Arterial coronary artery bypass grafting is safe and effective in elderly patients

Multiarterial vs Single-Arterial Coronary Surgery: 10-Year Follow-up of 1 Million Patients

BACKGROUND

Although many options exist for multivessel coronary revascularization, controversy persists over whether multiarterial grafting (MAG) confers a survival advantage over single-arterial grafting (SAG) with saphenous vein in coronary artery bypass grafting (CABG). This study sought to compare longitudinal survival between patients undergoing MAG and those undergoing SAG.

METHODS

All patients undergoing isolated CABG with ≥2 bypass grafts in The Society of Thoracic Surgeons Adult Cardiac Surgery Database (2008-2019) were linked to the National Death Index. Risk adjustment was performed using inverse probability weighting and multivariable modeling. The primary end point was longitudinal survival. Subpopulation analyses were performed and volume thresholds were analyzed to determine optimal benefit.

RESULTS

A total of 1,021,632 patients underwent isolated CABG at 1108 programs (100,419 MAG [9.83%]; 920,943 SAG [90.17%]). Median follow-up was 5.30 years (range, 0-12 years). After risk adjustment, all characteristics were well balanced. At 10 years, MAG was associated with improved unadjusted (hazard ratio, 0.59; 95% CI 0.58-0.61) and adjusted (hazard ratio, 0.86; 95% CI, 0.85-0.88) 10-year survival. Center volume of ≥10 MAG cases/year was associated with benefit. MAG was associated with an overall survival advantage over SAG in all subgroups, including stable coronary disease, acute coronary syndrome, and acute infarction. Survival was equivalent to that with SAG for patients age ≥80 years and those with severe heart failure, renal failure, peripheral vascular disease, or obesity. Only patients with a body mass index ≥40 kg/m2 had superior survival with SAG.

CONCLUSIONS

Multiarterial CABG is associated with superior long-term survival and should be the surgical multivessel revascularization strategy of choice for patients with a body mass index of less than 40 kg/m2.

Impact of Graft Strategies on the Outcome of Octogenarians Undergoing Coronary Artery Bypass Grafting

PURPOSE

To analyse the outcome of coronary artery bypass grafting (CABG) in octogenarians with coronary multivessel disease and the impact of different graft strategies and other factors.

METHODS

Out of 1654 patients with multivessel disease who underwent CABG at our institution between January 2014 and March 2020, we investigated 225 consecutive patients with a median age of 82.1 years for survival prediction and need for coronary reintervention; a detailed outcome analysis was performed.

RESULTS

At mean follow-up of 3.3 years, the overall survival was 76.4%. An indication for emergency operation (p = 0.002), age (p <0.001), chronic pulmonary disease (p = 0.024), and reduced renal or ventricular function (p <0.001) had the highest impact on limited survival. The combination outcome of survival and coronary reintervention was 1.7-fold improved (p = 0.024) after use of the bilateral internal thoracic artery (BITA) (66.2%). Off-pump CABG (12%) revealed no impact on survival. Smokers showed a poorer outcome (p = 0.004). The logistic European System for Cardiac Operative Risk Evaluation was highly effective for evaluating long-term outcomes (p <0.001).

CONCLUSIONS

BITA grafting normalizes survival and reveals a better outcome in octogenarians with multivessel disease. However, patients at risk of poorer survival were operated under emergency conditions and those with pulmonary disease and reduced ventricular or renal function.

2023 AHA/ACC/ACCP/ASPC/NLA/PCNA Guideline for the Management of Patients With Chronic Coronary Disease: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2023 AHA/ACC/ACCP/ASPC/NLA/PCNA Guideline for the Management of Patients With Chronic Coronary Disease" provides an update to and consolidates new evidence since the "2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS Guideline for the Diagnosis and Management of Patients With Stable Ischemic Heart Disease" and the corresponding "2014 ACC/AHA/AATS/PCNA/SCAI/STS Focused Update of the Guideline for the Diagnosis and Management of Patients With Stable Ischemic Heart Disease."

METHODS

A comprehensive literature search was conducted from September 2021 to May 2022. Clinical studies, systematic reviews and meta-analyses, and other evidence conducted on human participants were identified that were published in English from MEDLINE (through PubMed), EMBASE, the Cochrane Library, Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline.

