Arrhythmias, catecholamines and electrolytes

Long-term impact of β-blocker in elderly patients without myocardial infarction after percutaneous coronary intervention

AIMS

Little is known about the long-term outcomes of β-blockers use in patients with coronary artery disease (CAD) without myocardial infarction (MI) and reduced ejection fraction (rEF). However, more attention should be paid to the oral administration of β-blockers in elderly patients who are susceptible to heart failure (HF), sinus node dysfunction, or rate response insufficiency. We aimed to evaluate the long-term impact of β-blockers in elderly patients with CAD without MI or systolic HF who have undergone percutaneous coronary intervention.

METHODS AND RESULTS

A total of 1018 consecutive elderly patients with CAD (mean age, 72 ± 7 years; 77% men) who underwent their first intervention between 2010 and 2018 were included in this study. According to the presence or absence of the use of β-blockers, 514 patients (50.5%) were allocated to the β-blocker group, and 504 (49.5%) to the non-β-blocker group. We evaluated the incidence of 4-point major adverse cardiovascular events (4P-MACE), including cardiovascular death, non-fatal MI, non-fatal stroke, admission for HF, target vessel revascularization (TVR), and all-cause death. We focused on the association between chronotropic incompetence of β-blockers and incidence of a new HF and analysed the results using an exercise electrocardiogram regularly performed in the outpatient department after percutaneous coronary intervention. During a median follow-up duration of 5.1 years, 83 patients (8.3%) developed 4P-MACE, including cardiovascular death in 17, non-fatal MI in 13, non-fatal stroke in 25, and admission for HF in 39 patients. Additionally, 124 patients (12.2%) had a TVR and 104 (10.2%) died of other causes. Kaplan-Meier analysis showed that the cumulative incidence rate of 4P-MACE in the β-blocker group was significantly higher than that in the non-β-blocker group (15.4% vs. 10.0%, log-rank test, P = 0.015). Above all, the cumulative incidence rate of admission for HF in the β-blocker group was significantly higher (8.8% vs. 3.2%, log-rank test, P < 0.001). The β-blocker group had significantly lower resting heart rate, stress heart rate, and stress-rest Δ heart rate on exercise electrocardiogram. Multivariate Cox hazard analysis revealed that EF, β-blocker use, stress-rest Δ heart rate, and CKD were strong independent predictors of admission for HF.

CONCLUSIONS

Long-term β-blocker use was significantly associated with an increased risk of adverse cardiovascular events in elderly patients with CAD without MI or systolic HF. In particular, the chronotropic incompetence action of β-blockers could increase the risk of admission for HF in elderly patients with CAD without MI and systolic HF, and the present findings warrant further investigation.

Neurohormonal regulation of cardiac ion channels in chronic heart failure

Alteration of neurohormonal homeostasis is a hallmark of the pathophysiology of chronic heart failure (CHF). In particular, overactivation of the renin-angiotensin-aldosterone system and the sympathetic catecholaminergic system is consistently observed. Chronic overactivation of these hormonal pathways leads to a detrimental arrhythmogenic remodeling of cardiac tissue due to dysregulation of cardiac ion channels. Sudden cardiac death resulting from ventricular arrhythmias is a major cause of mortality in patients with CHF. All the drug classes known to reduce mortality in patients with CHF are neurohormonal blockers. The aim of this review was to provide an overview of how cardiac ion channels are regulated by hormones known to play a central role in the pathogenesis of CHF.

Safety and efficacy of sertraline for depression in patients with CHF (SADHART-CHF): a randomized, double-blind, placebo-controlled trial of sertraline for major depression with congestive heart failure

BACKGROUND

Sertraline, a selective serotonin-reuptake inhibitor, has demonstrated substantial mood improvement in patients with post myocardial infarction or with unstable angina. The impact of sertraline on the prognosis and depression of patients with chronic heart failure (HF) and comorbid major depressive disorder (MDD) is unknown.

METHOD

This is a prospective, randomized, double-blind, placebo-controlled study designed to assess the safety and efficacy of sertraline in the treatment of MDD in patients with HF. The study is designed also to examine the effects of treating depression on cardiac events and morbidity/mortality in patients with HF. Approximately 500 men and women who are >or=45 years of age with current MDD and chronic systolic HF, characterized by left ventricular ejection fraction or=II, comprise the study population. Eligible participants are randomized to either sertraline or placebo for a 12-week acute treatment phase. All patients, regardless of acute treatment phase completion, are followed routinely until the last subject completes 6-month follow-up. Quality of life and certain physiologic parameters, as well as pro-inflammatory and HF biomarkers, that may reflect the impact of sertraline in this particular population are measured at baseline and at the end of the acute treatment phase.

