Restrictive cardiomyopathy

Idiopathic restrictive cardiomyopathy is part of the clinical expression of cardiac troponin I mutations

Restrictive cardiomyopathy (RCM) is an uncommon heart muscle disorder characterized by impaired filling of the ventricles with reduced volume in the presence of normal or near normal wall thickness and systolic function. The disease may be associated with systemic disease but is most often idiopathic. We recognized a large family in which individuals were affected by either idiopathic RCM or hypertrophic cardiomyopathy (HCM). Linkage analysis to selected sarcomeric contractile protein genes identified cardiac troponin I (TNNI3) as the likely disease gene. Subsequent mutation analysis revealed a novel missense mutation, which cosegregated with the disease in the family (lod score: 4.8). To determine if idiopathic RCM is part of the clinical expression of TNNI3 mutations, genetic investigations of the gene were performed in an additional nine unrelated RCM patients with restrictive filling patterns, bi-atrial dilatation, normal systolic function, and normal wall thickness. TNNI3 mutations were identified in six of these nine RCM patients. Two of the mutations identified in young individuals were de novo mutations. All mutations appeared in conserved and functionally important domains of the gene. This article was published online in advance of the print edition. The date of publication is available from the JCI website, http://www.jci.org.

Diastolic heart failure: restrictive cardiomyopathy, constrictive pericarditis, and cardiac tamponade: clinical and echocardiographic evaluation

An understanding of the basic principles of diastolic function is important in order to recognize diseases that may result in diastolic dysfunction and diastolic heart failure. Although uncommon, restrictive cardiomyopathy, constrictive pericarditis, and cardiac tamponade are among the disorders that may affect primarily diastolic function with preservation of systolic function. Diastolic heart failure may manifest with chronic nonspecific symptoms or may present with acute hemodynamic compromise. Echocardiography plays a vital role in the diagnosis of diastolic dysfunction and differentiation of these disease processes. It also provides a basis for clinical decisions regarding management and surgical referral. This review summarizes the clinical features, pathophysiology, and hemodynamic and echocardiographic signs of restrictive cardiomyopathy, constrictive pericarditis, and cardiac tamponade.

Genes and their polymorphisms in mono- and multifactorial cardiomyopathies: towards pharmacogenomics in heart failure

Cardiomyopathies are diseases of the myocardium associated with cardiac dysfunction, and are classified as dilated cardiomyopathy (DCM), hypertropic cardiomyopathy (HCM) and restrictive cardiomyopathy. Heart failure and sudden death are the two major complications. Also, since DCM is the primary indication for heart transplantation and HCM the primary cause of sudden death in young athletes, the socioeconomic impact of these diseases is important. Recently, the role of the genetic background in both monogenic and multifactorial cardiomyopathies has been studied, which has led to a better understanding of the underlying mechanisms that promote the development and progression of these diseases. Preliminary data suggest interactions between pharmacological treatment and genetic polymorphisms, which appear to be the first steps towards the application of pharmacogenetics in heart failure.

The failing heart

Cardiomyopathies are disorders affecting heart muscle that usually result in inadequate pumping of the heart. They are the most common cause of heart failure and each year kill more than 10,000 people in the United States. In recent years, there have been breakthroughs in understanding the molecular mechanisms involved in this group of conditions, with knowledge of the genetic basis for cardiomyopathies perhaps seeing the largest advance, enabling clinicians to devise improved diagnostic strategies and preparing the stage for new therapies.

Molecular Mechanisms of Inherited Cardiomyopathies

Cardiomyopathies are diseases of heart muscle that may result from a diverse array of conditions that damage the heart and other organs and impair myocardial function, including infection, ischemia, and toxins. However, they may also occur as primary diseases restricted to striated muscle. Over the past decade, the importance of inherited gene defects in the pathogenesis of primary cardiomyopathies has been recognized, with mutations in some 18 genes having been identified as causing hypertrophic cardiomyopathy (HCM) and/or dilated cardiomyopathy (DCM). Defining the role of these genes in cardiac function and the mechanisms by which mutations in these genes lead to hypertrophy, dilation, and contractile failure are major goals of ongoing research. Pathophysiological mechanisms that have been implicated in HCM and DCM include the following: defective force generation, due to mutations in sarcomeric protein genes; defective force transmission, due to mutations in cytoskeletal protein genes; myocardial energy deficits, due to mutations in ATP regulatory protein genes; and abnormal Ca2+ homeostasis, due to altered availability of Ca2+ and altered myofibrillar Ca2+ sensitivity. Improved understanding that will result from these studies should ultimately lead to new approaches for the diagnosis, prognostic stratification, and treatment of patients with heart failure.

