David H. Tian

A meta-analysis comparing bilateral internal mammary artery with left internal mammary artery for coronary artery bypass grafting

BACKGROUND Increasing evidence continues to demonstrate a survival advantage for bilateral internal mammary artery (BIMA) over left internal mammary artery (LIMA) for coronary artery bypass grafting (CABG). We performed an updated meta-analysis of published studies comparing BIMA versus LIMA in CABG operations and assessed differences in long-term survival. METHODS Electronic searches for studies comparing BIMA versus LIMA were performed using three databases from 1972 to December 2012. Studies with at least four years of follow-up and at least 100 patients in each group were included for review. We used a random-effect model and pooled hazard ratios from across all included studies. RESULTS No randomized controlled trials and 27 observational studies totaling 79,063 patients (19,277 BIMA, 59,786 LIMA) were included for final analysis. The BIMA group demonstrated significantly better long-term survival than the LIMA group [hazard ratio, 0.78; confidence interval, 0.72-0.84; P<0.00001]. CONCLUSIONS In an updated meta-analysis, we demonstrate an increase in long-term survival in patients receiving BIMA as a primary grafting strategy over those receiving a LIMA. Although no randomized controlled trials were included in this meta-analysis, the survival benefit seen with a BIMA cannot be overlooked when determining which operation to perform in CABG patients. Until the long-term results of the ART trial are published, we offer best available evidence in favor of BIMA over LIMA for CABG surgery.

Systematic review and meta-analysis of transcatheter aortic valve implantation versus surgical aortic valve replacement for severe aortic stenosis

BACKGROUND Transcatheter aortic valve implantation (TAVI) has emerged as an acceptable treatment modality for patients with severe aortic stenosis who are deemed inoperable by conventional surgical aortic valve replacement (AVR). However, the role of TAVI in patients who are potential surgical candidates remains controversial. METHODS A systematic review was conducted using five electronic databases, identifying all relevant studies with comparative data on TAVI versus AVR. The primary endpoint was all-cause mortality. A number of periprocedural outcomes were also assessed according to the Valve Academic Research Consortium endpoint definitions. RESULTS Fourteen studies were quantitatively assessed and included for meta-analysis, including two randomized controlled trials and eleven observational studies. Results indicated no significant differences between TAVI and AVR in terms of all-cause and cardiovascular related mortality, stroke, myocardial infarction or acute renal failure. A subgroup analysis of randomized controlled trials identified a higher combined incidence of stroke or transient ischemic attacks in the TAVI group compared to the AVR group. TAVI was also found to be associated with a significantly higher incidence of vascular complications, permanent pacemaker requirement and moderate or severe aortic regurgitation. However, patients who underwent AVR were more likely to experience major bleeding. Both treatment modalities appeared to effectively reduce the transvalvular mean pressure gradient. CONCLUSIONS The available data on TAVI versus AVR for patients at a higher surgical risk showed that major adverse outcomes such as mortality and stroke appeared to be similar between the two treatment modalities. Evidence on the outcomes of TAVI compared with AVR in the current literature is limited by inconsistent patient selection criteria, heterogeneous definitions of clinical endpoints and relatively short follow-up periods. The indications for TAVI should therefore be limited to inoperable surgical candidates until long-term data become available.

A systematic review and meta-analysis of surgical treatments for malignant pleural mesothelioma

BACKGROUND Malignant pleural mesothelioma (MPM) is an aggressive disease of the pleural lining with a dismal prognosis. Surgical treatments of MPM with a curative intent include extrapleural pneumonectomy and extended pleurectomy/decortication (P/D). This meta-analysis aimed to compare the perioperative and long-term outcomes of EPP and extended P/D for selected surgical candidates. METHODS A systematic review of the literature was performed on six electronic databases to identify all relevant data on comparative outcomes of extended P/D and EPP in a multimodality setting. Endpoints included perioperative mortality and morbidity, as well as long-term overall survival. RESULTS Seven relevant studies with comparative data on EPP (n=632) versus extended P/D (n=513) were identified from the current literature. Comparison of these two groups demonstrated significantly lower perioperative mortality (2.9% vs. 6.8%, p=0.02) and morbidity (27.9% vs. 62.0%, p<0.0001) for patients who underwent extended P/D compared to EPP. Median overall survival ranged between 13-29 months for extended P/D and 12-22 months for EPP, with a trend favouring extended P/D. CONCLUSIONS Although it must be emphasized that patient selection and treatment strategies differ between EPP and extended P/D, a number of comparative studies have recently been conducted to compare these two surgical techniques for patients with resectable MPM. The present study indicated that selected patients who underwent extended P/D had lower perioperative morbidity and mortality with similar, if not superior, long-term survival compared to EPP, in the context of multi-modality therapy. This may represent an important paradigm shift in the surgical management of MPM.

