Lower Survival After Coronary Artery Bypass in Patients Who Had Atrial Fibrillation Missed by Widely Used Definitions

Objective

To investigate the impact of limiting the definition of post-coronary artery bypass graft (CABG) atrial fibrillation (AF) to AF/flutter requiring treatment-as in the Society of Thoracic Surgeons' (STS) database- on the association with survival.

Patients and Methods

We assessed in-hospital incidence of post-CABG AF in 7110 consecutive isolated patients with CABG without preoperative AF at 4 hospitals (January 1, 2004 to December 31, 2010). Patients with ≥1 episode of post-CABG AF detected via continuous in-hospital electrocardiogram (ECG)/telemetry monitoring documented by physicians were assigned to the following: Group 1, identified as having post-CABG AF in STS data and Group 2, not identified as having post-CABG AF in STS data. Patients without documented post-CABG AF constituted Group 3. Survival was compared via a Cox model, adjusted for STS risk of mortality and accounting for site differences.

Results

Over 7 years' follow-up, 16.0% (295 of 1841) of Group 1, 18.7% (79 of 422) of Group 2, and 7.9% (382 of 4847) of Group 3 died. Group 2 had a significantly greater adjusted risk of death than both Group 1 (hazard ratio [HR]: 1.16; 95% confidence interval [CI], 1.02 to 1.33) and Group 3 (HR: 1.94; 95% CI, 1.69 to 2.22).

Conclusions

The statistically significant 16% higher risk of death for patients with AF post-CABG missed vs captured in STS data suggests treatment and postdischarge management should be investigated for differences. The historical misclassification of "missed" patients as experiencing no AF in the STS data weakens the ability to observe differences in risk between patients with and without post-CABG AF. Therefore, STS data should not be used for research examining post-CABG AF.

Preoperative β-Blockers as a Coronary Surgery Quality Metric: The Lack of Evidence of Efficacy

BACKGROUND

Two quality measures used in public reporting and value-based payment programs require β-blockers be administered less than 24 hours before isolated coronary artery bypass graft surgery to prevent atrial fibrillation and mortality. Questions have arisen about continued use of these measures.

METHODS

We conducted a systematic search for randomized controlled trials (RCTs) examining the impact of preoperative β-blockers on atrial fibrillation or mortality after isolated coronary artery bypass graft surgery to determine what evidence of efficacy supports the measures.

RESULTS

We identified 11 RCTs. All continued β-blockers postoperatively, making it unfeasible to separate the benefits of preoperative vs postoperative administration. Meta-analysis was precluded by methodologic variation in β-blocker utilized, timing and dosage, and supplemental and comparison treatments. Of the eight comparisons of β-blockers/β-blocker plus digoxin versus placebo (n = 826 patients), six showed significant reductions in atrial fibrillation/supraventricular arrhythmias. Of the three comparisons (n = 444) of β-blockers versus amiodarone, two found no significant difference in atrial fibrillation; the third showed significantly lower incidence with amiodarone. One RCT compared β-blocker plus amiodarone versus each of those drugs separately; the combination reduced atrial fibrillation significantly better than the β-blocker alone, but not amiodarone alone. Seven RCTs reported short-term mortality, but this outcome was too rare and the sample sizes too small to provide any meaningful comparisons.

CONCLUSIONS

Existing RCT evidence does not support the structure of quality measures that require β-blocker administration specifically within 24 hours before coronary artery bypass graft surgery to prevent postoperative atrial fibrillation or short-term mortality. Quality measures should be revised to align with the evidence, and further studies conducted to determine optimal timing and method of prophylaxis.

Epidemiology of new-onset atrial fibrillation following coronary artery bypass graft surgery

OBJECTIVES

Postoperative atrial fibrillation (AF) following coronary artery bypass graft surgery (CABG) is significantly associated with reduced survival, but poor characterisation and inconsistent definitions present barriers to developing effective prophylaxis and management. We sought to address this knowledge gap.

METHODS

From 2002 to 2010, 11 239 consecutive patients without AF underwent isolated CABG at five sites. Clinical data collected for the Society of Thoracic Surgeons (STS) Database were augmented with details on AF detected via continuous in-hospital ECG/telemetry monitoring to assess new-onset post-CABG AF (adjusted for STS risk of mortality); time to first AF; durations of first and longest AF episodes; total in-hospital time in AF; number of in-hospital AF episodes; operative mortality; stroke; discharge in AF; and length of stay (LOS).

