Research Spotlight

Edgerton, J. R. (2019). “Surgical Ablation of Atrial Fibrillation in Patients with Tachycardia-Induced Cardiomyopathy (Commentary).” Ann Thorac Surg. Apr 2. [Epub ahead of print].

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In this issue of The Annals of Thoracic Surgery, the Washington University group reports the results of surgical ablation of atrial fibrillation in 34 patients with tachycardia induced cardiomyopathy (TIC) defined as left ventricular ejection fraction (LVEF) <41% and absent another etiology. Excluding one death, 33 patients were available for follow-up and 27 of these had an evaluable echo at about 12 months. At 12 months 94% of patients were free of atrial tachyarrhythmias with/without antiarrhythmic drugs (AADs). Mean LVEF improved from 32% to 55%. Of 11 pts in NYHA Class III/IV, 8 improved to Class I/II. These changes reached statistical significance. It is important to note that LV function improved in all patients and it improved to >55% in 19/27 patients. The prognostic significance of the presence of fibrosis (inhibits recovery of function), as reported in the CAMERA-MRI study and reiterated in this report, should be stressed. In patient selection, it is important to differentiate between TIC and a dilated cardiomyopathy with secondary atrial fibrillation (AF). The former will not be helped by performing a Maze and the latter will. To differentiate, the authors perform a cardiac MRI to assess for myocardial viability and the degree of left ventricular fibrosis by late gadolinium enhancement (LGE). On multivariate analysis, only the absence of LGE was found to predict LVEF normalization. Any presence of fibrosis rules the patient out as a candidate for surgical ablation. If there is any other abnormality on cardiac MRI, or a high index of suspicion, endomyocardial biopsies are performed. Thus, a pre-op MRI will help the clinician in deciding whether to operate for TIC. Although the numbers of patients are small, documenting these findings is very significant. It would be easy for a reader to dismiss this paper as a small retrospective series of little significance. This would be a grave error. Yes, the numbers are small, but few groups have adequate volume to accumulate this many patients and most lack the investigatory rigor to document the post-op course in such detail. Additionally, very few groups have pre-op MRIs on these patients. As the authors point out, current guideline statements on the treatment of TIC, “include only non-surgical rhythm control strategies.” This is the true significance of this paper. Based on the findings documented here, a Class IIa, LOE B-NR is justified for surgical ablation of AF in patients with TIC who are undergoing cardiac surgery for another reason or have failed AADs and catheter ablation. Future guideline committees need to consider this work when revising current guidelines. (Excerpt from text, p. 1 of article-in-press.)

Djamali, A., T. Singh, M. L. Melamed, J. H. Stein, F. Aziz, S. Parajuli, M. Mohamed, N. Garg, D. Mandelbrot, D. E. Wesson and B. C. Astor (2019). “Metabolic Acidosis 1 Year Following Kidney Transplantation and Subsequent Cardiovascular Events and Mortality: An Observational Cohort Study.” Am J Kidney Dis 73(4): 476-485.

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RATIONALE & OBJECTIVE: Recent studies suggest that metabolic acidosis is associated with mortality and graft failure in kidney transplant recipients. However, it is unknown whether serum bicarbonate (measured as total carbon dioxide [tCO2] in serum) levels predict cardiovascular events (CVEs) following kidney transplantation. STUDY DESIGN: Observational cohort study. SETTINGS & PARTICIPANTS: Single-center study of 2,128 kidney transplant recipients free of CVEs during the first 13.5 months following transplantation. PREDICTOR: tCO2 level at 1 year posttransplantation. OUTCOMES: Ischemic, arrhythmic, and heart failure CVEs and death from any cause. ANALYTICAL APPROACH: Independent associations were assessed using multivariable proportional hazards regression models. Restricted cubic spline Poisson models were used to explore nonlinear associations. Linear spline proportional hazards models were used to assess associations at different tCO2 levels. RESULTS: The prevalence of metabolic acidosis defined as tCO2 level < 24 mEq/L was 38.8% (n=826). There were 384 recipients with a CVE and 610 deaths during a median follow-up of 4.0 years. CVEs included 241 ischemic, 137 arrhythmic, and 150 heart failure events. tCO2 level < 20 mEq/L was associated with increased risk for CVEs (adjusted HR [aHR], 2.00; 95% CI, 1.29-3.10) compared to the reference category of tCO2 level of 24.0 to 25.9 mEq/L. This association was primarily due to ischemic CVEs (aHR, 2.28; 95% CI, 1.34-3.90). For every 1 mEq/L lower tCO2 level for those with tCO2 < 24 mEq/L, risks for all CVEs and ischemic events were 17% and 15% higher, respectively (aHR for all CVEs of 0.83 [95% CI, 0.74-0.94] and aHR for ischemic CVEs of 0.85 [95% CI, 0.74-0.99]). Notably, tCO2 level < 20 mEq/L, compared to tCO2 level of 24.0 to 25.9 mEq/L, was independently associated with all-cause mortality (aHR, 1.43; 95% CI, 1.02-2.02). For every 1-mEq/L lower tCO2 level for those with tCO2 < 24 mEq/L, there was 17% higher risk for death (aHR, 0.83; 95% CI, 0.75-0.92). LIMITATIONS: Single-center observational study. CONCLUSIONS: Metabolic acidosis is an independent risk factor for ischemic CVEs after kidney transplantation. It is unknown whether correction of acidosis improves outcomes in these patients.

