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(4, 5, or 6 mm), position in relation to gical community,attentionto the details cited 2 meta-analyses2,3 of randomized neoaorta (right or left of the aorta), and in its construction is needed. Material– controlled trials of off-pump coronary anastomosis both proximally either compliance mismatch (eg, Gore-Tex artery bypass grafting without cardio- with ventricular fixation or epicardial to PA or Gore-Tex to pericardial patch pulmonary bypass (OPCAB) versus fixation as well as distally with Gore- to pulmonary artery) at the distal anas- conventional coronary artery bypass Tex or biologic patch or direct anasto- tomosis is another boundary that could grafting with cardiopulmonary bypass mosis. A review of controlled trials2-5 be associated with further reinterven- (ONCAB) that demonstrated similar is given in Table 1. Each of these tech- tions in the RV to PA conduit. late mortality. The meta-analysis (pub- nical modifications can behave as If we were to revisit our techniques lished in 2008) by Møller and associ- a confounder at the time of the RV to critically and systematically and ates2 of 18 trials (2864 patients) PA conduit reconstruction. Further- reinterpret the intricate boundaries showed no significant difference in more, they can have long-term effects for each surgical variable, we could late (>30 day) mortality (3.1% in OP- on the PA architecture, whether cen- provide a quality improvement initia- CAB vs 2.7% in ONCAB; P ¼ .55). In tral or branch pulmonary artery steno- tive and reduce the rate of reinterven- the meta-analysis (published in 2009) sis. The PAs are essential for healthy tion after the Norwood procedure. by Feng and colleagues3 of 10 trials Fontan circulation. (2018 patients), late (1 year) mortal- Jeffrey H. Shuhaiber, MD This lack of a standardized surgical ity was not significantly reduced (odds Heart Institute technique for the RV to PA shunt ratio, 1.00; 95% confidence interval Cincinnati Children’s Hospital construction in itself allows for [CI], 0.56–1.77; P ¼ 1.00). More re- Cincinnati, Ohio error-generating boundaries. All of cently (published in 2010), we4 per- the entities in Norwood procedures formed a meta-analysis of 11 results are essential but have limitations inher- of 12 trials (4326 patients) including References ent in the surgeon’s cognition that is 1. Ohye RG, Sleeper LA, Mahony L, Newburger JW, the Randomized On/Off Bypass 5 worthy of appraisal and understanding. Pearson GD, Lu M, et al. Comparison of shunt (ROOBY) trial. Despite the results These are difficult to measure with ex- types in the Norwood procedure for single- of previous meta-analyses,2,3 our ventricle lesions. NEnglJMed. 2010;362: isting tools. We should not, however, 1980-92. pooled analysis demonstrated underestimate the role of variable 2. Schreiber C, Kasnar-Samprec J, Horer€ J, Eicken A, a statistically significant increase in surgical technique in contributing to Cleuziou J, Prodan Z, et al. Ring-enforced right late (1-year) mortality by a factor ventricle-to-pulmonary artery conduit in Norwood increased rate of reinterventions. stage I reduces proximal conduit stenosis. Ann of 1.37 with OPCAB relative to Simple randomization in the trial Thorac Surg. 2009;88:1541-5. ONCAB (risk ratio, 1.373; 95% CIs, of Ohye and colleagues1 to2different 3. Hasaniya NW, Shattuck H, Razzouk A, Bailey L. 1.043–1.808; P ¼ .024).4 Furthermore, Modification of ventricular-to-pulmonary shunt to shunts does not mean that these minimize proximal conduit obstruction after stage our updated meta-analysis of 15 results shunts were constructed in the same I Norwood reconstruction. Ann Thorac Surg. of 16 trials (by a comprehensive search exact manner at each surgery and by 2010;89:e4-6. current through September 2010) 4. Reinhartz O, Reddy VM, Petrossian E, every surgeon. In particular, the RV MacDonald M, Lamberti JJ, Roth SJ, et al. Homo- (4865 patients) also demonstrated to PA shunt more often can be con- graft valved right ventricle to pulmonary artery a statistically significant increase in structed in different ways given the conduit as a modification of the Norwood proce- late (1-year) mortality by a factor dure. Circulation. 2006;114(1 Suppl):I594-9. modifications, predetermined patient 5. Barron DJ, Brooks A, Stickley J, Woolley SM, of 1.39 with OPCAB relative to sample selection, and unweighted Stumper€ O, Jones TJ, et al. The Norwood procedure ONCAB (risk ratio, 1.39; 95% CIs, confounding. For example, surgeons using a right ventricle-pulmonary artery conduit: 1.07–1.80; P ¼ .01; Figure 1). This re- comparison of the right-sided versus left-sided con- elect not to place RV to PA shunts if duit position. J Thorac Cardiovasc Surg. 2009;138: sult was robust in sensitivity analy- there is a crossing coronary artery or 528-37. ses: exclusion of any single result presence of an important papillary (including the result of the ROOBY muscle. doi:10.1016/j.jtcvs.2011.01.007 trial5) from the analysis did not sub- With regard to the modified Blalock– stantively alter the overall result of Taussig shunt, the major variations are our analysis. Therefore, on the basis limited to length and diameter. The CONVENTIONAL RATHER of the best evidence of our newest number of variable boundaries in the THAN OFF-PUMP CORONARY meta-analyses of randomized con- RV to PA shunt construction is thus ARTERY BYPASS GRAFTING trolled trials, ONCAB rather than far greater than that in the Blalock– SHOULD BE PERFORMED FOR OPCAB should be considered for pa- Taussig shunt. The blood flow patterns NON–HIGH-RISK PATIENTS tients at least who meet the criteria vary in each shunt as well as each To the Editor: for enrollment in the randomized reconstruction. Although the RV to PA We read with great interest an trials (typically not high-risk but shunt has been popular among the sur- editorial by Patel and Angelini,1 which low- to moderate-risk patients),

