Predictors and impact of postoperative atrial fibrillation on patients’ outcomes: a report from the Randomized On Versus Off Bypass trial

Almassi GH, Pecsi SA, Collins JF, Shroyer AL, Zenati MA, Grover FL.
J Thorac Cardiovasc Surg. 2012 Jan;143(1):93-102.

Reviewers: Henry Liu, MD; Daisuke Inui, MD; Nakeisha Pierre, MD
Tulane University Medical Center, New Orleans, Louisiana

Background

Postoperative atrial fibrillation (POAF) is a common complication after cardiac surgery. However there is no reliable predictor(s) for this common and severe complication. In this study, Dr. Almassi et al randomized 2103 patients into two groups (on-pump group and off-pump group) to illustrate the potential predictors for the pathogenesis of POAF, compare the two groups and the impact on the clinical outcomes.

Methods

There were 2203 enrollees in this ROOBY trial. Out of 2203, 2103 patients in the Randomized On Versus Off Bypass trial with no POAF was studied (1056 patients in the ONCAB group and 1047 patients in the OPCAB group). Patients with pre-existing atrial fibrillation were excluded. Univariate and multivariate analyses were used to identify the predictors of POAF and the impact of POAF on outcomes.

Results

Predictors of POAF: Older age (P < .0001), white race (P < .001), and hypertension (P < .002) were predictors of POAF on multivariate analysis. However, use of ONCAB versus OPCAB was not associated with increased rates of POAF.

Negative impact on clinical outcomes: In general, POAF led to higher rates of reintubation (ONCAB: 6.3% vs 0.8% no POAF, P < .001; OPCAB: 7.4% vs 1.8% no POAF, P < .0001) and prolonged ventilatory support (ONCAB: 7.1% vs 2.3% no POAF, P = .001; OPCAB: 9.2% vs 3.4% no POAF, P = .0003). The rate of any early adverse outcome was higher in patients with POAF (all patients: 10% POAF vs 4.7% no POAF, P < .0001; ONCAB: 9% POAF vs 4.3% no POAF, P = .008; OPCAB: 11% POAF vs 5.1% no POAF, P = .001). The 1-year all cause mortality was higher with POAF for both groups (ONCAB: 5.4% POAF vs 2% no POAF, P = .009; OPCAB: 5.1% POAF vs 2.6% no POAF, P = .07). POAF was independently associated with early composite end point (odds ratio [OR], 2.23; confidence interval [CI], 1.55-3.22; P < .0001), need for new mechanical support (OR, 3.25; CI, 1.39-7.61; P = .007), prolonged ventilatory support (OR, 2.93; CI, 1.89-4.55; P < .0001), renal failure (OR, 5.42; CI, 1.94-15.15; P = .001), and mortality at 12 months (OR, 1.94; CI, 1.14-3.28; P = .01).

Conclusions

In the Randomized On Versus Off Bypass trial, the strategy of revascularization did not affect the rate of POAF. Age, race, and hypertension were predictors of POAF. POAF may cause higher rates of reintubation, prolonged mechanical ventilation, and renal insufficiency. Diabetes is not a predictor. POAF was independently associated with a higher short-term morbidity and higher 1-year mortality rates.

Comments

This study identified several predictors of POAF: age, white and hypertension. These factors will help early diagnosis of POAF, and early management of POAF.
Interestingly they found white is more prone to develop POAF and diabetes is not a predictor of POAF.
This study was conducted in the VA population with only male patients studied. These results may not apply to female patients.
POAF and prolonged ventilation, renal insufficiency and other affected adverse complications may not necessarily the relationship of cause and effect.