Delayed de-induction of CYP2C9 compared to CYP3A after discontinuation of rifampicin: Report of two cases
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OBJECTIVE: Timely dose reduction of concomitant medications is important after withdrawal of rifampicin, a CYP inducer. However, little is known about the differences in the time course of deinduction for various CYP isoforms. To clarify the time courses of deinduction of CYP2C9 and -CYP3A activities after rifampicin withdrawal, we monitored these enzyme activities in 2 patients over time after discontinuing rifampicin. MATERIALS AND METHODS: Two patients (aged 70 and 80 years) received warfarin and rifampicin for anticoagulation and antituberculosis therapy, respectively. Warfarin doses were increased due to rifampicin-induced CYP activity. Upon completion of antituberculosis therapy, rifampicin was discontinued and warfarin doses were titrated downward according to prothrombin time. We monitored CYP2C9 and CYP3A activities over their clinical courses by measuring the metabolic clearance of S-warfarin to S-7-hydroxywarfarin and that of cortisol to 6ß-hydroxycortisol, respectively. RESULTS: In both patients, the time courses of CYP2C9 deinduction appeared to be delayed compared to CYP3A. CONCLUSION: Our findings suggest that a uniform dose reduction protocol for drugs metabolized by different CYP isoforms may be unsafe after rifampicin withdrawal.
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Plasma exchange for the patients with dilated cardiomyopathy in children is safe and effective in improving both cardiac function and daily activities.

Autoantibodies against cardiac proteins play an important role in the development of dilated cardiomyopathy (DCM). The efficacy and safety of apheresis such as immunoadsorption (IA) or plasma exchange (PE) to remove such antibodies have been reported in adult DCM patients. However, apheresis for pediatric DCM has not been performed because of technical difficulty due to relatively low blood volume and instability of hemodynamics. As we have experiences of preforming apheresis on hemodynamically unstable children, we have preformed ten courses of PE on seven child DCM patients including both patients in chronic and acute phase to assess the safety and efficacy to PE. Under general anesthesia, the patients were administered PE three times during 3 days as 1 course. Simultaneously, continuous hemodiafiltration (CHDF) was performed in series with the PE circuit to stabilize hemodynamic status and to minimize the adverse effects of PE. The changes in LVEF, CTR, mBP, the dosage of furosemide and NYHA were assessed before and after the procedure of PE. There were no severe adverse effects such as systemic bleeding or refractory hypotension due to apheresis. Echocardiography showed that mean baseline LVEF was 24.3 ± 7.8%. Mean LVEF significantly increased 1 week after PE to 30.5 ± 12.5%. CTR significantly decreased after PE. Mean BP significantly increased 1 month after PE (54.5 ± 10.7 to 60.7 ± 9.8 mmHg). NYHA improved after PE significantly (NYHA; 3.4 ± 1.1 to 2.5 ± 1.1). PE is safe and effective in improving both cardiac function and daily activities.

Immunoadsorption therapy for dilated cardiomyopathy using tryptophan column-A prospective, multicenter, randomized, within-patient and parallel-group comparative study to evaluate efficacy and safety.

Over the past few decades, several cardiac autoantibodies have been reported in sera from patients with dilated cardiomyopathy (DCM). Immunoadsorption (IA) therapy is one of the therapeutic tools to remove such autoantibodies. The objective of this study was to investigate functional effects of IA therapy using a tryptophan column in severe DCM patients. Of 49 patients enrolled, 44 were randomized from 10 sites in Japan. IA therapy was conducted in 40 patients with DCM (refractory to standard therapy for heart failure, New York Heart Association [NYHA] class III/IV, left ventricular ejection fraction [LVEF] <30%). Mean echocardiographic LVEF was significantly improved (23.8 ± 1.3% to 25.9 ± 1.3%, P = 0.0015). However, mean radionuclide LVEF over 3 months of IA therapy was not significantly improved (20.8 ± 1.1% to 21.9 ± 1%, P = 0.0605). The cardiothoracic ratio was also significantly decreased (P = 0.0010). NYHA functional class (P < 0.0001), subjective symptoms assessed by a quality of life questionnaire (P = 0.0022), maximum oxygen consumption (P = 0.0074), and 6-minute walk distance (P = 0.0050) were improved after IA therapy. Subgroup analysis revealed improvement of echocardiographic LVEF in patients with higher baseline autoantibody scores but not in those with lower scores. IA therapy improved subjective symptoms and exercise capacity in patients with refractory heart failure resulting from DCM. Favorable effect on cardiac function was noted in patients with higher autoantibody scores. J. Clin. Apheresis 31:535-544, 2016. © 2015 Wiley Periodicals, Inc.