RESULTS

Unadjusted incidence of new-onset post-CABG AF was 29.5%. Risk-adjusted incidence was 33.1% and varied little over time (P=0.139). Among 3312 patients with post-CABG AF, adjusted median time to first AF was 52 (IQR: 48-55) hours; mean (SD) duration of first and longest events were 7.2 (5.3,9.1) and 13.1 (10.4,15.9) hours, respectively, and adjusted median total time in AF was 22 (IQR: 18-26) hours. Adjusted rates of operative mortality, stroke and discharge in AF did not vary significantly over time (P=0.156, P=0.965 and P=0.347, respectively). LOS varied (P=0.035), but in no discernible pattern.

CONCLUSIONS

Each year, ~800 000 people undergo CABG worldwide; >264 000 will develop post-CABG AF. Onset is typically 2-3 days post-CABG and episodes last, on average, several hours. Effective prophylaxis and management is urgently needed to reduce associated risks of adverse outcomes.

Efficacy and effectiveness of on- versus off-pump coronary artery bypass grafting: A meta-analysis of mortality and survival

BACKGROUND

Despite many studies comparing on- versus off-pump coronary artery bypass graft (CABG), there is no consensus as to whether one of these techniques offers patients better outcomes.

METHODS

We searched PubMed from inception to June 30, 2015, and identified additional studies from bibliographies of meta-analyses and reviews. We identified 42 randomized controlled trials (RCTs) and 31 rigorously adjusted observational studies (controlling for the Society of Thoracic Surgeons-recognized risk factors for mortality) reporting mortality for off-pump versus on-pump CABG at specified time points. Trial data were extracted independently by 2 researchers using a standardized form. Differences in probability of mortality (DPM) were estimated for the RCTs and observational studies separately and combined, for time points ranging from 30 days to 10 years.

RESULTS

RCT-only data showed no significant differences at any time point, whereas observational-only data and the combined analysis showed short-term mortality favored off-pump CABG (n = 1.2 million patients; 36 RCTs, 26 observational studies; DPM [95% confidence interval (CI)], -44.8% [-45.4%, -43.8%]) but that at 5 years it was associated with significantly greater mortality (n = 60,405 patients; 3 RCTs, 5 observational studies; DPM [95% CI], 10.0% [5.0%, 15.0%]). At 10 years, only observational data were available, and off-pump CABG showed significantly greater mortality (DPM [95% CI], 14.0% [11.0%, 17.0%]).

CONCLUSIONS

Evidence from RCTs showed no differences between the techniques, whereas rigorously adjusted observational studies (with >1.1 million patients) and the combined analysis indicated that off-pump CABG offers lower short-term mortality but poorer long-term survival. These results suggest that, in real-world settings, greater operative safety with off-pump CABG comes at the expense of lasting survival gains.

Underestimation of the incidence of new-onset post-coronary artery bypass grafting atrial fibrillation and its impact on 30-day mortality

OBJECTIVE

Inconsistent definitions of atrial fibrillation after coronary artery bypass grafting have caused uncertainty about its incidence and risk. We examined the extent to which limiting the definition to post-coronary artery bypass grafting atrial fibrillation events requiring treatment underestimates its incidence and impact on 30-day mortality.

METHODS

We assessed in-hospital atrial fibrillation and 30-day mortality in 9268 consecutive patients without preoperative atrial fibrillation who underwent isolated coronary artery bypass grafting at 5 US hospitals (2004-2010). Patients who experienced 1 or more episode of post-coronary artery bypass grafting atrial fibrillation detected via continuous in-hospital electrocardiogram/telemetry monitoring were divided into those for whom Society of Thoracic Surgeons data (applying the definition "atrial fibrillation/flutter requiring treatment") also indicated atrial fibrillation versus those for whom it did not. Risk-adjusted 30-day mortality was compared between these 2 groups and with patients without post-coronary artery bypass grafting atrial fibrillation.

RESULTS

Risk-adjusted incidence of post-coronary artery bypass grafting atrial fibrillation incidence was 33.4% (27.0% recorded in Society of Thoracic Surgeons data, 6.4% missed). Patients with post-coronary artery bypass grafting atrial fibrillation missed by Society of Thoracic Surgeons data had a significantly greater risk of 30-day mortality (odds ratio, 2.08, 95% confidence interval, 1.17-3.69) than those captured. By applying the significant underestimation of post-coronary artery bypass grafting atrial fibrillation incidence we observed (odds ratio [Society of Thoracic Surgeons vs missed], 0.78; 95% confidence interval, 0.72-0.83) to the approximately 150,000 patients undergoing isolated coronary artery bypass grafting in the United States each year estimates this increased risk of mortality is carried by 9600 patients (95% confidence interval, 9420-9780) annually.