CONCLUSION

Because of the high prevalence of depression and its significant adverse impact on prognosis of patients with ischemic heart disease (IHD) and HF, the Safety and Efficacy of Sertraline for Depression in Patients with Chronic Heart Failure (SADHART-CHF) trial aims to assess the effects of sertraline on response of depression as well as on the cardiac prognosis of patients with HF.

A new casemix adjustment index for hospital mortality among patients with congestive heart failure

OBJECTIVES

Comparative analysis of hospital outcomes requires reliable adjustment for casemix. Although congestive heart failure is one of the most common indications for hospitalization, congestive heart failure casemix adjustment has not been widely studied. The purposes of this study were (1) to describe and validate a new congestive heart failure-specific casemix adjustment index to predict in-hospital mortality and (2) to compare its performance to the Charlson comorbidity index.

METHODS

Data from all 4,608 admissions to the Massachusetts General Hospital from January 1990 to July 1996 with a principal ICD-9-CM discharge diagnosis of congestive heart failure were evaluated. Massachusetts General Hospital patients were randomly divided in a derivation and a validation set. By logistic regression, odds ratios for in-hospital death were computed and weights were assigned to construct a new predictive index in the derivation set. The performance of the index was tested in an internal Massachusetts General Hospital validation set and in a non-Massachusetts General Hospital external validation set incorporating data from all 1995 New York state hospital discharges with a primary discharge diagnosis of congestive heart failure.

RESULTS

Overall in-hospital mortality was 6.4%. Based on the new index, patients were assigned to six categories with incrementally increasing hospital mortality rates ranging from 0.5% to 31%. By logistic regression, "c" statistics of the congestive heart failure-specific index (0.83 and 0.78, derivation and validation set) were significantly superior to the Charlson index (0.66). Similar incrementally increasing hospital mortality rates were observed in the New York database with the congestive heart failure-specific index ("c" statistics 0.75).

CONCLUSION

In an administrative database, this congestive heart failure-specific index may be a more adequate casemix adjustment tool to predict hospital mortality in patients hospitalized for congestive heart failure.

Depressed arterial baroreflex sensitivity and not reduced heart rate variability identifies patients with chronic heart failure and nonsustained ventricular tachycardia: the effect of high ventricular filling pressure

In chronic heart failure (CHF) the contributing role of increased sympathetic activity and hemodynamic dysfunction in the genesis of ventricular arrhythmias has not been well established. To assess the relation between severe ventricular arrhythmias, hemodynamic impairment, and autonomic nervous system derangement, 142 patients with CHF in sinus rhythm underwent 24-hour electrocardiographic recording, right-sided heart catheterization, and evaluation of sympathovagal balance by heart rate variability (HRV) and baroreflex sensitivity (BRS). Patients were grouped according to the absence (without nonsustained ventricular tachycardia [NSVT]; n = 87) or presence (with NSVT; n = 55) of NSVT. Patients with NSVT had higher pulmonary artery and capillary pressures and more pronounced signs of sympathetic activation and parasympathetic withdrawal compared with those without NSVT. However, logistic regression analysis revealed that depressed BRS but not reduced HRV was significantly associated with the presence of NSVT, at both univariate analysis and after adjustment for clinical and hemodynamic variables. Moreover, it was found that when depressed BRS was associated with high pulmonary capillary pressure, the odds ratio for having NSVT rose markedly from 3.8 to 6.5. In conclusion, this study indicates that in stable CHF the assessment of arterial baroreflex function, but not HRV analysis, allows identification of patients at high risk of NSVT. It is suggested that the effect of depressed BRS is strengthened by the simultaneous presence of increased myocardial wall stress. These data support the hypothesis of a contributory role of autonomic nervous system dysfunction as expressed by the inability to activate effective vagal reflexes and an indirect index of ventricular stretch in the genesis of life-threatening arrhythmias.

