Effects of Spironolactone on Exercise Capacity and Neurohormonal Factors in Patients with Heart Failure Treated with Loop Diuretics and Angiotensin-Converting Enzyme Inhibitor

Gen. Pharmac. Vol. 31, No. 1, pp. 93–99, 1998 Copyright  1998 Elsevier Science Inc. Printed in the USA.

ISSN 0306-3623/98 $19.00 1 .00 PII S0306-3623(97)00396-0 All rights reserved

Effects of Spironolactone on Exercise Capacity and Neurohormonal Factors in Patients with Heart Failure Treated with Loop Diuretics and Angiotensin-Converting Enzyme Inhibitor Toru Kinugawa,* Kazuhide Ogino, Masahiko Kato, Yoshiyuki Furuse, Masaki Shimoyama, Masatake Mori, Akihiro Endo, Tatsuo Kato, Hiroki Omodani, Shuichi Osaki, Hiroyuki Miyakoda, Ichiro Hisatome, and Chiaki Shigemasa The First Department of Internal Medicine, Tottori University School of Medicine, Yonago, 683, Japan [Tel: 81-859-34-8101; Fax: 81-859-34-8099; E-mail: [email protected]] ABSTRACT. 1. Treatment with spironolactone is reported to be useful when combined with loop diuretics and an angiotensin-converting enzyme (ACE) inhibitor in severe congestive heart failure (CHF). However, the effects of the addition of spironolactone on exercise capacity and neurohormonal variables have not been demonstrated. This study determined the effects of additive spironolactone on exercise capacity and neurohormonal factors in patients with mild CHF. 2. Oxygen uptake (VO2), plasma norepinephrine (NE), renin activity (PRA), angiotensin II (AII), aldosterone (ALD), and atrial natriuretic peptide (ANP) were measured at rest and after peak exercise in nine patients with CHF (six idiopathic and three ischemic cardiomyopathy; New York Heart Association (NYHA) classes II and III) who were already taking furosemide (mean 2965 mg/day) and enalapril (mean 4.760.8 mg/day). Studies were repeated after 16 weeks of treatment with additive single daily dose of 25 mg of spironolactone. In four of nine patients, the exercise test was repeated after a 4-weeks washout of spironolactone. 3. Treatment with spironolactone caused natriuresis, decreased cardiothoracic ratio in chest X-ray (before vs. after treatment: 53.761.2 vs. 50.761.4%, P,0.01), and improved NYHA functional class. Peak VO2 (17.161.6 vs. 17.562.2 ml/min/kg, NS) and heart rate and blood pressure responses to exercise were not altered. Resting NE (215641 vs. 492685 pg/ml, P,0.01) and resting PRA (8.262.3 vs. 16.264.1 ng/ml/hr, P,0.01) as well as peak NE (16186313 vs. 27126374 pg/ml, P,0.01) and peak PRA (12.863.2 vs. 28.1611.8 ng/ml/hr, P50.17) were augmented after additive spironolactone. ALD and AII were insignificantly increased, and ANP was insignificantly decreased at peak exercise after spironolactone treatment. Spironolactone washout was associated with a trend of the neurohormones to return toward pretreatment values. 4. In conclusion, chronic additive treatment with spironolactone was associated with neurohormonal activation both at rest and during exercise without changing the exercise capacity of patients with mild CHF who were already on loop diuretics and ACE inhibitor therapy. gen pharmac 31;1:93–99, 1998.  1998 Elsevier Science Inc. KEY WORDS. Spironolactone, ACE inhibitor, neurohumoral factor, cardiopulmonary exercise test, congestive heart failure INTRODUCTION On the basis of positive mortality results from large-scale randomized trials (AIRE Study Investigators, 1993; CONSENSUS Trial Group, 1987; SOLVD Investigators, 1991) in which angiotensinconverting enzyme (ACE) inhibitors were used in patients with congestive heart failure (CHF) and other studies showing that ACE inhibitors improve symptoms and exercise performance in patients with symptomatic left ventricular dysfunction (Captopril-Digoxin Multicenter Group, 1988; Captopril Multicenter Research Group, 1983), ACE inhibitors with diuretics with or without concomitant *To whom all correspondence should be addressed. Received 28 March 1997; revised 1 September 1997; accepted 18 September 1997.

therapy with digitalis have become the standard therapy for patients with CHF. However, CHF is a condition with a high morbidity and mortality despite the use of ACE inhibitors. In patients with severe CHF refractory to conventional therapy, the efficacy of adding spironolactone, an aldosterone (ALD) receptor antagonist, in symptomatology and natriuresis has been reported (Barr et al., 1995; Dahlstrom and Karlsson, 1992; Ikram et al., 1986; van Vilet et al., 1993). The rationale for the use of spironolactone for patients with CHF who are already taking loop diuretics and ACE inhibitor is that the suppressive effects of ACE inhibitor on ALD production may not be satisfactory (Pitt, 1995; Struthers, 1996). Indeed, recent data suggest that continuous ACE inhibitor therapy does not necessarily produce a sufficient decrease in ALD levels, which may remain high or increase eventually during long-term use of ACE in-

