Benjamin D. Pollock M.S.P.H.

Filardo, G., B. D. Pollock, B. da Graca, T. K. Phan, R. J. Damiano, Jr., G. Ailawadi, V. Thourani and J. R. Edgerton (2020). “Postcoronary Artery Bypass Graft Atrial Fibrillation Event Count and Survival: Differences by Sex.” Ann Thorac Surg 109(5): 1362-1369.

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BACKGROUND: New-onset atrial fibrillation (AF) after coronary artery bypass graft surgery (CABG) is associated with poor outcomes, but data on the effects of its characteristics are lacking and conflicting. We examined the effect number of post-CABG AF events has on long-term mortality risk, and whether this is sex dependent. METHODS: Routinely collected Society of Thoracic Surgeons (STS) data were supplemented with details on new-onset post-CABG AF (detected in-hospital by continuous electrocardiogram/telemetry monitoring) and long-term survival for 9203 consecutive patients with isolated-CABG (2002-2010). With the use of Cox regression, we determined the propensity-adjusted (STS-recognized risk factors) effect of number of AF events on survival, testing for effect modification by sex and controlling for AF duration. RESULTS: AF occurred in 739 women (29.4%) and 2157 men (32.3%) (P < .001). Adjusted results showed 2 or more AF events significantly (P < .001) increased 5-year mortality risk, independently of total AF duration. However, mortality risk differed between the sexes (P < .001): women with 2 AF episodes had the greatest increase (hazard ratio [HR] = 2.98; 95% confidence interval [CI], 1.43-4.83; versus women without AF), followed by women and men with 4 or more AF events (HR = 2.76 [95% CI, 1.27-4.55] and HR = 2.73 [95% CI, 2.30-3.19], respectively). A single post-CABG AF episode was not associated with increased mortality risk. CONCLUSIONS: Both men and women who experienced 2 or more post-CABG AF episodes showed increased risk of 5-year mortality, independent of total AF duration. Although men's risk increased as the number of AF events increased, women's risk peaked at 2 AF events. Future research needs to determine whether this divergence stems from differences in treatment/management or underlying biology.

Filardo, G., G. Ailawadi, B. D. Pollock, B. da Graca, T. K. Phan, V. Thourani and R. J. Damiano, Jr. (2020). “Postoperative atrial fibrillation: Sex-specific characteristics and effect on survival.” J Thorac Cardiovasc Surg 159(4): 1419-1425.e1411.

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BACKGROUND: We sought to fill important gaps in the existing evidence regarding new-onset atrial fibrillation (AF) after coronary artery bypass graft surgery (CABG) by comparing the incidence, characteristics, and effect on long-term survival between men and women. METHODS: Nine thousand two hundred three consecutive patients without preoperative AF underwent isolated CABG from 2002 to 2010 at 3 US academic medical centers and 1 high-volume specialty cardiac hospital. Detailed data on CABG AF events detected via continuous in-hospital electrocardiogram/telemetry monitoring were supplemented with Society of Thoracic Surgeons data, and survival data, censored at October 31, 2011, using a copy of the Social Security Death Master File archived before state-owned data were removed (November 1, 2011). RESULTS: Propensity-adjusted (Society of Thoracic Surgeons-recognized risk factors) incidence of post-CABG AF was 31.5% overall, 32.8% in men, and 27.4% in women. Over the 9-year study period, women had a significantly lower risk of post-CABG AF (absolute difference, -5.3% [95% confidence interval (CI), -10.5% to -0.6%]), and significantly shorter first (-2.9 hours; 95% CI, -5.8 to 0.0), and longest (-4.3 hours; 95% CI, -8.3 to -0.3) AF duration. Post-CABG AF was associated with significantly increased risk of long-term mortality (overall hazard ratio [HR], 1.56; 95% CI, 1.45-1.67; men HR, 1.57; 95% CI, 1.49-1.65; women HR, 1.54; 95% CI, 1.14-2.07). CONCLUSIONS: In our study, women had lower adjusted risk of post-CABG AF and experienced shorter episodes. The adjusted risk of long-term mortality was 56% greater among patients who developed post-CABG AF compared with those who did not. The effect of post-CABG AF on long-term survival did not differ between the sexes.

Squiers, J., H. Baumgarten, G. Filardo, D. Sass, B. Pollock, J. Edgerton, R. Marcel, J. M. DiMaio and R. L. Smith (2019). “Prospective Evaluation of a Blood Transfusion Protocol for Patients Undergoing Cardiac Surgery.” Ann Thorac Surg Nov 23. [Epub ahead of print].