Heart transplant candidates at high risk can be identified at the time of initial evaluation

The increasing discrepancy between the numbers of patients selected for cardiac transplantation and the available donor organs requires validation of markers of high risk at the time of initial evaluation that may help to determine which patients profit from aggressive therapy. We retrospectively examined the case records of 91 heart transplant candidates selected out of a total of 140 consecutive patients referred for evaluation. Of these 91 patients, 48 were transplanted during follow-up. Of the remaining 43 patients, 25 died after a mean survival time of 1.6 +/- 2.5 months. The causes of death were pump failure in 18 (72%) and sudden cardiac death in 7 (28%). Multivariate analysis identified 4 out of 26 parameters at initial evaluation that distinguished the 25 nonsurvivors from the 18 survivors. These were: mean arterial pressure (P = 0.03), pulmonary capillary wedge pressure (P = 0.002), mean pulmonary artery pressure (P = 0.001), and fractional shortening (P = 0.007). The mode of death could not be predicted. We conclude that there are prognostic markers at initial evaluation that allow more restrictive selection of patients for cardiac transplantation and mechanical bridging.

Electrolyte disturbances in chronic heart failure: metabolic and clinical aspects

The pathophysiology of congestive heart failure (CHF) includes conditions (e.g., activation of the renin-angiotensin-aldosterone system) which, when combined with CHF therapies, make patients afflicted with this syndrome quite susceptible to electrolyte disturbances. The most commonly encountered are hyponatremia, hypokalemia, and hypomagnesemia. These derangements are of vast clinical importance; their development not only represents an immediate threat to the CHF patient (e.g., dysrhythmias secondary to hypokalemia), but are also indicative of underlying pathophysiologic events, an unfavorable clinical course, and occasionally an adverse therapeutic response. The optimal care of CHF patient includes the recognition and management of these electrolyte disturbances.

The Interdisciplinary Heart Failure and Transplant Program Münster: a 5-year experience

The variety and complexity of therapeutic options available for the increasing number of patients with advanced chronic heart failure has lead to the institution of specialized heart failure/heart transplant programs. The central task consists of carefully evaluating and selecting potential transplant recipients, based on the comparative benefit rationale, i.e. the expected gain in life expectancy and quality of life by cardiac transplantation compared with all other treatment options. Further tasks include a comprehensive chronic heart failure management, high risk conventional cardiac surgery, mechanical and antiarrhythmic bridging and dedicated posttransplant care. This concept is described on the basis of the 5-year experience of the Interdisciplinary Heart Failure and Transplant Program Münster.

Relevance of plasma noradrenaline concentrations to estimate autonomic effects of antihypertensive drugs

The sympathetic nervous system is important in regulating cardiovascular function. It is therefore of interest to study the influence of antihypertensive drugs on sympathetic nerve activity. For this purpose, measurements of noradrenaline concentrations in forearm venous plasma have often been used. For several reasons, this provides limited information: i) the sympathetic nervous system is highly differentiated, i.e. activity may be high in some organs and low in others; ii) noradrenaline in forearm venous plasma is largely derived from sympathetic activity to the forearm skeletal muscle; iii) plasma noradrenaline concentrations are determined not only by noradrenaline spillover from sympathetic nerve endings, which is related to sympathetic nerve activity, but also by noradrenaline clearance. Under most circumstances plasma noradrenaline concentrations are not high enough to produce hormonal effects. Many types of antihypertensive drugs may cause acute and long-term increases in forearm venous noradrenaline concentrations. The mechanisms underlying these increases are not fully understood but seem to differ between drug classes: Diuretics increase renal noradrenaline spillover; beta-blockers do not affect spillover but reduce total noradrenaline clearance; calcium antagonists and alpha-blockers probably increase noradrenaline spillover, but it is not known which organs are involved, particularly during long-term treatment. ACE inhibitors seem to have a sympatholytic action, which counteract reflex increases in sympathetic nerve activity during blood pressure reduction, and plasma noradrenaline concentrations are generally not affected. To be able to judge the possible clinical consequences of changes in plasma noradrenaline concentrations during chronic antihypertensive treatment, assessments of noradrenaline spillover from individual organs are needed.