94

T. Kinugawa et al. TABLE 1. Characteristics of the study population Patient No. 1 2 3 4 5 6 7 8 9 Mean 6 SEM

Age (years) and sex

Diagnosis

NYHA class

LVEF (%)

Furosemide (mg/day)

Enalapril (mg/day)

79M 77M 68M 55M 78M 73M 44M 45M 65F

DCM DCM DCM DCM OMI OMI DCM DCM OMI

III III II II II II II II II

10 51 49 59 31 49 41 29 29

20 20 40 20 40 20 60 20 20

2.5 2.5 5 10 5 5 2.5 5 5

39 6 5

29 6 5

4.7 6 0.8

65 6 5

Abbreviations: DCM, dilated cardiomyopathy; OMI, old myocardial infarction; LVEF, left ventricular ejection fraction; SEM, standard error of the mean.

hibitor (Borghi et al., 1993; Staessen et al., 1981). Because the increase in ALD levels has several adverse cardiovascular consequences (Pitt, 1995), treatment with ALD receptor blockade in patients with CHF who are treated with loop diuretics and ACE inhibitor may have potential benefits in the management of patients with CHF. Although the effects of combination therapy with spironolactone and ACE inhibitor in patients with severe CHF treated with loop diuretics have been demonstrated, the effects of the addition of spironolactone on exercise capacity and neurohormonal variables have not been studied in mild to moderate CHF treated with loop diuretics and ACE inhibitor therapy. Therefore, this study was undertaken to determine the effects of additive spironolactone therapy on exercise capacity and neurohormonal factors during exercise in patients with mild to moderate CHF. MATERIALS AND METHODS

Patients Nine patients (eight males and one female; mean age 6565 years) with CHF were enrolled in this study (Table 1). Patients performed at least one cardiopulmonary exercise test with ramp protocol before the start of the study. Only candidates who were able to perform exercise to exhaustion on a bicycle ergometer were included. The etiology of their heart disease was idiopathic cardiomyopathy in six patients and old myocardial infarction in three patients. Mean left ventricular ejection fraction determined by echocardiogram was 3965%. According to the New York Heart Association (NYHA) classification, two patients were in functional class III, and seven were in class II. All patients were in normal sinus rhythm. Patients with CHF received a salt-restricted diet providing 6 g (or 102 mmol/ l) of sodium intake per day. Each patient was treated with furosemide (mean 2965 mg/day) and enalapril (mean 4.760.8 mg/day). Eight patients received digitalis glycoside, three received an antiarrhythmic agent, two received nitrate, and one received a calcium antagonist. Two patients had non-insulin-dependent diabetes mellitus controlled either with diet alone or with an oral hypoglycemic agent. Serum creatinine levels of all patients were less than 1.5 mg/ dl. The protocol was approved by the Ethical Committee of the Tottori University, and all patients gave written informed consent to perform the protocol.

Study protocol In the control period, NYHA functional status, chest X-ray, echocardiogram, blood chemistry, urinary electrolytes and cardiopulmo-

nary exercise testing were assessed. Spironolactone 25 mg/day was added. The same protocol was repeated after 16 weeks of treatment with additive spironolactone. In a subgroup of patients (n54), spironolactone was discontinued for 4 weeks, and cardiopulmonary exercise testing was repeated.

Echocardiography Conventional echocardiographic studies were performed by using a phased array sector scanner (model SSH-140A, Toshiba, Tokyo, Japan). Two-dimensional images were obtained along the parasternal long-axis view. Left ventricular diameters were measured from the two-dimensional targeted M-mode echocardiographic traces. The left ventricular volume was calculated by using Teichholz modification (Teichholz et al., 1976). The left ventricular ejection fraction was calculated as follows: [(end-diastolic volume—end-systolic volume)/end-diastolic volume]3100.

Exercise testing with respiratory gas analysis On the morning of the control period, each patient underwent physical and cardiovascular examinations. Chest X-ray, echocardiogram, blood chemistry and determination of urinary electrolytes were done before the exercise test. A symptom-limited ramp exercise test was performed with respiratory gas analysis in a temperature-controlled room. After a 4-min rest on the bicycle ergometer (Ergomedic 829, Monark, Norway), exercise began with a 4-min warm-up at 0 watt at 50 rpm, followed by 10 watts incremental loading each minute. Patients stopped exercise when they had severe leg fatigue or dyspnea or both. Twelve lead electrocardiogram and heart rate were continuously monitored (CASE 12, Marquette Electronics Co., Milwaukee, WI, USA), and blood pressure was measured with cuff technique during each minute of exercise and recovery. Oxygen uptake (VO2), carbon dioxide output, and minute ventilation were measured at rest and throughout the exercise period by using a Cardiopulmonary Exercise System (Medical Graphics Corporation, St. Paul, MN, USA). Anaerobic threshold was determined mainly by the V-slope method (Beaver et al., 1986; Sue et al., 1988) in addition to the following conventional criteria: (1) the equivalent of minute ventilation to VO2 increases after being stable or decreasing while the equivalent of minute ventilation to carbon dioxide output remains constant or is decreasing and (2) the gas exchange ratio, which had been stable or slowly rising, begins to increase more steeply (Wasserman, 1984; Wasserman and Whipp, 1975). Peak VO2 was defined as the maximal VO2 attained during exercise.

