CONCLUSIONS

Men with CHF have a higher mortality than women with CHF. Men and women who survive have similar and substantial impairment for all non-fatal outcomes (ADLs, shortness of breath upon walking, perceived health, living situation, and rehospitalization).

An open, parallel group comparison of quinapril and captopril, when added to diuretic therapy, in the treatment of elderly patients with heart failure

This study aimed to compare the efficacy, tolerability and first-dose blood-pressure response of once-daily quinapril and twice-daily captopril when added to diuretic therapy in elderly patients with heart failure. The study was performed at a single centre as an open randomised parallel-group study, patients being selected for inclusion from the outpatient population. Following a starting dose of either 2.5 mg once-daily quinapril, or 6.25 mg twice-daily captopril, patients were reviewed at two-weekly intervals, and following clinical assessment a decision was made either to titrate up to the next medication stage or to enter the patient into the 16-week maintenance phase. Efficacy was assessed using a six-minute walking test, the New York Heart Association (NYHA) class, a functional lifescale (FLS) questionnaire and the cardiothoracic ratio (CTR)-at study entry and at the end of the maintenance phase. Blood pressure was measured for 5 h post-first-dose of medication. Sixty-one patients were randomised to treatment: 30 to quinapril and 31 to captopril. Following withdrawals, data from 36 patients (20 on quinapril, 16 on captopril) were available for analysis. The distance walked during the six-minute walking test improved in both groups; the difference between the treatment groups was not statistically significant. There were no significant changes in the FLS or CTR. An analysis of change in the NYHA status from study entry to study end showed a statistically significant difference between the two groups (p = 0.02) in favour of quinapril. Five patients in each group experienced hypotension during the 5 h following the first dose of medication. This study has shown heart failure to be as well controlled by once-daily quinapril as by twice-daily captopril, with comparable effects on first-dose blood-pressure response.

Double-blind, placebo-controlled study of the effects of carvedilol in patients with moderate to severe heart failure. The PRECISE Trial. Prospective Randomized Evaluation of Carvedilol on Symptoms and Exercise

BACKGROUND

Carvedilol has improved the symptomatic status of patients with moderate to severe heart failure in single-center studies, but its clinical effects have not been evaluated in large, multicenter trials.

METHODS AND RESULTS

We enrolled 278 patients with moderate to severe heart failure (6-minute walk distance, 150 to 450 m) and a left ventricular ejection fraction < or = 0.35 at 31 centers. After an open-label, run-in period, each patient was randomly assigned (double-blind) to either placebo (n = 145) or carvedilol (n = 133; target dose, 25 to 50 mg BID) for 6 months, while background therapy with digoxin, diuretics, and an ACE inhibitor remained constant. Compared with placebo, patients in the carvedilol group had a greater frequency of symptomatic improvement and lower risk of clinical deterioration, as evaluated by changes in the NYHA functional class (P = .014) or by a global assessment of progress judged either by the patient (P = .002) or by the physician (P < .001). In addition, treatment with carvedilol was associated with a significant increase in ejection fraction (P < .001) and a significant decrease in the combined risk of morbidity and mortality (P = .029). In contrast, carvedilol therapy had little effect on indirect measures of patient benefit, including changes in exercise tolerance or quality-of-life scores. The effects of the drug were similar in patients with ischemic heart disease or idiopathic dilated cardiomyopathy as the cause of heart failure.

CONCLUSIONS

These findings indicate that, in addition to its favorable effects on survival, carvedilol produces important clinical benefits in patients with moderate to severe heart failure treated with digoxin, diuretics, and an ACE inhibitor.

HCFA's health care quality improvement program: the medical informatics challenge

The peer-review organizations (PROs) were created by Congress in 1984 to monitor the cost and quality of care received by Medicare beneficiaries. In order to do this, the Health Care Financing Administration (HCFA) contracted with the PROs through a series of contracts referred to as "Scopes of Work." Under the Fourth Scope of Work, the HCFA initiated the Health Care Quality Improvement Program (HCQIP) in 1990, as an application of the principles of continuous quality improvement. Since then, the PROs have participated with health care providers in cooperative projects to improve the quality of primarily inpatient care provided to Medicare beneficiaries. Through HCFA-supplied administrative data and clinical data abstracted from patient records, the PROs have been able to identify opportunities for improvements in patient care. In May 1995, the HCFA proposed a new Fifth Scope of Work, which will shift the focus of HCQIP from inpatient care projects to projects in outpatient and managed care settings. This article describes the HCQIP process, the types of data used by the PROs to conduct cooperative projects with health care providers, and the informatics challenges in improving the quality of care received by Medicare beneficiaries.