CONCLUSIONS

Defining post-coronary artery bypass grafting atrial fibrillation as episodes requiring treatment significantly underestimates incidence and misses patients at a significantly increased risk for mortality. Further research is needed to determine whether this increased risk carries over into long-term outcomes and whether it is mediated by differences in treatment and management.

Sex Differences in the Epidemiology of New-Onset In-Hospital Post-Coronary Artery Bypass Graft Surgery Atrial Fibrillation: A Large Multicenter Study

BACKGROUND

New-onset atrial fibrillation (AF) after coronary artery bypass graft surgery (CABG) is associated with increased morbidity and poorer long-term survival. Although many studies show differences in outcome in women versus men after CABG, little is known about the sex-specific incidence and characteristics of post-CABG AF.

METHODS AND RESULTS

Overall, 11 236 consecutive patients without preoperative AF underwent isolated CABG from 2002 to 2010 at 4 US academic medical centers and 1 high-volume specialty cardiac hospital. Data routinely collected for the Society of Thoracic Surgeons database were augmented with details on new-onset post-CABG AF events detected via continuous in-hospital ECG/telemetry monitoring. Unadjusted incidence of post-CABG AF was 29.5% (3312/11 236) overall, 30.2% (2485/8214) in men, and 27.4% (827/3022) in women. After adjustment for Society of Thoracic Surgeons-recognized risk factors, women had significantly lower risk for post-CABG AF (odds ratio [95% confidence interval]=0.75 [0.64-0.89]), shorter first, longest, and total duration of AF episodes (mean difference [95% confidence interval]=-2.7 [-4.7 to -0.8] hours; -4.1 [-6.9 to -1.2] hours; -2.4 [-2.5 to -2.3] hours, respectively). At 48 hours, AF-free probabilities were 77% for women and 72% for men (P<0.001). Number of episodes (P=0.18), operative mortality (P=0.048), stroke (P=0.126), and discharge in AF (P=0.234) did not differ significantly by sex.

CONCLUSIONS

These novel data on sex-specific characteristics of new-onset AF after isolated CABG show that women had lower adjusted risk for post-CABG AF and experienced shorter episodes. Investigation of sex-specific impacts on outcomes is needed to identify optimal strategies for prevention and management to ensure all patients achieve the best possible outcomes.

The Impact of Aneurysm Morphology and Anatomic Characteristics on Long-Term Survival after Endovascular Abdominal Aortic Aneurysm Repair

BACKGROUND

Hostile anatomic characteristics in patients undergoing endovascular abdominal aortic aneurysm repair (EVAR) and the placement of endografts not in concordance with the specific device anatomic guidelines (or instructions for use [IFU]) have shown decreased technical success of the procedure. But these factors have never been evaluated in regard to patient postoperative survival. We sought to assess the association between survival and (1) aneurysm anatomy and characteristics and (2) implantation in compliance with manufacturer's anatomic IFU guidelines in patients undergoing endovascular aortic aneurysm repair.

METHODS

The cohort included 273 consecutive patients who underwent EVAR at Baylor Heart and Vascular Hospital between January 1, 2002 and December 31, 2009 and had their preoperative computed tomography (CT) scan digitally retrievable. The CT scans and operative notes were then reviewed, and the anatomic severity grading (ASG) score, maximum aneurysm diameter, thrombus width, patency of aortic side branch vessels, and implantation in compliance with IFU guidelines were assessed. The unadjusted association between survival (assessed until November 1, 2011) and these variables was assessed with the Kaplan-Meier method. Moreover, propensity-adjusted (for a comprehensive array of clinical and nonclinical risk factors) proportional hazard models were developed to assess the adjusted associations.

RESULTS

Seven (2.56%) patients died within 30 days from EVAR, and 88 (30.04%) patients died during the study follow-up. Patient mean survival was 6.3 years. The unadjusted analysis showed a statistically significant association between survival and thrombus width (P = 0.007), ASG score (P = 0.004), and implantation in compliance with IFU guidelines (P = 0.007). However, the adjusted analysis revealed that none of the anatomic and compliance factors were significantly associated with long-term survival (ASG, P = 0.149; diameter, P = 0.836; thrombus, P = 0.639; patency, P = 0.219; and implantation compliance, P = 0.219).

CONCLUSIONS

Unfavorable aneurysm morphologic characteristics and endograft implantation not in compliance with IFU guidelines did not adversely affect patient survival after EVAR in this group of patients. This implies that unfavorable anatomy, even that which would necessitate implantation of the EVAR device outside of the IFU guidelines, should not necessarily contraindicate EVAR.