Spironolactone and Neurohormonal Response to Exercise in CHF

Neurohumoral factors Blood specimens were drawn through an indwelling cannula placed in the forearm vein after a period of at least 30 min of supine rest and immediately after exercise. Blood samples for determination of plasma norepinephrine (NE), plasma renin activity (PRA), angiotensin II (AII), and aldosterone (ALD) were collected into a chilled vacutainer containing ethylenediamine tetraacetate (EDTA). Blood samples for atrial natriuretic peptides (ANP) were collected into tubes containing aprotinin and EDTA. Samples were centrifuged at 3,000 rpm at 48C for 15 min, and were frozen at 2708C until the assay. Plasma NE was determined by the high-performance liquid chromatography with diphenylethylene diamine (DPE) method (Yoshimura et al., 1993) with the use of HLC-725CA (Tosoh, Tokyo, Japan). PRA was measured by radioimmunoassay (RIA) with a g-Coat Renin Kit (Incstar Corporation, Stillwater, MN, USA) (Ogihara et al., 1980), and AII by RIA with the polyethylenglycol method (Morimoto et al., 1983). Plasma ALD concentration was measured by RIA with a SPAC-S Aldosterone RIA Kit (Daiichi Radioisotope Laboratories Ltd., Tokyo, Japan) (Shionoiri et al., 1989). ANP was determined by using the Shionoria RIA Kit (Shionogi Laboratory, Osaka, Japan) (Hama et al., 1991). Blood samples for lactate also were collected at rest and immediately after exercise. Lactate was determined enzymatically by a lactate analyzer (model 23L, YSI, Yellow Springs, CO, USA) (Henry, 1968). Normal values of the neurohormones at rest were as follows: NE 60–450 pg/ml, PRA 0.5–2.0 ng/ml/hr, AII ,25 pg/ml, ALD 35.7–240 pg/ml and ANP ,40 pg/ml. The intraassay variability in our laboratory for NE, PRA, AII, ALD and ANP is 1.8%, 5.4%, 6.3%, 4.7% and 6.1%, respectively.

Statistical analysis Statistical analysis was performed by using analysis of variance. When appropriate, Student t-test for pairwise comparison was applied. The differences were considered significant when P values were less than 0.05. Data are expressed as mean6SEM. RESULTS

Effects of spironolactone on NYHA functional class, echocardiographic variables, cardiothoracic ratio and blood chemistry and urinary electrolytes NYHA functional class improved in three patients with CHF (class III to II in one, class II to I in two patients) after additive spironolactone treatment. The left atrial dimension, left ventricular dimension or left ventricular ejection fraction remained unchanged after spironolactone treatment (Table 2). The cardiothoracic ratio in chest X-ray decreased significantly after additive spironolactone treatment. Serum electrolytes including sodium, potassium, chloride and magnesium concentrations were not changed significantly after spironolactone. Urinary sodium excretion was significantly augmented, and urinary potassium excretion was insignificantly decreased. As a result, the urinary sodium/potassium ratio significantly increased after spironolactone treatment.

Effects of spironolactone on cardiac and ventilatory indices during exercise Heart rate, systolic blood pressure or diastolic blood pressure remained unchanged after the administration of spironolactone (Table 3). Peak work rate, anaerobic threshold and peak VO2 were not significantly different between pre- and postspironolactone treatment, demonstrating that the exercise capacity in patients with

95 CHF was not altered after additive spironolactone. Levels of lactate both at rest and after exercise were not altered after additive spironolactone treatment.

Effects of spironolactone on neurohormonal responses to exercise Resting NE levels (251641 vs. 492685 pg/ml, P,0.01) and PRA (8.262.3 vs. 16.264.1 ng/ml/hr, P,0.01) were significantly elevated after treatment with spironolactone (Fig. 1). Plasma AII at rest was not significantly different after additive spironolactone, and resting plasma ALD (4367 vs. 67613 pg/ml, P50.09) tended to be higher after spironolactone. Resting plasma ANP values (42615 vs. 40610 pg/ml) were similar before and after spironolactone. Exercise-induced increases in neurohormones were observed both pre- and postspironolactone treatment, and peak NE levels (16186313 vs. 27126347 pg/ml, P,0.01) were significantly higher after spironolactone treatment. PRA, AII and ALD levels after exercise tended to be higher after spironolactone, but the differences did not reach statistical significance. Peak plasma ANP levels (104659 vs. 73624 pg/ml) were insignificantly lower after spironolactone treatment.