Comparative study of MAFLD as a predictor of metabolic disease treatment for NAFLD.

A novel concept of Metabolic Associated Fatty Liver Disease (MAFLD) was proposed, incorporating metabolic abnormalities such as obesity and diabetes, which are risk factors that affect the prognosis. Non-Alcoholic Fatty Liver Disease (NAFLD), entails fat accumulation in the liver without alcohol consumption and is often linked to obesity, insulin resistance, and metabolic syndrome. However, the broad nature of the disease concept has hindered prognosis accuracy. In this study, we assess the contribution of the impact of diagnostic criteria for MAFLD on metabolic disease progression compared to conventional diagnostic criteria for NAFLD. A total of 7159 patient who were presented to the health screening center in Tokai University Hospital both in 2015 and 2020 were included in the study. Fatty liver was diagnosed using abdominal ultrasonography. The diagnostic criteria for NAFLD were consistent with the global guidelines based on alcohol consumption. The diagnostic criteria for MAFLD were based on the International Consensus Panel. Medications (anti-hypertensive, diabetic, and dyslipidemia medications) were evaluated by self-administration in the submitted medical questionnaire. A total of 2500 (34.9%) participants were diagnosed with fatty liver (FL +), 1811 (72.4%) fit both NAFLD and MAFLD diagnostic criteria (overlap), 230 (9.2%) fit only the NAFLD diagnostic criteria (NAFLD group) and 404 (16.1%) fit the MAFLD diagnostic criteria (MAFLD group) at 2015. Over the next 5 years, medication rates increased in the NAFLD group for anti-hypertensive, + 17 (7.4%); diabetes, + 3 (1.3%); and dyslipidemia, + 32 (13.9%). In contrast, the only-MAFLD group showed a more significant increase with + 49 (12.1%), + 21 (5.2%), and + 49 (12.1%), for the respective medications, indicating a substantial rise in patients starting new medications. Our analysis of repeated health check-ups on participants revealed that the diagnostic criteria for MAFLD are more predictive of future treatment for metabolic disease than conventional diagnostic criteria for NAFLD.

Specific immunoadsorption therapy using a tryptophan column in patients with refractory heart failure due to dilated cardiomyopathy.

BACKGROUND: Certain cardiac-specific autoantibodies found in patients with dilated cardiomyopathy (DCM) play a role in mediating myocardial damage and fatal ventricular arrhythmias resulting in sudden cardiac death. Immunoadsorption therapy (IA) is one of the therapeutic tools to remove such autoantibodies. Clinical studies from Germany have shown that nonspecific IA using columns loaded by sheep antihuman IgG or protein A improved hemodynamic data and affected favorably cardiac function and survival in patients with heart failure (HF) due to DCM. The goal of this study is to determine if IA therapy using the high-profile tryptophan column, which has high affinity for IgG3 subclass, affects favorably cardiac function in patients with severe HF who are refractory to conventional therapy. METHODS AND RESULTS: IA therapy was conducted in 16 patients with DCM (age 53 ± 4, male 8, New York Heart Association functional class III/IV, mean ejection fraction 18 ± 2%). Study subjects had autoantibodies directed against either ß1-adrenergic or M2-muscarinic receptors. Plasma brain natriuretic peptide levels were significantly decreased after IA (P = 0.016). Plasma inflammatory cytokines including interleukin-6 and tumor necrosis factor-α did not change after each session of IA. Six-minute walk distance was significantly increased after IA (P = 0.01). Left ventricular ejection fraction increased by 3% 3 months after IA (P = 0.039). CONCLUSIONS: Our initial experience demonstrated safety and short-term efficacy of IA using a new IgG3-specific tryptophan column for patients with advanced HF due to DCM. Long-term follow-up is needed to confirm the effects on cardiac function and morbidity/mortality in such patients.

Successful Conservative Treatment of Cardiac Rupture Associated with Takotsubo Syndrome.