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BACKGROUND: The Society of Thoracic Surgeons clinical practice guidelines recommend the creation of an interdisciplinary blood management team to implement protocols for improved blood transfusion practices. We report our center’s prospective evaluation of a blood transfusion protocol. METHODS: An interdisciplinary blood management team developed protocols for transfusion of packed red blood cells, fresh frozen plasma, platelets, and cryoprecipitate. The protocols were prospectively evaluated by tracking transfusions administered to consecutive patients undergoing cardiac surgery, and the primary outcome of interest was the mean number of adjusted units of blood product transfused per patient. Protocol implementation phases were separated by washout phases to control for a potential Hawthorne effect associated with protocol implementation. Protocol compliance was also assessed. RESULTS: A total of 1441 patients underwent cardiac surgery during the 16-month study period. Although there was no statistically significant reduction in transfusions with an unadjusted analysis, there was a significant trend towards reduction of mean adjusted total units transfused per patient over the course of the study period (p<0.001). The mean adjusted total units transfused per patient were significantly less during the second washout phase (2.8 units, 95%CI 2.3-3.3) and second protocol phase (2.8 units, 95%CI 2.32-3.27) as compared to the initial baseline survey phase (3.6 units, 95%CI 3.1-4.1; p<0.05 for both comparisons). Only 55.2% of all units were transfused in compliance to the implemented protocols: platelets (46.8%), cryoprecipitate (32.1%), packed red blood cells (60.7%), and fresh frozen plasma (53.6%). CONCLUSIONS: During a prospective evaluation of blood transfusion protocols, a risk-adjusted analysis demonstrated a reduction in transfusions despite poor protocol compliance.

Filardo, G., B. da Graca, D. M. Sass, J. Hamilton, B. D. Pollock and J. R. Edgerton (2019). “Preoperative B-Blockers as a Coronary Surgery Quality Metric: The Lack of Evidence of Efficacy.” Ann Thorac Surg Sep 9. [Epub ahead of print].

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BACKGROUND: Two quality measures used in public-reporting and value-based payment programs require beta-blockers be administered <24 hours before isolated coronary artery bypass graft surgery (CABG) to prevent atrial fibrillation (AF) 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 pre-operative beta-blockers on AF or mortality following isolated CABG to determine what evidence of efficacy supports the measures. RESULTS: We identified 11 RCTs. All continued B-blockers post-operatively, making it unfeasible to separate the benefits of pre- vs post-operative administration. Meta-analysis was precluded by methodological variation in beta-blocker utilized, timing and dosage, and supplemental and comparison treatments. Of the 8 comparisons of beta-blockers/beta-blocker+digoxin versus placebo (n=826 patients), 6 showed significant reductions in AF/supraventricular arrhythmias. Of the 3 comparisons (n=444) of beta-blockers versus amiodarone, 2 found no significant difference in AF; the third showed significantly lower incidence with amiodarone. One RCT compared beta-blocker+amiodarone versus each of those drugs separately; the combination reduced AF significantly better than the beta-blocker alone, but not amiodarone alone. 7 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 B-blocker administration specifically within 24 hours prior to CABG to prevent post-operative AF 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.

Sannino, A., S. Potluri, B. Pollock, G. Filardo, A. Gopal, R. C. Stoler, M. Szerlip, A. Chowdhury, M. J. Mack and P. A. Grayburn (2019). “Impact of Mitral Stenosis on Survival in Patients Undergoing Isolated Transcatheter Aortic Valve Implantation.” Am J Cardiol 123(8): 1314-1320.

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This study was performed to investigate the prevalence and impact on survival of baseline mitral stenosis (MS) in patients who underwent transcatheter aortic valve implantation (TAVI) due to the presence of severe symptomatic aortic stenosis. This retrospective study included 928 consecutive patients with severe, symptomatic aortic stenosis who underwent TAVI in 2 institutions, from January 2012 to August 2016. Mean follow-up was 40.8 +/- 13.9 months. Based on the mean mitral gradient (MMG) at baseline, 3 groups were identified: MMG <5 mm Hg (n=737, 81.7%); MMG >/=5 and <10 mm Hg (n=147, 16.3%); MMG >/=10 mm Hg (n=17, 1.9%). These latter were more frequently women, with a smaller body surface area, a higher prevalence of atrial fibrillation, chronic obstructive pulmonary disease, and previous history of coronary-artery bypass graft/percutaneous coronary intervention. At baseline, patients with MMG >/=10 mm Hg compared with >/=5 and <10 mm Hg and <5 mm Hg patients had a lower mitral valve area (2.4 +/- 0.94 vs 2.1 +/- 0.86 vs 1.5 +/- 0.44 cm(2)), a lower prevalence of MR >/=2+ (5.9% vs 28.6% and 15.6%, p <0.0001), a higher prevalence of severe mitral annular calcium (70.6% vs 45.6% and 13.0%, p <0.0001) and a higher systolic pulmonary arterial pressure (50.6 +/- 12.1 vs 47.2 +/- 14.5 and 41.6 +/- 14.4, p <0.0001). Despite the low prevalence of MMG >/=10 mm Hg, these patients had higher 5-year mortality compared with the other groups (adjusted hazard ratio 2.91, 95% confidence interval 1.17 to 7.20, p=0.02). In conclusion, severe calcific MS is uncommon in patients who underwent TAVI. Its presence is associated with higher long-term mortality whereas moderate MS is not.