Effects of spironolactone washout on neurohormonal profiles in a subgroup of CHF patients In four patients (numbers 2, 3, 4, and 6) with CHF, treatment with spironolactone was discontinued for a 4-week period and the same exercise test was repeated. Peak VO2 was not significantly different between treatment period and after the drug washout (treatment vs. washout: 18.262.1 vs. 17.262.2 ml/min/kg). There were no significant differences in heart rate or blood pressure responses between treatment period and after the drug washout (data not shown). Figure 2 shows the effects of washout of spironolactone on neurohormonal variables at rest and after peak exercise. Plasma NE at rest (treatment vs. washout: 6756105 vs. 343672 pg/ml, P,0.05) and PRA at rest (17.363.0 vs. 3.761.2 ng/ml/hr, P,0.05) significantly decreased after spironolactone washout. Plasma AII (45.5618.7 vs. 14.565.4 pg/ml, P,0.05) and plasma ALD (218655 vs. 99623 pg/ ml, P,0.05) at peak exercise significantly decreased after the discontinuation of spironolactone compared with those during spironolactone therapy. DISCUSSION The main findings of the current study were that in patients with CHF who were already treated with furosemide and enalapril: (1) treatment with additive spironolactone produced natriuresis, decreased cardiothoracic ratio in chest X-ray, and improved functional class; (2) exercise capacity as determined by peak VO2 was not altered by additive spironolactone; and (3) plasma NE levels and renin-angiotensin system activity both at rest and at peak exercise were augmented after spironolactone, and washout of spironolactone for 4 weeks was associated with a trend of these neurohormones to return toward pretreatment values. Until recently, spironolactone was not widely used in patients with CHF who were already being treated with ACE inhibitors, because it has been assumed that ACE inhibitors suppress ALD secretion sufficiently and the addition of spironolactone might increase the potential for hyperkalemia due to hypoaldosteronism (Texter et al., 1982). However, increasing evidence suggests that currently recommended doses of ACE inhibitors do not completely suppress ALD production, and there may be an “escape” of ALD from ACE inhibition (Pitt, 1995; Struthers, 1996). After long-term captopril

96

T. Kinugawa et al. TABLE 2. Echocardiographic parameters, cardiothoracic ratio, serum and urinary electrolytes and renal function before and after spironolactone treatment

Echo data LAD (mm) LVDd (mm) LVDs (mm) LVEF (%) CTR (%) Serum electrolytes Na (mEq/l) K (mEq/l) Cl (mEq/l) Mg (mEq/l) Renal function BUN (mg/dl) Cr (mg/dl) Urinary electrolytes* Na (mEq/l) K (mEq/l) Cl (mEq/l) Mg (mEq/l) Na/K ratio

Before spironolactone

After spironolactone

P value

34.2 6 2.2 59.9 6 2.5 48.3 6 3.2 38.7 6 5.1 53.7 6 1.2

34.9 6 1.8 57.9 6 2.0 45.5 6 3.1 44.3 6 6.1 50.7 6 1.4

n.s. n.s. n.s. n.s. P , 0.05

141 6 1 4.2 6 0.1 101 6 1 2.0 6 0.1

139 6 1 4.5 6 0.1 100 6 1 2.0 6 0.2

n.s. n.s. n.s. n.s.

18 6 2 1.1 6 0.1

20 6 2 1.1 6 0.1

n.s. n.s.

85.5 6 13.6 58.0 6 11.5 90.6 6 25.3 3.7 6 0.7 2.2 6 0.7

132.8 6 5.2 35.2 6 5.3 123.8 6 16.6 3.4 6 0.7 4.5 6 0.8

P , 0.05 n.s. n.s. n.s. P , 0.01

Abbreviations: LAD, left atrial dimension; LVDd, left ventricular diastolic dimension; LVDs, left ventricular systolic dimension; LVEF, left ventricular ejection fraction; CTR, cardiothoracic ratio; Na, sodium; K, potassium; Cl, chloride; Mg, magnesium; n.s., not significant. *Data were obtained from seven subjects. Values are mean 6 SEM.

therapy and continued inhibition of AII production, Staessen et al. (1981) reported that ALD levels increased in patients with hypertension. A similar escape of ALD production was recently shown in patients with myocardial infarction treated with ACE inhibitor (Borghi et al., 1993). Although the mechanisms for the increase in ALD and AII are unknown, several possibilities have been postulated, including the presence of chymase for the production of AII by a non-ACE pathway, stimulation of ALD production by decreased plasma potassium and magnesium levels, the buildup of an-

giotensin I as substrate for ACE and poor compliance with ACE inhibitor therapy (Dzau, 1992; Husain, 1993; Pouleur et al., 1993; Rousseau et al., 1994; van den Meiracker et al., 1992). Because an increase in ALD production has several important cardiovascular consequences such as sodium retention, potassium and magnesium loss, myocardial collagen production, ventricular hypertrophy and so forth, treatment with spironolactone has a potential importance in the management of patients with CHF treated with ACE inhibitors. Several studies (Barr et al., 1995; Dahlstrom and Karlsson, 1992;

TABLE 3. Heart rate, blood pressure, peak work rate, ventilatory indices and lactate before and after spironolactone treatment during exercise

HR (beats/min) rest peak SBP (mm Hg) reat peak DBP (mm Hg) rest peak Peak work rate (watts) AT (ml/min/kg) Peak VO2 (ml/min/kg) Lactate (mmol/l) rest peak

Before spironolactone

After spironolactone

P value

78 6 4 138 6 6

81 6 5 137 6 8

n.s. n.s.

