Influence of metoprolol on heart rate variability in survivors of remote myocardial infarction

We assessed the influence of metoprolol on heart rate variability in survivors of remote myocardial infarction. In 43 survivors of myocardial infarction 12 to 18 months previously (26 men and 17 women, aged 38 to 69 years), two 24-hour ambulatory electrocardiograms were recorded 2 weeks apart. In patients in group A (n=28), who had taken metoprolol for the previous year, the drug was discontinued for 2 weeks, after which the first recording was done. The second recording was done 2 weeks after metoprolol was resumed. In patients in group B (n=15), who had not taken metoprolol for the previous year, it continued to be withheld, and two 24-hour recordings were done 2 weeks apart. In group A, metoprolol increased the time domain variables indicative of enhanced vagal tone; root-mean-square successive difference in normal RR (NN) intervals was 20 +/- 11 ms (mean +/- SD) without and 24 +/- 9 ms with metoprolol (p<0.05), and the proportion of NN that differ by >50 ms (pNN50%) was 3.6 +/- 6.0 without and 5.5 +/- 6.0 with metoprolol (p<0.05). In the frequency domain, the logarithms of the 24-hour very low frequency and the 24-hour high-frequency power (reflecting parasympathetic activity) were increased (5.12 +/- 1.03 and 4.48 +/- 1.51, respectively, without metoprolol; 5.32 +/- 0.99 and 4.83 +/- 1.24, respectively, with metoprolol, p <0.05 for both). Thus, in survivors of remote myocardial infarction, metoprolol enhances parasympathetic cardiac activity in the time and frequency domain measures of heart rate variability.

Decreased blood viscosity and serum levels of erythropoietin after anti-hypertensive treatment with amlodipine or metoprolol: results of a cross-over study

The increased viscosity of blood of hypertensive patients can be assumed to be a risk factor for the development of cardiovascular diseases. The aim of the present study was to elucidate whether anti-hypertensive treatment has any impact on blood rheology. Twenty patients with previously untreated hypertension who consecutively attended our outpatient hypertension clinic were included in this prospective, open, cross-over study. The patients were randomly selected to treatment with amlodipine or metoprolol. The anti-hypertensive therapy was switched after 4 months. Haemorheological and haemodynamic variables were measured with rotational viscometry and impedance cardiography, respectively. Fifteen and 16 patients could be evaluated after amlodipine or metoprolol treatment respectively. The mean blood pressure (BP) decreased from 159 +/- 22/105 +/- 7 to 139 +/- 21/91 +/- 6 mm Hg on amlodipine and from 162 +/- 22/104 +/- 5 to 145 +/- 24/90 +/- 8 mm Hg on metoprolol therapy. After amlodipine treatment, the total peripheral resistance index decreased whereas metoprolol treatment was accompanied by a decrease in the cardiac index. Decreases in whole blood viscosity, haematocrit and serum erythropoietin were found after amlodipine as well as metoprolol treatment. After amlodipine the plasma viscosity decreased and the erythrocyte deformability increased in the majority of patients. Plasma fibrinogen decreased after metoprolol treatment. Despite the differences in haemodynamic mechanisms underlying the decrease in BP, amlodipine and metoprolol exert beneficial effects on blood viscosity. Haemodilution and a decrease in serum erythropoietin may be factors underlying this decrease in blood viscosity.

Combined alpha-beta blockade (doxazosin plus metoprolol) compared with beta blockade alone in chronic congestive heart failure

There has been growing evidence for the benefits of beta blockers, but alpha blockers have not shown sustained benefits in chronic congestive heart failure (CHF). Thirty patients with moderate to severe CHF (New York Heart Association class II to IV) were sequentially assigned to receive metoprolol 6.25 mg with the alpha-1 antagonist doxazosin 4 mg/day or metoprolol alone. The dose of metoprolol was gradually increased to a target dose of 50 mg orally twice daily. Hemodynamic measurements were obtained before drug therapy, 2 hours after the first dose of combined alpha-beta therapy or metoprolol alone, and after 3 months of continuous treatment. Nuclear ejection fraction, plasma norepinephrine, and submaximal and maximal exercise capacity were also measured before and after chronic therapy. With initial combined drug administration, mean arterial pressure, left ventricular filling pressure, and systemic vascular resistance decreased significantly compared with results after metoprolol alone. However, after 3 months of continuous therapy, both treatment groups showed similar and significant reductions in systemic vascular resistance and heart rate, with significant increases in cardiac index, stroke volume index, stroke work index, ejection fraction, and exercise capacity. Furthermore, the next dose of chronic combined medication no longer showed vasodilating effects. Chronic therapy with fixed-dose doxazosin and increasing doses of metoprolol produced identical effects as those seen in patients receiving metoprolol alone.

Relationship between sodium-lithium countertransport and insulin sensitivity in mild hypertension

OBJECTIVES

To study the relationship between insulin sensitivity and sodium-lithium countertransport (Na(+)-Li+ CT) in mild, essential hypertension, and to investigate the effect of metformin and metoprolol, respectively.

