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Abstract & Commentary
Synopsis: Pericardial thickness was not increased in 1 out of 5 patients with clinical evidence of constrictive pericarditis who underwent pericardiectomy and improved postoperatively. Thus, pericardiectomy should not be withheld in patients with clinical evidence of constrictive pericarditis and normal pericardial thickness.
Source: Talreja DR, et al. Circulation. 2003;108:1852-1857.
Since the hemodynamic characteristics of constrictive pericarditis and restrictive myocardial disease are often similar, a determination of normal pericardial thickness is thought to rule out constrictive pericarditis. However, reports of pericardial constriction with normal pericardial thickness exist. Thus, Talreja and colleagues from the Mayo Clinic in Rochester, Minn, reviewed biopsy specimens and clinical features of 143 patients who had pericardiectomy for proven pericardial constriction. The patients were divided into 2 groups: 26 (18%) with pericardial thickness < 2 mm (nlThick) and 117 with > 2 mm (Thick). Previous cardiac surgery was the most common cause in nlTh (42%), and idiopathic was most common in Thick (31%). Age, comorbidity, clinical features, x-ray visualization of pericardial calcium, or hemodynamics were not markedly different between the 2 groups. Postsurgical improvement in hemodynamics was similar in the 2 groups. No patient in nlTh had a normal pericardium on histology; most had focal fibrosis or calcium. Mortality was not different perioperatively or late. Talreja et al concluded that pericardial thickness was not increased in 1 out of 5 patients with clinical evidence of constrictive pericarditis who underwent pericardiectomy and improved postoperatively. Thus, pericardiectomy should not be withheld in patients with clinical evidence of constrictive pericarditis and normal pericardial thickness.
Comment by Michael H. Crawford, MD
The decision to refer someone for thoracic surgery to strip the pericardium is always difficult, given the clinical uncertainty of the diagnosis of constrictive pericarditis. I used to rely on imaging evidence of pericardial thickening to reassure myself that I was making the right decision. In this series, 72% of the patients had a thick pericardium by CT—11% of the normal thickness group and 86% of the thick pericardium group. Would MRI have done a better job? Regardless, this report clearly makes requiring imaging evidence of pericardial thickening untenable, so how do we arrive at a comfort level with the decision to operate? No clinical, echocardiographic, or hemodynamic parameter emerged as a highly accurate measure. The best were 2 hemodynamic measures: diastolic pressure equalization present in 77% and the classic dip and plateau of the right ventricular pressure tracing in diastole, also present in 77%. Interestingly, atrial enlargement was found in 61% of their patients, which is one of the classic features of restrictive cardiomyopathy. Talreja et al used myocardial biopsy when they were uncertain, which they were in 7 patients, all of whom showed no evidence of restrictive cardiomyopathy on histology.
There are problems with this study, which temper Talreja et al’s conclusions. It is a retrospective study of only patients with a very strong suspicion of constrictive pericarditis who underwent surgery. There is no control group. Are there patients with thick pericardiums who do not have constriction? What about the patients in whom the diagnosis of constrictive pericarditis was seriously considered but rejected. What happened to them? Also, this is a study done at a quaternary referral center. Would the incidence of normal pericardial thickness in patients with strong clinical evidence of pericardial restriction in a less selected population be almost 20%? Also, the type of echocardiography performed was not mentioned in the study. I have been impressed that transesophageal echo is very useful for establishing the diagnosis of constriction. The bottom line on this study is that imaging evidence of normal pericardial thickness should not be used as sole criteria for withholding surgery in suspected pericardial constriction. Again, we are left with a difficult clinical decision requiring considerable judgment and bereft of one pivotal diagnostic test.
Dr. Crawford, Associate Chief of Cardiology for Clinical Programs, University of California, San Francisco, is Editor of Clinical Cardiology Alert.