Clinical and molecular studies of a large family with desmin-associated restrictive cardiomyopathy

Patients with restrictive cardiomyopathy (RC) have impaired diastolic function, but intact systolic function until later stages of the disease, ultimately leading to heart failure. Primary RC is often sporadic, but also may be inherited in an autosomal dominant fashion, particularly the idiopathic forms. Recently there has been great interest in inherited cardiomyopathy associated with myocyte desmin deposition ('desminopathies'). In some such families, desmin or alpha-B crystallin gene mutation is the underlying cause, and the desmin accumulation affects skeletal muscle as well, usually causing skeletal myopathy. We describe a large family with apparent autosomal dominant inheritance of desmin-associated RC spanning four generations, with the age of onset and severity/rate of progression being highly variable. This family is relatively unique in that there is no symptom-based evidence of skeletal muscle involvement, and the known desminopathy and cardiomyopathy genes/loci have been ruled out. These data support literature suggesting that desmin deposition may be associated with different underlying gene defects, and that a novel desminopathy gene is responsible for the condition in this family.

Infiltrative nonamyloidotic monoclonal immunoglobulin light chain cardiomyopathy: an underappreciated manifestation of plasma cell dyscrasias

BACKGROUND

Infiltrative cardiomyopathies are characterized by diastolic dysfunction. In monoclonal plasma cell dyscrasias, organ compromise may be produced by tissue deposition of monoclonal immunoglobulins or their constituent peptides independently of the effects of unbridled plasma cell proliferation. The deposits may be fibrillar, as in light chain amyloid (AL) or nonfibrillar, as in light chain deposition disease (LCDD). AL disease of the heart is a restrictive cardiomyopathy. We hypothesized that, despite differences in physical properties, nonamyloidotic light chain deposition in the myocardium could produce similar clinical and physiological abnormalities.

METHODS

Cardiac tissue from five patients with LCDD and cardiac dysfunction was examined by immunohistochemical and electron microscopic techniques. Hospital charts, electrocardiograms, echocardiograms and cardiac catheterization results were reviewed. In two cases, the original echocardiograms were reanalyzed.

RESULTS

The five patients with nonamyloidotic light chain deposits in the myocardium had either mechanical or electrocardiographic abnormalities. In four with adequate clinical documentation, the diastolic dysfunction and conduction abnormalities were similar or identical to that described in cardiac AL disease.

CONCLUSIONS

Although nonamyloidotic immunoglobulin light chain deposits in the myocardium differ in distribution and ultrastructural organization from the fibrillar deposits of AL disease, an analogous pattern of diastolic dysfunction and conduction disturbances results. The diagnosis should be considered in patients with a plasmacytic dyscrasia and restrictive cardiomyopathy in whom Congo red staining of endomyocardial biopsy tissue is negative. The diagnosis can be established by using the appropriate immunohistochemical and ultrastructural tissue examinations.

Restrictive Cardiomyopathy

Of the three major functional categories of cardiomyopathies (dilated, hypertrophic, and restrictive), the restrictive cardiomyopathies (RCMs) are the least common in the Western world, but unfortunately often are associated with the greatest morbidity and mortality. Infiltrative disease of the myocardium (often caused by amyloidosis) is a common cause of RCMs and has a significantly lower long-term survival rate when compared to cardiomyopathies of various other causes. Treatment of the RCM is, in general, difficult and often ineffective. Because of the abnormalities of diastolic filling that are characteristic of this condition, general measures to reduce venous and systemic congestion such as with the use of diuretics, are desirable but often result in an attendant reduction in stroke volume and cardiac output. Digoxin, calcium channel blocking drugs, and beta-adrenergic blocking agents are of limited value, although they may be used with benefit to control the heart rate response in the subgroup of patients with atrial fibrillation. Angiotensin-converting enzyme inhibitors are generally ineffective in RCM. Targeted therapy directed against specific causal entities (such as the use of somatostatin analogues in carcinoid syndrome or iron chelation with desferrioxamine in hemochromatosis) may be more effective than simple symptomatic therapy. Differentiation of RCM from constrictive pericarditis is crucial, since constriction may be treated effectively by surgical removal of the thickened pericardium. A limited number of patients appear to have benefited from novel treatment strategies, such as autologous stem cell transplant in amyloidosis, balloon valvuloplasty of stenotic tricuspid or pulmonary valves in cardiac carcinoid syndrome, and cardiac transplantation. Truly effective therapy for RCM is generally lacking, and the best chance for optimizing the clinical outcome is early detection and aggressive medical treatment in an attempt to maintain the highest possible level of patient function for as long as possible.