We herein report a 75-year-old woman who was diagnosed with Takotsubo syndrome (TTS) complicated by left ventricular outflow tract obstruction on admission. Treatment with beta-blocker and anticoagulant was started; however, her hemoglobin level decreased gradually, and computed tomography performed one week later revealed hemopericardium. Oozing-type cardiac rupture was suspected; therefore, we discontinued heparin treatment. Finally, she recovered uneventfully without cardiac surgery. It is noteworthy that cardiac rupture may occur with TTS, especially in patients treated with prophylactic anticoagulation therapy for apical thrombus. Furthermore, conservative, careful observation is an alternative approach in patients with oozing-type cardiac rupture associated with TTS.

The Japanese Society for Apheresis clinical practice guideline for therapeutic apheresis.

Most of the diseases for which apheresis therapy is indicated are intractable and rare, and each patient has a different background and treatment course prior to apheresis therapy initiation. Therefore, it is difficult to conduct large-scale randomized controlled trials to secure high-quality evidence. Under such circumstances, the American Society for Apheresis (ASFA) issued its guidelines in 2007, which were repeatedly revised until the latest edition in 2019. The ASFA guidelines are comprehensive. However, in the United States, a centrifugal separation method is mainly used for apheresis, whereas the mainstream procedure in Japan is the membrane separation method. The target diseases and their backgrounds are different from those in Japan. Due to these differences, the direct adoption of the ASFA guidelines in Japanese practice creates various problems. One of the features of apheresis in Japan is the development of treatment methods using hollow-fiber devices such as double filtration plasmapheresis (DFPP) and selective plasma exchange and adsorption-type devices such as polymyxin B-immobilized endotoxin adsorption columns. Specialists in emergency medicine, hematology, collagen diseases/rheumatology, respiratory medicine, cardiovascular medicine, gastroenterology, neurology, nephrology, and dermatology who are familiar with apheresis therapy gathered for this guideline, which covers 86 diseases. In addition, since apheresis therapy involves not only physicians but also clinical engineers, nurses, dieticians, and many other medical professionals, this guideline was prepared in the form of a worksheet so that it can be easily understood at the bedside. Moreover, to the clinical purposes, this guideline is designed to summarize apheresis therapy in Japan and to disseminate and further develop Japanese apheresis technology to the world. As diagnostic and therapeutic techniques are constantly advancing, the guidelines need to be revised every few years. In order to ensure the high quality of apheresis therapy in Japan, both the Japanese Society for Apheresis Registry and the guidelines will be inseparable.

Complete elimination of cardiodepressant IgG3 autoantibodies by immunoadsorption in patients with severe heart failure.

BACKGROUND: Cardiodepressant IgG3 autoantibodies (CD-Abs) can be targeted by apheresis. Using blinded measurements of CD-Abs before and after immunoadsorption (IA), the cardiac function of patients who did or did not achieve complete CD-Abs elimination was compared. METHODS AND RESULTS: Autoantibodies were completely removed from 18 patients with heart failure (New York Heart Association class 3 or 4, left ventricular ejection fraction (LVEF) <30%) using a selective IgG3 adsorption column. All patients had anti-beta1-adrenergic and/or M2-muscarinic autoantibodies before IA, and all LVEF were measured on radionuclide ventriculography. CD-Abs were measured before and after IA, and patient status was blinded until all measurements were collected. Treatment was defined as complete when CD-Abs status changed from positive to negative after IA. Other instances were defined as incomplete. Six-min walk test results and brain natriuretic peptide levels improved significantly after IA (P<0.01). The increase in LVEF 3 months after IA was significantly greater after complete treatment in comparison to the incomplete treatment group (19+/-8-29+/-9% vs 18+/-9-17+/-8%, P<0.01). Cardiac insufficiency events were also more frequent in the incomplete treatment group. CONCLUSIONS: Complete elimination of CD-Abs with apheresis may be related to improved cardiac function in the treatment of heart failure.

A pilot study on the role of autoantibody targeting the beta1-adrenergic receptor in the response to beta-blocker therapy for congestive heart failure.