DESIGN

A double-blind, triple cross-over, placebo-controlled study over a total period of 18 weeks. SETTING. A hypertension out-patient clinic and research laboratory at Sahlgrenska University Hospital.

SUBJECTS

Seventeen non-obese men with mild essential -hypertension and 17 weight-matched, healthy controls.

INTERVENTIONS

Metformin 850 mg b.i.d., metoprolol CR 100 mg once daily and placebo were given during 18 weeks. Each treatment period was 6 weeks. A euglycaemic clamp was performed and erythrocyte Na(+)-Li+ CT measured after each 6-week treatment period.

MAIN OUTCOME MEASURES

Insulin sensitivity, erythrocyte Na(+)-Li+ CT, their interrelation, and the effect of metformin and metoprolol CR on both variables, respectively.

RESULTS

The hypertensive men tended to have an elevated Na(+)-Li+ CT compared with the control subjects (0.34 +/- 0.03 versus 0.26 +/- 0.02 mmol L-1 h-1, P < 0.1). Glucose disposal rate was similar, but plasma insulin levels higher (P < 0.05) among the hypertensives than the controls. Na(+)-Li+ CT exhibited a positive relationship to BMI (r = 0.53, P = 0.03) and a negative correlation to glucose disposal rate (r = -0.66, P = 0.008) in the hypertensive subjects. In multiple regression analysis, Na(+)-Li+ CT showed a significant correlation to glucose disposal rate only. In the control subjects, there was no relation between glucose metabolism and Na(+)-Li+ CT. Neither metformin nor metoprolol influenced Na(+)-Li+ CT, glucose disposal rate or plasma insulin.

CONCLUSION

Erythrocyte Na(+)-Li+ CT seemed to be closely related to insulin-glucose metabolism in mild hypertension, but was not influenced by metformin or metoprolol.

Effects of antihypertensive therapy on platelet cytosolic calcium responses to low density lipoprotein cholesterol

This study examines the effects of antihypertensive therapy on platelet cytosolic calcium [Ca2+]i responses to low-density lipoprotein cholesterol (LDL) and vasopressin (AVP) in 15 patients (50-80 years) participating in the Hypertension Optimal Treatment International Study. All patients (diastolic blood pressure (DBP) > or = 100 mm Hg and < or = 115 mm Hg) were treated with the calcium antagonist felodipine (10 mg p.o.) with or without addition of enalapril (up to 20 mg daily as needed) to lower diastolic pressures to < 85 mm Hg. This antihypertensive therapy lowered DBP (104 +/- 0.8 to 78 +/- 1.6 mm Hg, P < 0.0001), but had no effect on basal [Ca2+]i or AVP-stimulated [Ca2+]i responses. Basal platelet [Ca2+]i following antihypertensive therapy (49 +/- 3.4 ng/ml) were not different from those prior to therapy (52 +/- 4.7 ng/ml). Additionally, [Ca2+]i responses to AVP following therapy (554 +/- 74 units) were not different from those prior to treatment (595 +/- 49 units). Following antihypertensive therapy, [Ca2+]i responses to 200 micrograms/ml of LDL were decreased fourfold (P < 0.05). These results suggest that antihypertensive therapy with a calcium channel blocker may potentially impact the atherogenic process by reducing the platelet [Ca2+]i rise, and potentially the aggregatory response, to LDL.

Combination therapy with metoprolol and nifedipine versus monotherapy in patients with stable angina pectoris. Results of the International Multicenter Angina Exercise (IMAGE) Study

OBJECTIVES

This study was designed to investigate whether combination therapy with metoprolol and nifedipine provides a greater anti-ischemic effect than does monotherapy in individual patients with stable angina pectoris.

BACKGROUND

Combination therapy with a beta-adrenergic blocking agent (which reduces myocardial oxygen consumption) and a dihydropyridine calcium antagonist (which increases coronary blood flow) is a logical approach to the treatment of stable angina pectoris. However, it is not clear whether, in individual patients, this combined therapy is more effective than monotherapy.

METHODS

Two hundred eighty patients with stable angina pectoris were enrolled in a double-blind trial in 25 European centers. Patients were randomized (week 0) to metoprolol (controlled release, 200 mg once daily) or nifedipine (Retard, 20 mg twice daily) for 6 weeks; placebo or the alternative drug was then added for a further 4 weeks. Exercise tests were performed at weeks 0, 6 and 10.