Plasma proatrial natriuretic factor is predictive of clinical status in patients with congestive heart failure

Atrial stretch results in myocyte release of the prohormone atrial natriuretic factor (1-126). The N-terminal (1-98) fragment, proatrial natriuretic factor (proANF) is released on an equimolar basis with the C-terminal (99-126) active hormone and may be assayed simply due to in vitro stability. This study was undertaken to evaluate the relation between proANF and routinely available measures of clinical status. ProANF was sampled from 202 patients (median age 68 years [range 15 to 85], 77% men) recruited from an active outpatient heart failure clinic. Patients were subgrouped according to New York Heart Association functional class, radionuclide ejection fraction (EF), echocardiographic left ventricular (LV) end-diastolic diameter, and Doppler-determined systolic pulmonary arterial pressure. The median proANF (pmol/L) values for patients in New York Heart Association classes I, II, III, IV were 725, 1,527, 1,750, and 5,172, respectively. The proANF value for the group with EF > 40% was 1,534 versus 1,993 for EF < or = 40% (p < 0.05). The value for the group with LV diameter < 60 mm ws 838 versus 1,751 for LV diameter > or = 60 mm (p < 0.01). The value for the group with systolic pulmonary artery pressure < 45 mm Hg was 1,241 versus 2,660 for systolic pulmonary artery pressure > or = 45 mm Hg (p < 0.01). ProANF correlated better than the other variables with New York Heart Association functional class and was more closely associated with noninvasive measurements than New York Heart Association functional class.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical efficacy of ibopamine in patients with chronic heart failure

Ibopamine, the most widely studied dopaminergic drug for the treatment of chronic heart failure, appears to have beneficial hemodynamic, renal, and neurohormonal effects in this setting. Angiotension-converting enzyme (ACE) inhibitors have become the recommended standard treatment for chronic heart failure; however, some patients may benefit from additional drugs to improve their symptoms and functional capacity. Ibopamine may be effective as an additive drug for patients with chronic heart failure. It is also possible that ibopamine will improve survival in these patients. Large-scale trials are needed to assess the effects on morbidity and mortality when ibopamine is added to ACE inhibitors, diuretics, and possibly digitalis.

Making judgements about treatment effectiveness based on health outcomes: theoretical and practical issues

ISSUES

This article considers the problem of deciding which health care outcomes are important and relevant for (1) developing management recommendations for clinical practice guidelines and (2) evaluating patients' responses to treatment.

DECISIONS

The Heart Failure Guideline Panel sponsored by the Agency for Health Care Policy and Research (AHCPR) decided that for both purposes the relevant outcomes are those experienced directly by patients: mortality and health-related quality of life (HRQOL). Changes in intermediate outcomes, such as test results of various kinds, were deemed insufficient evidence of effectiveness.

CONCLUSIONS

In the context of heart failure, mortality risk (prognosis) can be measured using a variety of biochemical and physiological variables, but changes in these variables do not appear to correspond to changes in prognosis. For this reason, the Heart Failure Guideline Panel recommended that patients' responses to treatment be guided by signs and symptoms, rather than test results (for example, echocardiographic measurement of left-ventricular function or exercise-tolerance testing). HRQOL is best assessed by direct patient self-reports. Although patients may be influenced by a host of other variables (for example, mood, adaptation to chronic disease, placebo effect), self-reports will probably always represent the "gold standard" in assessing HRQOL. The reliability and validity of these reports can be enhanced by using standardized instruments or by incorporating questions from such instruments into the history-taking aspect of patient evaluation and monitoring. Finally, physical examination and submaximal exercise testing can provide additional information that can supplement patient reports. Information from these sources must be evaluated carefully in light of patients' self-reported HRQOL.

Long-term iloprost infusion therapy for severe pulmonary hypertension in patients with connective tissue diseases

OBJECTIVE

To determine the effects of short-term, maximum-tolerated-dose and long-term, optimum-dose iloprost treatment of severe pulmonary hypertension associated with systemic sclerosis (SSc) and the primary antiphospholipid syndrome (APS).

METHODS

Three patients with SSc and 2 with APS who had failed to respond to oral vasodilator therapy for pulmonary hypertension were enrolled in a 32-week, open, prospective trial. Short-term infusion of maximum-tolerated doses and continuous infusion of optimum doses of iloprost were carried out following baseline cardiac catheterization. Catheterization was repeated at 2 and 32 weeks. All 5 patients completed the study and continued therapy for an average of 82 weeks (range 58-103).