Systematic review and meta-analysis: techniques and a guide for the academic surgeon

With the rapidly growing literature across the surgical disciplines, there is a corresponding need to critically appraise and summarize the currently available evidence so they can be applied appropriately to patient care. The interpretation of systematic reviews is particularly challenging in cases where few robust clinical trials have been performed to address a particular question. However, risk of bias can be minimized and potentially useful conclusions can be drawn if strict review methodology is adhered to, including an exhaustive literature search, quality appraisal of primary studies, appropriate statistical methodology, assessment of confidence in estimates and risk of bias. Therefore, the following article aims to: (I) summarize to the important features of a thorough and rigorous systematic review or meta-analysis for the surgical literature; (II) highlight several underused statistical approaches which may yield further interesting insights compared to conventional pair-wise data synthesis techniques; and (III) propose a guide for thorough analysis and presentation of results.

A meta-analysis of deep hypothermic circulatory arrest versus moderate hypothermic circulatory arrest with selective antegrade cerebral perfusion

INTRODUCTION A recent concern of deep hypothermic circulatory arrest (DHCA) in aortic arch surgery has been its potential association with increased risk of coagulopathy, elevated inflammatory response and end-organ dysfunction. Recently, moderate hypothermic circulatory arrest (MHCA) with selective antegrade circulatory arrest (SACP) seeks to negate potential hypothermia-related morbidities, while maintaining adequate neuroprotection. The present meta-analysis aims to compare postoperative outcomes in arch surgery using DHCA or MHCA+SACP as neuroprotective strategies. METHODS Electronic searches were performed using six databases from their inception to January 2013. Two reviewers independently identified all relevant studies comparing DHCA with MHCA+SACP, as defined by a recent hypothermia temperature consensus. Data were extracted and meta-analyzed according to pre-defined clinical endpoints. RESULTS Nine comparative studies were identified for inclusion in the present meta-analysis. Stroke rates were significantly lower in patients undergoing MHCA+SACP (P=0.0007, I(2)=0%), while comparable results were observed with temporary neurological deficit, mortality, renal failure or bleeding. Infrequent and inconsistent reporting of systemic outcomes precluded analysis of other systemic outcomes. CONCLUSIONS The present meta-analysis indicated the superiority of MHCA+SACP in terms of stroke risk.

Surgical left atrial appendage occlusion during cardiac surgery for patients with atrial fibrillation: a meta-analysis

OBJECTIVES Concomitant left atrial appendage occlusion (LAAO) during surgical ablation has emerged as a potential treatment strategy to reduce stroke and perioperative mortality in patients with atrial fibrillation (AF). The present meta-analysis aims to assess current evidence on the efficacy and safety between LAAO and LAA preservation cohorts for patients undergoing cardiac surgery. METHODS Electronic searches were performed using six electronic databases from their inception to November 2013, identifying all relevant comparative randomized and observational studies comparing LAAO with non-LAAO in AF patients undergoing cardiac surgery. Data were extracted and analysed according to predefined endpoints including mortality, stroke, postoperative AF and reoperation for bleeding. RESULTS Seven relevant studies identified for qualitative and quantitative analyses, including 3653 patients undergoing LAAO (n = 1716) versus non-LAAO (n = 1937). Stroke incidence was significantly reduced in the LAAO occlusion group at the 30-day follow-up [0.95 vs 1.9%; odds ratio (OR) 0.46; P = 0.005] and the latest follow-up (1.4 vs 4.1%; OR 0.48; P = 0.01), compared with the non-LAAO group. Incidence of all-cause mortality was significantly decreased with LAAO (1.9 vs 5%; OR 0.38; P = 0.0003), while postoperative AF and reoperation for bleeding was comparable. CONCLUSIONS While acknowledging the limitations and inadequate statistical power of the available evidence, this study suggests LAAO as a promising strategy for stroke reduction perioperatively and at the short-term follow-up without a significant increase in complications. Larger randomized studies in the future are required, with clearer surgical and anticoagulation protocols and adequate long-term follow-up, to validate the clinical efficacy of LAAO versus non-LAAO groups.

Systematic review of trimodality therapy for patients with malignant pleural mesothelioma

BACKGROUND Malignant pleural mesothelioma (MPM) is an aggressive form of cancer arising from the pleural mesothelium. Trimodality therapy (TMT) involving extrapleural pneumonectomy with neoadjuvant or adjuvant chemotherapy and adjuvant radiotherapy is a recognized treatment option with a curative intent. Despite encouraging results from institutional studies, TMT in the treatment of MPM remains controversial. The present systematic review aims to assess the safety and efficacy of TMT in the current literature. METHODS A systematic review was performed using five electronic databases from 1 January 1985 to 1 October 2012. Studies were selected independently by two reviewers according to predefined selection criteria. The primary endpoint was overall survival. Secondary endpoints included disease-free survival, disease recurrence, perioperative morbidity and length of stay. RESULTS Sixteen studies were included for quantitative assessment, including one randomized controlled trial and five prospective series. Median overall survival ranged from 12.8-46.9 months. Disease-free survival ranged from 10-16.3 months. Perioperative mortality ranged from 0-12.5%. Overall perioperative morbidity ranged from 50-82.6% and the average length of stay was 9-14 days. CONCLUSIONS Outcomes of patients who underwent TMT in the current literature appeared to be inconsistent. Four prospective series involving a standardised treatment regimen with neoadjuvant chemotherapy indicated encouraging results based on intention-to-treat analysis. However, a small study assessing the feasibility of conducting a randomized controlled trial for TMT versus conservative treatment reported poor short- and long-term outcomes for patients who underwent pneumonectomy. Overall, results of the present systematic review suggest TMT may offer acceptable perioperative outcomes and long-term survival in selected patients treated in specialized centers.