RESULTS

At week 6, both metoprolol and nifedipine increased the mean exercise time to 1-mm ST segment depression in comparison with week 0 (both p < 0.01); metoprolol was more effective than nifedipine (p < 0.05). At week 10, the groups randomized to combination therapy had a further increase in time to 1-mm ST segment depression (p < 0.05 vs. placebo). Analysis of the results in individual patients revealed that 7 (11%) of 63 patients adding nifedipine to metoprolol and 17 (29%) of 59 patients (p < 0.0001) adding metoprolol to nifedipine showed an increase in exercise tolerance that was greater than the 90th percentile of the distribution of the changes observed in the corresponding monotherapy + placebo groups. However, among these patients, an additive effect was observed only in 1 (14%) of the 7 patients treated with metoprolol + nifedipine and in 4 (24%) of the 17 treated with nifedipine + metoprolol.

CONCLUSIONS

The mean additive anti-ischemic effect shown by combination therapy with metoprolol and nifedipine in patients with stable angina pectoris is not the result of an additive effect in individual patients. Rather, it may be attributed to the recruitment by the second drug of patients not responding to monotherapy.

Delayed right heart failure following lung transplantation

Dynamic right ventricular outflow tract obstruction (RVOTO) has been reported following lung transplantation for pulmonary hypertension, usually in association with the use of inotropic agents. This report describes delayed severe right-sided heart failure associated with right ventricular outflow tract obstruction following sequential bilateral lung transplantation and closure of a ventricular septal defect. The patient had no evidence of outflow tract obstruction in the early posttransplant period but developed progressive right heart failure more than 2 months later. Catheterization revealed dynamic RVOTO and an elevated right ventricular end-diastolic pressure. The patient was treated with metoprolol tartrate and diltiazem hydrochloride with resolution of the outflow tract obstruction and heart failure. This case demonstrates that RVOTO can occur in the late posttransplant period and must be included in the differential diagnosis for patients who develop right-sided heart failure.

Effect of quinapril or metoprolol on heart rate variability in post-myocardial infarction patients

The effect of quinapril or metoprolol on heart rate variability (HRV) indexes was studied in patients who had recovered from acute myocardial infarction. Patients with stable coronary artery disease and normal volunteers were used as controls. Sixty patients with uncomplicated myocardial infarction (aged 32 to 74 years [mean 56.7]) were randomized to quinapril (n = 25), metoprolol (n = 25), and placebo (n = 10). HRV was assessed 5 days (baseline) and 35 days after the onset of acute myocardial infarction. After the baseline studies, the post-myocardial infarction patients were treated with metoprolol (50 to 100 mg/day), quinapril (5 to 10 mg/day), or placebo. Twenty patients with stable coronary artery disease and 20 healthy volunteers, age- and sex-matched to myocardial infarction patients, were used as controls. Compared with placebo, quinapril and metoprolol increased HRV indexes significantly 35 days after the onset of myocardial infarction. HRV indexes were not statistically different between the 2 treatment groups. At baseline and after therapy, HRV was similar in patients with anterior or inferior wall myocardial infarction. HRV 35 days after the onset of myocardial infarction was not different from HRV in patients with stable coronary artery disease, but was decreased when compared with that in normal volunteers. Data suggest that quinapril has the same beneficial effect on HRV indexes as metoprolol in patients who have recovered from uncomplicated acute myocardial infarction.

Prostacyclin biosynthesis in essential hypertension before and during treatment

Protacyclin biosynthesis was investigated in 133 untreated newly diagnosed patients with uncomplicated essential hypertension. Urinary excretion of 6-oxo-prostaglandin F1 alpha and of 2,3-dinor-6-oxo-prostaglandin F1 alpha, stable breakdown products of prostacyclin, was measured following a 1 month run-in period. To determine whether lowering blood pressure (BP) influenced prostacyclin biosynthesis, 106 consenting patients with diastolic pressure 90-120 mm Hg were allocated randomly to treatment with bendrofluazide, metoprolol, quinapril or amlodipine in an open parallel group design. Dose was increased to reduce diastolic arterial pressure to <90 mm Hg. Terazosin was added if this target BP was not achieved, and its dose increased if necessary. Urinary excretion rates of prostaglandins were measured after 1 year in patients in whom the target diastolic pressure was achieved. Mean arterial pressure varied from 106-168 mm Hg in untreated patients and excretion of both prostacyclin-derived products varied from <5 to >350 ng/g creatinine. Arterial pressure and prostaglandin excretion were not significantly correlated. In 57 patients in whom target pressure was achieved, BP before treatment was 166 +/- 2/100 +/- 1 at baseline and 144 +/- 2/86 +/- 1 mm Hg at 1 year. Excretion rates of each prostacyclin-derived product were similar before treatment and at 1 year, with no significant differences between the drugs. These findings do not support the hypothesis that deficient prostacyclin biosynthesis contributes to the pathogenesis of essential hypertension, or that increased prostacyclin biosynthesis plays a part in the response to treatment with antihypertensive medication.

Effects of metoprolol vs verapamil in patients with stable angina pectoris. The Angina Prognosis Study in Stockholm (APSIS)

OBJECTIVE

To study long-term treatment effects of metoprolol or verapamil on combined cardiovascular end points and psychological variables in patients with stable angina pectoris.