BACKGROUND: Autoantibodies directed against the beta1-adrenergic receptor exert agonist-like actions by inducing receptor uncoupling and cause myocardial damage as well as fatal ventricular arrhythmias. Previous studies have shown that beta-blockers can modulate these actions of the autoantibodies. We investigated the influence of such autoantibodies in patients with congestive heart failure (CHF) receiving beta-blocker therapy. METHODS AND RESULTS: Eighty-two CHF patients were randomly assigned to treatment with metoprolol or carvedilol for 16 weeks. Autoantibodies were detected in 20 patients (24%) by enzyme-linked immunosorbent assay. Left ventricular function in response to beta-blocker therapy did not differ significantly by the presence of the autoantibody in global analysis. However, changes of the left ventricular end-diastolic dimension (P = .04), end-systolic dimension (P < .01), and ejection fraction on radionuclide ventriculography (P = .02) were significantly larger in autoantibody-positive patients than antibody-negative patients. Changes in the plasma level of brain natriuretic peptide tended to be larger in autoantibody-positive patients (P = .09). The increase of heart rate normalized by the increase of plasma norepinephrine during exercise (an index of adrenergic responsiveness) showed a greater decrease in autoantibody-positive patients than autoantibody-negative patients (P = .035). CONCLUSION: Our data suggest that beta-blocker therapy might be more effective in CHF patients with autoantibodies targeting the beta1-adrenergic receptor.

Antigen-specific effects of autoantibodies against sarcolemmal Na-K-ATPase pump in immunized cardiomyopathic rabbits.

OBJECTIVES: We examine antigen-specific actions of autoantibodies directed against sarcolemmal Na-K-ATPase. BACKGROUND: Autoantibodies against some receptors or pumps were detected in patients with dilated cardiomyopathy. Although immunoglobulin adsorption therapy improved cardiac function in such patients, direct pathogenic effects of autoantibodies remain to be proven. METHODS: Japanese white rabbits were immunized once a month with purified Na-K-ATPase (NKA rabbits, n=10) or a synthetic peptide corresponding to the second extracellular loop of beta1-adrenergic receptors (beta rabbits, n=10), respectively. Control rabbits (n=10) received vehicle in the same manner. RESULTS: At 6 months, cardiac hypertrophy along with increased left ventricular end-diastolic pressure was observed in both NKA and beta rabbits, and inhibitory G protein level increased in both NKA and beta rabbits. Histological findings showed similar myocyte hypertrophy and interstitial fibrosis in both rabbits. Enzymatic activities of Na-K-ATPase were lower in NKA rabbits than in other groups. Immunoblotting showed that alpha3-isoform of Na-K-ATPase was selectively reduced in myocardium from NKA rabbits. CONCLUSIONS: Our present findings suggested that isoform-specific alterations of myocardial Na-K-ATPase activity were induced by immunizing rabbits. This was not secondary change due to cardiac hypertrophy. Thus, autoantibodies against sarcolemmal Na-K-ATPase have antigen-specific effect on the heart in vivo.

Autoantibodies produced against sarcolemmal Na-K-ATPase: possible upstream targets of arrhythmias and sudden death in patients with dilated cardiomyopathy.

OBJECTIVES: We sought to test the hypothesis that autoantibodies (Abs) produced against sarcolemmal Na-K-ATPase play a role in the development of ventricular tachycardia (VT) and cardiac sudden death in patients with dilated cardiomyopathy (DCM). BACKGROUND: Autoimmunity is one of the mechanisms of pathogenesis of DCM as well as virus infection and genetic predisposition. METHODS: One hundred patients with DCM and age-matched control subjects (CTL) were screened for Abs produced against Na-K-ATPase by using enzyme-linked immunosorbent assay. RESULTS: Abs were detected in 26 DCM and 2 CTL patients. Na-K-ATPase activity in the presence of patient IgG was lower in DCM with Abs than without Abs, but there was no difference between two groups in CTL. Western blots showed that Abs recognized the alpha subunit of Na-K-ATPase, and 3H-ouabain bindings in the presence of patient IgG showed that dissociation constant was higher in DCM with Abs than without Abs. No difference existed between subjects with regard to age, gender, New York Heart Association functional class, cardiac function, or neurohormone levels, except for plasma norepinephrine, which was higher in patients with Abs than without Abs. VTs were more common in patients with Abs than without Abs, and multiple logistic regression analysis demonstrated that the presence of Abs, but not plasma norepinephrine, was an independent predictor for the occurrence of VT. Cardiac sudden death was independently predicted by the presence of Abs, as well as poor systolic function. CONCLUSION: We conclude that there are Abs produced against sarcolemmal Na-K-ATPase in patients with DCM and that Abs could be responsible for the electrical instability in some cases.

Autoimmunity against the second extracellular loop of beta(1)-adrenergic receptors induces early afterdepolarization and decreases in K-channel density in rabbits.