RESULTS

Acute infusion of maximum tolerated doses significantly ameliorated the cardiac index (0.92 liters/minute/m2; P < 0.01), pulmonary artery O2 saturation (10.6%; P < 0.05), and pulmonary resistance (-6.7 units; P < 0.05). After 2 weeks of continuous infusion of optimum doses, there was improvement in pulmonary resistance (> or = 16%) and pulmonary artery O2 saturation (> 30%) in the 2 patients with primary APS. After 2 and 32 weeks, the 3 SSc patients showed variable hemodynamic responses. New York Heart Association functional class and exercise tolerance improved in all patients. There was 1 episode of bacteremia, and 1 patient died after 72 weeks of study.

CONCLUSION

Continuous iloprost infusion may improve exercise tolerance and quality of life in patients with severe pulmonary hypertension associated with SSc and primary APS.

Exercise testing in heart failure. A critical review

Exercise intolerance is one of the primary characteristics of chronic congestive heart failure (CHF). Therefore, exercise testing has been widely used in the assessment of CHF patients, both to define the severity of the disease and to assess the efficacy of pharmaceutical agents in clinical trials. A number of different exercise tests can be used, although maximal exercise testing is the most common. Maximal exercise capacity can be determined by measuring exercise duration during incremental exercise, or maximal oxygen (O2) consumption, or it can be estimated by anaerobic threshold. While baseline exercise testing in CHF patients accurately identifies and quantifies cardiac failure and determines prognosis, it is of limited value in assessing changes that occur as a result of drug therapy. A key drawback of exercise testing as a measurement of drug effect is the fact that exercise changes produced by drug intervention do not correlate well with changes in the mortality rate. Several examples of the lack of correlation between exercise testing and mortality rates have been observed in clinical trials with angiotensin converting enzyme (ACE) inhibitors and vasodilators. ACE inhibitors have a modest effect on maximal exercise capacity but they improve survival. It is thought that neuroendocrine activation more closely reflects mortality rates and also the changes in survival observed with pharmacological intervention compared with other modes of evaluation.

The effects of afterload reduction on myocardial carbon 11-labeled acetate kinetics and noninvasively estimated mechanical efficiency in patients with dilated cardiomyopathy

METHODS AND RESULTS

With echocardiography and dynamic carbon 11-labeled acetate (C-11 acetate) positron emission tomographic imaging, C-11 acetate kinetics and a parameter that estimates mechanical ventricular efficiency (the work metabolic index) were defined in eight patients with dilated cardiomyopathy. The effect of afterload reduction with nitroprusside on these parameters was evaluated in six of these patients. Nitroprusside increased stroke work index but decreased the C-11 clearance rate. The work metabolic index determined noninvasively increased and correlated well with an invasive approach. The work metabolic index was inversely correlated with systemic vascular resistance. Nitroprusside shifted this relationship upward and to the left.

CONCLUSION

This method of estimating efficiency is feasible and may represent a unique noninvasive approach for the evaluation of cardiac performance and responses to therapy.

Effect on exercise performance of enalapril therapy initiated early after myocardial infarction. Nordic Enalapril exercise Trial

OBJECTIVES

The Nordic Enalapril Exercise Trial was a multicenter subtrial of the Cooperative New Scandinavian Enalapril Survival Study (CONSENSUS II) designed to evaluate the effect on maximal exercise performance of a 6-month period of enalapril treatment initiated early after myocardial infarction.

BACKGROUND

When begun early after myocardial infarction, converting enzyme inhibition therapy has been shown to attenuate infarct expansion and reduce left ventricular volume. Therapy has been associated with improved exercise performance.

METHODS

Three hundred twenty-seven men (mean age 63.3 +/- 10.9 years) with documented acute myocardial infarction were randomized to treatment with enalapril or placebo on a double-blind basis. Intravenous enalaprilat or placebo therapy was initiated within 24 h after the onset of symptoms. Oral therapy was continued at a target dose of 20 mg/day. Patients exercised maximally at 1 month and 6 months after infarction to symptom-limited end points on a cycle ergometer with a 20 W/min incremental protocol.

RESULTS

The treatment and control groups were comparable in patient age, concurrent therapy and type and site of infarction. At 1 month, for all patients, mean total work performed was 34.9 +/- 20.9 kJ in the enalapril group (n = 169) versus 28.5 +/- 20.6 kJ in the placebo group (n = 158) (difference = 18.4%, p < 0.01). This between-group difference in favor of enalapril was greatest in patients > 70 years old (difference = 41.4%, p < 0.01, n = 105) and those with clinical evidence of heart failure (difference = 33.0%, p < 0.01, n = 122). At 6 months for all patients, mean total work performed was 35.4 +/- 23.8 kJ in the enalapril group versus 34.0 +/- 23.9 kJ in the placebo group (difference = 4.1%, NS).

