CARDIOMYOPATHY Restrictive cardiomyopathy versus constrictive pericarditis : role of endomyocardial biopsy in avoiding unnecessary thoracotomy

Despite careful clinical, noninvasive, and hemodynamic assessment of patients with constrictive/restrictive physiology, the differentiation of restrictive cardiomyopathy from constrictive pericarditis remains difficult. We examined the role of right ventricular endomyocardial biopsy in defining the underlying process in 54 patients with evidence of constrictive/restrictive physiology, including 38 patients with profound symptoms of heart failure in whom diagnostic/therapeutic thoracotomy was contemplated (group I) and 16 patients with milder symptoms (group II). All patients in group I had NYHA class III or IV heart failure with depressed cardiac index (mean 2.5 liters/minIm2), right atrial hypertension (mean 15 mm Hg), and normal left ventricular ejection fraction (mean 59%). Endomyocardial biopsy identified a specific source of restrictive cardiomyopathy in 15 of 38 patients (39%) (1 1 amyloid, four myocarditis). Of the 23 remaining patients with either normal biopsy findings or nonspecific abnormalities on biopsy, 18 had intraoperative or autopsy evaluation of their pericardium, and constriction was found in 14 (77%). A specific form of restrictive cardiomyopathy was also identified in four of the 16 patients with milder symptoms (group II). We conclude that endomyocardial biopsy is useful in patients with severe constrictive/restrictive physiology. It identifies a large subset of patients with specific forms of restrictive cardiomyopathy in whom thoracotomy should be avoided. It supports the need for thoracotomy and the likelihood of finding pericardial constriction in patients without specific pathologic findings. Circulation 75, No. 5, 1012-1017, 1987. THE DIFFERENTIATION of restrictive cardiomyopathy from constrictive pericarditis remains one of the major diagnostic dilemmas encountered in clinical cardiology. For patients with symptoms of heart failure in whom these diagnoses are considered, the distinction of these two conditions is critical, since both their management and ultimate prognoses are quite different. ' Similarities in clinical presentation between these two conditions have long been recognized,5-8 and efforts to separate them on the basis of noninvasive methods'-" or angiographic/hemodynamic characteristics7' ', 1"16 have been fraught with difficulty. Exploratory thoracotomy for pericardial From the Cardiac Unit and the Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston. Address for correspondence: Igor F. Palacios, M.D., Cardiac Unit, Massachusetts General Hospital, Boston, MA 02114. Received Oct. 15, 1986; revision accepted Jan. 22, 1987. Presented in part at the 58th Scientific Sessions of the American Heart Association, November 1985, Washington, DC. *Present address: Co-Director, Cardiac Electrophysiology and Pacing Laboratory, Hospital of Saint Raphael, 175 Sherman Ave., New Haven, CT 06511. **Present address: Lahey Clinic, Burlington, MA 01805. evaluation, with its attendant risks,7 17. 15 remains the definitive technique for establishing a diagnosis in