DESIGN

Randomized, double-blind, double-dummy trial.

PATIENTS

The study included 809 patients under 70 years of age with stable angina pectoris. The mean age of the patients was 59 +/- 7 years and 31% were women. Exclusion criteria were myocardial infarction within the previous 3 years and contraindications to beta-blockers and calcium antagonists. The patients were followed between 6 and 75 months (median 3.4 years and a total of 2887 patient years).

INTERVENTION

The patients were treated with either metoprolol (Seloken ZOC 200 mg o.d.) or verapamil (Isoptin Retard 240 b.i.d.). Acetylsalicylic acid, ACE inhibitors, lipid lowering drugs and long acting nitrates were allowed in the study.

END POINTS

Death, non-fatal cardiovascular events including acute myocardial infarction, incapacitating or unstable angina, cerebrovascular or peripheral vascular events. Psychological variables reflecting quality of life i.e. psychosomatic symptoms, sleep disturbances and an evaluation of overall life satisfaction.

RESULTS

Combined cardiovascular events did not differ and occurred in 30.8% and 29.3% of metoprolol and verapamil treated patients respectively. Total mortality in metoprolol and verapamil treated patients was 5.4 and 6.2%, respectively. Cardiovascular mortality was 4.7% in both groups. Non-fatal cardiovascular events occurred in 26.1 and 24.3% of metoprolol and verapamil-treated patients, respectively. Psychosomatic symptoms and sleep disturbances were significantly improved in both treatment groups. The magnitudes of change were small and did not differ between treatments. Life satisfaction did not change on either drug. Withdrawals due to side effects occurred in 11.1 and 14.6% respectively.

CONCLUSION

This long term study indicates that both drugs are well tolerated and that no difference was shown on the effect on mortality, cardiovascular end points and measures of quality of life.

Power spectral analysis of heart rate in elderly hypertensive subjects with or without silent coronary disease

Much evidence indicates an involvement of the sympathetic nervous system in the genesis of silent myocardial ischemia. The authors assessed autonomic system activity by power spectrum analysis of heart rate variability in 21 elderly hypertensive men with and without angiographically confirmed coronary artery disease and compared the results with those from an age-matched control group. In the analysis an autoregressive algorithm was used to determine the power spectrum from an electrocardiographic recording of 512 consecutive RR intervals. The autonomic nervous system induces two distinct sinusoids: a low-frequency signal attributable to sympathetic activity and a high-frequency vagal response. In the hypertensive patients with coronary disease the authors also evaluated sympathetic activation after double-blind, placebo-controlled administration of metoprolol (100 mg/day), followed by amlodipine (10 mg/day), quinapril (20 mg/day), and amlodipine (5 mg/day) plus quinapril (10 mg/day).

Evaluation of importance of central effects of atenolol and metoprolol measured by heart rate variability during mental performance tasks, physical exercise, and daily life in stable postinfarct patients

BACKGROUND

Physical exercise and mental work cause alterations in cardiac autonomic control. beta-Blockers protect the heart against stress, and this effect may be in part centrally mediated. In this context, the lipophilicity of the drug would be clinically relevant.

METHODS AND RESULTS

Thirty postinfarct patients were randomized to receive 100 mg atenolol or 200 mg metoprolol CR in a double-blind, crossover manner, each for a 6-week period. Heart rate (HR) variability was used to study autonomic effects during mental and physical stress and to study circadian variations. Mean 24-hour HR decreased from 77 +/- 7 to 60 +/- 6 beats per minute after atenolol and to 62 +/- 6 beats per minute after metoprolol (P = .046). At baseline, mental performance tasks did not affect HR, but decreased HR variability (SDNN index from 51 +/- 26 to 30 +/- 13 milliseconds [ms], P < .001; high-frequency power from 130 +/- 143 to 110 +/- 125 ms2, P = .046; and low-frequency power from 538 +/- 447 to 290 +/- 275 ms2, P < .001). Both beta-blockers decreased HR during mental performance tasks (P < .001) and increased SDNN index and high-frequency power. Before treatment, bicycle exercise decreased HR variability; root-mean-square of successive difference decreased from 21 +/- 8 to 15 +/- 10 ms (P = .004). beta-Blockade could not prevent this decrease. No differences between atenolol and metoprolol were observed for absolute high- and low-frequency power or after adjustment for HR. Vagal blockade with methylatropine during chronic beta-blocker treatment nearly abolished all components of spectral power. HR was found to be the parameter most strongly affected by beta-blockade but not by an influence on vagal tone. No differences were found between atenolol and metoprolol.

CONCLUSIONS

In stable postinfarct patients, chronic treatment with metoprolol and atenolol attenuates the reduction in HR variability induced by mental performance tasks, but the effects during exercise are limited. beta-Blockers do not appear to increase vagal tone in this stable patient group. The point of action in these patients is mainly a reduction in HR, probably due to a reduction in stress-induced sympathetic activation. Clinically significant differences between atenolol and metoprolol were absent, indicating that the degree of lipophilicity does not distinguish among the beta-blockers what their salutary effects are on HR variability during the specific challenges used.