STRUCTURE

This guideline provides an evidenced-based and patient-centered approach to management of patients with chronic coronary disease, considering social determinants of health and incorporating the principles of shared decision-making and team-based care. Relevant topics include general approaches to treatment decisions, guideline-directed management and therapy to reduce symptoms and future cardiovascular events, decision-making pertaining to revascularization in patients with chronic coronary disease, recommendations for management in special populations, patient follow-up and monitoring, evidence gaps, and areas in need of future research. Where applicable, and based on availability of cost-effectiveness data, cost-value recommendations are also provided for clinicians. Many recommendations from previously published guidelines have been updated with new evidence, and new recommendations have been created when supported by published data.

2023 AHA/ACC/ACCP/ASPC/NLA/PCNA Guideline for the Management of Patients With Chronic Coronary Disease: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2023 AHA/ACC/ACCP/ASPC/NLA/PCNA Guideline for the Management of Patients With Chronic Coronary Disease" provides an update to and consolidates new evidence since the "2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS Guideline for the Diagnosis and Management of Patients With Stable Ischemic Heart Disease" and the corresponding "2014 ACC/AHA/AATS/PCNA/SCAI/STS Focused Update of the Guideline for the Diagnosis and Management of Patients With Stable Ischemic Heart Disease."

METHODS

A comprehensive literature search was conducted from September 2021 to May 2022. Clinical studies, systematic reviews and meta-analyses, and other evidence conducted on human participants were identified that were published in English from MEDLINE (through PubMed), EMBASE, the Cochrane Library, Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline.

STRUCTURE

This guideline provides an evidenced-based and patient-centered approach to management of patients with chronic coronary disease, considering social determinants of health and incorporating the principles of shared decision-making and team-based care. Relevant topics include general approaches to treatment decisions, guideline-directed management and therapy to reduce symptoms and future cardiovascular events, decision-making pertaining to revascularization in patients with chronic coronary disease, recommendations for management in special populations, patient follow-up and monitoring, evidence gaps, and areas in need of future research. Where applicable, and based on availability of cost-effectiveness data, cost-value recommendations are also provided for clinicians. Many recommendations from previously published guidelines have been updated with new evidence, and new recommendations have been created when supported by published data.

Meta-Analysis of Bilateral Versus Single Internal Thoracic Artery Grafting in Patients ≥70 Years of Age

The optimal choice of graft material in patients ≥70 years of age undergoing coronary artery bypass grafting remains unknown. A systematic review of literature was conducted by searching PubMed, Embase, Web of Science, and Cochrane Library databases for original publications that compared bilateral internal thoracic artery (BITA) grafting with single internal thoracic artery grafting in patients ≥70 years of age. Data were extracted by 2 independent investigators and meta-analyzed with the use of random effects. A total of 10 studies, including 11,185 patients, met the inclusion criteria. No differences in early mortality and morbidity, with the exemption of sternal wound complications which were more frequently observed in the BITA group (odds ratio 1.72, 95% 1.00 to 2.96 confidence interval [CI], p = 0.05; propensity score-matched population odds ratio 1.58, 95% CI 1.09 to 2.29, p = 0.02), were observed. Overall survival was superior in the overall patient population (hazard ratio [HR] 0.76, 95% CI 0.66 to 0.86, p <0.001), after applying a blanking period of 3 months to the overall patient population (HR 0.77, 95% CI 0.64 to 0.92, p = 0.005) as well as in the matched population (HR 0.72, 95% CI 0.58 to 0.89, p = 0.002); in all cases, a benefit was readily seen within a few years after surgery. The difference in freedom from major adverse cardiac and cerebrovascular events failed to reach statistical significance (overall patient population HR 0.55, 95% CI 0.27 to 1.13, p = 0.10; matched population HR 0.52, 95% CI 0.23 to 1.16, p = 0.11). In conclusion, BITA grafting can be safely performed in patients ≥70 years of age as late clinical benefits are expected to manifest themselves readily within a few years after surgery.

Does Age Affect the Short- and Long-Term Outcomes of Coronary Bypass Grafting?

