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The Association of Acute Kidney Injury and Atrial Fibrillation after Cardiac Surgery in an Asian Prospective Cohort Study

View Article: PubMed Central - PubMed

ABSTRACT

Acute kidney injury (AKI) and atrial fibrillation (AF) after cardiac surgery are common occurrences and increase patient morbidity and mortality. Inflammation plays a role in increased incidence of AF in patients with chronic kidney disease (CKD); reactive oxygen species and inflammatory markers which are increased in patients with CKD were found to affect the proper functioning of the intracellular ion channels, connexions (transmembrane proteins found in intercellular gap junctions), and electrical homogeneity of the extracellular matrix which are essential for electrical stability and proper conduction of electrical impulses in the atrium. However, it is not known if similar mechanisms are also involved in AKI. We tested the hypothesis that patients with AKI after cardiac surgery have a higher incidence of postoperative AF.

Data from 2885 patients, who had undergone cardiac surgery between August 2008 and July 2012 from the Singapore's 2 major heart centers, were obtained prospectively. Postoperative AKI was defined using the Acute Kidney Injury Network criteria. The primary outcome was postoperative AF, and subjects were considered to have postoperative AF if the AF lasted more than an hour, affected hemodynamics, or required medical treatment.

The incidence of AKI was 29.7% and the incidence of postoperative AF was 16.8%. A total of 27.7% of AKI patients developed AF. Patients with AKI had a 2-fold increased risk of developing AF (relative risk [RR], 1.716; 95% confidence interval [CI], 1.433–2.055; P < 0.001). The following factors were found to independently increase the risk of AF in patients with AKI: age (RR, 1.011; 95% CI, 1.000–1.022; P = 0.04), low preoperative hemoglobin (RR, 0.942; 95% CI, 0.888–1.000; P = 0.05), low preoperative estimated glomerular filtration rate (eGFR) (RR, 0.987; 95% CI, 0.980–0.994; P < 0.001), and lowest hematocrit during bypass (RR, 0.943; 95% CI, 0.910–0.978; P < 0.001).

Patients with AKI are more likely to develop postoperative AF. These patients were older and had lower preoperative hemoglobin, eGFR, and lower nadir hematocrit during bypass. Identification of high-risk AKI patients with early prevention and treatment of AF should reduce the long-term morbidity and mortality among Asian patients undergoing cardiac surgery.

No MeSH data available.


Related in: MedlinePlus

Flowchart from recruitment to outcomes. AF = atrial fibrillation; AKI = acute kidney injury.
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Figure 1: Flowchart from recruitment to outcomes. AF = atrial fibrillation; AKI = acute kidney injury.

Mentions: A total of 2885 patients who underwent cardiac surgery in the 2 heart centers were enrolled in our study during this period. Of these, 313 patients were excluded as 10 of them were on regular dialysis and 303 of the patients had other postoperative arrhythmias other than AF. Therefore, there were 2572 patients who met our inclusion and exclusion criteria. Of the 2572, 432 (16.8%) and 763 (29.7%) patients developed postoperative AF and AKI, respectively (Figure 1).


The Association of Acute Kidney Injury and Atrial Fibrillation after Cardiac Surgery in an Asian Prospective Cohort Study
Flowchart from recruitment to outcomes. AF = atrial fibrillation; AKI = acute kidney injury.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4998370&req=5

Figure 1: Flowchart from recruitment to outcomes. AF = atrial fibrillation; AKI = acute kidney injury.
Mentions: A total of 2885 patients who underwent cardiac surgery in the 2 heart centers were enrolled in our study during this period. Of these, 313 patients were excluded as 10 of them were on regular dialysis and 303 of the patients had other postoperative arrhythmias other than AF. Therefore, there were 2572 patients who met our inclusion and exclusion criteria. Of the 2572, 432 (16.8%) and 763 (29.7%) patients developed postoperative AF and AKI, respectively (Figure 1).

View Article: PubMed Central - PubMed

ABSTRACT

Acute kidney injury (AKI) and atrial fibrillation (AF) after cardiac surgery are common occurrences and increase patient morbidity and mortality. Inflammation plays a role in increased incidence of AF in patients with chronic kidney disease (CKD); reactive oxygen species and inflammatory markers which are increased in patients with CKD were found to affect the proper functioning of the intracellular ion channels, connexions (transmembrane proteins found in intercellular gap junctions), and electrical homogeneity of the extracellular matrix which are essential for electrical stability and proper conduction of electrical impulses in the atrium. However, it is not known if similar mechanisms are also involved in AKI. We tested the hypothesis that patients with AKI after cardiac surgery have a higher incidence of postoperative AF.

Data from 2885 patients, who had undergone cardiac surgery between August 2008 and July 2012 from the Singapore's 2 major heart centers, were obtained prospectively. Postoperative AKI was defined using the Acute Kidney Injury Network criteria. The primary outcome was postoperative AF, and subjects were considered to have postoperative AF if the AF lasted more than an hour, affected hemodynamics, or required medical treatment.

The incidence of AKI was 29.7% and the incidence of postoperative AF was 16.8%. A total of 27.7% of AKI patients developed AF. Patients with AKI had a 2-fold increased risk of developing AF (relative risk [RR], 1.716; 95% confidence interval [CI], 1.433–2.055; P < 0.001). The following factors were found to independently increase the risk of AF in patients with AKI: age (RR, 1.011; 95% CI, 1.000–1.022; P = 0.04), low preoperative hemoglobin (RR, 0.942; 95% CI, 0.888–1.000; P = 0.05), low preoperative estimated glomerular filtration rate (eGFR) (RR, 0.987; 95% CI, 0.980–0.994; P < 0.001), and lowest hematocrit during bypass (RR, 0.943; 95% CI, 0.910–0.978; P < 0.001).

Patients with AKI are more likely to develop postoperative AF. These patients were older and had lower preoperative hemoglobin, eGFR, and lower nadir hematocrit during bypass. Identification of high-risk AKI patients with early prevention and treatment of AF should reduce the long-term morbidity and mortality among Asian patients undergoing cardiac surgery.

No MeSH data available.


Related in: MedlinePlus