Effect of metoprolol on death and cardiac events during a 2-year period after coronary artery bypass grafting. The MACB Study Group

PURPOSE

To evaluate the effect of long-term treatment with metoprolol after coronary bypass grafting on death and cardiac events.

METHODS

Patients in western Sweden on whom coronary artery bypass grafting was performed between June 1988 and June 1991 were evaluated for inclusion during the first 3 weeks after surgery. Major exclusion criteria were age > 75 years, concomitant valve surgery, traditional contraindications to beta-blockers and unwillingness to participate. Patients were randomized in a double-blind fashion to 100 mg of metoprolol/placebo daily for 2 weeks and thereafter 200 mg daily for 2 years.

RESULTS

Of 2365 patients who were operated on, 967 were randomized to either metoprolol (n = 480) or placebo (n = 487). Primary end points (death, non-fatal myocardial infarction, unstable angina pectoris, need for coronary artery bypass grafting or percutaneous transluminal angioplasty), were reached by 42 patients in the metoprolol group (8.8%), as compared with 39 in the placebo group (8.0%) (P = 0.73). Of all the patients randomized to metoprolol, 34% withdrew from blind treatment prematurely compared with 44% for placebo (P < 0.01).

CONCLUSION

Prophylactic treatment with metoprolol over a 2-year period after coronary artery bypass grafting did not reduce death or the development of cardiac events. However, the 95% confidence limits ranged from the possibility of a 30% reduction in events to a 68% increase in events if patients were treated with metoprolol as compared with placebo.

The effect of beta-blockade therapy on the response to exercise training in postmyocardial infarction patients

Cardiac rehabilitation after a myocardial infarction has been shown to improve exercise capacity. Beta blockade has been shown to be effective in treating angina and reducing mortality, but studies are controversial as to whether beta-blockade therapy attenuates the effects of training. We attempted to study the effects of beta blockade (metoprolol) on the response to training in patients enrolled in a cardiac rehabilitation program after an uncomplicated myocardial infarction. We studied 27 patients with a recent uncomplicated myocardial infarction who were subdivided in two groups: Group 1 (13 patients) not taking a beta blocker, and Group 2 (14 patients) taking metoprolol (mean 142 +/- 57 mg daily). All patients underwent a maximal cardiopulmonary exercise test before and after a 3-month training program. The training intensity was designed to approximate the ventilatory threshold. Results showed an increase in peak VO2 in both Group 1 (27%, p < 0.01) and Group 2 (33%, p < 0.001), and an increase in VO2 at the ventilatory threshold (39% in Group 1 and 28% in Group 2, p < 0.01). The mean changes in exercise capacity were not different between groups. It was concluded that metoprolol did not influence the beneficial effects of a cardiac rehabilitation program in postmyocardial infarction patients.

Effect of low dose beta blockers on atrial and ventricular (B type) natriuretic factor in heart failure: a double blind, randomised comparison of metoprolol and a third generation vasodilating beta blocker

OBJECTIVES

This study examines the acute effects of two differing beta adrenergic blocking agents (metoprolol and a third generation vasodilating beta blocker) on plasma concentrations of atrial natriuretic factor (ANF), brain (ventricular) natriuretic factor (BNF), and haemodynamic variables in patients with heart failure.

SETTING

University teaching hospital.

METHODS

20 patients with impaired left ventricular systolic function [ejection fraction 32 (SEM 2.3)%] were randomised in a double blind manner to receive either oral metoprolol 6.25 mg twice daily or celiprolol 25 mg daily. Haemodynamic variables were evaluated by Swan-Ganz pulmonary artery catheter over 24 hours. ANF and BNF concentrations were measured at baseline, 5 h, and 24 h by radioimmunoassay.

RESULTS

At baseline ANF and BNF concentrations were considerably raised compared to the normal range. Treatment with metoprolol caused ANF to rise further to 147% of the basal level at 5 h (P = 0.017) and 112% at 24 h (P = 0.029). This was associated with a small but non-significant rise in pulmonary capillary wedge pressure. Cardiac output and systemic vascular resistance were unchanged at 24 h. In contrast, after celiprolol ANF fell to 90% of basal levels at 5 h and to 74% of basal level at 24 h (P = 0.019), associated with a small but non-significant fall in pulmonary capillary wedge pressure [-3.3 (2.7) mm Hg] and systemic vascular resistance, and rise in cardiac output from 3.2 (0.2) to 4.0 (0.4) l/min (P = 0.04). BNF concentrations rose to 112% of baseline at 5 h (P = 0.09) after metoprolol but fell slightly, to 91% of baseline values, after celiprolol (NS).