135 6 7 179 6 13

133 6 9 174 6 18

n.s. n.s.

79 6 5 93 6 8 93 6 12 12.0 6 1.0 17.1 6 1.6

80 6 6 90 6 7 97 6 14 12.0 6 1.1 17.5 6 2.2

n.s. n.s. n.s. n.s. n.s.

0.8 6 0.1 3.7 6 0.5

0.7 6 0.1 3.6 6 0.6

n.s. n.s.

Abbreviations: HR, heart rate; SBP, systolic blood pressure; DBP, diastolic blood pressure; AT, anaerobic threshold; n.s., not significant. Values are mean 6 SEM.

Spironolactone and Neurohormonal Response to Exercise in CHF

97

FIGURE 1. Bar graphs showing plasma NE, PRA, AII, ALD, and ANP at rest and immediately after peak exercise before (open bars) and after (solid bars) treatment with spironolactone. *P,0.05 before vs. after spironolactone treatment. Values are mean6SEM.

Ikram et al., 1986; van Vilet et al., 1993) demonstrated the usefulness of additive spironolactone treatment in patients with severe CHF who had already been treated with ACE inhibitor and a large dose of loop diuretics. van Vliet et al. (1993) reported that, in patients with refractory CHF treated with diuretics and ACE inhibitors, coadministration of 100 mg of spironolactone per day was highly effective in the majority (81%) of the patients. Dahlstrom and Karlsson (1992) reported that the addition of spironolactone resulted in a clinical improvement in CHF patients (NYHA class II and III) who showed clinical deterioration with long-term captopril and loop-diuretic therapy. They noted that the subset of patients who benefited from the additive spironolactone was characterized by an increase in urinary ALD excretion rates despite the continued captopril therapy. Their findings are consistent with the theory of ALD “escape” during long-term ACE inhibition (Pitt, 1995). In the current study, we observed an improvement in NYHA functional

FIGURE 2. Bar graphs showing plasma NE, PRA, AII, ALD, and ANP at rest and immediately after peak exercise before (open bars), after treatment with spironolactone (solid bars), and 4 weeks after the cessation of spironolactone treatment (hatched bars). *P,0.05 before vs. after spironolactone treatment. #P,0.05 treatment vs. washout of spironolactone. Values are mean6SEM.

status, a decrease in cardiothoracic ratio in chest X-ray, and a natriuresis in our patients with CHF after additive spironolactone, the effects of which were attributed to the diuretic property of the spironolactone. During 4 months of therapy with spironolactone, we did not observe any significant changes in serum potassium concentration, and none of the patients developed hyperkalemia. These findings are consistent with reports (Dahlstrom and Karlsson, 1992; van Vilet et al., 1993) that showed a low incidence of hyperkalemia in patients with CHF treated with spironolactone, ACE inhibitor and loop diuretics. Therefore, it seems that the combination of ACE inhibitors and spironolactone may be administered safely for most CHF patients, though serum potassium levels should be monitored carefully for the potential for hyperkalemia. Exercise intolerance is a hallmark of heart failure, and the improvement of exercise performance is an important goal in the treatment of CHF patients. Factors such as impaired increase in cardiac

98 output during exercise, impaired oxygen utilization in the peripheral muscle, an increase in filling pressure during exercise, impaired muscle metabolism and physical deconditioning (Sullivan et al., 1991; Wilson et al., 1984) contribute to the exercise intolerance in CHF. The effects of diuretic therapy on exercise hemodynamics and exercise tolerance were previously investigated (Cheitlin et al., 1991; Haerer et al., 1990; Stampfer et al., 1968), and a significant reduction in exercise pulmonary wedge pressure with an increase in exercise tolerance has been demonstrated. Cardiac output during exercise after diuretics therapy was reported to be reduced (Stampfer et al., 1968) or unchanged (Cheitlin et al., 1991; Haerer et al., 1990). It seems that the fall in cardiac preload due to diuresis and the redistribution of blood away from the central circulation are main hemodynamic effects of diuretic therapy and may contribute to the improved exercise tolerance in patients with CHF. In our patients with CHF, exercise capacity, as measured by peak work rate, anaerobic threshold, and peak VO2, was not altered after the additive spironolactone treatment. The reasons why spironolactone did not change exercise capacity in our patients are not clear; however, there are several possibilities. First, 4 months of treatment with spironolactone might not be long enough to show improved exercise tolerance. Second, the dose of spironolactone used in the current study (25 mg/day) may not be sufficient, because previous studies used 50– 100 mg of spironolactone per day (Dahlstrom and Karlsson, 1992; Hensen et al., 1991; van Vilet et al., 1993). However, a recent report (RALES Investigators, 1996) recommends daily doses of 12.5 to 25 mg of spironolactone as a safe and effective dose when combined with ACE inhibitor, loop diuretics and digitalis. Third, before the initiation of spironolactone, our patients showed only a mild increase in plasma levels of ANP, a marker of preload condition. Therefore, the effects of spironolactone on preload reduction might be too small to cause a significant effect on exercise capacity in our patients. Furthermore, our patients did not show elevated resting plasma ALD levels before the initiation of spironolactone. Thus, the benefits of adding spironolactone to standard loop diuretics and ACE inhibitor therapy may have been limited in our patients with mild CHF. Plasma levels of neurohormones increased during dynamic exercise in our patients with CHF, which was consistent with the previously reported findings from our laboratory (Kinugawa et al., 1991, 1996) and from others (Kirlin et al., 1986; Nishikimi et al., 1986). As for the effects of spironolactone on baseline neurohormonal factors, Hensen et al. (1991) reported that treatment with spironolactone (100 mg/day) increased PRA and plasma NE significantly in patients with CHF and edema. Barr et al. (1995) also reported that PRA and ALD concentrations were significantly elevated after spironolactone treatment (50–100 mg/day) in patients with class II and III CHF who were already taking standard diuretic–ACE inhibitor therapy. In the current study, additive spironolactone treatment was associated with an augmented renin-angiotensin system activity both at rest and at peak exercise. Because spironolactone blocks ALD receptors, the concentration of plasma ALD and PRA was expected to be increased owing to ALD receptor blockade activity causing a secondary increase in PRA and ALD from loss of negative feedback inhibition (Barr et al., 1995). Additive spironolactone treatment was also associated with a significant increase in plasma NE both at rest and at peak exercise, suggesting that sympathetic nervous system activity was augmented both at rest and during exercise. The finding that the washout of spironolactone caused a trend of the neurohormones to return toward pretreatment values supports the notion that the increased levels of plasma NE and augmented renin-angiotensin system activity were associated with the