Clinical relevance and management of the major electrolyte abnormalities in congestive heart failure: hyponatremia, hypokalemia, and hypomagnesemia

Electrolyte disturbances are a common complication of CHF. CHF provides a perfect milieu for the development of these disturbances; renal dysfunction, elevation of neurohormonal substances, activation of the renin-angiotensin-aldosterone axis, and diuretic therapy represent the major contributory factors. Hyponatremia is closely aligned with an unfavorable clinical course. Hypokalemia is associated with increased ventricular dysrhythmias. Hypomagnesemia noted in advanced CHF can be accompanied by arrhythmias and refractory hypokalemia. CHF also offers the ideal milieu (diseased, ischemic, and arrhythmogenic myocardium; elevated catecholamines; and arrhythmogenic drugs) for the threatening clinical consequences (clinical deterioration, dysrhythmias, or death) of these disturbances. These consequences underscore the importance of the recognition, appreciation, and management of these electrolyte abnormalities.

Ventricular arrhythmias and the autonomic tone in patients with mitral valve prolapse

The aim of this study was to evaluate a possible relation between the autonomic tone determined by daily urine catecholamine excretion and the incidence of ventricular arrhythmias (VA) in patients with mitral valve prolapse (MVP). The study included 53 patients (31 women and 22 men) aged 19-52 years (mean age 32.7). The diagnosis of MVP was based on medical history, physical examination, and echocardiography. Cardiac arrhythmias were detected by Holter monitoring and classified according to Lown grades. Daily heart rate and duration of corrected QT interval using Basett's formula were also analyzed. Daily urine adrenaline and noradrenaline levels were determined fluorometrically by Von Euler and Lishajko's method. The patients with Lown's grade III-V VA were evaluated with particular consideration. Student's t-test was used for statistical analysis. On Holter monitoring 26 patients showed VA, including 6 with grade I, 11 with grade II, 2 with grade III, 4 with grade IV, and 3 with grade V according to Lown's classification. The remaining 27 patients were free of cardiac arrhythmias. Mean daily heart rate ranged from 54-93 beats/min (73 +/- 8.44, mean +/- SD) and corrected QT from 336-494 ms (411 +/- 37.17). Daily adrenaline and noradrenaline excretion for the whole group of patients were 0.01-16.2 micrograms (2.1 +/- 2.38) and 1.6-31.0 micrograms (13.1 +/- 7.27), respectively, which was within normal range. However, the patients with serious ventricular arrhythmias showed significantly higher daily adrenaline excretion. Individual analysis of two-thirds of patients with ventricular arrhythmias grade III-V showed daily urine noradrenaline levels exceeding mean values for the whole group.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of converting enzyme inhibition on baroreflex sensitivity in patients with myocardial infarction

BACKGROUND

Baroreflex sensitivity provides useful prognostic information in patients after acute myocardial infarction. However, no data are available about the effects of converting enzyme inhibition on this variable.

OBJECTIVES

The aim of the study was to evaluate the effects of angiotensin-converting enzyme inhibition on baroreflex sensitivity in patients after uncomplicated myocardial infarction.

METHODS

Twenty-five patients after uncomplicated myocardial infarction underwent baroreflex sensitivity evaluation 72 to 96 h after symptom onset and after 4 days of captopril therapy. Twenty additional patients with the same characteristics were evaluated at the same time intervals before and after placebo administration to identify spontaneous baroreflex sensitivity variations. Baroreflex sensitivity was assessed by calculating the regression line relating phenylephrine-induced increases in systolic blood pressure to the attendant changes in the RR interval.

RESULTS

The mean baroreflex sensitivity value increased after captopril administration from 6.5 +/- 4.2 to 11.8 +/- 6.1 ms/mm Hg (p less than 0.01) and in individual analyses increased by greater than 2 ms/mm Hg in 68% of patients. Mean plasma renin activity increased after captopril from 3.7 +/- 2.4 to 8.5 +/- 4.9 ng/ml per h (p less than 0.005). No difference was detectable in baroreflex sensitivity and plasma renin activity values according to the site of necrosis. In the control group, baroreflex sensitivity and plasma renin activity remained unchanged between the two studies.

CONCLUSIONS

This study demonstrates that in patients with uncomplicated myocardial infarction, captopril significantly improves the chronotropic response to baroreceptor stimulation.

Arrhythmogenic potencies of amrinone and milrinone in unanesthetized dogs with myocardial infarct

1. In dogs with a 2-4 day old myocardial infarct and a predominantly sinus heart rhythm, we examine arrhythmogenic potencies of amrinone (0.5 mg/kg/min, 1 and 3 mg/kg) and milrinone (10 micrograms/kg/min, 75 and 100 micrograms/kg). 2. Amrinone and milrinone significantly reinduced ventricular ectopic beats on day 2 after coronary occlusion. 3. These effects were preceded by a cardioacceleration which intensified as the ventricular arrhythmias developed. 4. Over the following days the arrhythmogenic potencies of these inotropic drugs were modest. 5. Thus, amrinone and milrinone can impair heart rhythm chiefly in a recent myocardial infarct.