CONCLUSIONS

Metoprolol, even in very low doses (6.25 mg), produced a rise in ANF and BNF, although minimal haemodynamic changes were detected. In contrast, a vasodilating beta blocker was associated with a significant fall in ANF and BNF and a small rise in cardiac output. This study confirms both the advantages of vasodilating beta blockers over metoprolol for initial treatment of heart failure and the usefulness of ANF and BNF measurements for the assessment of drug effects in heart failure compared to traditional haemodynamic measurements.

Treatment of silent ischemia in unstable angina: a randomized comparison of sustained-release verapamil versus metoprolol

Silent ischemia is a frequent finding in patients with unstable angina and portends a poor prognosis. We compared the efficacy of sustained-release (SR) verapamil and metoprolol in reducing silent ischemia in patients with unstable angina and assessed whether detection of silent ischemia was related to unfavorable outcomes in the contemporary setting of concurrent therapy with heparin and aspirin. Holter monitoring (leads a VF, V2, V5) for the first 72 h was used to assess the frequency and duration of ST-shift episodes. There were 37 patients in the verapamil-SR group and 40 patients in the metoprolol group, with both groups having similar baseline characteristics. There were more episodes of angina in the verampamil-SR group (29 vs. 12, p = 0.05). There was no difference between the two groups in the frequency (51 vs. 49 episodes, p = 0.9) or duration (23 +/- 48 vs. 18 +/- 50 min, p = 0.6) of ST-shift episodes. There were 20 unfavorable in-hospital outcomes distributed equally between the two groups (p = 0.9). Patients with unfavorable outcomes had ST shift more often (50 vs. 28%, p = 0.07) and for a longer duration (40 +/- 69 vs. 13 +/- 38 min, p = 0.03). Patients with ST shift > or = 60 min had a 60% probability of unfavorable outcome compared with 33% for ST shift of 1-59 min duration and 20% for no ST shift (p = 0.04). We conclude that metoprolol appears to reduce symptoms better than verapamil-SR, but no difference in silent ischemia or unfavorable outcomes was seen. Silent ischemia remains a common occurrence in these patients despite heparin and aspirin therapy and its detection continues to have prognostic value.

Usefulness of heart rate variability in predicting drug efficacy (metoprolol vs diltiazem) in patients with stable angina pectoris

We investigated whether analysis of heart rate (HR) variability may be used to predict the efficacy of drug treatment of myocardial ischemia. In a double-blind, crossover study, 28 patients with stable angina pectoris, proven coronary artery disease, and myocardial ischemia during Holter monitoring received metoprolol controlled-release 200 mg once daily and diltiazem 60 mg 4 times daily. After a placebo run-in phase and after each treatment period, 72-hour Holter recordings were obtained for HR variability and ST-segment analysis. At baseline, the total duration of myocardial ischemia was 11.4 +/- 13.9 minutes (mean +/- SD per 24 hours), and the total number of episodes was 2.2 +/- 2.3. Metoprolol significantly reduced the total duration of ischemia by -8.7 minutes (95% CI -14.5 to -2.8) and the total number of episodes by -1.9 (-2.9 to -0.8) in patients with a low SD of normal-to-normal intervals at baseline (SDNN), using the median value of 50 ms as a cut-off value. In contrast, significant treatment effects were not observed in patients with a high SDNN at baseline. Similar results were obtained using baseline total power or low-frequency power, but not when using baseline heart rate. Diltiazem reduced the total duration of ischemia by -4.9 minutes (-9.7 to -0.1), but not the number of episodes. Moreover, in contrast to metoprolol, efficacy of diltiazem was not related to baseline HR variability. In conclusion, patients with reduced HR variability at baseline responded to treatment with metoprolol.(ABSTRACT TRUNCATED AT 250 WORDS)

Reductions in muscle sympathetic nerve activity after long-term metoprolol for dilated cardiomyopathy: preliminary observations

OBJECTIVE

To determine whether efferent muscle sympathetic nerve activity diminishes in subjects with dilated cardiomyopathy who improve after long term treatment with metoprolol.

METHODS

Microneurographic, echocardiographic, plethysmographic, and neurohumoral data were obtained immediately before and 20 months after the addition of beta blockade in seven subjects with idiopathic dilated cardiomyopathy with clinical deterioration despite conventional treatment.

RESULTS

Six subjects (three men, three women, aged 24-62 years) were restudied after a mean (SEM) of 20 (2.4) months treatment with metoprolol (45.8 (2.6) mg/d). Long term treatment was associated with decreases in left ventricular end diastolic and end systolic diameter (P < 0.005), left ventricular mass index (P < 0.05), and atrial natriuretic factor (P < 0.05), and increases in fractional shortening (P < 0.05) and mean blood pressure (P < 0.05). There was a 50% reduction in peroneal muscle sympathetic nerve activity (from 49.2 (10.1) to 24.5 (4.7) bursts/min; (P < 0.005) and a 62% decrease in calf vascular resistance (from 56.2 (4.4) to 21.2 (5.7) units; P < 0.005). This reduction in pulse synchronous nerve activity was not simply a function of bradycardia (heart rate fell from 94.2 (4.6) to 62.8 (5.7) beats/min; P < 0.005) since muscle sympathetic burst incidence also decreased (from 51 (8.7) to 37.5 (5.2) bursts/100 heart beats; P < 0.05). Similar haemodynamic improvement was observed in the seventh subject, who was switched to sotalol 200 mg/d and restudied after 20 months, but burst frequency was 50% higher and calf vascular resistance 93% higher.