The etiology of coronary artery disease (CAD) is multifactorial, stemming from both modifiable and nonmodifiable risk factors such as age. Several studies have reported the effects of age on various outcomes of coronary artery bypass grafting (CABG). This article reviews age-related outcomes of CABG and offers direction for further studies in the field to create comprehensive, evidence-based guidelines for the treatment of CAD. Ninety-two primary sources were analyzed for relevance to the subject matter, of which 17 were selected for further analysis: 14 retrospective cohort studies, 2 randomized clinical trials, and 1 meta-analysis. Our review revealed four broad age ranges into which patients can be grouped: those with CAD (1) below the age of 40 years, (2) between the ages of 40 and 60 years, (3) between the ages of 60 and 80 years, and (4) at or above 80 years. Patients below the age of 40 years fare best overall with total arterial revascularization (TAR). Patients between the ages of 40 and 60 years also fare well with the use of multiarterial grafts (MAGs) whereas either MAGs or single-arterial grafts may be of significant benefit to patients at or above the age of 60 years, with younger and diabetic patients benefitting the most. Arterial grafting is superior to vein grafting until the age of 80 years, at which point there is promising evidence supporting the continued use of the saphenous vein as the favored graft substrate. Age is a factor affecting the outcomes of CABG but should not serve as a barrier to offering patients CABG at any age from either a cost or a health perspective. Operative intervention starts to show significant mortality consequences at the age of 80 years, but the increased risk is countered by maintenance or improvement to patients' quality of life.

Robustness of the Comparative Observational Evidence Supporting Class I and II Cardiac Surgery Procedures

Background

Current cardiac surgery guidelines give Class I and II recommendations to valve‐sparing root replacement over the Bentall procedure, mitral valve (MV) repair over replacement, and multiple arterial grafting with bilateral internal thoracic artery based on observational evidence. We evaluated the robustness of the observational studies supporting these recommendations using the E value, an index of unmeasured confounding.

Methods and Results

Observational studies cited in the guidelines and in the 3 largest meta‐analyses comparing the procedures were evaluated for statistically significant effect measures. Two E values were calculated: 1 for the effect‐size estimate and 1 for the lower limit of the 95% CI. Thirty‐one observational studies were identified, and E values were computed for 75 effect estimates. The observed effect estimates for improved clinical outcomes with valve‐sparing root replacement versus the Bentall procedure, MV repair versus replacement, and grafting with bilateral internal thoracic artery versus single internal thoracic artery could be explained by an unmeasured confounder that was associated with both the treatment and outcome by a risk ratio of more than 16.77, 4.32, and 3.14, respectively. For MV repair versus replacement and grafting with bilateral internal thoracic artery versus single internal thoracic artery, the average E values were lower than the effect sizes of the other measured confounders in 33.3% and 60.9% of the studies, respectively. For valve‐sparing root replacement versus the Bentall procedure, no study reported effect sizes for associations of other covariates with outcomes.

Conclusions

The E values for observational evidence supporting the use of valve‐sparing root replacement, MV repair, and grafting with bilateral internal thoracic artery over the Bentall procedure, MV replacement, and grafting with single internal thoracic artery are relatively low. This suggests that small‐to‐moderate unmeasured confounding could explain most of the observed associations for these procedures.

Multi-arterial and total-arterial coronary revascularization: Past, present, and future perspective

BACKGROUND AND AIM OF THE STUDY

Although abundant biological, clinical, and scientific evidence exists on the superiority of multi-arterial (MAR) and total-arterial revascularization (TAR) over the conventional strategy with a single internal thoracic artery, only 10% of patients undergoing coronary artery bypass grafting (CABG) in the United States receives a second arterial conduit, and only 5% of patients receives TAR.

METHODS AND RESULTS

In January 2020, the authors performed comprehensive search to identify studies that evaluated MAR and TAR strategies through the MEDLINE database.

CONCLUSIONS

In this paper, the authors reviewed the literature on the historical and current evidence in favor of MAR and TAR, thus underlying why current CABG practice needs qualitative improvement.

Bilateral internal thoracic artery grafting in patients with left main disease: a single-center experience

OBJECTIVE

We compared early and long-term outcomes between bilateral internal thoracic artery (BITA) grafting and single internal thoracic artery (SITA) grafting in patients with LM disease.