Sarcoidosis and the Heart

The treatment of sarcoid cardiomyopathy can be considered in part the treatment of the systemic disorder, and in part cardiac involvement, the manifestations of which may differ greatly. Therapy for the systemic disease is corticosteroid. Therapy for cardiac involvement includes prednisone, but because treatment must ameliorate or abolish many differing manifestations, therapy differs among patients. Asymptomatic patients (the majority) who are free from serious manifestations of the disease do not require pharmacologic or interventional treatment. Patients with dilated cardiomyopathy require treatment for congestive heart failure. High-grade atrioventricular conduction delay usually necessitates a permanent electronic pacemaker. Life-threatening arrhythmia usually requires implantation of an automatic implantable cardiac defibrillator (AICD). Antiarrhythmic drugs may also be needed. Cardiac tamponade should be treated by drainage of pericardial fluid. Pericardiectomy is usually the appropriate treatment for patients who develop significant constrictive pericarditis. Calcium channel blockers may be helpful for severe diastolic dysfunction that occurs in those with restrictive cardiomyopathy. Therapy should be given to those few patients who manifest hypertrophic cardiomyopathy to relieve left ventricular outflow obstruction. Cardiac transplantation for intractable heart failure or arrhythmia may be needed.

The genetic basis of cardiac function: dissection by zebrafish (Danio rerio) screens

The vertebrate heart differs from chordate ancestors both structurally and functionally. Genetic units of form, termed 'modules', are identifiable by mutation, both in zebrafish and mouse, and correspond to features recently acquired in evolution, such as the ventricular chamber or endothelial lining of the vessels and heart. Zebrafish (Danio rerio) genetic screens have provided a reasonably inclusive set of such genes. Normal cardiac function may also be disrupted by single-gene mutations in zebrafish. Individual mutations may perturb contractility or rhythm generation. The zebrafish mutations which principally disturb cardiac contractility fall into two broad phenotypic categories, 'dilated' and 'hypertrophic'. Interestingly, these correspond to the two primary types of heart failure in humans. These disorders of early cardiac function provide candidate genes to be examined in complex human heart diseases, including arrhythmias and heart failure.

Clinical profile and outcome of idiopathic restrictive cardiomyopathy

BACKGROUND

Idiopathic restrictive cardiomyopathy is a poorly recognized entity of unknown cause characterized by nondilated, nonhypertrophied ventricles with diastolic dysfunction resulting in dilated atria and variable systolic function.

METHODS AND RESULTS

Between 1979 and 1996, 94 patients (61% women) 10 to 90 years old (mean, 64 years) met strict morphological echocardiographic criteria for idiopathic restrictive cardiomyopathy, mainly dilated atria with nonhypertrophied, nondilated ventricles. None had known infiltrative disease, hypertension of >5 years' duration, or cardiac or systemic conditions associated with restrictive filling. Nineteen percent were in NYHA class I, 53% in class II, and 28% in class III or IV. Atrial fibrillation was noted in 74% of patients and systolic dysfunction in 16%. Follow-up (mean, 68 months) was complete for 93 patients (99%). At follow-up, 47 patients (50%) had died, 32 (68%) of cardiovascular causes. Four had heart transplantation. The death rate compared with actuarial statistics was significantly higher than expected (P<0.0001). Kaplan-Meier 5-year survival was 64%, compared with expected survival of 85%. Multivariate analysis using proportional hazards showed that the risk of death approximately doubles with male sex (hazard ratio [HR] = 2.1), left atrial dimension >60 mm (HR = 2.3), age >70 years (HR = 2.0), and each increment of NYHA class (HR = 2.0).

CONCLUSIONS

Idiopathic restrictive cardiomyopathy or nondilated, nonhypertrophic ventricles with marked biatrial dilatation, as defined morphologically by echocardiography, affects predominantly elderly patients but can occur in any age group. Patients present with systemic and pulmonary venous congestion and atrial fibrillation and have a poor prognosis, particularly men >70 years old with higher NYHA class and left atrial dimension >60 mm.

Echocardiographic features of primary, secondary and familial amyloidosis

BACKGROUND

Currently recognized types of amyloidosis include primary, familial and secondary, each of which may affect the heart. There may be differences in the heart response to the deposition of amyloid fibrils in these three forms of the disease.

MATERIALS AND METHODS

Over a period of 10 years (1985-95), 28 consecutive patients with primary, 11 with secondary and 17 with familial amyloidosis were studied at the Departments of Cardiology of Laiko and Hammersmith Hospitals. The diagnosis of amyloidosis was confirmed by biopsies of subcutaneous fat, rectum, kidney, bone marrow, gum or sural nerve. Diagnosis of cardiac involvement was based on typical electrocardiographic and echocardiographic findings.

