Research Spotlight

Posted February 19th 2016

Two-Year Outcomes of Surgical Treatment of Severe Ischemic Mitral Regurgitation.

Michael J. Mack M.D.

Michael J. Mack, M.D.

Goldstein, D., A. J. Moskowitz, A. C. Gelijns, G. Ailawadi, M. K. Parides, L. P. Perrault, J. W. Hung, P. Voisine, F. Dagenais, A. M. Gillinov, V. Thourani, M. Argenziano, J. S. Gammie, M. Mack, P. Demers, P. Atluri, E. A. Rose, K. O’Sullivan, D. L. Williams, E. Bagiella, R. E. Michler, R. D. Weisel, M. A. Miller, N. L. Geller, W. C. Taddei-Peters, P. K. Smith, E. Moquete, J. R. Overbey, I. L. Kron, P. T. O’Gara, M. A. Acker, M. Mack, T. A. Settele, N. Settele, W. Ryan, R. L. Smith and P. Grayburn (2016). “Two-Year Outcomes of Surgical Treatment of Severe Ischemic Mitral Regurgitation.” N Engl J Med 374(4): 344-353.

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BACKGROUND: In a randomized trial comparing mitral-valve repair with mitral-valve replacement in patients with severe ischemic mitral regurgitation, we found no significant difference in the left ventricular end-systolic volume index (LVESVI), survival, or adverse events at 1 year after surgery. However, patients in the repair group had significantly more recurrences of moderate or severe mitral regurgitation. We now report the 2-year outcomes of this trial. METHODS: We randomly assigned 251 patients to mitral-valve repair or replacement. Patients were followed for 2 years, and clinical and echocardiographic outcomes were assessed. RESULTS: Among surviving patients, the mean (+/-SD) 2-year LVESVI was 52.6+/-27.7 ml per square meter of body-surface area with mitral-valve repair and 60.6+/-39.0 ml per square meter with mitral-valve replacement (mean changes from baseline, -9.0 ml per square meter and -6.5 ml per square meter, respectively). Two-year mortality was 19.0% in the repair group and 23.2% in the replacement group (hazard ratio in the repair group, 0.79; 95% confidence interval, 0.46 to 1.35; P=0.39). The rank-based assessment of LVESVI at 2 years (incorporating deaths) showed no significant between-group difference (z score=-1.32, P=0.19). The rate of recurrence of moderate or severe mitral regurgitation over 2 years was higher in the repair group than in the replacement group (58.8% vs. 3.8%, P<0.001). There were no significant between-group differences in rates of serious adverse events and overall readmissions, but patients in the repair group had more serious adverse events related to heart failure (P=0.05) and cardiovascular readmissions (P=0.01). On the Minnesota Living with Heart Failure questionnaire, there was a trend toward greater improvement in the replacement group (P=0.07). CONCLUSIONS: In patients undergoing mitral-valve repair or replacement for severe ischemic mitral regurgitation, we observed no significant between-group difference in left ventricular reverse remodeling or survival at 2 years. Mitral regurgitation recurred more frequently in the repair group, resulting in more heart-failure-related adverse events and cardiovascular admissions. (Funded by the National Institutes of Health and Canadian Institutes of Health Research; number, NCT00807040.).

Posted February 19th 2016

Organ Allocation: The Only Way to Predict Your Future Is to Know Your Past.

Goran Klintmalm M.D.

Goran Klintmalm, M.D.

Klintmalm, G. B. (2016). “Organ Allocation: The Only Way to Predict Your Future Is to Know Your Past.” Am J Transplant 16(2): 383-384.

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Organ allocation is already a heated issue, and proposed redistricting changes to the allocation system based solely on mathematical models serve to further stoke this fire. In this issue, Gentry et al. provide further fuel, focusing on the financial impact of these redistricting plans. Recent attention has focused on allocation, debating optimal distribution of deceased donor livers to patients. The problems lie in the donor liver supply–demand mismatch, further amplified by lower donation rates in regions having more liver disease. In 2013, the United Network for Organ Sharing (UNOS) proposed changing the geographic basis for organ allocation, following a 2013 publication by Gentry et al. regarding optimization of organ allocation. A September 2014 UNOS Public Forum presenting the proposal met criticism that it focused on mathematical models, avoiding financial and operational implications. A 2015 UNOS Public Forum saw the discussion dominated by audience members’ concerns about the financial and operational burdens of the proposal.