A systematic review and meta-analysis on the safety and efficacy of the frozen elephant trunk technique in aortic arch surgery

BACKGROUND The treatment of complex pathologies of the aortic arch and proximal descending aorta represents a significant challenge for cardiac surgeons. Various surgical techniques and prostheses have been implemented over the past several decades, all with varying degrees of success. The introduction of the frozen elephant trunk (FET) technique facilitates one-stage repair of such pathologies. The present systematic review and meta-analysis aims to assess the safety and efficacy of the FET approach in the current literature. METHODS Electronic searches were performed using six databases from their inception to July 2013. Relevant studies utilizing the FET technique were identified. Data were extracted and analyzed according to predefined clinical endpoints. RESULTS Seventeen studies were identified for inclusion for qualitative and quantitative analyses, all of which were observational reports. Pooled mortality was 8.3%, while stroke and spinal cord injuries were 4.9% and 5.1% respectively. Cardiopulmonary bypass time, myocardial ischemia time, and circulatory arrest time strongly correlated with perioperative mortality in a linear relationship, while moderate correlations between cerebral perfusion time and mortality, and circulatory arrest time and spinal cord injury, were also identified. Five-year survival, reported in five studies, ranged between 63-88%. CONCLUSIONS Overall, results of the present systematic review and meta-analysis suggest that the FET procedure can be performed with acceptable mortality and morbidity risks.

Systematic review and meta-analysis of surgical ablation for atrial fibrillation during mitral valve surgery.

BACKGROUND Surgical ablation has emerged as an acceptable treatment modality for patients with atrial fibrillation (AF) undertaking concomitant cardiac surgery. However, the efficacy of surgical ablation in patient populations undergoing mitral valve surgery is not well established. The present meta-analysis aims to establish the current randomized evidence on clinical outcomes of surgical ablation versus no ablative treatment in patients with AF undergoing mitral valve surgery. METHODS Electronic searches were performed using six databases from their inception to September 2013, identifying all relevant randomized controlled trials (RCTs) comparing surgical ablation versus no ablation in AF patients undergoing mitral valve surgery. Data were extracted and analyzed according to predefined clinical endpoints. RESULTS Nine relevant RCTs were identified for inclusion in the present analysis. The number of patients in sinus rhythm (SR) was significantly improved in the surgical ablation group compared to the non-ablation group at discharge. This effect on SR remained at all follow-up periods until >1 year. Results indicated that there was no significant difference between surgical ablation and no ablation in terms of 30-day mortality, all-cause mortality, pacemaker implantation, stroke, thromboembolism, cardiac tamponade, reoperation for bleeding and myocardial infarction. CONCLUSIONS Results from the present meta-analysis demonstrate that the addition of surgical ablation for AF leads to a significantly higher rate of sinus rhythm in mitral valve surgical patients, with no increase in the rates of mortality, pacemaker implantation, stroke and thromboembolism. Further research should be directed at correlating different surgical ablation subtypes to cardiac and cerebrovascular events at long-term follow-up.

A systematic review on the safety and efficacy of percutaneous edge-to-edge mitral valve repair with the MitraClip system for high surgical risk candidates

Background MitraClip implantation has emerged as a viable option in high surgical risk patients with severe mitral regurgitation (MR). We performed the present systematic review to assess the safety and efficacy of the MitraClip system for high surgical risk candidates with severe organic and/or functional MR. Methods Six electronic databases were searched for original published studies from January 2000 to March 2013. Two reviewers independently appraised studies, using a standard form, and extracted data on methodology, quality criteria, and outcome measures. All data were extracted and tabulated from the relevant articles’ texts, tables, and figures and checked by another reviewer. Results Overall 111 publications were identified. After applying selection criteria and removing serial publications with accumulating number of patients or increased length of follow-up, 12 publications with the most complete dataset were included for quality appraisal and data extraction. All 12 studies were prospective observational studies. Immediate procedural success ranged from 72–100%; 30 day mortality ranged from 0–7.8%. There was a significant improvement in haemodynamic profile and functional status after implantation. One year survival ranged from 75–90%. No long term outcomes have been reported for high surgical risk patients. Conclusions MitraClip implantation is an option in managing selected high surgical risk patients with severe MR. The current evidence suggests that MitraClip can be implanted with reproducible safety and feasibility profile in this subgroup of patients. Further prospective trials with mid- to long-term follow-up are required.