Coronary artery disease
Usefulness of Postoperative Atrial Fibrillation as an Independent Predictor for Worse Early and Late Outcomes After Isolated Coronary Artery Bypass Grafting (Multicenter Australian Study of 19,497 Patients)

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Several studies have shown that postoperative atrial fibrillation (POAF) is associated with poorer short- and long-term outcomes after isolated coronary artery bypass grafting surgery. Nevertheless, there is considerable debate as to whether this reflects an independent association of POAF with poorer outcomes or confounding by other factors. We sought to investigate this issue. Data obtained from June 2001 through December 2009 by the Australasian Society of Cardiac and Thoracic Surgeons National Cardiac Surgery Database Program were retrospectively analyzed. Demographic and operative data were compared between patients who developed POAF and those who did not using chi-square and t tests. The independent impact of POAF on 14 short-term complications and long-term mortality was determined using binary logistic and Cox regression, respectively. Excluding patients with preoperative arrhythmia, isolated coronary artery bypass grafting surgery was performed in 19,497 patients. Of these, 5,547 (28.5%) developed POAF. Patients with POAF were generally older (mean age 69 vs 65 years, p <0.001) and presented more often with co-morbidities including congestive heart failure (p <0.001), hypertension (p <0.001), cerebrovascular disease (p <0.001), and renal failure (p = 0.046). Patients with POAF demonstrated a greater 30-day mortality on univariate analysis but not on multivariate analysis (p = 0.376). Patients with POAF were, however, at an independently increased risk of perioperative complications including permanent stroke (p <0.001), new renal failure (p <0.001), infective complications (p <0.001), gastrointestinal complications (p <0.001), and return to the theater (p <0.001). POAF was also independently associated with shorter long-term survival (p = 0.002). In conclusion, POAF is a risk factor for short-term morbidity and decreased long-term survival. Rigorous evaluation of various therapies that prevent or decrease the impact of POAF is imperative. Moreover, patients who develop POAF should undergo strict surveillance and be routinely screened for complications after discharge.

Section snippets

Methods

The inclusion criterion for the study was patients undergoing isolated CABG from June 1, 2001 through December 31, 2009 at hospitals in Australia participating in the Australasian Society of Cardiac and Thoracic Surgeons (ASCTS) Cardiac Surgery Database. Patients having concomitant valve surgery or other concurrent cardiac surgical procedures were excluded from this study. Moreover, only patients with documented preoperative sinus rhythm without a history of AF were included. All 6 Victorian

Results

CABG surgery was undertaken in 21,534 patients at 18 Australian institutions. Of these 1,991 patients present preoperatively with arrhythmia and were excluded from the analysis; the remaining 19,497 are the principal subjects of the present study. Of the remaining patients, 5,547 (28.5%) developed POAF. Preoperative and demographic characteristics of the POAF and no-POAF groups are presented in Table 1. There were some differences in intraoperative variables between the 2 groups. These are

Discussion

In our study of 19,497 patients, 5,547 (28.5%) developed POAF. This incidence is consistent with the reported literature. Early mortality rate was significantly higher in patients with POAF on univariate analysis (1.7% vs 1.2%, p = 0.007) but not multivariate analysis (p = 0.376). To this end, our data suggest that confounding factors more prevalent in the POAF study population largely account for the higher incidence of early mortality observed in that group. Indeed, patients with POAF were 5

Appendix

The following investigators, data managers, and institutions participated in the ASCTS database: Alfred Hospital: A. Pick, J. Duncan; Austin Hospital: S. Seevanayagam, M. Shaw; Cabrini Health: G. Shardey; Geelong Hospital: M. Morteza, C. Bright; Flinders Medical Centre: J. Knight, R. Baker, J. Helm; Jessie McPherson Private Hospital: J. Smith, H. Baxter H; John Hunter Hospital: A. James, S. Scaybrook; Lake Macquarie Hospital: B. Dennett, M. Jacobi; Liverpool Hospital: B. French, N. Hewitt;

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    The Australasian Society of Cardiac and Thoracic Surgeons National Cardiac Surgery Database Program is funded by the Department of Human Services, Melbourne, Victoria, Australia and the Health Administration Corporation and Clinical Excellence Commission, Sydney, New South Wales, Australia.

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