By Michael H. Crawford, MD, Editor

SYNOPSIS: An observational study of patients with chronic, large, hemodynamically insignificant, C-reactive protein-negative, idiopathic pericarditis in which the majority were treated by pericardiocentesis or surgical drainage showed most patients treated conservatively remained stable. The invasive approach did not reveal an etiology for the effusions.

SOURCE: Lazaros G, Antonopoulos AS, Lazarou E, et al. Long-term outcome of pericardial drainage in cases of chronic, large, hemodynamically insignificant, C-reactive protein negative, idiopathic pericardial effusions. Am J Cardiol 2020;126:89-93.

Current guidelines recommend drainage of large chronic idiopathic pericardial effusions, even if they are not of hemodynamic significance and the patient is asymptomatic. However, there is a paucity of data supporting this practice.

Lazaros et al studied such patients who were seen at one pericardial disease referral center and three other clinics in Greece from 2013 to 2018. Inclusion criteria were that the effusions were large (> 2 cm diastolic echo-free space), chronic (> 3 months), idiopathic, hemodynamically insignificant, and that the patients were asymptomatic and had normal serum C-reactive protein (CRP) levels. These criteria excluded 304 of 378 patients with pericardial effusions identified, leaving a study population of 74 patients.

Among these 74 patients, 52 chose drainage of the effusion. The attending physician and patient decided whether this was accomplished by pericardiocentesis or pericardial window. This resulted in 39 patients who chose pericardiocentesis, 13 a pericardial window, and 22 who were conservatively treated. The primary endpoint was re-accumulation of fluid over a median follow-up of 24 months. Complications of drainage and other clinical events also were recorded.

At baseline, there were no significant differences in the demographics or pericardial disease characteristics among the three groups. An analysis of the pericardial fluid and pericardial biopsies taken in those undergoing surgery all failed to reveal a specific fluid etiology. Re-accumulation of fluid occurred in 32 of 52 patients drained (30 in the pericardiocentesis group and two in the surgical group; P < 0.001). Those who re-accumulated experienced longer disease duration and larger effusions compared to those who did not re-accumulate. Among conservatively treated patients, most remained stable over time (77%), some regressed (14%), and a few developed impending tamponade and were drained (9%). Procedural complications occurred in 13% of patients undergoing pericardiocentesis and 15% of surgical drainage patients (P = not significant). There were seven deaths during follow-up and all were non-cardiac. No one developed constrictive pericarditis. The authors concluded a conservative approach is reasonable in patients with chronic, large, hemodynamically insignificant, CRP-negative, idiopathic pericardial effusion.

COMMENTARY

There is an old clinical adage that large pericardial effusions should be drained because they are more likely to result in cardiac tamponade. This may be true, but probably only in the acute or early phase of pericarditis. Draining the fluid may be associated with less tamponade, but usually other therapies (e.g., anti-inflammatory drugs) are given at the same time, so the effect of pericardial drainage per se is difficult to discern. Lazaros et al, in their interesting observational study, assessed the value of pericardial drainage in large, chronic, idiopathic, asymptomatic, hemodynamically insignificant, and CRP-negative effusions. Thus, these are patients with no clear indication for any therapy. They found pericardiocentesis did not prevent re-accumulation, since almost two-thirds re-accumulated. Although surgical pericardial window was superior at preventing re-accumulation, 15% experienced significant complications from the procedure. Also, routine biopsy of the pericardial tissue uncovered no occult diagnoses. Paradoxically, re-accumulation was associated with longer disease duration and larger effusions, two factors that might be thought to favor drainage. There appears to be little advantage to draining the fluid in this small asymptomatic subgroup of patients.

There were study limitations. Although the data were collected prospectively, it was an observational study subject to the biases of this type of investigation. Also, most patients came from one pericardial disease referral center, which emphasizes the uniqueness of the observed population. Further, we cannot translate the findings of this study to other, more acute patients with large pericardial effusions. Nor can the results be applied to symptomatic patients or those with a known inflammatory condition. These results do support routine follow-up of similar patients. In the conservatively treated patients, 9% developed tamponade, but this low rate also does not justify routine drainage of large effusions in this type of patient. Current guidelines suggest follow-up every three to six months, which seems reasonable.