CONCLUSIONS

This trial found that chronic converting enzyme inhibition initiated early after myocardial infarction was associated with significantly greater exercise capacity in men tested at 1 month. This difference was independent of type or site of infarction, patient age or the presence of clinical heart failure. The difference between the treatment and control groups was not significant at 6 months because of improvement in the placebo group. Further research is needed to elucidate the potential mechanisms involved, profile those patients most likely to profit from early therapy and establish the optimal timing and duration for intervention.

Role of surrogate end points in the evaluation of drugs for heart failure

To be of clinical value in the treatment of heart failure, a drug must permit patients either to feel better or to live longer, or both. Yet, because the assessment of both quality and quantity of life is difficult, many investigators have proposed using alternate measures (namely, surrogate end points) that may indicate the probable effect of a drug on symptoms or survival but are not direct measures of clinical benefit. Surrogate end points are usually physiologic variables that are known to be statistically associated and are believed to be pathophysiologically related to the clinical outcome. Although the adoption of such surrogate end points would dramatically facilitate the evaluation of new drugs, experience to date has shown that the effect of a drug on a surrogate end point is not a reliable predictor of the clinical utility of the drug, usually because the assumption that the end point is pathophysiologically related to the outcome proves to be invalid. Consequently, the evaluation of the effect of a drug on a surrogate end point provides us with a hypothesis rather than data about the possible effect of a drug on clinical events; such a hypothesis can be tested in controlled clinical trials that directly measure the clinical benefit of the therapeutic intervention. In the area of heart failure, no surrogate end point currently exists that can be used in lieu of the direct assessment of a drug on symptoms or survival, ideally in the context of a placebo-controlled trial.

The push, the pull and the periphery

If the failing left ventricle could be given an effective push, other approaches to the treatment of heart failure would not be needed. We have inotropes only for short-term parenteral use. We have no safe inotrope for chronic oral use. The effect of digitalis is only feeble and the phosphodiesterase inhibitors seem to increase mortality from sudden death. Diuretics are dramatic for acute pulmonary oedema and the mainstay for chronic fluid retention but do not improve the pump and by reducing blood volume stimulate the renin angiotensin system to vasoconstriction, further fluid retention and hypokalaemia. Nitrates drop pre-load without reducing blood volume but tolerance is a problem and stroke volume does not increase. Reduction of afterload helps the failing ventricle to empty, the pull and output increases. The angiotensin converting enzyme inhibitors (ACEI) are now the cornerstone of heart failure treatment, reducing mortality in severe heart failure (CONSENSUS) and superior to standard vasodilator therapy (V-HeFT-2) at improving the survival of patients with mild to moderate heart failure. ACEI can reduce the incidence of ventricular ectopy and probably do this through improving left ventricular function, from decreasing sympathetic tone, reducing myocardial oxygen demand or increasing serum potassium but ACEI did not diminish the incidence of sudden death in the SOLVD trial despite reducing mortality. Disappointingly little improvement in exercise tolerance and persistence of chronic fatigue in heart failure concentrated attention on the periphery.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of acute and chronic ibopamine administration on resting and exercise hemodynamics, plasma catecholamines and functional capacity of patients with chronic congestive heart failure

The effects of acute and chronic ibopamine treatment on resting and exercise hemodynamics, exercise capacity and plasma catecholamines were evaluated in 25 patients with chronic heart failure, using a double-blind, parallel, placebo-controlled design. During 2 months of therapy with either placebo or ibopamine (100 mg, 3 times daily), 1 patient was withdrawn from each group for worsening heart failure, New York Heart Association functional class improved in 4 patients on ibopamine and in 1 on placebo, and furosemide dose could be decreased in 4 on ibopamine and in no patient on placebo. Acute ibopamine administration induced, in comparison with placebo, a significant increase of cardiac and stroke volume indexes both at rest and peak exercise, with a reduction of systemic vascular resistance. These hemodynamic changes were maintained also after chronic therapy, with no evidence of tolerance development. Exercise capacity (evaluated as peak exercise duration and oxygen consumption, and ventilatory threshold) did not significantly change. Resting and peak exercise norepinephrine plasma levels were significantly reduced after both acute and chronic ibopamine administration. Thus, the hemodynamic and neurohumoral effects of ibopamine make this drug potentially useful for the chronic treatment of congestive heart failure.