OBJECTIVES: We sought to define the electrophysiologic property of the rabbit heart associated with autoimmunity against the second extracellular loop of the beta(1)-adrenergic receptor. BACKGROUND: Sudden death of patients with cardiomyopathy, probably due to lethal ventricular arrhythmias, can be predicted by the presence of autoantibodies against the second extracellular loop of the beta(1)-adrenergic receptor. METHODS: Rabbits were immunized by repetitive subcutaneous administration of a synthetic peptide corresponding to the second extracellular loop of beta(1)-adrenergic receptors (beta group; n = 30) for a mean of 4.2 months. Control rabbits received only vehicle (control group; n = 30). RESULTS: One of the rabbits in the beta group died suddenly during the observation period, but none of the control animals died. The prevalence of sustained ventricular tachycardia was significantly higher in the beta group (beta: 4 of 27 vs. control: 0 of 30), and a standard microelectrode experiment revealed prolongation of the action potential duration (APD) in the right ventricular papillary muscle (beta: 156 +/- 5 ms vs. control: 131 +/- 4 ms; p < 0.05). Early afterdepolarization (EAD) was observed in one rabbit in the beta group (1 of 26), but not in any animals in the control group (0 of 17). A dose of 100 nmol/l of E-4031 induced EAD in the beta group (10 of 10), but not in the control group, except for one rabbit (1 of 10). The whole-cell, patch-clamp experiment on left ventricular M cells showed significant decreases in transient outward current (I(to1)) (-43%) and slowly activated delayed rectifier current (I(Ks)) densities (-33%), whereas the inward-rectifying K current (I(K1)) and rapidly activated delayed rectifier current (I(Kr)) densities remained unchanged. CONCLUSIONS: Long-term immunization against the second extracellular loop of the beta(1)-adrenergic receptor caused EAD and APD prolongation and decreased the K-channel density, suggesting that an arrhythmic substrate via autoimmune mechanisms is present in cardiomyopathic patients who have autoantibodies directed against the receptors.

A low-cost digital filing system for echocardiography data with MPEG4 compression and its application to remote diagnosis.

The high cost of digital echocardiographs and the large size of data files hinder the adoption of remote diagnosis of digitized echocardiography data. We have developed a low-cost digital filing system for echocardiography data. In this system, data from a conventional analog echocardiograph are captured using a personal computer (PC) equipped with an analog-to-digital converter board. Motion picture data are promptly compressed using a moving pictures expert group (MPEG) 4 codec. The digitized data with preliminary reports obtained in a rural hospital are then sent to cardiologists at distant urban general hospitals via the internet. The cardiologists can evaluate the data using widely available movie-viewing software (Windows Media Player). The diagnostic accuracy of this double-check system was confirmed by comparison with ordinary super-VHS videotapes. We have demonstrated that digitization of echocardiography data from a conventional analog echocardiograph and MPEG 4 compression can be performed using an ordinary PC-based system, and that this system enables highly efficient digital storage and remote diagnosis at low cost.

Autoimmune mechanisms underlying dilated cardiomyopathy.

Autoimmune abnormalities, as well as viral infection and genetic abnormalities, appear to be major predisposing factors for dilated cardiomyopathy (DCM). Abnormalities of cell-mediated immunity are mainly involved in the onset of cardiomyopathy secondary to myocarditis. However, various antimyocardial antibodies are detected in the serum of patients with DCM. The appearance of these antibodies was considered to be an epiphenomenon associated with myocyte injury resulting from myocarditis, but recent findings have suggested that at least some of them are directly related to the pathophysiology of DCM. In particular, an autoantibody targeting the beta1-adrenergic receptor that exhibits an agonist-like effect is related to the persistent myocardial damage resulting in DCM and provides substrates for fatal ventricular arrhythmias. In addition, an antibody for the muscarinic M2 receptor is related to atrial fibrillation, an antibody targeting Na-K-ATPase is closely related to sudden cardiac death as a result of fatal ventricular arrhythmias, and an autoantibody for troponin I increases the L-type calcium current and is related to the myocardial damage. Based on these findings, immunoadsorption therapy was developed to remove such autoantibodies in patients with refractory heart failure as a result of DCM.

A case of echocardiographic evaluation of ruptured pseudoaneurysm of the mitral-aortic intervalvular fibrosa by infective endocarditis.

This report describes an unusual case of ruptured pseudoaneurysm (PSA) of mitral-aortic intervalvular fibrosa (MAIVF) caused by infective endocarditis. The PSA ruptured into the left sinus of Valsalva in addition to the left atrium, resulting in complicated shunting among the aorta, left ventricle and left atrium, leading to refractory heart failure. The transesophageal echocardiography provided the precise information concerning the anatomical detail of the PSA, which is crucial for the surgical repair. This is the first report describing a patient with PSA of MAIVF with two rupture sites.