METHODS

We evaluated the outcomes of all patients with LM disease who underwent revascularization in our center during 1996-2011. Variables that were adjusted for in a multivariate analysis and in propensity matching included age, sex, comorbid diseases, repeat operation, the number of diseased vessels, other conduits used, the use of sequential grafting, the number of grafts constructed, and the operative era (1996-2000 vs. 2001-2011).

RESULTS

In total, 949 patients with LM disease underwent BITA grafting and 564 underwent SITA grafting during the study period. SITA patients were more often female and more likely to have comorbidities such as chronic obstructive pulmonary disease, ejection fraction <30%, recent myocardial infarction, diabetes, congestive heart failure, chronic renal failure, and peripheral vascular disease, and to have undergone an emergency operation. We found no statistically significant difference between the SITA and BITA groups in 30-day mortality (4.8% vs. 3.3%, P = 0.136), sternal wound infection (2.0% vs. 2.4%, P = 0.548), and stroke (3.2% vs. 4.4%, P = 0.234). BITA patients had improved long-term survival (70.1% vs. 52.0% p<0.001), median follow-up of 15 years. In multivariate analysis, after propensity score matching (477 matched pairs), this finding was not statistically significant (P = 0.135).

CONCLUSION

This study did not demonstrate a clear benefit of BITA grafts among patients with LM disease.

Are two internal thoracic grafts better than one in patients with peripheral vascular disease?

BACKGROUND

The use of two bilateral internal thoracic artery grafting (BITA) was shown to lead to survival benefit. However, operators are reluctant to use BITA with peripheral vascular disease (PVD) because of concerns of increased rates of sternal wound infection and lack of studies supporting survival benefit compared with single internal thoracic artery (SITA) grafting. The aim of this study is to compare outcome BITA grafting versus of SITA and vein grafts in PVD patients.

PATIENTS AND METHODS

Six hundred and twenty-one PVD patients who underwent BITA between 1996 and 2011 were compared with 372 patients who underwent SITA.

RESULTS

SITA patients were older and more likely more likely to have comorbidities (female, insulin-dependent diabetes, chronic obstructive lung disease, congestive heart failure, previous coronary artery bypass grafting, renal insufficiency, cerebrovascular disease, and emergency operation). Operative mortality (5.1 vs. 4.5%, in the SITA and BITA, respectively, P=0.758), rate of sternal wound infection (5.1 vs. 3.9%, P=0.421), and strokes (4.8 vs. 7.4%, P=0.141) were not significantly different between groups. BITA patients did not have significantly better 10-year survival (52.6 vs. 45.9%, P=0.087) and after propensity score matching (302 well-matched pairs), BITA was not associated with improved survival (hazard ratio: 0.902; 95% confidence interval: 0.742-1.283; P=0.784) (Cox model).

CONCLUSION

The routine use of BITA versus SITA in PVD patients does not improve long-term survival. Selective use of BITA in lower risk patients might unmask the benefits of BITA.

The impact of the radial artery or the saphenous vein in addition to the bilateral internal mammary arteries on late survival: A propensity score analysis

BACKGROUND

Long-term survival benefits of full arterial revascularization with radial artery (RA) used in addition to bilateral internal mammary arteries (BIMA) compared with saphenous vein (SV) used in addition to BIMA has not been clearly defined.

METHODS

We retrospectively analyzed 660 3-vessel coronary artery disease subjects who received BIMA in addition to either RA (n = 206) or SV (n = 454) grafting in a period between June 1999 and November 2017. After propensity score matching, we obtained 190 matched pairs for analysis.

RESULTS

In the matched population, in-hospital mortality occurred in 4 patients (1%), with 2 deaths (1.1%) in the BIMA + RA group and 2 deaths (1.1%) in BIMA + SV group (P > .99). The median follow-up time was 9.2 years (interquartile range, 5.6-13 years) with a maximum follow-up time of 18.5 years. There was not a significant difference in long-term survival between the 2 groups over the follow-up period. Survival at 5, 10, and 15 years were 94.8 ± 1.7%, 83.7 ± 3.1%, and 78.6 ± 3.9% in the BIMA + RA group and 96.2 ± 1.4%, 85.1 ± 2.9%, and 80.4 ± 3.6% in the BIMA + SV group (stratified log-rank P = .78). Cox proportional hazard regression model was used to estimate that the use of RA in addition to BIMA did not affect the late mortality (propensity score adjusted hazard ratio, 1.05; 95% confidence interval, 0.62-1.79; P = .83).

