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J Thorac Cardiovasc Surg 2002;124:979-983
© 2002 The American Association for Thoracic Surgery
Cardiothoracic Transplantation (TX) |
From the Department of Cardiovascular and Thoracic Surgery, University of Texas Southwestern Medical Center at Dallas, Tex.
Received for publication Sept 13, 2001. Revisions requested Jan 3, 2002; revisions received Jan 23, 2002. Accepted for publication Feb 7, 2002. Address for reprints: Michael E. Jessen, MD, Department of Cardiovascular and Thoracic Surgery, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-8879 (E-mail: michael.jessen{at}utsouthwestern.edu).
| Abstract |
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| Introduction |
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Pericardial effusions tend to occur within the first 3 months after transplantation, and late development is uncommon.
8 Their appearance may mandate surgical or catheter drainage, but the effect of effusions on survival or other outcome measures has not been well established. This study was undertaken to identify characteristics of the donor, the recipient, the operative procedure, and the early postoperative course that predict the development of significant pericardial effusion after orthotopic cardiac transplantation. The study also examined the influence of pericardial effusions on common posttransplantation outcome measures.
| Methods |
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Outcome data, including recipient survival, length of postoperative hospital stay, and rejection episodes, were also recorded for all patients. The incidence of posttransplantation graft rejection was assessed by review of all surveillance biopsies done for each patient within the first 3 months after transplantation. Rejection episodes were recorded if biopsy specimens demonstrated histologic changes of grade 2 or higher according to the International Society for Heart & Lung Transplantation guidelines
10 and patients received treatment for rejection.
Statistical analysis
Data were analyzed with commercially-available software (SAS Institute, Inc, Cary, NC). A univariate analysis of all variables listed in Table 1
was performed initially to assess for differences between groups with and without significant pericardial effusion. A
2 analysis was used for discrete variables, with P < .05 according to 2-tailed Fisher exact test used to select factors with potential significance. For continuous variables, the Student t test with the Welch approximation for unequal variances was used to compare the two groups. Group differences were also considered potentially significant at P < .05.
To account for a lack of independence among the variables, additional testing was used. Variables with the potential for significant difference between groups according to univariate analysis were entered as candidate variables in a mulitvariate stepwise logistic regression analysis. For each element remaining in the multivariate model, a parameter estimate was calculated from which a P value, odds ratio (OR), and 95% confidence interval (CI) for the variable were derived.
To examine patient survival and freedom from rejection, estimates based on the Kaplan-Meier method were created and compared statistically with a log-rank test. Data are expressed as mean ± SD except in the case of survival data, which are reported as mean ± SEM.
| Results |
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Variables found to correlate with significant pericardial effusion according to the univariate analysis are listed in Table 2. Patients with significant pericardial effusion were less likely to have had previous cardiac surgery and more likely to be undergoing transplantation for idiopathic dilated cardiomyopathy, to be younger, to be lighter, and to have higher central venous pressure at time of transplant evaluation. The use of hearts from female donors was associated with significant effusion, as was intraoperative administration of the antifibrinolytic agent aminocaproic acid (Amicar). Patients with significant pericardial effusion were found to have a lower incidence of postoperative pedal edema.
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The development of a postoperative pericardial effusion did not appear to be related to any common outcome measures in this population. Actuarial survival calculated by the Kaplan-Meier method was not different between transplant recipients with and without significant postoperative effusions. The 5-year survivals of patients with and without pericardial effusions were 92% ± 4% and 83% ± 3%, respectively (P = .15). Postoperative hospital stays were 19 ± 3 days and 18 ± 1 days among patients with and without pericardial effusions, respectively (P = .66).
| Discussion |
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According to univariate analysis, recipients with dilated cardiomyopathy, no previous cardiac surgery, and younger age were more likely to have significant pericardial effusions develop. Other groups have reported associations with dilated cardiomyopathy
12 and the absence of previous cardiac surgery.
5,6 These variables are related, because patients receiving transplants for dilated cardiomyopathy are significantly younger and significantly less likely to have undergone previous cardiac surgical procedures. It is therefore not surprising that only one of these variables (the absence of previous cardiac surgery) emerged as an independent predictor of pericardial effusions in the multivariate analysis.
Although previous studies have suggested that the development of acute rejection may contribute to the development of significant pericardial effusions,
5,8 no such association was identified in this study. However the incidence of early acute rejection in this cohort was relatively low (45 of 203 patients), which may have influenced our ability to detect an association. The use of cyclosporine, cited by others as a possible cause of pericardial effusions,
7 could not be analyzed because all transplant recipients in this study were treated with this drug after transplantation.
A statistical association between recipient weight and the development of pericardial effusions was found, with heavier recipients slightly protected from this complication. This association was found only for absolute recipient weight and not for the donor-recipient weight difference (P = .17 by univariate analysis), as has been reported by others.
