European Journal of Cardio-Thoracic Surgery Advance Access published November 27, 2013
The impact of race and postoperative atrial fibrillation on operative mortality after elective coronary artery bypass grafting Jimmy T. Efirda,b, Stephen W. Daviesc, Wesley T. O’Neald,*, Curtis A. Andersona, Ethan J. Andersona,b,e, Jason B. O’Nealf, T. Bruce Fergusona, W. Randolph Chitwooda and Alan P. Kypsona a b c d e f
Department of Cardiovascular Sciences, East Carolina Heart Institute, Brody School of Medicine, East Carolina University, Greenville, NC, USA Center for Health Disparities, Brody School of Medicine, East Carolina University, Greenville, NC, USA Department of General Surgery, University of Virginia School of Medicine, Charlottesville, VA, USA Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, USA Department of Pharmacology and Toxicology, Brody School of Medicine, East Carolina University, Greenville, NC, USA Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
* Corresponding author. Department of Internal Medicine, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC, USA. Tel: +1-919-288-4616; e-mail: [email protected] (W.T. O’Neal). Received 17 June 2013; received in revised form 18 September 2013; accepted 16 October 2013
Abstract OBJECTIVE: Black patients are less likely to develop postoperative atrial fibrillation (POAF) following coronary artery bypass grafting (CABG) than whites. However, the influence of race and POAF on operative mortality has not been examined. The objective of this study was to determine the influence of race and POAF on operative mortality after CABG. METHODS: Patients undergoing elective CABG between 1992 and 2011 were included. Operative mortality was compared between patients with and those without new-onset POAF by race. Relative risk (RR) and 95% confidence intervals (CI) were computed using Poisson (robust variance estimates) and log-binomial regression models. RESULTS: A total of 1215 (23%) patients developed POAF (white n = 1060; black n = 155) following CABG (N = 5387). Operative mortality differed by POAF status within race category (white POAF: adjusted RR = 1.4, 95% CI = 0.86–2.2; black POAF: adjusted RR = 5.0, 95% CI = 1.9–13; Pinteraction = 0.0016). Black POAF patients had a 2-fold increased risk of operative death compared with white POAF patients (Padjusted = 0.052). CONCLUSION: POAF was observed to be a stronger predictor of operative mortality in black compared with white patients undergoing elective CABG. Keywords: CABG • Operative mortality • Race • Survival
INTRODUCTION
METHODS
Postoperative atrial fibrillation (POAF) is a common arrhythmia following coronary artery bypass grafting (CABG), occurring in up to 40% of cases [1–4]. POAF is associated with increased postoperative complications and longer periods of stay after surgery [1–4]. Additionally, patients who develop POAF have an increased risk of in-hospital or operative mortality than patients without POAF [5]. Recently, it has been shown that black CABG patients are less likely to develop POAF than their white counterparts [6, 7]. However, the influence of race on operative mortality after isolated CABG has not been examined in this population. The purpose of this study was to examine the impact of race on operative mortality among patients who develop POAF after CABG.
Study design This was a retrospective cohort study. Details of the study database and methodology have been previously described and are summarized below [8, 9]. Demographic and comorbid data were collected at the time of surgery. Patients with and those without POAF were compared and stratified by race. Racial identity was self-reported. The study was approved by the Institutional Review Board at the Brody School of Medicine, East Carolina University.
Inclusion and exclusion criteria Patients undergoing first-time, isolated, elective CABG at the East Carolina Heart Institute between 1992 and 2011 were included in
© The Author 2013. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
ADULT CARDIAC
ORIGINAL ARTICLE
European Journal of Cardio-Thoracic Surgery (2013) 1–6 doi:10.1093/ejcts/ezt529
2
J.T. Efird et al./European Journal of Cardio-Thoracic Surgery
this analysis. The study population was limited to elective cases because of potential differences in insurance status, timing of surgery and selection of patients and/or their surgeons. Races other than black or white were excluded to minimize the potential for residual confounding (1%). Additionally, patients were excluded if they had a preoperative history of paroxysmal, persistent or permanent atrial fibrillation (AF)/atrial flutter.