RESULTS

The left ventricular fractional shortening (%) was reduced in primary compared with familial or secondary amyloidosis (29.8 +/- 10.2 vs. 36.2 +/- 6.5 vs. 36 +/- 5.9, P < 0.05). The transmitral flow velocity pattern was compatible with abnormal relaxation in most patients in the three groups [primary 16 (57%), familial 11 (64. 7%), secondary 6 (54.5%), P = NS]. Right ventricular systolic dysfunction (right ventricular dP/dt < 220 mmHg s-1 or tricuspid annulus systolic excursion < 10 mm) was present in 8 (28.6%), 2 (11. 8%) and 0 patients. Patients with primary amyloidosis were followed up for 15 +/- 6 months. There were 12 deaths, and repeat echocardiography in the survivors revealed a significant deterioration of left ventricular systolic function (fractional shortening = 23.6% +/- 8.8%, P < 0.05 vs. baseline).

CONCLUSION

Primary amyloidosis is characterized by more severe cardiac involvement than the familial or secondary amyloidosis and has an ominous course.

Atrial thrombosis in cardiac amyloidosis: diagnostic contribution of transesophageal echocardiography

Few cases of atrial thrombosis detected by transesophageal echocardiography (TEE) in cardiac amyloidosis have been reported recently. We present the cases of 3 consecutive patients affected by AL-type cardiac amyloidosis, symptomatic for heart failure and in sinus rhythm. All patients had a cardiac restrictive pattern at Doppler examination. TEE showed left atrial thrombus in 2 patients and biatrial thrombi in 1 patient; conventional transthoracic echocardiography detected only 1 left atrial thrombus. Our experience confirms the association between cardiac amyloidosis and atrial thrombosis, even in sinus rhythm. TEE should be considered to assess thromboembolic risk in all cases of cardiac amyloidosis with severe diastolic dysfunction.

Hypertrophic and restrictive cardiomyopathies in the elderly

Congestive heart failure (CHF) increases with age, but most CHF in the elderly is due to diastolic dysfunction with preserved systolic function. The etiology, pathophysiology, diagnosis, natural history, and treatment of hypertrophic and restrictive cardiomyopathies in the elderly are discussed as a paradigm for CHF with normal systolic function. Hypertrophic obstructive and hypertensive hypertrophic cardiomyopathies are compared and contrasted. As an example of a restrictive cardiomyopathy, the various types of amyloidosis and their clinical import in older patients are covered.

Morphologic spectrum of primary restrictive cardiomyopathy

A restrictive hemodynamic profile with left ventricular (LV) end-diastolic volume < 100 ml/m2 and LV end-diastolic pressure > 18 mm Hg, in the absence of endomyocardial, pericardial, and specific cardiomyopathy, is a peculiar feature of primary restrictive cardiomyopathy. From 1985 to 1994, 7 hearts of patients who met the above hemodynamic criteria and underwent endomyocardial biopsy because of heart failure, were studied through gross (5 cardiectomies and 2 autopsies), histologic, and electron microscopic investigations. Ages ranged from 9 to 48 years (mean age 29 +/- 13). Four patients (57%) had a positive family history: 2 for hypertrophic and 2 for restrictive cardiomyopathy. Three patterns were identified in the 7 hearts: (1) pure restrictive form in 4 cases with mass/volume ratio 1.2 +/- 0.5 g/ml, ejection fraction 58 +/- 5%, LV end-diastolic volume 67.5 +/- 12.6 ml/m2, LV end-diastolic pressure 26.7 +/- 3.5 mm Hg; (2) hypertrophic-restrictive form in 2 cases with mass/volume ratio 1.5 +/- 0.07 g/ml, ejection fraction 62 +/- 1%, LV end-diastolic volume 69 +/- 10 ml/m2, LV end-diastolic pressure 30 +/- 7 mm Hg; and (3) mildly dilated restrictive form in 1 case with mass/volume ratio 0.9 g/ml, ejection fraction 25%, LV end-diastolic volume 98 ml/m2, LV end-diastolic pressure 40 mm Hg. Histology and electron microscopy disclosed myocardial and myofibrillar disarray and endoperimysial interstitial fibrosis in each pattern. The familial forms suggest the presence of a genetic abnormality. Primary restrictive cardiomyopathy may present with or without hypertrophy and shares similar microscopic pictures with hypertrophic cardiomyopathy. The 2 entities may represent a different phenotypic expression of the same genetic disease.

Diastolic hibernation masquerading as constrictive pericarditis

BACKGROUND

Hibernating myocardium has traditionally been characterized in terms of systolic dysfunction.

METHODS

We describe a case in which a 75-year-old patient with significant coronary artery disease was operated upon for classic constrictive pericarditis.

RESULTS

At sternotomy, there was no evidence of pericarditis, but marked diastolic without systolic dysfunction remained. After successful coronary revascularization, the patient immediately exhibited dramatic improvement of diastolic performance. Ex vivo evaluation of myocardial contractile function revealed normal myocardial adrenergic responsiveness, indicating a reversible impairment of contractility.

CONCLUSION

Diastolic hibernation may therefore represent a unique form of surgically correctable restrictive cardiomyopathy.