6 The reason for this finding was not determined by this study, but one might speculate that a larger recipient would have a greater pericardial surface over which postoperative pericardial fluid could be distributed or absorbed. This would be difficult to ascertain, because cardiac dimensions are typically grossly enlarged before transplantation, and body weight may not be a precise surrogate for heart size in patients with heart failure. Direct measurements of donor and recipient heart sizes with quantitative imaging may provide more meaningful comparative data.
Use of the antifibrinolytic agent aminocaproic acid (administered intravenously in a dose of 10 g after heparinization plus 5 g added to the cardiopulmonary bypass circuit) was found to be associated with a dramatically increased incidence of postoperative pericardial effusion, a finding not previously reported. Agents such as aminocaproic acid and aprotinin are used in the perioperative setting to reduce postoperative bleeding.
13,14 They are used more frequently for patients who have had previous cardiac surgery, because of the increased risk for bleeding in this group. However, aminocaproic acid use was identified as a predictor of pericardial effusions independent of reoperative status according to the multivariate analysis, whereas no association with aprotinin was observed. It is possible that the administration of an antifibrinolytic agent may contribute to retention of clots within the pericardial sac. Subsequent clot lysis could encourage fluid inspissation, leading to an effusion. However, it is noteworthy that the amount of mediastinal chest drainage, duration of chest tube drainage, and the quantities of blood products administered after transplantation were not found to correlate with the development of pericardial effusions. Also, the amount of mediastinal blood loss within the first 48 postoperative hours was not different between patients who received aminocaproic acid (1500 ± 210 mL), aprotinin (1673 ± 186 mL), or neither (1483 ± 100 mL).
This study has several limitations. It is retrospective in design, and some data could not be obtained because of the unavailability of records. Harvesting and implantation procedures were performed by several surgeons, and there may have been subtle differences in operative technique that could have influenced outcomes. In addition, there may have been evolutionary changes in management protocols or patient selection criteria during the 12-year study interval that were not accounted for in this analysis. Antifibrinolytic agents were administered according to the judgment of the surgeon, anesthesiologist, and perfusionist at the time of surgery rather than according to a predetermined protocol. Finally, echocardiographic data may be somewhat subjective, and other definitions of pericardial effusions may be more appropriate. We applied the echocardiographic criteria defined by Martin and coworkers,
9 because these guidelines have been used in other reports examining pericardial effusions in transplantation. When the analysis was repeated with a significant pericardial effusion defined as one necessitating surgical or catheter drainage (n = 19), multivariate analysis identified a diagnosis of dilated cardiomyopathy (OR 8.03, 95% CI 2.61-24.66, P < .0001) and use of aminocaproic acid (OR 5.44, 95% CI 1.76-16.87, P < .0019) as significant predictors.
As with any retrospective study, there are limitations to the statistical analysis and its interpretation. The number of patients in whom pericardial effusions developed totaled only 42, and the number of predictors initially screened by univariate techniques exceeded this value. Even the entry of 8 candidate variables into the multivariate analysis may risk overfitting with this number of outcomes.
15 Continuous variables such as recipient weight are modeled with the assumption that the risk for the outcome is linear across the range of weights included. This analysis does not account for the possibility that risk is not linear (as might be seen if the risk for pericardial effusion increases for very low weights and then levels off at higher weights). Finally, the meaning of the significant effects observed in this or any other retrospective study must be interpreted with caution. The variables identified as predictors may represent surrogates for other conditions that more directly affect the outcome.
To our knowledge, this is the largest study evaluating factors contributing to the development of significant pericardial effusions after orthotopic cardiac transplantation. Previous cardiac procedures and greater recipient weight appear protective, whereas the use of aminocaproic acid appears to increase the risk of this complication. An association with acute rejection was not identified. On the basis of the currently identified factors, the development of pericardial effusions may be difficult to prevent, although avoiding the use of aminocaproic acid should be considered. The development of pericardial effusion does not appear to prolong hospital stay or affect survival. However, the presence of one or more risk factors in the patient undergoing orthotopic heart transplantation should lead to heightened awareness of this potential complication.
| References |
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-aminocaproic acid. J Thorac Cardiovasc Surg. 1996;112:1098-107.This article has been cited by other articles:
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E. A. Ashikhmina, H. V. Schaff, L. J. Sinak, Z. Li, J. A. Dearani, R. M. Suri, S. J. Park, T. A. Orszulak, and T. M. Sundt III Pericardial Effusion After Cardiac Surgery: Risk Factors, Patient Profiles, and Contemporary Management Ann. Thorac. Surg., January 1, 2010; 89(1): 112 - 118. [Abstract] [Full Text] [PDF] |
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Task Force members, B. Maisch, P. M. Seferovic, A. D. Ristic, R. Erbel, R. Rienmuller, Y. Adler, W. Z. Tomkowski, G. Thiene, M. H. Yacoub, et al. Guidelines on the Diagnosis and Management of Pericardial Diseases Executive Summary: The Task Force on the Diagnosis and Management of Pericardial Diseases of the European Society of Cardiology Eur. Heart J., April 1, 2004; 25(7): 587 - 610. [Full Text] [PDF] |
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