Dewan, P., R. Rorth, P. S. Jhund, J. P. Ferreira, F. Zannad, L. Shen, L. Kober, W. T. Abraham, A. S. Desai, K. Dickstein, M. Packer, J. L. Rouleau, S. D. Solomon, K. Swedberg, M. R. Zile and J. J. V. McMurray (2019). “Income Inequality and Outcomes in Heart Failure: A Global Between-Country Analysis.” JACC Heart Fail 7(4): 336-346.

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OBJECTIVES: This study examined the relationship between income inequality and heart failure outcomes. BACKGROUND: The income inequality hypothesis postulates that population health is influenced by income distribution within a society, with greater inequality associated with worse outcomes. METHODS: This study analyzed heart failure outcomes in 2 large trials conducted in 54 countries. Countries were divided by tertiles of Gini coefficients (where 0% represented absolute income equality and 100% represented absolute income inequality), and heart failure outcomes were adjusted for standard prognostic variables, country per capita income, education index, hospital bed density, and health worker density. RESULTS: Of the 15,126 patients studied, 5,320 patients lived in Gini coefficient tertile 1 countries (coefficient: <33%), 6,124 patients lived in tertile 2 countries (33% to 41%), and 3,772 patients lived in tertile 3 countries (>41%). Patients in tertile 3 were younger than tertile 1 patients, were more often women, and had less comorbidity and several indicators of less severe heart failure, yet the tertile 3-to-1 hazard ratios (HRs) for the primary composite outcome of cardiovascular death or heart failure hospitalization were 1.57 (95% confidence interval [CI]: 1.38 to 1.79) and 1.48 for all-cause death (95% CI: 1.29 to 1.71) after adjustment for recognized prognostic variables. After additional adjustments were made for per capita income, education index, hospital bed density, and health worker density, these HRs were 1.46 (95% CI: 1.25 to 1.70) and 1.30 (95% CI: 1.10 to 1.53), respectively. CONCLUSIONS: Greater income inequality was associated with worse heart failure outcomes, with an impact similar to those of major comorbidities. Better understanding of the societal and personal bases of these findings may suggest approaches to improve heart failure outcomes.

Dearani, J. A., T. K. Rosengart, M. B. Marshall, M. J. Mack, D. R. Jones, R. L. Prager and R. J. Cerfolio (2019). “Incorporating Innovation and New Technology Into Cardiothoracic Surgery.” Ann Thorac Surg 107(4): 1267-1274.

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The appropriate implementation of new technology, root cause analysis of “imperfect” outcomes, and the continuous reappraisal of postgraduate training are needed to improve the care of tomorrow’s patients. Healthcare delivery remains one of the most expensive sectors in the United States, and the application of new and expensive technology that is necessary for the advancement of this complex specialty must be aligned with providing the best care for our patients. There are a several pathways to innovation: One is partnering with industry and the other is the investigational laboratory. Innovation and the funding thereof come from both the public and private sector. Most new trials that are likely to impact cardiothoracic surgery are industry-sponsored trials to meet the requirements necessary for regulatory approval. Cost considerations are paramount when considering integration of innovative technology and treatments into a clinical cardiothoracic surgical practice. The value of any new innovation is determined by the quality divided by the cost, and lean initiatives maximize this equation. The importance and implications of conflict of interest have been a concern for physicians, particularly when new technology or procedures are incorporated into clinical practice, and full disclosures by medical professionals and others involved are essential. Our societies and associations provide a platform for presentation and peer-reviewed discussion of new procedures, innovations, and trials and provide a venue for the sharing of knowledge on the highest quality patient care through education and research.

Cookinham, B. and C. Swank (2019). “Concussion History and Career Status Influence Performance on Baseline Assessments in Elite Football Players.” Arch Clin Neuropsychol Mar 30. [Epub ahead of print].

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OBJECTIVE: To determine if concussion history and career status is associated with neurocognitive performance in elite football players. METHODS: The study design was a cross-sectional single assessment. Fifty-seven elite football players (age 29.39 +/- 7.49 years) categorized as draft prospects, active professional players, and retired professional players were assessed on the Sport Concussion Assessment Tool – third edition (SCAT-3), in an outpatient therapy setting. RESULTS: Common symptoms were the following: fatigue (45.6%), trouble falling asleep (35.1%), difficulty remembering (33.3%) and irritability (22.8%); 36.8% reported no symptoms. The low concussion (0-1) group reported fewer symptoms (U = 608.50, p < .001), less symptom severity (U = 598.00, p = -.001), and produced greater scores on the Standardized Assessment of Concussion (SAC) total scores compared to the multiple concussion (2+) group (U = 253.00, p = .024), but no differences were observed on modified Balance Error Scoring System (m-BESS) scores (U = 501.50, p = .066) on the Mann-Whitney U test. The Kruskal-Wallis test and post-hoc analysis indicated retired players were significantly different from draft prospects and current professional players for total symptom scores (p < .001), total symptom severity (p < .001), SAC total scores (p = .030), and m-BESS (p < .001). CONCLUSIONS: Concussion history and career status appear associated with total symptoms, symptom severity, performance on the SAC, and the m-BESS in elite football players. With this in mind, future research is recommended to determine longitudinal impact for elite football players.