How Can Relation Between Pericardial Effusion and Acute Kidney Injury Be Explained?

Reply by the Authors of the Original Article

We read the article written by Kaya et al titled “The Preventive Effects of Posterior Pericardiotomy with Intrapericardial Tube on the Development of Pericardial Effusion (PE), Atrial Fibrillation (AF), and Acute Kidney Injury (AKI) after Coronary Artery Surgery: A Prospective, Randomized, Controlled Trial.”[1] We appreciate the authors for this article. However, there are some conflicting points that should be highlighted.

First of all, authors cited an article by Kaleda et al in the introduction section for relation between PE and AKI.[2] However, when we read this reference for this association, we could not find any information about this relation.[2]

In “Materials and Method” section under the subheading “Follow-up of Patients in the Ward,” the authors stated “Asymptomatic moderate cases were followed up by echocardiography every day,” whereas authors did not mention how they chose “asymptomatic moderate cases” with which method or classification system. It is important to mention the diagnostic criteria for “asymptomatic moderate cases.” Also in the same section, under the subheading “Follow-up of Patients in the Intensive Care Unit,” the authors stated that “The chest and mediastinal tubes were removed routinely on the second postoperative day, when the total drainage was under 20 mL in 4 hours.” They did not mention if they included the patients with total drainage over 20 mL/4 hour and after second postoperative day. Did they include such group of patients to the study? Also, what was the reason for the authors to start echocardiographic follow-up on the second postoperative day?

In “Materials and Method” section, the authors stated that “Patients with greater than small PE were treated with nonsteroid anti-inflammatory drugs and diuretics.” These drugs have also been known to develop AKI and the usage of these drugs routinely can create bias. To overwhelm this bias, the authors could include the usage of these drugs into regression and multivariate analysis or should exclude the patients who used these drugs.

In the “Results” section, in study group PE volume is smaller in postoperative second and fifth day; yet the difference between the two groups is approximately 1 mL, which is really tiny volumes to able to make a decision on that. Additionally, the mean value of PE volume of both study and control group is considered to be in a small PE group. Are those amounts of PEs really clinically important? What is the scientific background for this?

In the “Results” section, the authors showed that the incidence of cardiac tamponade and AF is lower in the study group. As a matter of fact, these results have been shown in many studies in the literature and are common knowledge. For example, in 1999, Kuralay et al have already shown that posterior pericardiotomy lowers the risk of development of cardiac tamponade, PE, and AF in 200 coronary artery bypass patients.[3] Even if, in this study (Kaya et al), AKI was evaluated, unlike other studies, as the authors mentioned in the “Discussion” section, AKI already can appear as a complication of AF.

In conclusion, we thank the authors for this study. We will be happy if the authors highlight our contradictory questions.

• References

• 1 Kaya M, Utkusavaş A, Erkanlı K , et al. The Preventive Effects of Posterior Pericardiotomy with Intrapericardial Tube on the Development of Pericardial Effusion, Atrial Fibrillation, and Acute Kidney Injury after Coronary Artery Surgery: A Prospective, Randomized, Controlled Trial. Thorac Cardiovasc Surg 2015; ; (this issue)
• 2 Kaleda VI, McCormack DJ, Shipolini AR. Does posterior pericardiotomy reduce the incidence of atrial fibrillation after coronary artery bypass grafting surgery?. Interact Cardiovasc Thorac Surg 2012; 14 (4) 384-389
• 3 Kuralay E, Ozal E, Demirkili U, Tatar H. Effect of posterior pericardiotomy on postoperative supraventricular arrhythmias and late pericardial effusion (posterior pericardiotomy). J Thorac Cardiovasc Surg 1999; 118 (3) 492-495