Concomitant surgical ablation for atrial fibrillation is associated with increased risk of acute kidney injury but improved late survival

Abstract

Background: Acute kidney injury (AKI) after cardiac surgery remains a common complication that has been associated with increased morbidity and mortality. This study implemented Kidney Disease Improving Global Outcomes criteria to evaluate renal outcomes after concomitant surgical ablation for atrial fibrillation.

Methods: Patients with a history of atrial fibrillation who underwent elective cardiac surgery at our institution from 2008 to 2018 were retrospectively reviewed. Those with preoperative renal dysfunction were excluded. Patients were classified as those who underwent concomitant Cox-Maze IV (CMP-IV) (n = 376) or no surgical ablation (n = 498). Nearest neighbor 1:1 propensity matching was conducted on fourteen covariates. AKI was evaluated by mixed effects logistic regression analysis. Long-term survival was evaluated by proportional hazards regression.

Results: Propensity matching yielded 308 patients in each group (n = 616). All preoperative variables were similar between groups. The concomitant CMP-IV group had a greater incidence of AKI: 32% (n = 99) versus 16% (n = 49), P < .001. After accounting for bypass time and nonablation operations on mixed effects analysis, concomitant CMP-IV was associated with increased risk of AKI (odds ratio, 1.89; confidence interval, 1.12-3.18; P = .017). While AKI was associated with decreased late survival (P < .001), patients who received a concomitant CMP-IV maintained superior 7-year survival to patients who received no ablation (P < .001). No patients required permanent dialysis.

Conclusions: Concomitant CMP-IV was independently associated with increased risk of AKI in the acute postoperative period. However, the long-term risks of AKI were offset by the significant survival benefit of CMP-IV. Concerns regarding new-onset renal dysfunction should not prohibit recommendation of this procedure in appropriate patients.

Keywords: Cox-Maze IV procedure; acute kidney injury; dialysis; propensity score match; renal failure; surgical ablation.

Figure 1A:

Distribution of the incidence of renal impairment after surgery between concomitant CMP-IV (n=308) and no AF surgery (n=308) groups after propensity score matching. Renal impairment was evaluated by clinical severity: acute kidney injury, renal failure, dialysis, and dialysis at discharge. Absolute numbers can be found in Table 2. AF, atrial fibrillation; AKI, acute kidney injury; CMP-IV, Cox-Maze IV.

Figure 1B.

Distribution of the incidence of AKI after surgery between concomitant CMP-IV and no AF surgery groups, separated by primary operation. Absolute procedure numbers can be found in Table E2. AF, atrial fibrillation; AKI, acute kidney injury; AV, aortic valve; MV, mitral valve; CMP-IV, Cox-Maze IV; CABG, coronary artery bypass graft.

Figure 2.

Kaplan-Meier depiction of late survival for patients who underwent concomitant CMP-IV, stratified by new onset postoperative AKI with 95% confidence intervals: no AKI after concomitant CMP-IV (blue) and AKI after concomitant CMP-IV (red) (P<0.001). AKI, acute kidney injury; CMP-IV, Cox-Maze IV.

Figure 3.

Kaplan-Meier depiction of late survival for patients with AF after cardiac surgery, stratified by receipt of concomitant surgical ablation with 95% confidence intervals: concomitant CMP-IV (blue) and no AF surgery (red) (P<0.001). AF, atrial fibrillation; CMP-IV, Cox-Maze IV.

Figure 4.

Depiction of the propensity score matched analysis of acute kidney injury. Patients with atrial fibrillation were stratified based on ablation decision at the time of surgery (concomitant Cox-Maze IV vs no AF ablation). Concomitant CMP-IV was associated with increased risk of AKI in the acute postoperative period (P<0.001), which was counterbalanced by prolonged late survival due to restoration of sinus rhythm. AF, atrial fibrillation; AKI, acute kidney injury; CMP-IV, Cox-Maze IV.