T. Kinugawa et al. use of spironolactone. It should be pointed out, however, that the renin-angiotensin system is blocked by the combination therapy with ACE inhibitor and spironolactone; therefore the activated renin-angiotensin system observed in CHF patients would not be expected to exert its effects (deleterious effects, if any) on the cardiovascular system. On the other hand, increased plasma NE after spironolactone may have some adverse consequences in patients with CHF. It is widely accepted that the excess increase in sympathetic nervous activity is deleterious to patients with CHF (Swedberg et al., 1990). Higher resting plasma NE levels relate to a poor prognosis for patients with CHF (Cohn et al., 1984). In this context, one should be careful to follow the levels of plasma NE in patients with CHF treated with ACE inhibitor, loop diuretics, and spironolactone. The reasons for the increased plasma NE after spironolactone may be related to the following factors. The use of diuretics is associated with the activation of renin-angiotensin system by several mechanisms (Bayliss et al., 1987; Francis et al., 1990). The augmented renin-angiotensin system activity may stimulate sympathetic nervous system activity in our patients with CHF. Another factor includes the baroreceptor mechanisms with preload reduction and volume depletion after diuresis with spironolactone treatment (Hirsch et al., 1987). This study has several limitations. Because the aim of this study was to assess the effects of additive spironolactone on exercise capacity and on neurohormonal response to exercise, we selected mild CHF patients. Therefore, the effects of spironolactone on exercise capacity and neurohormonal profiles in severe CHF patients, which are of great interest, remain to be determined. Our findings should not be extrapolated to patients with severe CHF, and further studies are necessary to determine the effects of spironolactone on these variables in patients with severe CHF. We also acknowledge that this study is not placebo controlled and that small numbers of the study population made it difficult to yield a statistical difference with great statistical power. In this regard, it is important to note that there is an ongoing large-scale trial, the Randomized Aldactone Evaluation Study (RALES Investigators, 1996). This study is a multicenter mortality trial to determine the effects of adding lowdose spironolactone to standard diuretics and ACE inhibitor therapy in patients with CHF. This randomized trial will give us substantial information on the effects of spironolactone when used in conjunction with an ACE inhibitor in patients with CHF. In conclusion, chronic additive treatment with spironolactone, an aldosterone receptor antagonist, was associated with neurohormonal activation both at rest and during exercise without changing the exercise capacity of patients with mild CHF. It seems important to identify subgroups of patients with CHF who will most benefit from receiving spironolactone in addition to the conventional therapy with loop diuretics and ACE inhibitor. We would like to express thanks to Miss Saigou and Miss Iwasa for their excellent secretarial assistance.

References Acute Infarction Ramipril Efficacy (AIRE) Study Investigators (1993) Effect of ramipril on mortality and morbidity of survivors of acute myocardial infarction with clinical evidence of heart failure. Lancet 342, 821–828. Barr C. S., Lang C. C., Hanson J., Arnott M., Kennedy N. and Struthers A. D. (1995) Effects of adding spironolactone to an angiotensin-converting enzyme inhibitor in chronic congestive heart failure secondary to coronary artery disease. Am. J. Cardiol. 76, 1259–1265. Bayliss J., Norell M., Anson R. C., Sutton G. and Wilson P. P. (1987) Untreated heart failure: clinical and neuroendocrine effects of introducing diuretics. Br. Heart J. 57, 17–22. Beaver W. L., Wasserman K. and Whipp B. J. (1986) A new method for de-