Excess short-term mortality in women after isolated coronary artery bypass graft surgery

Objective

Female sex is considered a risk factor for adverse outcomes following isolated coronary artery bypass graft (CABG) surgery. We assessed the association between sex and short-term mortality following isolated CABG, and estimated the ‘excess’ deaths occurring in women.

Methods

Short-term mortality was investigated in 13 327 consecutive isolated CABG patients in North Texas between January 2008 and December 2012. The association between sex and CABG short-term mortality, and the excess deaths among women were assessed via a propensity-adjusted (by Society of Thoracic Surgeons-recognised risk factors) generalised estimating equations model approach.

Results

Short-term mortality was significantly higher in women than men (adjusted OR=1.39; 95% CI 1.04 to 1.86; p=0.027). This significantly greater risk translates into 35 ‘excess’ deaths among women included in this study (>10% of the total 343 deaths in the study cohort) and into 392 ‘excess’ deaths among the ∼40 000 women undergoing isolated CABG in the USA each year.

Conclusions

The higher risk associated with female sex lead to 35 ‘excess’ deaths in women in this study cohort (over 10% of the total deaths) and to 392 ‘excess’ deaths among women undergoing isolated CABG in the USA each year. Further research is needed to assess the causal mechanisms underlying this sex-related difference. Results of such work could inform the development and implementation of sex-specific treatment and management strategies to reduce women's mortality following CABG. Based on our results, if such work brought women's short-term mortality into line with men's, total short-term mortality could be reduced by up to 10%.

Trends and comparison of female first authorship in high impact medical journals: observational study (1994-2014)

OBJECTIVE

To examine changes in representation of women among first authors of original research published in high impact general medical journals from 1994 to 2014 and investigate differences between journals.

DESIGN

Observational study.

STUDY SAMPLE

All original research articles published in Annals of Internal Medicine, Archives of Internal Medicine, The BMJ, JAMA, The Lancet, and the New England Journal of Medicine (NEJM) for one issue every alternate month from February 1994 to June 2014.

MAIN EXPOSURES

Time and journal of publication.

MAIN OUTCOME MEASURES

Prevalence of female first authorship and its adjusted association with time of publication and journal, assessed using a multivariable logistic regression model that accounted for number of authors, study type and specialty/topic, continent where the study was conducted, and the interactions between journal and time of publication, study type, and continent. Estimates from this model were used to calculate adjusted odds ratios against the mean across the six journals, with 95% confidence intervals and P values to describe the associations of interest.

RESULTS

The gender of the first author was determined for 3758 of the 3860 articles considered; 1273 (34%) were women. After adjustment, female first authorship increased significantly from 27% in 1994 to 37% in 2014 (P<0.001). The NEJM seemed to follow a different pattern, with female first authorship decreasing; it also seemed to decline in recent years in The BMJ but started substantially higher (approximately 40%), and The BMJ had the highest total proportion of female first authors. Compared with the mean across all six journals, first authors were significantly less likely to be female in the NEJM (adjusted odds ratio 0.68, 95% confidence interval 0.53 to 0.89) and significantly more likely to be female in The BMJ (1.30, 1.01 to 1.66) over the study period.

CONCLUSIONS

The representation of women among first authors of original research in high impact general medical journals was significantly higher in 2014 than 20 years ago, but it has plateaued in recent years and has declined in some journals. These results, along with the significant differences seen between journals, suggest that underrepresentation of research by women in high impact journals is still an important concern. The underlying causes need to be investigated to help to identify practices and strategies to increase women's influence on and contributions to the evidence that will determine future healthcare policies and standards of clinical practice.

Effect of gender and race on operative mortality after isolated coronary artery bypass grafting

Studies examining outcomes after coronary artery bypass grafting (CABG) by gender and/or race have shown conflicting results. It remains to be determined if, or how, gender and race are independent risk factors for CABG operative mortality. Using all consecutive patients who underwent isolated CABG at Baylor University Medical Center in Dallas, Texas, from January 2004 to October 2011, the risk-adjusted associations between gender and race, respectively, and operative mortality were estimated using a generalized propensity approach, accounting for recognized Society of Thoracic Surgeons risk factors for mortality. Women were nearly 2 times more likely to die during or within 30 days of the operation than men (odds ratio 1.96, 95% confidence interval 1.44 to 2.66, p <0.0001), while no significant mortality differences were observed among races. In conclusion, these findings suggest that women face a significantly greater risk for operative death that should be taken into account during the treatment decision-making process but that race is not associated with CABG mortality and so should not be among the factors considered.