Variations in potassium concentration modify the inhibitory effect of lorcainide on myocardial Na(+)-K(+)-ATPase activity

1. The inhibitory action of lorcainide on the myocardial Na(+)-K(+)-ATPase (EC 3.6.1.3) activity was studied in guinea-pig heart preparations at medium K+ concentrations of 2.5, 5.0 and 10 mM. 2. Lorcainide exhibited characteristically similar concentration-dependent inhibitory effects at all three K+ concentrations tested. However, the inhibitory potencies were significantly increased at decreased K+ concentrations. 3. The IC50 values were 10.4 +/- 3.2 microM at 2.5 mM, 28.3 +/- 7.9 microM at 5.0 mM and 40.7 +/- 9.2 microM at 10.0 mM K+ respectively. Thus, reduction in the K+ concentration from the 'standard' 5.0 to 2.5 mM enhanced the inhibitory potency of lorcainide, the effective concentrations being shifted towards much lower ranges, while increasing it to 10 mM on the other hand produced opposite but less marked effects. 4. These results show that the inhibition of myocardial Na(+)-K(+)-ATPase activity by lorcainide depends on the K+ concentration of the incubation medium. These effects are probably related to the mechanism by which lorcainide interferes with the electrogenic Na+/K+ pump activity of the enzyme, and hence may contribute to some of its cardiac actions.

The influence of potassium concentration on the inhibitory effect of amiodarone on guinea-pig microsomal Na(+)-K(+)-ATPase activity

The effects of varying incubation K+ concentration on the inhibitory action of amiodarone on the Mg(2+)-dependent ATP hydrolysis by myocardial Na(+)-K(+)-ATPase (EC 3.6.1.3) were studied in guinea pig heart preparations. In the first part of the study, it was established that the activity of the enzyme increased with growing concentrations up to approximately 20 mM K+. The concentration-response relationships for amiodarone were investigated in incubation media containing 2.5, 5.0 and 10 mM K+ respectively. Amiodarone exhibited similar concentration-dependent inhibitory effects in the range of 0.01 nM-80 microM at 2.5 mM, 0.13-150 microM at 5.0 mM and 0.3-700 microM at 10.0 mM K+. The corresponding IC50 values were 10.4 +/- 3.2 microM, 28.3 +/- 7.6 microM at 5.0 mM and 33.3 +/- 9.2 microM at 10.0 mM K+, respectively. Thus, reduction in the K+ concentration from the "standard" 5.0 to 2.5 mM was accompanied by a significant right-to-left shift in the inhibitory potency of amiodarone, the effective concentrations being shifted from microM into nM ranges. Increasing K+ concentration to 10 mM on the other hand attained opposite but less remarkable effects. The results show that the in vitro inhibition of myocardial Na(+)-K(+)-ATPase activity by amiodarone is related to the K+ concentration of the incubation medium. These effects may be pertinent to the mechanism by which this drug interferes with the electrogenic Na+/K+ pump activity of the enzyme, thereby probably contributing to the mechanism(s) responsible for some of its cardiac actions.

The role of ACE inhibitors in the treatment of arrhythmias

Several experimental models have been studied to determine the role of angiotensin-converting enzyme (ACE) inhibitors in reducing ischemic and reperfusion arrhythmias. Studies of left main coronary artery occlusion in isolated perfused rat hearts have shown that the ACE inhibitor captopril reduced reperfusion ventricular fibrillation from 100% to 0% and was associated with a reduction in purine overflow and in norepinephrine release. These effects were abolished in the presence of indomethacin. In an anesthetized rat model of acute myocardial infarction (MI), ACE inhibition reduced mean duration of ventricular fibrillation from 1,133 to 135. ACE inhibition at programmed electrical stimulation of the heart in a closed-chest pig model of acute MI reduced the inducibility of sustained, reproducible ventricular tachycardia from a mean of 42 to 8%. In this model, ventricular tachycardia could not be provoked in animals treated with captopril from the time of acute ischemia. Studies on the rate of ventricular ectopy in patients with poor left ventricular function have demonstrated a significant reduction with ACE inhibition. However, while a protective effect has been shown, the mechanism of action is still speculative.