Review of randomized trials of digoxin therapy in patients with chronic heart failure

Although digitalis glycosides were introduced in the treatment of cardiac maladies greater than 200 years ago, controversy persists regarding the precise role of digoxin in any multidrug approach to the treatment of congestive heart failure (CHF). Despite its widespread use for more than 2 centuries, only recently have double-blind, randomized, placebo-controlled trials of digoxin therapy been conducted in patients with moderate CHF and sinus rhythm. These trials demonstrate that digoxin is superior to placebo in improving left ventricular (LV) ejection fraction, increasing exercise capacity, and preventing CHF worsening. Digoxin produces benefits similar to those seen with angiotensin converting enzyme (ACE) inhibitors with regard to clinical compensation and improvement in LV function. However, improved survival is demonstrated only in response to ACE inhibitors. The recently completed RADIANCE study addresses the value of combining digoxin with ACE inhibitor therapy in patients with mild-to-moderate CHF. Because increased mortality has been reported with the newer oral inotropic agents, it currently appears that digoxin is the only oral inotropic agent useful in clinical practice in the treatment of CHF. However, the effects of digoxin on mortality in patients with CHF remain unknown. In the large, double-blind, randomized trial conducted by the National Heart, Lung, and Blood Institute, the effects of digoxin on mortality in patients with CHF and already being treated with ACE inhibitors are currently being evaluated. Presently, based on the results of placebo-controlled studies, it appears that digoxin, alone or in combination with ACE inhibitors, is beneficial in patients with any signs or symptoms of CHF due to systolic LV dysfunction.

Symptom-limited, self-paced walking in the assessment of cardiovascular disease in patients with and without heart failure: the predictive value of clinical, anthropometric, echocardiographic and ergonometric parameters

The assessment of functional capacity in heart disease remains problematic, and it is unclear whether maximal exercise testing is physiologically reflective of the activities of daily living or the quality of life. We therefore employed a symptom-limited, self-paced walking protocol to assess the physical conditions of 41 Nigerian cardiac patients, with and without heart failure. The walking time, walking speed and distance as well as the energy expenditure (Kcal.min-1) were markedly reduced (P less than 0.001) in patients with heart failure (n = 26) compared to the cardiac patients not in failure (n = 15). The double product corrected for exercise time (an index of myocardial oxygen use) was, however, significantly higher (P less than 0.001) in the group with heart failure. Using multiple regression analysis, the parameters of self-paced walking capacity (distance, walking time, and speed) could reliably be predicted (r2 greater than 0.9) from age, body surface area, energy expenditure, and echocardiographic left ventricular dimension in the patients without heart failure. The presence of heart failure appeared to weaken the predictability of the regressions. A significant correlation was obtained between the self paced exercise time and the Bruce protocol treadmill time (r2 = 0.91, P = 0.004) in a subgroup of the patients with heart failure. Thus, the self-paced walking test is sensitive to changes in congestive heart failure and the exercise capacity can be predicted from age and biophysical parameters. The wider clinical usage of this modality, especially in frail patients, is hereby recommended.

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)

Efficacy of inotropic support of the failing heart

The clinical literature on the subject of inotropic therapy of heart failure, particularly use of digitalis glycosides, is full of contradictions. Most of this disparity can be accounted for if not reconciled by taking the methodology of the clinical trials into consideration. Because drug interventions may produce subtle effects requiring a subjective determination, the questions being asked in these studies cannot be answered without removing as many sources of bias as possible from the patient management and data analysis. If a study has not been adequately randomized, double-blinded, and placebo-controlled, the clinical findings will be inconclusive at best. Systolic myocardial dysfunction plays a pivotal role in the pathogenesis of CHF in many patients and is a prerequisite for the use of cardiotonic drugs. Although the clinical signs of heart failure may be relieved initially by diuretics and vasodilators, compensation may require the addition of a positive inotrope, particularly in advanced cases. In veterinary medicine, the choice of positive inotrope is limited to digoxin, digitoxin, dobutamine, or amrinone. Digoxin possesses superior pharmacokinetics and is the cardiac glycoside of choice for use in the dog. Dobutamine and amrinone are more potent inotropes, but since they must be administered by continuous intravenous infusion, their use is limited to critical care therapy. At the present time, only digoxin can be administered orally for sustained long-term maintenance therapy. Milrinone, a more potent derivative of amrinone, also offers this option, but it has not been available since its brief trial debut as an investigational drug. None of the nonglycoside alternatives couples the benefits of positive inotropic and negative chronotropic effects. Consequently, digoxin remains the mainstay for chronic inotropic support of the heart. Atrial fibrillation with a rapid ventricular response rate is the prime indication for digoxin. In the last few years, evidence from methodologically sound clinical trials on humans has also restored faith in the efficacy of digoxin for treating heart failure in patients with normal sinus rhythm. From these studies, the profile of a digitalis responsive heart failure patient has emerged. Digoxin is most likely to be efficacious when heart failure is associated with chronic, severe ventricular systolic dysfunction, which has resulted in ventricular dilatation. The most reliable clinical marker is the presence of a third heart sound (gallop rhythm). Although the patients in the worst heart failure generally have the shortest survival time, they may also have the most dramatic short-term clinical benefit. However, once cardiac reserve is exhausted in the terminal stages of failure, cardiotonic stimulation ceases to be effective.(ABSTRACT TRUNCATED AT 400 WORDS)

