Controversy exists over the role of endomyocardial biopsy in evaluating patients with dilated cardiomyopathy, particularly in detecting myocarditis and in assessing prognosis. Interobserver variability, if high, could explain conflicting reports. To assess this possibility, we submitted biopsy specimens from 16 patients with dilated cardiomyopathy to seven cardiac pathologists. The same slides were independently reviewed by each and assessed for fibrosis, hypertrophy, nuclear changes on a 0 to 3 + scale, mean lymphocyte count per high-power field, and myocarditis. The prevalance of significant fibrosis ranged from 25% to 69%, hypertrophy from 19% to 88%, nuclear changes from 31% to 94%, and abnormal lymphocyte count from 0 to 38%. One or more pathologists diagnosed definite or possible myocarditis in 11 of the 16 patients. Of these 11 patients, three pathologists agreed about three and two pathologists agreed about five. Myocarditis was diagnosed by a single pathologist in three cases. We conclude that interobserver variability is high in interpreting biopsy specimens from patients with dilated cardiomyopathy and that quantitative and standardized methods are needed to increase diagnostic consistency.
Prognosis in classically described dilated congestive cardiomyopathy has been reported to be related to ventricular size. Mildly dilated congestive cardiomyopathy (MDCM) has been defined as end-stage heart failure of unknown etiology (New York Heart Association class IV, left ventricular ejection fraction less than 30%), occurring with neither typical hemodynamic signs of restrictive myopathy nor significant ventricular dilatation (less than 15% above normal range). The present study includes follow-up in 12 nontransplant patients. In the first 4 months after diagnosis, two patients improved and are living, and two showed cardiac dilation and clinical deterioration and died. Six of the remaining eight with persistent MDCM died (four with intractable heart failure and two, sudden deaths) without change in ventricular size before death, despite medical therapy over 20±8 months. Eight comparable transplanted patients with persistent MDCM demonstrated improved total survival by life table analysis (p<0.05). A family history of congestive cardiomyopathy was found in nine of 16 patients (56%) with persistent MDCM. Nontransplant patients were older (p<0.02), but other findings were similar in the two groups. Endomyocardial biopsies available in 14 of 16 cases showed little or no myofibrillar loss in spite of severe hemodynamic impairment. The degree of myofibrillar loss did not correlate with hemodynamic parameters but showed good correlation with left ventricular size, that is, five of six patients with no myofibrillar loss had normal ventricular size, whereas all eight patients with mild myofibrillar loss had mild cardiomegaly (p<0.002).Our current experience suggests a somewhat variable but negative prognosis after prospective diagnosis of MDCM, with poor survival in patients with persistence of the original diagnostic features during follow-up. Preservation of heart size in MDCM is probably related to lack of significant myofibrillar loss. Thus, irrespective of heart size or myofibrillar preservation on biopsy, heart transplantation should be strongly considered in MDCM if signs of severe cardiac dysfunction persist despite therapy. (Circulation 1990;81:506-517) V entricular dilation is considered the earliest and most distinguishing morphologic feature of congestive cardiomyopathy, which is often called "dilated cardiomyopathy."1-5 Lack of significant ventricular dilation is typically found in hypertrophic and in restrictive cardiomyopathies.1,24-8 Restrictive cardiomyopathy has also been termed "nondilated cardiomyopathy" by some authors to emphasize its morphological appearance and differentiate it from dilated
Five patients with only mildly dilated ventricles but other features typical of congestive cardiomyopathy underwent cardiac transplantation for class IV NYHA heart failure. The findings of clinical studies, cardiac catheterization, endomyocardial biopsy, and pathologic examination of the removed hearts in this group with mildly dilated congestive cardiomyopathy (MDCM) were compared with similar data in four patients with idiopathic restrictive cardiomyopathy (IRCM) and in 10 patients with typical dilated congestive cardiomyopathy (DCM). In comparison with the other groups, patients with MDCM had a higher incidence of familial cardiomyopathy (p = .02) and a shorter symptomatic period than patients with IRCM (p < .02). Patients with both MDCM and DCM had globular hearts (with predominant left ventricular dilatation), congestive hemodynamics and poor left ventricular contractility (ejection fraction 12% to 1.9%), and high incidence of ventricular thrombi. Patients with IRCM showed normal ventricular size, marked atrial dilatation, restrictive hemodynamics, mild-tomoderate decrease in left ventricular contractility (ejection fraction 29% to 55%), and absence of ventricular thrombi. Cardiac index, ventricular wall thickness, and light microscopic findings were similar in the three groups of patients. Electron microscopy showed no myofibrillar loss in patients with IRCM but mild (partial) or moderate-to-severe (almost total) myofibrillar loss in those with MDCM and DCM, respectively. We conclude that (1) end-stage congestive cardiomyopathy may occur without significant ventricular dilatation and (2) 302-309, 1985. CONGESTIVE and restrictive cardiomyopathies represent distinct entities with different hemodynamic and morphologic features.' Congestive cardiomyopathy is characterized by ventricular dilatation and poor systolic function with greatly reduced ejection fraction.' Dilatation of the ventricles usually occurs earlier than heart failure and is considered the most important manifestation of the disease. 5 For this reason, the terms "dilated"2'6 or "dilated congestive"3' 4 cardiomyopathy are currently preferred. Light and electron microscopic assessment show major but nonspecific abnormal changes.' 1. 6 Restrictive cardiomyopathy is characterized by normal or near normal ventricular size and systolic function but compromised ventricular relaxation leading to distinctive hemodynamic findings. 4 The term re-
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