Posted February 19th 2016

Proposed Diagnostic Criteria for Chronic Antibody-Mediated Rejection in Liver Allografts.

Jacqueline O'Leary M.D.

Jacqueline O’Leary, M.D.

O’Leary, J. G., J. Cai, R. Freeman, N. Banuelos, B. Hart, M. Johnson, L. W. Jennings, H. Kaneku, P. I. Terasaki, G. B. Klintmalm and A. J. Demetris (2016). “Proposed Diagnostic Criteria for Chronic Antibody-Mediated Rejection in Liver Allografts.” Am J Transplant 16(2): 603-614.

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Donor-specific alloantibodies (DSA) can cause acute antibody-mediated rejection (AMR) in all solid organ allografts. However, long-term outcome in patients with posttransplant DSA needs further study. We retrospectively evaluated prospectively collected paired serum, tissue, and data on 45 matched DSA- positive [DSA+; mean florescence intensity (MFI) >/=10 000] and -negative (DSA-) recipients of a primary liver-only allograft from January 2000 to April 2009. Blinded histopathologic evaluation demonstrated that DSA+ versus DSA- patients were more likely to have subtle inflammation and unique patterns of fibrosis, despite normal or near-normal liver function tests. Stepwise multivariable modeling developed a score (putatively named the chronic AMR [cAMR] score) that included interface activity, lobular inflammation, portal tract collagenization, portal venopathy, sinusoidal fibrosis, and hepatitis C virus status. The score was developed (c = 0.811) and cross-validated (c = 0.704) to predict allograft failure. Two cutoffs were employed to optimize sensitivity and specificity (80% each); a value >27.5 predicted 50% 10-year allograft failure. We propose chronic AMR as a potential new entity defined by (1) a high cAMR score, (2) DSA, and (3) elimination of other potential causes of a similar injury pattern. In conclusion, cAMR score calculation identified liver allograft recipients with DSA at highest risk for allograft loss, although independent validation is needed.

Posted February 19th 2016

Current Status of Minimally Invasive Surgery for Rectal Cancer

James W. Fleshman M.D.

James W. Fleshman, M.D.

Fleshman, J. (2016). “Current Status of Minimally Invasive Surgery for Rectal Cancer.” J Gastrointest Surg.

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Recent randomized controlled data have shown possible limitations to laparoscopic treatment of rectal cancer. The retrospective data, used as the basis for designing the trials, and which showed no problems with the technique, are discussed. The design of the randomized trials is discussed relative to the future meta-analysis of the recent data. The implications of the current findings on practice are discussed as surgeons try to adjust their practice to the new findings. The possible next steps for clinical and research innovations are put into perspective as new technology is considered to compensate for newly identified limitations in the laparoscopic treatment of rectal cancer.

Posted February 19th 2016

Endoscopic button gastrostomy: Comparing a sutured endoscopic approach to the current techniques.

Jessica Gonzalez-Hernandez M.D.

Jessica Gonzalez-Hernandez, M.D.

Gonzalez-Hernandez, J., Y. Daoud, A. C. Fischer, B. Barth and H. G. Piper (2016). “Endoscopic button gastrostomy: Comparing a sutured endoscopic approach to the current techniques.” J Pediatr Surg 51(1): 72-75.

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PURPOSE: Button gastrostomy is the preferred feeding device in children and can be placed open or laparoscopically (LBG). Alternatively, a percutaneous endoscopic gastrostomy (PEG) can be placed initially and exchanged for a button. Endoscopic-assisted button gastrostomy (EBG) combines both techniques, using only one incision and suturing the stomach to the abdominal wall. The long-term outcomes and potential costs for EBG were compared to other techniques. METHODS: Children undergoing EBG, LBG, and PEG (2010-2013) were compared. Patient demographics, procedure duration/complications, and clinic and emergency room (ER) visits for an eight-week follow-up period were compared. RESULTS: Patient demographics were similar (32 patients/group). Mean procedure time (min) for EBG was 38+/-9, compared to 58+/-20 for LBG and 31+/-10 for PEG (p<0.0001). The most common complications were granulation tissue and infection with a trend toward fewer infections in EBG group. Average number of ER visits was similar, but PEG group had fewer clinic visits. 97% of PEG patients had subsequent visits for exchange to button gastrostomy. CONCLUSIONS: EBG is safe and comparable to LBG and PEG in terms of complications. It has a shorter procedure time than LBG and does not require laparoscopy, device exchange, or subsequent fluoroscopic confirmation, potentially reducing costs.