CONCLUSIONS

Muscle sympathetic nerve activity and calf vascular resistance decrease in patients with dilated cardiomyopathy who improve after long term treatment with metoprolol. Inhibition of central sympathetic outflow may be one mechanism by which metoprolol benefits such subjects.

[Safety and tolerability of beta-blockers in severe cardiac decompensation from dilated cardiomyopathy]

BACKGROUND

Several reports from controlled and uncontrolled studies, mainly in the setting of heart failure due to dilated cardiomyopathy (DCM), indicate that chronic betablockade may improve hemodynamics and clinical function. There are few reports on the effects of betablockers in patients with severe heart failure.

METHODS

Thirty-five patients (27 M; 8 F; mean age 44.3 +/- 16.7 years; range 14-66 years) with DCM, advanced functional (NYHA III-IV) and severe left ventricular dysfunction (LVEF < or = 25%) underwent a test dosage with metoprolol (5 mg b.i.d.). Five patients (14%) did not tolerate the drug; 30 were chronically treated with metoprolol (mean dosage 127 +/- mg/die). No differences in baseline characteristics were observed between tolerant and not tolerant patients, except for the E-deceleration time (103 +/- 42 ms vs 84 +/- 17 ms; p<0.05). Seven alive patients did not reach a minimum follow up of 18 months. Nineteen patients (54.3%) had a follow up of at least 18 months. They were classified as ¿improved¿ (11 pts; and ¿not improved¿ (8 pts; 42%) on the basis of a score, which included left ventricular ejection fraction (> or = 0.10), left ventricular end diastolic diameter (> or = 10%), regression of restrictive filling pattern, NYHA functional class (> or = 1), cardio-thoracic ratio (> or = 10%) and exercise time (> or = 2 min). No differences were observed at baseline between ¿improved¿ and ¿not improved¿ patients, with exception for a history of slight hypertension (p<0.01), congestive heart failure score (p<0.04) and right ventricular function (p<0.05).

RESULTS

An overall improvement of all the main clinical-instrumental parameters were observed in the 19 long term treated patients. At the end of follow up 16 long term treated patients were in NYHA class > or = 2 and in 9 LVEF was > or = 40%. During follow up, among the 30 patients who tolerated the drug, 1 pt died suddenly after 12 months of betablocker therapy and 5 pts were transplanted. No major events occurred among ¿improved¿ patients, after 24 +/- 6 months of follow-up. The actuarial survival curve of our study population shows that survival at 1, 2, 3 and 4 years was respectively 87%, 75%, 67% and 66%. These results confirm previous trials evidence that a progressively increasing dose of beta-blockers confers functional benefit in DCM with severe heart failure.

Metoprolol versus sotalol in the treatment of sustained ventricular tachycardia

The efficacy of sotalol in the treatment of sustained ventricular arrhythmias has been proved; however, whether its antiarrhythmic effect is due to a beta-blocking activity, a class III antiarrhythmic activity, or a combination of both is not known. We conducted a prospective randomized study to compare the effects of metoprolol, a "pure" beta-blocking agent, and of sotalol, a beta-blocking agent with additional class III antiarrhythmic properties, in 34 consecutive patients with documented sustained monomorphic ventricular tachycardia (VT) unrelated to transient causes. After undergoing baseline programmed electrical stimulation (PES-1) to assess arrhythmia inducibility, the patients were randomly assigned to a (double-blind) treatment of either metoprolol (16 patients) or sotalol (18 patients). Before the chronic regimen was initiated, arrhythmia inducibility was reassessed after the intravenous administration of either 0.15 mg/kg metoprolol or 1.5 mg/kg sotalol (PES-2), according to drug assignment. During the chronic oral regimen, a third PES (PES-3) was performed after a median follow-up of 72 days. Resting and exercise ECG, Holter monitoring and echocardiography were performed at baseline and during follow-up. During a 2-year follow-up, a non-fatal arrhythmia recurred in 1 patient of the metoprolol arm and in 5 patients of the sotalol arm; 1 patient in the latter group died suddenly 2 months after the recurrence, while receiving amiodarone therapy. Intention-to-treat analysis showed no difference in the incidence of arrhythmia recurrence, sudden death, or total mortality between the two groups. During PES-1, a sustained ventricular arrhythmia was inducible in 18 of 34 patients (53%), 8 in the metoprolol and 10 in the sotalol arm.(ABSTRACT TRUNCATED AT 250 WORDS)