Evidence for or against the efficacy of afterload reducers for management of heart failure in dogs

Therapeutic decision making is facilitated by knowledge of the short-term and long-term hemodynamic effects of the available vasodilating agents, the nature and prevalence of their adverse side effects, and their abilities to ameliorate the signs of heart disease, to improve exercise capacity, and to prolong patient survival. This article is intended to provide the reader with a comprehensive list of the available afterload-reducing agents, to review the relevant studies of these drugs in humans and dogs with heart failure, and to provide guidelines for their use in commonly encountered clinical situations.

Effect of long-term enalapril therapy on cardiopulmonary exercise performance in men with mild heart failure and previous myocardial infarction

Forty-one men with documented myocardial infarction greater than 6 months previously were randomized to long-term (48 weeks) therapy with placebo or enalapril on a double-blind basis. All patients were receiving concurrent therapy with digitalis and a diuretic drug for symptomatic heart failure (functional class II or III). The mean age was 64 +/- 7.3 years and no patient suffered from exertional chest pain. Patients underwent maximal cardiopulmonary exertional chest pain. Patients underwent maximal cardiopulmonary exercise testing to exhaustion on an ergometer cycle nine times over the course of 48 weeks. Gas exchange data were collected on a breath by breath basis with use of a continuous ramp protocol. In the placebo group (n = 21), the mean (+/- SD) peak oxygen consumption (VO2) at baseline was 18.8 +/- 5.2 versus 18.5 +/- 5.5 ml/kg per min at 48 weeks (-1.4%, p = NS). In the enalapril group (n = 20), the corresponding values were 18.1 +/- 3.1 versus 18.3 +/- 2.6 ml/kg per min (+2.8%, p = NS). The mean VO2 at the anaerobic threshold for the placebo group at baseline study was 13.1 +/- 3.5 versus 12.8 +/- 2.1 ml/kg per min at 48 weeks (-2.2%, p = NS). The corresponding values for the enalapril group were 11.8 +/- 2.3 versus 11.8 +/- 2.4 ml/kg per min (+1.4%, p = NS). The mean total exercise duration in the placebo group at baseline study was 589 +/- 153 versus 620 +/- 181 s at 48 weeks (+5.4%, p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of long-term enalapril therapy on cardiopulmonary exercise performance after myocardial infarction

BACKGROUND

The Enalapril Postinfarction Exercise (EPIE) trial was designed to study the effect of enalapril treatment on peak and submaximal cardiopulmonary exercise performance over the course of 1 year in men after myocardial infarction with mild exercise intolerance.

METHODS AND RESULTS

One hundred sixty men with a peak VO2 less than 25 ml/kg/min and without effort angina were randomized to receive enalapril 20 mg qd or placebo on a double-blind basis. The mean age was 60.3 +/- 7.6 years. All patients received concurrent beta-blocker therapy for secondary prophylaxis. Treatment began at 21 days (group 1, n = 100) or more than 6 months after infarction (group 2, n = 60). Patients underwent exercise with real-time gas-exchange analysis nine times over the course of 48 weeks. In group 1, improvement in exercise performance occurred during the course of the trial in both groups of patients receiving placebo or enalapril. The mean peak VO2 for the placebo-treated patients in group 1 increased from 18.3 +/- 3.4 ml/kg/min by 4.9% at 48 weeks (p less than 0.05). The corresponding values for enalapril-treated patients were 18.9 +/- 3.8 ml/kg/min with a 3.7% increase (p = 0.07). Total exercise time increased in the placebo-treated patients from 645 +/- 96 seconds by 7.3% (p less than 0.01). Corresponding values for enalapril-treated patients were 674 +/- 103 seconds with a 5.4% increase (p less than 0.01). In group 2, the mean peak VO2 at baseline for the placebo-treated patients of 20.3 +/- 3.8 ml/kg/min increased by 4.4% at 48 weeks (p = NS). The corresponding values for enalapril-treated patients were 19.2 +/- 3.6 ml/kg/min with a 2.6% increase (p = NS). Total exercise time increased in the placebo-treated patients from 677 +/- 114 seconds by 0.7% (p = NS). Corresponding values for enalapril-treated patients were 659 +/- 99 seconds with a 1.1% increase (p = NS). There were no significant differences between the placebo and enalapril subgroups at any time with regard to peak VO2, exercise duration, or the VO2 at the anaerobic threshold.