Spironolactone and Neurohormonal Response to Exercise in CHF

99

tecting the anaerobic threshold by gas exchange. J. Appl. Physiol. 60, 2020–2027. Borghi C., Boschi S., Ambrosioni E., Melandri G., Branzi A. and Magnani B. (1993) Evidence of a partial escape of renin-angiotensin-aldosterone blockade in patients with acute myocardial infarction treated with ACE inhibitors. J. Clin. Pharmac. 33, 40–45. Captopril-Digoxin Multicenter Research Group (1988) Comparative effects of therapy with captopril and digoxin in patients with mild-to-moderate heart failure. JAMA 259, 539–544. Captopril Multicenter Research Group (1983) A placebo-controlled trial of captopril in refractory chronic congestive heart failure. J. Am. Coll. Cardiol. 2, 755–763. Cheitlin M. D., Byrd R., Benowitz N., Liu E. and Modin G. (1991) Amiloride improves hemodynamics in patients with chronic congestive heart failure treated with chronic digoxin and diuretics. Cardiovasc. Drug Ther. 5, 719–726. Cohn N. J., Levine T. B., Olivari M. T., Garberg V., Lura D., Francis G. S., Simon A. B. and Rector T. (1984) Plasma norepinephrine as a guide to prognosis in patients with chronic heart failure. N. Engl. J. Med. 311, 819–823. CONSENSUS Trial Study Group (1987) Effects of enalapril on mortality in severe congestive heart failure: results of the Cooperative North Scandinavian Enalapril Survival Study (CONSENSUS). N. Engl. J. Med. 316, 1429–1435. Dahlstrom U. and Karlsson E. (1992) Captoril and spironolactone therapy in patients with refractory congestive heart failure. Curr. Ther. Res. 51, 235–248. Dzau V. J. (1992) Vascular renin angiotensin pathways: a new therapeutic target. J. Cardiovasc. Pharmac. 10(Suppl. 7), S13–S26. Francis G. S., Benedict C., Johnstone D. E., Kirlin P. C., Nicklas J., Liang C., Kubo S. H., Rudin-Toresky E. and Yusuf S. (1990) Comparison of neuroendocrine activation in patients with left ventricular dysfunction with and without congestive heart failure: a substudy of the studies of left ventricular dysfunction (SOLVD). Circulation 82, 1724–1729. Haerer W., Bauer U., Sultan N., Cernoch K., Mouselimis N., Fehske K. J., Hetzel M., Stauch M. and Hombach V. (1990) Acute and chronic effects of a diuretic monotherapy with piretanide in congestive heart failure: a placebo-controlled trial. Cardiovasc. Drugs Ther. 4, 515–522. Hama N., Nakao K., Nukouyama M., Suga S., Ogawa Y., Kawabata Y., Sugawara T. and Imura H. (1991) Fundamental and clinical evaluation of Shionoriaw ANP: human atrial natriuretic peptide IRMA kit. Kiso to Rinsyo 25, 455–462. Henry R. J. (1968) Clinical Chemistry: Principles and Techniques. pp. 655–656. Harper & Row, New York. Hensen J., Abraham W. T., Durr J. A. and Schrier R. W. (1991) Aldosterone in congestive heart failure: analysis of determinants and role in sodium retention. Am. J. Nephrol. 11, 441–446. Hirsch A. T., Dzau V. J. and Creager M.A. (1987) Baroreceptor function in congestive heart failure: effect on neurohumoral activation and regional vascular resistance. Circulation 75(Suppl. IV), IV-36–IV-48. Husain A. (1993) The chymase-angiotensin system in humans. J. Hypertens. 11, 1155–1159. Ikram H., Webster M. W. I., Nicholls M. G., Lewis G. R. J., Richards A. M. and Crozier I. G. (1986) Combined spironolactone and converting enzyme inhibitor therapy for refractory heart failure. Aust. N. Z. J. Med. 16, 61–63. Kinugawa T., Ogino K., Kitamura H., Miyakoda H., Saitoh M., Hasegawa J., Kotake H. and Mashiba H. (1991) Response of sympathetic nervous system activity to exercise in patients with congestive heart failure. Eur. J. Clin. Invest. 21, 542–547. Kinugawa T., Ogino K., Kitamura H., Saitoh M., Omodani H., Osaki S., Hisatome I. and Miyakoda H. (1996) Catecholamines, renin-angiotensinaldosterone system, and atrial natriuretic peptide at rest and during submaximal exercise in patients with congestive heart failure. Am. J. Med. Sci. 312, 110–117. Kirlin P. C., Grekin R., Das S., Ballor E., Johnson T. and Pitt B. (1986) Neurohumoral activation during exercise in congestive heart failure. Am. J. Med. 81, 623–629. Morimoto T., Aoyama M., Gotoh E. and Shionoiri H. (1983) A method of radioimmunoassay of plasma angio-tensin II using florisil. Folia Endocrinol. Jpn. 59, 215–229. Nishikimi T., Kohno M., Matsuura T., Akioka K., Teragaki M., Yasuda M., Oku H., Takeuchi K. and Takeda T. (1986) Effect of exercise on circu-