Autoantigen estimation and simple screening assay against cardiodepressant autoantibodies in patients with dilated cardiomyopathy.

The objective of this study was to identify the cardiodepressant autoantibodies that could directly influence left ventricular ejection fraction (LVEF) in patients with dilated cardiomyopathy (DCM), as well as to establish a simple screening method for these antibodies. Not only acute hemodynamic but also chronic prognosis improvements were reported with immunoadsorption in some patients with DCM. Various antibodies determined by immunohistochemistry, immunoblotting, and enzyme-linked immunosorbent assay (beta1-adrenergic [beta1-] receptors, muscarinic M2-acetylcholine [M2-] receptors, troponin I, or Na-K-ATPase) were measured in 104 patients with DCM. Cardiodepressant antibodies were also determined by ultrasonic echocardiography (UCG) of 18 day old chick embryos after adding the patients' purified immunoglobulin G, and the following clinical features were compared: age, gender, New York Heart Association class, LVEF, neurohumoral factors, arrhythmias, and other antibodies. We also checked the in vitro immunoadsorption effect against these cardiodepressant antibodies. Cardiodepressant antibodies were found in 63% of 104 patients with DCM and had no relation to other clinical parameters, except for some antibodies such as anti-beta1-receptor antibodies (81% vs. 52%, P < 0.01), anti-M2-receptor antibodies (83% vs. 48%, P < 0.01), or anti-Na-K-ATPase antibodies (85% vs. 55%, P < 0.01). However, cardiodepressant antibodies were similarly found in patients with and without antibodies against troponin I (56% vs. 64%). The LVEF of chick embryos measured by UCG in the presence of patient serum was improved after in vitro immunoadsorption. The ex vivo system using chick embryos was able to determine cardiodepressant antibodies. By multivariate analysis, antibodies against beta1- or M2-receptors was a predictor of these autoantibodies.

Autoantibodies in atrial fibrillation: actor, biomaker or bystander?

Atrial fibrillation (AF) is one of the most common arrhythmias in patients with congestive heart failure, although the underlying mechanism has still to be determined. There is increasing evidence to suggest that autoimmunity may play an important role in the pathogenesis of AF. To date, at least three types of autoantibody have been found in AF: the anti-myosin heavy chain autoantibody, the anti-M2 muscarinic receptor autoantibody and the anti-heat shock protein autoantibody. The question is: are these autoantibodies actors, biomakers or merely bystanders? How much knowledge do we have?

[Autoantibodies against sarcolemmal Na-K-ATPase in patients with dilated cardiomyopathy: autoimmune basis for ventricular arrhythmias in patients with congestive heart failure].

BACKGROUND: Autoimmunity is one of the mechanisms of pathogenesis of idiopathic dilated cardiomyopathy (DCM) as well as virus infection and genetic predisposition. Autoantibodies against sarcolemmal Na-K-ATPase may be involved in the development of ventricular tachycardia and cardiac sudden death in patients with DCM. METHODS AND RESULTS: By using enzyme-linked immunosorbent assay, autoantibodies were detected in 26% patients with DCM and in 2% age-matched control subjects. Na-K-ATPase activity in the presence of patient IgG was lower in patients with autoantibodies than without autoantibodies, but there was no difference in the control subjects. Western blots showed that autoantibodies recognized the alpha-subunit of Na-K-ATPase, and 3H-ouabain bindings in the presence of patient IgG showed that the dissociation constant was higher in patients with autoantibodies than without autoantibodies, although maximal binding sites were similar between the two groups. No difference existed between subjects with regard to age, sex, New York Heart Association functional class, cardiac function, or neurohormone levels, except for plasma norepinephrine which was higher in patients with autoantibodies than without autoantibodies, Ventricular arrhythmias were more common in patients with autoantibodies than without autoantibodies, and multiple logistic regression analysis demonstrated that the presence of autoantibodies, but not plasma norepinephrine, was an independent predictor for the occurrence of ventricular tachycardia. Cardiac sudden death was independently predicted by the presence of autoantibodies, as well as poor systolic function. CONCLUSIONS: Patients with DCM express autoantibodies against sarcolemmal Na-K-ATPase, and these autoantibodies could be responsible for the electrical instability in some patients.