CONCLUSIONS

This trial demonstrates that long-term converting enzyme inhibition with enalapril had no significant effect on the peak or submaximal cardiopulmonary exercise performance over the course of 1 year in men after myocardial infarction with only mildly reduced exercise capacity.

Assessment of exercise tolerance in chronic congestive heart failure

In patients with chronic heart failure, exercise capacity is poorly related to cardiac hemodynamics, and peripheral circulation is an important determinant of exercise tolerance. The ability of the muscle vasculature to dilate is markedly impaired, in part, because of exaggerated neurohumoral activity increasing vascular wall stiffness. For this reason, increasing cardiac output is not sufficient to increase exercise capacity if not accompanied by improving vascular reactivity. The poor reliability and reproducibility of exercise tolerance assessed by maximal exercise duration or maximal attained work load (particularly on a treadmill) has led to widespread measurement of respiratory gas during exercise. Peak oxygen consumption (peak VO2), even if it is symptom-limited, has been shown to be a very reproducible criterion of exercise tolerance; moreover, because VO2 is the product of cardiac output and arteriovenous oxygen difference, it also has a qualitative hemodynamic significance. Ventilatory threshold can be determined before maximal exercise; however, problems of determination limit the practical value of this criterion. Unfortunately, peak VO2 lacks sensitivity to detect minor improvement or impairment of symptoms during daily life, although these are significant to the patient. Submaximal exercises have been proposed for this purpose and are currently being evaluated.

The use of magnetic resonance imaging in the study of edema

A method of studying edema using magnetic resonance imaging (MRI) is presented. Three patients with lower extremity edema due to congestive heart failure were imaged with a 0.6 tesla system before and after diuresis. Edge detection algorithms were utilized to precisely outline regions of interest for quantification. Water and nonwater elements were separated within the region of interest to quantify water content. The results show that: (1) Edema can be quantified by use of MRI. (2) Subcutaneous edema is distributed along defined planes (ie, nonuniformly). (3) Increased water content is present not only in the subcutaneous tissue but also in deeper lying muscle.

The placebo effect in heart failure

Many patients who are enrolled in controlled clinical trials of new drugs for the treatment of heart failure show favorable hemodynamic and clinical responses to placebo therapy. This "placebo effect" results from both the creation of a supportive therapeutic environment and the spontaneous improvement that is commonly seen when measurements of symptoms and cardiac function are repeated frequently over long intervals of time. Three months of treatment with a placebo produces a reduction in symptoms in 25% to 35% of patients, an increase in cardiac output and a decrease in pulmonary wedge pressure, and an increase in exercise tolerance of up to 90 to 120 seconds. Physicians commonly seek to maximize the "placebo effect," since the goal of treatment in the clinical setting is to improve the quality of the patient's life. On the other hand, clinical investigators seek to minimize the "placebo effect," since the goal of a research study is to test the hypothesis that the new drug is superior to a placebo.

Duration and reproducibility of initial hemodynamic effects of flosequinan in patients with congestive heart failure

The duration and reproducibility of hemodynamic effects of flosequian, a direct-acting, balanced-type vasodilator, were studied in 19 heart failure patients (NYHA class 3.0 +/- 0.7) receiving 100 mg orally (day 1), placebo (day 2), and again 100 mg (day 3). Flosequinan immediately reduced systemic and pulmonary resistance (23% and 35%, respectively, at 60-90 minutes postdrug) and decreased pulmonary wedge, right atrial, mean pulmonary artery, and mean arterial pressure by 38%, 50%, 25%, and 7%, respectively. Concomitantly, cardiac output, and stroke volume and work increased by 26%, 20%, and 22%, respectively. Most hemodynamic effects persisted for 48 hours. In contrast, changes in pulmonary wedge and arterial pressures, stroke volume, and stroke work only lasted for 2-12 hours. Maximum absolute changes on day 3 were generally comparable with first-dose effects with, again, long-lasting effects on systemic resistance and cardiac output. However, changes in pulmonary artery, wedge, and resistance were significantly shorter than after first dose administration. These data indicate sustained and reproducible arterial dilating effects of flosequinan, but less pronounced and shorter lasting pulmonary arterial and venodilator properties.