Effect of age on survival between open repair and surveillance for small abdominal aortic aneurysms

Randomized controlled trials have shown no significant difference in survival between immediate open repair and surveillance with selective repair for asymptomatic abdominal aortic aneurysms of 4.0 to 5.5 cm in diameter. This lack of difference has been shown to hold true for all diameters in this range, in men and women, but the question of whether patients of different ages might obtain different benefits has remained unanswered. Using the pooled patient-level data for the 2,226 patients randomized to immediate open repair or surveillance in the United Kingdom Small Aneurysm Trial (UKSAT; September 1, 1991, to July 31, 1998; follow-up 2.6 to 6.9 years) or the Aneurysm Detection and Management (ADAM) trial (August 1, 1992, to July 31, 2000; follow-up 3.5 to 8.0 years), the adjusted effect of age on survival in the 2 treatment groups was estimated using a generalized propensity approach, accounting for a comprehensive array of clinical and nonclinical risk factors. No significant difference in survival between immediate open repair and surveillance was observed for patients of any age, overall (p = 0.606) or in men (p = 0.371) or women separately (p = 0.167). In conclusion, survival did not differ significantly between immediate open repair and surveillance for patients of any age, overall or in men or women. Combined with the previous evidence regarding diameter, and the lack of benefit of immediate endovascular in trials comparing it with surveillance repair for small abdominal aortic aneurysms, these results suggest that surveillance should be the first-line management strategy of choice for asymptomatic abdominal aortic aneurysms of 4.0 to 5.5 cm.

Relation between topical application of platelet-rich plasma and vancomycin and severe deep sternal wound infections after a first median sternotomy

Deep sternal wound infections (DSWIs) are serious complications of sternotomy, leading to increased mortality and costs of care. Topical applications of autologous platelet concentrate and vancomycin have both shown promise in preventing DSWIs. From January 1, 1998, to November 30, 2010, 1,866 patients without previous sternotomy underwent cardiac surgery at the Baylor University Medical Center, Dallas, by a single surgeon who systematically adopted application of a paste containing vancomycin, calcium-thrombin, and platelet-rich plasma (PRP paste) to the edges of sternal wounds before closure in December 2005. A propensity-adjusted logistic regression model employing Firth's penalized maximum likelihood method was used to assess the association between the use of the PRP paste (intervention) and the incidence of severe DSWI. Eleven patients (0.59%) developed severe DSWIs. All were among the 1,318 patients in the control group (0.83%); no severe DSWIs developed in the 548 patients in the intervention group. Both the unadjusted and adjusted associations between the study intervention and DSWI were statistically significant (unadjusted p value=0.021; adjusted p value=0.005; adjusted odds ratio=0.05, 95% confidence interval 0.01, 0.50). In conclusion, the PRP paste appears to prevent severe DSWIs.

Risk of not being discharged home after isolated coronary artery bypass graft operations

BACKGROUND

The age and risk profile of patients undergoing isolated coronary artery bypass grafting (CABG) is increasing, which will likely increase the proportion of CABG patients discharged to nursing homes, rehabilitation, or long-term care. Because discharge disposition can be important to a patient's treatment goals, developing and using predictive tools will improve informed treatment decision making. We examined the utility of The Society of Thoracic Surgeons (STS) risk of mortality score in predicting discharge disposition after CABG.

METHODS

From January 1, 2004 to October 31, 2011, 5,119 patients underwent isolated CABG at The Heart Hospital Baylor Plano or Baylor University Medical Center (Texas) and were discharged alive. The association between STS risk of mortality and discharge to nursing home, rehabilitation, or long-term care was assessed using multivariable logistic regression, adjusted for age, body surface area, marital status, site, and year of operation.

RESULTS

At discharge, 216 patients (4.21%) went to nursing homes, 153 (2.99%) to rehabilitation, and 115 (2.25%) to long-term care. The STS risk of mortality score was significantly positively associated with discharge status (p < 0.001). Patients with 1%, 2%, 3%, 4%, and 5% STS risk of mortality had 11.25%, 22.10%, 29.45%, 35.00%, and 38.50% probability, respectively, of not being discharged home. When the STS risk of mortality was 5%, the risk of not being discharged home was 47.9% for off-pump patients and 38.10% for on-pump patients.

CONCLUSIONS

STS risk score is strongly associated with CABG discharge status. Patients with a risk score exceeding 2 are at high risk (>22%) of not being discharged home. This risk should be discussed when treatment decisions are being made.