lating atrial natriuretic polypeptide in valvular heart disease. Am. J. Cardiol. 58, 1119–1120. Ogihara T., Nishi K., Sonoyama A., Naka T., Nakamaru M., Miyai K., Kumazawa Y. and Iwanaga K. (1980) Determination of plasma renin activity using Gammer Coat[125I] PRA Kit. Horumon to Rinsyou 28, 63–69. Packer M. (1988) Neurohormonal interactions and adaptations in congestive heart failure. Circulation 77, 721–730. Pitt B. (1995) “Escape” of aldosterone production in patients with left ventricular dysfunction treated with an angiotensin converting enzyme inhibitor: implications for therapy. Cardiovasc. Drugs Ther. 9, 145–149. Pouleur H., Konstam M. A., Benedict C. R., Donckier J., Galanti L., Melin J., Kinan D., Ahn S. and Rousseau M. F. (1993) Progression of LV dysfunction during enalapril therapy: relationship with neurohormonal reactivation. Circulation 88, i–293. RALES Investigators (1996) Effectiveness of spironolactone added to an angiotension-converting enzyme inhibitor and a loop diuretic for severe chronic congestive heart failure (The Randomized Aldactone Evaluation Study [RALES]). Am. J. Cardiol. 78, 902–907. Rousseau M. F., Konstam M. A., Benedict C. R., Donckier J., Galanti L., Melin J., Kinan D., Ahn S., Ketesleger J. M. and Pouleur H. (1994) Progression of LV dysfunction secondary to coronary artery disease: sustained neurohormonal activation and effects of ibopamine therapy during long term therapy with ACE inhibitor. Am. J. Cardiol. 73, 488–493. Shionoiri H., Minamizawa K., Sugimoto K., Abe Y., Suzuki T., Ito S., Morishita R., Higaki J. and Ogiwara T. (1989) Fundamental and clinical studies on SPAC-S Aldosterone RIA Kit. Igaku to Yakugaku 21, 293–302. SOLVD Investigators (1991) Effect of enalapril on survival in patients with reduced left ventricular ejection fractions and congestive heart failure. N. Engl. J. Med. 325, 293–302. Staessen J., Lijnen P., Fagard R., Verscheren L. J. and Amery A. (1981) Rise in plasma concentration of aldosterone during long-term angiotensin II suppression. J. Endocrinol. 91, 457–465. Stampfer M., Epstein S. E., Beiser G. D. and Braunwald E. (1968) Hemodynamic effects of diuresis at rest and during intense upright exercise in patients with impaired cardiac function. Circulation 37, 900–911. Struthers A. D. (1996) Aldosterone escape during angiotensin-converting enzyme inhibitor therapy in chronic heart failure. J. Cardiac Failure 2, 47–54. Sue D. Y., Wasserman K., Morrica R. B. and Casburi R. (1988) Measurement of anaerobic threshold by V-slope method in patients with chronic obstructive lung disease and normal subjects. Chest 94, 931–938. Sullivan M. J., Green H. J. and Cobb F. R. (1991) Altered skeletal muscle metabolic response to exercise in patients with heart failure. Circulation 84, 1597–1607. Swedberg K., Eneroth P., Kjekshus J. and Wilhelmsen L. for The CONSENSUS Trial Study Group. (1990) Hormones regulating cardiovascular function in patients with severe congestive heart failure and their relation to mortality. Circulation 82, 1730–1736. Teichholz L. E., Kreulen T., Herman M. V. and Gorlin R. (1976) Problems in echocardiographic volume determinations: echocardiographic-angiographic correlations in the presence or absence of asynergy. Am. J. Cardiol. 37, 7–11. Textor S. C., Bravo E. L., Fouad F. M. and Tarazi R. C. (1982) Hyperkalemia in azotemic patients during angiotensin-converting enzyme inhibition and aldosterone reduction with captopril. Am. J. Med. 73, 719–725. van den Meiracker A. H., Man in’t Veld A. J. and Vaneck H. J. R. (1992) Partial escape of ACE inhibition during prolonged ACE inhibitor treatment: does it exist and does it affect the antihypertensive response? Hypertension 10, 803–812. van Vilet A., Donker A. J. M., Nauta J. J. P. and Verheugt F. W. A. (1993) Spironolactone in congestive heart failure refractory to high-dose loop diuretic and low-dose angiotensin-converting enzyme inhibitor. Am. J. Cardiol. 71, 21A–28A. Wasserman K. (1984) The anaerobic threshold measurement to evaluate exercise performance. Am. Rev. Respir. Dis. 129(Suppl.), S35–S40. Wasserman K. and Whipp B. J. (1975) Exercise physiology in health and disease. Am. Rev. Respir. Dis. 112, 219–249. Willson J. R., Martin J. L., Schwartz D. and Ferraro N. (1984) Exercise intolerance in patients with chronic heart failure: role of impaired nutritive flow to skeletal muscle. Circulation 69, 1079–1087. Yoshimura M., Komori T., Nakanishi T. and Takahashi H. (1993) Estimation of sulphoconjugated catecholamine concentrations in plasma by high-performance liquid chromatography. Ann. Clin. Biochem. 30, 135– 141.