Hemodynamic effects of oral nicorandil in congestive heart failure

Twenty-five patients with congestive heart failure (CHF) underwent a double-blind randomized study of the acute hemodynamic effects of orally administered nicorandil, a newly developed vasodilator drug. A dose range of 10 to 60 mg was studied. Nicorandil, at a dose of 60 mg, caused statistically significant decreases in systemic systolic and diastolic blood pressure, right atrial pressure, pulmonary capillary wedge pressure, systemic and pulmonary vascular resistance and systolic and diastolic pulmonary arterial pressure. A brief increase in cardiac index attributable to an increase in stroke volume without a change in heart rate was also observed. A dose of 40 mg produced similar results in cardiac index and systemic and pulmonary vascular resistance, but changes in other hemodynamic parameters were much smaller in magnitude and usually not of statistical significance. No significant hemodynamic response was seen to doses of 10 and 20 mg of nicorandil. Duration of action was short with nearly all hemodynamic parameters returning close to baseline within 3 hours. This rapid decrease in activity occurred in concert with a rapid plasma clearance of nicorandil as determined by serial measurements of plasma drug concentration. This study suggests that first-dose orally administered nicorandil elicits favorable, but brief, hemodynamic effects in CHF at doses greater than or equal to 40 mg.

Relationship between positive inotropic responses and plasma concentrations of xamoterol in middle-aged and elderly patients

1. We examined the relationship between the contractile state of the left ventricle and the plasma concentration of xamoterol in patients with ischaemic heart failure. 2. Identical studies were conducted in 14 middle-aged (all male; mean age 51.3 years, range 42-61) and 10 elderly patients (six male, four female; mean age 67.7 years, range 64-72). 3. Patients received seven cumulative doses (0.0005-0.2 mg kg-1) of xamoterol. After each dose the rate of change of pressure in the left ventricle at a developed pressure of 40 mm Hg and normalised for this pressure, (dP/dt)/DP40, and plasma concentrations of xamoterol were measured. 4. There were dose-related increases in (dP/dt)/DP40. Curves relating changes in (dP/dt)/DP40, expressed as a percent of the maximum observed response, to changes in xamoterol plasma concentrations were constructed for the middle-aged and elderly patients. From these curves the mean effective concentration (EC) value to produce a particular response could be calculated. In the sample sizes studied, the difference between the EC values over a range of responses for the middle-aged and elderly patients did not reach statistical significance, indicating that cardiac responsiveness to xamoterol was similar in the two groups of patients. 5. Plasma concentrations of xamoterol over the range of 39 to 150 ng ml-1 produced positive inotropic responses which varied between 70% and 90% of the maximum observed effect of xamoterol.

The effects of flosequinan on submaximal exercise in patients with chronic cardiac failure

1. Twenty patients with moderate to severe chronic cardiac failure were entered into a double-blind parallel group study comparing flosequinan 100 mg daily with matching placebo. 2. After at least three prior exercise tests, cardiopulmonary parameters were assessed at rest and during submaximal exercise before and after 2 and 8 weeks of active drug or placebo. 3. Resting minute ventilation and respiratory rate were reduced by flosequinan compared with placebo, but oxygen uptake was unchanged. 4. Comparison of minute ventilation, carbon dioxide production and venous lactate levels at the end of the exercise stage approximating to 50% of peak oxygen uptake demonstrated significant reductions in the flosequinan group compared with placebo at week 2 and week 8 (P less than 0.05). 5. Flosequinan increased the oxygen uptake at anaerobic threshold from 13.2 +/- 2.8 ml min-1 kg-1 to 15.9 +/- 3.4 ml min-1 kg-1 at week 2 and 15.8 +/- 3.7 ml min-1 kg-1 at week 8. These increases were significant when compared with placebo (P less than 0.05). 6. We conclude that flosequinan improves submaximal exercise performance in patients with chronic cardiac failure, probably by enhancing skeletal muscle blood flow.

Central and regional hemodynamic effects of flosequinan for congestive heart failure

The central and regional hemodynamic effects of flosequinan, a new orally administered vasodilator, were examined in 10 patients with moderate to severe congestive heart failure. A single-blind design was used to compare a standard dose of flosequinan (100 mg) with placebo. Flosequinan produced a statistically significant increase in cardiac output, primarily through its augmentation of stroke volume. This response was accompanied by significant reductions in systemic vascular resistances and right and left ventricular filling pressures. A reduction in pulmonary artery pressure and total pulmonary vascular resistance also was observed. The vasodilatory actions of flosequinan improved overall left ventricular performance; the inotropic indexes measured were not altered. There were no significant changes in upper limb, renal or hepatic-splanchnic blood flow or in the vascular resistances of these regions after flosequinan administration. The upper limb venous capacitance increased significantly. First-dose flosequinan evokes favorable central hemodynamic changes and improves overall left ventricular performance in patients with congestive heart failure. The acute augmentation in cardiac output, however, is not accompanied by a preferential alteration of flow to any of the major vascular regions studied.