Approaches to meeting the criteria for fixed dose antihypertensive combinations. Focus on metoprolol

Fixed dose antihypertensive combinations are being used increasingly in the management of hypertension. There are advantages and disadvantages of this form of therapy. The key aims are to: (i) achieve increased efficacy by using drugs that complement each other's actions; (ii) use low doses to minimise adverse effects; and (iii) provide a simple once daily regimen. Fixed dose combinations containing metoprolol have the advantage that beta-blockers are drugs for which there is most evidence that they are cardioprotective; metoprolol is the best documented beta-blocker in this context. The early combination of conventional release metoprolol and hydrochlorothiazide was inadequately investigated by modern standards, but proved well tolerated and effective in clinical practice. The introduction of the long acting metoprolol CR/ZOK (controlled release/zero order kinetics) produced a very satisfactory once daily preparation with no major pharmacokinetic interactions. The fixed dose combination of felodipine and metoprolol CR/ZOK has been well investigated. The two agents complement each other's actions and together provide very effective blood pressure control, cardioprotection and very good tolerability. A case can be made that this preparation more closely meets the requirements of an ideal antihypertensive than a single agent given alone.

Comparison of anti-ischemic effects of isosorbide-5-mononitrate, metoprolol and diltiazem: a study based on serial treadmill exercise test

A prospective double blind cross over study compared the anti-ischemic effect of 20 mg of isosorbide-5-mononitrate (IS-5-MN), 60 mg of diltiazem and 100 mg of metoprolol by performing serial treadmill tests (TMTs) following oral administration of single dose of each drug in 28 patients of ischemic heart disease with positive exercise TMT. The anti-ischemic effect of IS-5-MN, diltiazem and metoprolol was evaluated by assessing the time to onset of ischemia (400.8 +/- 41.1 vs 394.1 +/- 36.0 vs 412.7 +/- 36.6 secs respectively, all p > or = 0.05), duration of ischemia (390.9 +/- 58.5 vs 447.6 +/- 65.9 vs 419.4 +/- 58.7 secs respectively, all p > or = 0.05), duration of exercise 464.0 +/- 32.9 vs 476.8 +/- 32.5 vs 502.6 +/- 31.3 secs respectively, all p > or = 0.05) and severity of ischemia by scoring system (10.0 +/- 1.5 vs 10.7 +/- 1.4 vs 9.8 +/- 1.5 respectively, all p > or = 0.05). Thus, the present study suggests that there is no significant difference in the anti-ischemic effect of IS-5-MN, diltiazem and metoprolol and also suggests that the anti-ischemic effect of metoprolol is primarily by decreasing the heart rate while IS-5-MN and diltiazem exert anti-ischemic effect probably by decreasing oxygen demand and improving coronary blood flow.

Effect of perindopril and metoprolol on left ventricular hypertrophy and performance in essential hypertension

The effects of perindopril and metoprolol on left ventricular hypertrophy (LVH) and function were studied in 47 essential hypertensive patients with LVH. Previous antihypertensive drugs were discontinued for at least 2 weeks, after which patients were randomly divided into 2 groups. 25 subjects were treated with perindopril 4 to 8 mg once daily in the morning (Group A) and 22 subjects with metoprolol 25 to 62.5 mg twice daily (Group B). The subjects were evaluated before and after 4 and 8 weeks of treatment by use of echocardiography. Before treatment LV mass indexes (LVMI) of two groups were respectively 143.2 +/- 21.3 g/m2 and 140.6 +/- 23.7 g/m2 (P > 0.05). In Group A, reduction of LVMI occurred after 4 weeks of treatment, and more pronounced after 8 weeks (from 143.2 +/- 21.3 g/m2 to 126.6 +/- 15.3 g/m2, P < 0.001), whereas reduction of LVMI occurred only after 8 weeks in Group B (from 140.6 +/- 23.7 g/m2 to 133.4 +/- 13.2 g/m2, P < 0.001). In addition, there was a significant (P < 0.05) difference in LVMI between the two groups after 8 weeks. LV systolic function remained unchanged, whereas E/A increased significantly (P < 0.001) in two groups after 8 weeks. In conclusion, antihypertensive treatment with perindopril and metoprolol induced a significant regression of LVH associated with improvement in LV diastolic performance. Perindopril, compared with metoprolol, was more effective in reversing LVH.

[Calcium antagonists and primary prevention of coronary disease]

APSIS (Angina Prognosis Study in Stockholm) compared the effects of verapamil 480 mg/day and metoprolol 200 mg/day on the prognosis of 809 patients with stable angina over an average period of three and a half years. No difference was observed between the two treatment groups in terms of mortality, number of cardiovascular events or in term of quality of life. Verapamil seemed to be as effective and as well tolerated as the betablocker for long term therapy of stable angina. Moreover, an ancillary study suggests that it has a platelet anti-aggregant effect.