CONCLUSIONS

In a relatively small population of triple-vessel coronary artery disease, the use of RA as a third arterial conduit with BIMA did not confer a long-term survival benefit.

Are two internal thoracic grafts better than one in patients with chronic obstructive lung disease? Analysis of 387 cases between 1996-2011

Objectives

Bilateral internal thoracic artery (ITA) grafting is associated with improved survival. However, potential survival benefit of using two ITA`s in patients with chronic lung disease (CLD) is questionable due to their increased risk of sternal wound infection (SWI) compared to operations incorporating single ITA (SITA). The purpose of this study is to compare early and long-term outcome of bilateral internal thoracic artery (BITA) grafting to that of grafting with single internal thoracic grafts and vein grafts or radial artery (SITA) in CLD patients with multi-vessels coronary disease.

Methods

One hundred and forty eight CLD patients who underwent BITA between 1996 and 2011 were compared with 239 who underwent SITA at the same period.

Results

SITA patients were more often female, more likely to have insulin treated diabetes (DM), DM with end organ damage, neurologic dysfunction and unstable angina.

Despite of the difference in preoperative characteristics, early mortality (5.4% vs. 5.4%, in the SITA and BITA respectively, p = 0 < .999) and occurrences of SWI (6.3% vs 9.5%, p = 0.320) and strokes (3.8% vs 5.4%,p = 0.611) were not significantly different between groups. BITA patients did not have better Kaplan-Meier 10 year survival (52.8% vs. 42.6%, p = 0.088) and after matching, BITA and SITA had similar adjusted survival (HR 0.983[95%CI 0.755–1.280] p = 0.901) (cox model).

Conclusion

Our study results suggest that in patients with CLD, the choice of BITA grafting technique did not provide survival benefit compared to SITA with other conduits.

Use Rate and Outcome in Bilateral Internal Thoracic Artery Grafting: Insights From a Systematic Review and Meta-Analysis

Background

This meta‐analysis was designed to assess whether center experience affects the short‐ and long‐term results and the relative benefits of bilateral internal thoracic artery grafting (BITA) for coronary artery bypass grafting.

Methods and Results

MEDLINE and EMBASE were searched to identify all articles reporting the outcome of BITA in patients undergoing coronary artery bypass grafting. The BITA center experience was gauged according to the percentage use of BITA in the institutional overall coronary artery bypass grafting population (%BITA). The primary outcome was long‐term all‐cause mortality. Secondary outcomes were operative mortality, perioperative myocardial infarction, perioperative stroke, deep sternal wound infections (DSWIs), and major postoperative adverse event. The rates of the primary and secondary outcomes were calculated after adjusting for %BITA. Primary and secondary outcomes were also compared between the BITA and the single internal thoracic artery arms in the adjusted studies. Meta‐regression was used to evaluate the effect of %BITA on the primary and secondary outcomes. Thirty‐four studies (27 894 patients undergoing BITA) were included. In the pooled analysis, the incidence rate for long‐term mortality was 2.83% (95% confidence interval, 2.21%–3.61%). %BITA was significantly and inversely associated with long‐term mortality and the rate of DSWI. In the pairwise comparison, %BITA was significantly and inversely associated with the risk of long‐term mortality and DSWI in the group undergoing BITA.

Conclusions

BITA series with higher %BITA report significantly lower long‐term mortality and DSWI rate as well as higher long‐term survival advantage and lower relative risk of DSWI in their BITA cohort. These findings suggest that a specific volume‐outcome relationship exists for BITA grafting.

Unmeasured Confounders in Observational Studies Comparing Bilateral Versus Single Internal Thoracic Artery for Coronary Artery Bypass Grafting: A Meta-Analysis

Background

Observational studies suggest a survival advantage with bilateral single internal thoracic artery (BITA) versus single internal thoracic artery grafting for coronary surgery, whereas this conclusion is not supported by randomized trials. We hypothesized that this inconsistency is attributed to unmeasured confounders intrinsic to observational studies. To test our hypothesis, we performed a meta‐analysis of the observational literature comparing BITA and single internal thoracic artery, deriving incident rate ratio for mortality at end of follow‐up and at 1 year. We postulated that BITA would not affect 1‐year survival based on the natural history of coronary artery bypass occlusion, so that a difference between groups at 1 year could not be attributed to the intervention.

