Characteristics of early pleural effusions after orthotopic heart transplantation: comparison with coronary artery bypass graft surgery

Pleural effusions appearing within the first 30 postoperative days following coronary artery bypass grafting are classified as early and believed to be directly related to cardiac surgery. The characteristics of such effusions are well-described. Orthotopic heart transplantation is also known to be complicated by pleural effusions, but their characteristics have not been systematically reported. We assessed the features of early postoperative pleural effusions after heart transplantation and compared them to those of early effusions following coronary artery bypass grafting. We retrospectively collected demographic, clinical, and laboratory data for patients who underwent either orthotopic heart transplantation (study group) or coronary artery bypass grafting (comparison group) at our institution and whose postoperative course within 30 days was complicated by new or worsening pleural effusion. Patients subjected to analysis consisted only of those with sufficiently complete laboratory profiles to permit adequate characterization of the nature of their pleural fluid. Out of 251 orthotopic heart transplant recipients, 7 (2.8%) were found to have sufficiently complete pleural fluid results to be included. Out of 1506 patients who underwent coronary artery bypass grafting, 32 (2.1%) had sufficiently complete pleural fluid results. The radiological appearance of pleural effusions in both groups was similar: bilateral in at least half and exclusively moderate to large. Effusions complicating both surgeries were exudative in close to 90% of cases. For those with available leukocyte differential counts, the pleural fluid of the post-orthotopic heart transplantation group was more often neutrophilic (3/5, 60%), whereas the fluid of the post-coronary artery bypass grafting group was more often lymphocytic (22/32, 69%) and tended to be hemorrhagic (median red blood cell count 33,000 cells/µl vs 10,000 cells/µl). None of the comparisons of pleural fluid characteristics between the two groups reached statistical significance. This small, descriptive study is the first to systematically report the fluid characteristics of pleural effusions complicating orthotopic heart transplantation within the first 30 postoperative days and to compare this group to those who developed effusions after coronary artery bypass grafting. Our findings revealed both similarities and differences in the pleural fluid characteristics between these two types of patients.