1330 The Journal of Thoracic and Cardiovascular Surgery c May 2011 Letters to the Editor

FIGURE 1. Late (1-year) mortality among patients randomized to off-pump coronary artery bypass grafting without cardiopulmonary bypass (OPCAB) versus conventional coronary artery bypass grafting with cardiopulmonary bypass (ONCAB). BBS, Best Bypass Surgery trial; BHACAS, Beating Heart Against Cardioplegic Arrest Study; CI, confidence interval; MASS, Medicine, Angioplasty, or Surgery Study; M-H, Mantel–Haenszel; PROMISS, Prospec- tive Randomized Comparison of Off-Pump and On-Pump Multi-vessel Coronary Artery Bypass Surgery trial; ROOBY, Randomized On/Off Bypass trial; SMART, Surgical Management of Arterial Revascularization Therapies trial; df, degrees of freedom.

because late mortality reduction Reply to the Editor: these studies reveals comparable must imply the greatest clinical ben- mortality rates (risk ratio, 1.276; efit among patients undergoing coro- 95% confidence intervals, 0.858– nary artery bypass grafting. 1.898; P ¼ .229) between OPCAB Supplemental material is and ONCAB surgery. Second, the Hisato Takagi, MD, PhD available online. meta-analysis is heavily weighted by Masafumi Matsui, MD the Randomized On/Off Bypass Takuya Umemoto, MD, PhD (ROOBY) trial, which we have al- Department of Cardiovascular We read with interest the letter by ready critically analyzed and have Surgery Takagi and colleagues, who suggest shown to have several flaws. Removal Shizuoka Medical Center that coronary artery bypass graft sur- of this trial from the meta-analysis Shizuoka, Japan gery without cardiopulmonary bypass demonstrates no difference between (OPCAB) is associated with adverse the 2 surgical techniques (odds ratio, References long-term outcomes based on a recent 1.344; 95% confidence intervals, 1. Patel NN, Angelini GD. Off-pump coronary artery 1 1 bypass grafting: for the many or the few? J Thorac systematic review they have per- 0.952–1.896). Cardiovasc Surg. 2010;140:951-3, 953.e1. formed and recommend that the pre- Conversely and more fundamen- 2. Møller CH, Penninga L, Wetterslev J, ferred technique for non–high-risk tally, though, if we consider the find- Steinbruchel€ DA, Gluud C. Clinical outcomes in randomized trials of off- vs. on-pump coronary patients should be coronary artery by- ings of Takagi and colleagues to be artery bypass surgery: systematic review with pass graft surgery with cardiopulmo- robust, we may conclude that OPCAB meta-analyses and trial sequential analyses. Eur nary bypass (ONCAB). is not for all surgeons and patients. Heart J. 2008;29:2601-16. 3. Feng ZZ, Shi J, Zhao XW, Xu ZF. Meta-analysis We, however, question the validity Numerous observational studies from of on-pump and off-pump coronary arterial re- of their systematic review, which in- centers specializing in OPCAB dem- vascularization. Ann Thorac Surg. 2009;87: cluded 11 randomized controlled onstrate trends toward or significant 757-65. Erratum in: Ann Thorac Surg. 2009;87: 2008. trials (RCTs) evaluating long-term reductions in mortality in all groups 2-5 4. Shroyer AL, Grover FL, Hattler B, Collins JF, outcomes in more than 4000 low-risk of patients. OPCAB surgeons McDonald GO, Kozora E, et al. On-pump versus patients for the following reasons. achieved anastomotic numbers off-pump coronary-artery bypass surgery. N Engl J Med. 2009;361:1827-37. First, 7 of the 11 RCTs (please see ref- comparable with ONCAB surgeons 4 5. Takagi H, Matsui M, Umemoto T. Off-pump erences E1-E7) included in the meta- in these studies, and this is in contrast coronary artery bypass may increase late mortality: analysis carry moderate to high risk to RCTs performed to date. Results of a meta-analysis of randomized trials. Ann Thorac Surg. 2010;89:1881-8. of bias according to the Cochrane sys- the CRISP trial (Coronary artery tem for the evaluation of the methodo- grafting in high RISk patients rando- doi:10.1016/j.jtcvs.2010.10.055 logic quality of studies. Removal of mised to off Pump or on pump

The Journal of Thoracic and Cardiovascular Surgery c Volume 141, Number 5 1331