Methods and Results

We searched MEDLINE and Pubmed to identify all observational studies comparing the outcome of BITA versus single internal thoracic artery. One‐year and long‐term mortality for BITA and single internal thoracic artery were compared in the propensity‐score–matched (PSM) series, that is, the form of observational evidence less prone to confounders. Thirty‐eight observational studies (174 205 total patients) were selected for final comparison. In the 12 propensity‐score–matched series (34 019 patients), the mortality reduction for BITA was similar at 1 year and at the end of follow‐up (incident rate ratio, 0.70; 95% confidence interval, 0.60–0.82 versus 0.77; 95% confidence interval, 0.70–0.85; P for subgroup difference=0.43).

Conclusions

Unmeasured confounders, rather than biological superiority, may explain the survival advantage of BITA in observational series.

Coronary Artery Bypass Grafting with Arterial Conduits in the Elderly

Although improved long-term outcomes obtained with the use of arterial grafts for coronary revascularization in comparison with the traditional association of a single arterial and saphenous vein grafts have been demonstrated in the overall population, the efficacy of this newer technique in the elderly is difficult to prove because their shorter life expectancy due to advanced heart disease, associated with severe comorbidities. Moreover, more widespread use of this technique is limited by the concerns on the potential morbidity, particularly the longer time required to perform the operation and the possibility of deep sternal wound infection in case of bilateral internal thoracic artery harvesting due to the decreased blood supply to the sternum and surrounding tissues.The review of the recent literature indicates that the use of bilateral internal thoracic arteries in very elderly patients should not be considered routinely. It seems reasonable to avoid it in octogenarians in the presence of well-known predictors of sternal complications such as diabetes, morbid obesity, and severe chronic lung disease.There is also still controversy about the superiority of the radial artery over the saphenous vein graft as a second or third conduit for surgical myocardial revascularization, although the majority of recent studies seem to support more liberal use of the radial artery as second arterial conduit in the elderly. Although a clinical benefit of arterial graft revascularization cannot be formally excluded for elderly patients, the increased complexity of this technique suggests that careful clinical judgment is necessary to select grafts for individual patients.

Effects of age on systemic inflamatory response syndrome and results of coronary bypass surgery

Background

Coronary artery bypass (CAB) surgery triggerssystemic inflammatory response syndrome (SIRS) via severalmechanisms. Moreover, age is directly correlated with SIRS.We evaluated the effect of age on SIRS and postoperativeoutcome after CAB surgery.

Methods

We retrospectively reviewed the records of 229 patients who had undergone CAB surgery. The patients were divided into three groups according to age: group 1, < 40 years (n = 61); group 2, 40–75 years (n = 83); and group 3, > 75 years old (n = 85). Pre- and peri-operative data were assessed in all patients. SIRS was diagnosed according to the criteria established by Boehme.

Results

The average pre-operative EuroSCORE value in group 3 was higher than in the other groups and body surface areas were significantly lower in group 3 than in the other groups (p < 0.05). The postoperative SIRS rates were 68.9% in group 1, 84.3% in group 2 and 91.8% in group 3 (group 1 vs group 3; p < 0.05). Mortality rates were not significantly different between the groups (p > 0.05). The predictive factors for SIRS were age, EuroSCORE rate, on-pump CAB surgery and intra-aortic balloon pump use.

Conclusion

Age was an important risk factor for SIRS during the postoperative period after CAB.

Multiple arterial grafting for coronary revascularization: "A guide for the perplexed"

The surgical literature abounds with articles extolling the benefits of arterial grafting for patients with advanced coronary artery disease in need of surgical revascularization. However, examination of clinical performance demonstrates that extensive use of arterial grafting is highly selective and generally uncommon. Rather than to merely repeat multiple excellent recent literature reviews, the goal herein is to provide the reader with a guide to the evaluation of the current literature as well as to suggest fruitful areas for further research. More circumspect understanding of the strengths and weaknesses of our current knowledge base will not only help to explain the current apparent disparity between theory and practice but will hopefully inform future decision-making and patient care.