Definitions AF was defined as, ‘a supraventricular tachyarrhythmia characterized by uncoordinated atrial activation with consequent deterioration of atrial mechanical function’. POAF patients were those who had a first-time episode of AF lasting longer than 1 h after surgery, that required treatment. Peripheral arterial disease was defined as having any of the following at the time of surgery: claudication either during exertion or during rest; amputation for arterial insufficiency; aortoiliac occlusive disease reconstruction; peripheral vascular bypass surgery, angioplasty or stent; documented abdominal aortic aneurysm, repair or stent; documented non-invasive testing including ankle-arm index. Diabetes was defined as having a history of a diagnosis and/or treatment by a physician that was documented in the medical record. Diabetes management was recorded and indicated by medical therapies that were present at the time of admission. Insulin-dependent patients required insulin and insulin-independent patients were managed with diet or oral hypoglycemic agents. Heart failure was defined as having a preoperative diagnosis according to the standard Society of Thoracic Surgeons (STS) criteria. This included physician documentation or confirmatory medical reports (hospital admission notes, chest X-rays, consultations, physical exam, medication administration records, outpatient records and radiology reports). Stable or asymptomatic compensated failure or patients whose symptoms improved after medical therapy were not classified as having heart failure. Patients with a low ejection fraction (EF) without clinical symptoms (oedema, rales and nocturnal dyspnoea) also were not defined as having heart failure. Adjudication review was used to rule out non-definitive heart failure diagnoses. Only definitive cases were considered heart failure. Current echocardiographic reports were obtained to evaluate left ventricular EF and values
The impact of race and postoperative atrial fibrillation on operative mortality after elective coronary artery bypass grafting Jimmy T. Efirda,b, Stephen W. Daviesc, Wesley T. O’Neald,*, Curtis A. Andersona, Ethan J. Andersona,b,e, Jason B. O’Nealf, T. Bruce Fergusona, W. Randolph Chitwooda and Alan P. Kypsona a b c d e f
Department of Cardiovascular Sciences, East Carolina Heart Institute, Brody School of Medicine, East Carolina University, Greenville, NC, USA Center for Health Disparities, Brody School of Medicine, East Carolina University, Greenville, NC, USA Department of General Surgery, University of Virginia School of Medicine, Charlottesville, VA, USA Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, USA Department of Pharmacology and Toxicology, Brody School of Medicine, East Carolina University, Greenville, NC, USA Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
* Corresponding author. Department of Internal Medicine, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC, USA. Tel: +1-919-288-4616; e-mail: [email protected] (W.T. O’Neal). Received 17 June 2013; received in revised form 18 September 2013; accepted 16 October 2013
Abstract OBJECTIVE: Black patients are less likely to develop postoperative atrial fibrillation (POAF) following coronary artery bypass grafting (CABG) than whites. However, the influence of race and POAF on operative mortality has not been examined. The objective of this study was to determine the influence of race and POAF on operative mortality after CABG. METHODS: Patients undergoing elective CABG between 1992 and 2011 were included. Operative mortality was compared between patients with and those without new-onset POAF by race. Relative risk (RR) and 95% confidence intervals (CI) were computed using Poisson (robust variance estimates) and log-binomial regression models. RESULTS: A total of 1215 (23%) patients developed POAF (white n = 1060; black n = 155) following CABG (N = 5387). Operative mortality differed by POAF status within race category (white POAF: adjusted RR = 1.4, 95% CI = 0.86–2.2; black POAF: adjusted RR = 5.0, 95% CI = 1.9–13; Pinteraction = 0.0016). Black POAF patients had a 2-fold increased risk of operative death compared with white POAF patients (Padjusted = 0.052). CONCLUSION: POAF was observed to be a stronger predictor of operative mortality in black compared with white patients undergoing elective CABG. Keywords: CABG • Operative mortality • Race • Survival
INTRODUCTION
METHODS
Postoperative atrial fibrillation (POAF) is a common arrhythmia following coronary artery bypass grafting (CABG), occurring in up to 40% of cases [1–4]. POAF is associated with increased postoperative complications and longer periods of stay after surgery [1–4]. Additionally, patients who develop POAF have an increased risk of in-hospital or operative mortality than patients without POAF [5]. Recently, it has been shown that black CABG patients are less likely to develop POAF than their white counterparts [6, 7]. However, the influence of race on operative mortality after isolated CABG has not been examined in this population. The purpose of this study was to examine the impact of race on operative mortality among patients who develop POAF after CABG.
Study design This was a retrospective cohort study. Details of the study database and methodology have been previously described and are summarized below [8, 9]. Demographic and comorbid data were collected at the time of surgery. Patients with and those without POAF were compared and stratified by race. Racial identity was self-reported. The study was approved by the Institutional Review Board at the Brody School of Medicine, East Carolina University.
Inclusion and exclusion criteria Patients undergoing first-time, isolated, elective CABG at the East Carolina Heart Institute between 1992 and 2011 were included in
© The Author 2013. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
ADULT CARDIAC
ORIGINAL ARTICLE
European Journal of Cardio-Thoracic Surgery (2013) 1–6 doi:10.1093/ejcts/ezt529
2
J.T. Efird et al./European Journal of Cardio-Thoracic Surgery
this analysis. The study population was limited to elective cases because of potential differences in insurance status, timing of surgery and selection of patients and/or their surgeons. Races other than black or white were excluded to minimize the potential for residual confounding (1%). Additionally, patients were excluded if they had a preoperative history of paroxysmal, persistent or permanent atrial fibrillation (AF)/atrial flutter.
Definitions AF was defined as, ‘a supraventricular tachyarrhythmia characterized by uncoordinated atrial activation with consequent deterioration of atrial mechanical function’. POAF patients were those who had a first-time episode of AF lasting longer than 1 h after surgery, that required treatment. Peripheral arterial disease was defined as having any of the following at the time of surgery: claudication either during exertion or during rest; amputation for arterial insufficiency; aortoiliac occlusive disease reconstruction; peripheral vascular bypass surgery, angioplasty or stent; documented abdominal aortic aneurysm, repair or stent; documented non-invasive testing including ankle-arm index. Diabetes was defined as having a history of a diagnosis and/or treatment by a physician that was documented in the medical record. Diabetes management was recorded and indicated by medical therapies that were present at the time of admission. Insulin-dependent patients required insulin and insulin-independent patients were managed with diet or oral hypoglycemic agents. Heart failure was defined as having a preoperative diagnosis according to the standard Society of Thoracic Surgeons (STS) criteria. This included physician documentation or confirmatory medical reports (hospital admission notes, chest X-rays, consultations, physical exam, medication administration records, outpatient records and radiology reports). Stable or asymptomatic compensated failure or patients whose symptoms improved after medical therapy were not classified as having heart failure. Patients with a low ejection fraction (EF) without clinical symptoms (oedema, rales and nocturnal dyspnoea) also were not defined as having heart failure. Adjudication review was used to rule out non-definitive heart failure diagnoses. Only definitive cases were considered heart failure. Current echocardiographic reports were obtained to evaluate left ventricular EF and values
