A randomized comparison of right ventricular function after on-pump versus off-pump coronary artery bypass graft surgery

The Postoperative Paradoxical Septum (POPS): A Comprehensive Review on Physio-Pathological Mechanisms

The interventricular septum (IVS) is a core myocardial structure involved in biventricular coupling and performance. Physiologically, during systole, it moves symmetrically toward the center of the left ventricle (LV) and opposite during diastole. Several pathological conditions produce a reversal or paradoxical septal motion, such as after uncomplicated cardiac surgery (CS). The postoperative paradoxical septum (POPS) was observed in a high rate of cases, representing a unicum in the panorama of paradoxical septa as it does not induce significant ventricular morpho-functional alterations nor negative clinical impact. Although it was previously considered a postoperative event, evidence suggests that it might also appear during surgery and gradually resolve over time. The mechanism behind this phenomenon is still debated. In this article, we will provide a comprehensive review of the various theories generated over the past fifty years to explain its pathological basis. Finally, we will attempt to give a heuristic interpretation of the biventricular postoperative motion pattern based on the switch of the ventricular anchor points.

Interchangeability of transthoracic and transesophageal echocardiographic right heart measurements in the perioperative setting and correlation with hemodynamic parameters

Reduction of right ventricular (RV) function after cardiac surgery has been shown to impact outcomes. Conventional indices for right ventricular dysfunction are validated using transthoracic echocardiogram (TTE) which has limited use compared to transesophageal echocardiogram (TEE) in the perioperative settings. The aim of this study was to assess the agreement of RV systolic function assessment with TEE compared to TTE and assess the association of echocardiographic parameter with hemodynamic indices of RV dysfunction. This was a single center prospective observational study in an academic institution. Fifty adult patients undergoing elective cardiac surgery were included. TTE, TEE and stroke volume measurements pre-cardiopulmonary bypass (CPB) and post-CPB were performed. The variables of interest were anatomical M-mode tricuspid annular plane systolic excursion (AMM-TAPSE), fractional area change (FAC), tricuspid annular velocity (S') and myocardial performance index (MPI). FAC and AMM-TAPSE measured at the mid-esophageal 4 chamber view had substantial agreement with the TTE acquired parameters (Lin's concordance correlation coefficient (CCC) = 0.76, 95%CI 0.59-0.86 and CCC = 0.85, 95%CI 0.76-0.91). S' was significantly underestimated by TEE (CCC = 0.07, 95%CI 0.04-0.19) and MPI showed moderate agreement (CCC = 0.45 95%CI 0.19-0.65). Despite the significant changes in echocardiographic parameters, there were no corresponding changes in stroke volume (SV) or pulmonary artery pulsatility index at the post-CPB period. TEE acquired FAC and AMM-TAPSE had substantial agreement with pre-operative TTE values and no significant differences between the pre-CPB and post-CPB period. Systolic RV echocardiographic parameters decreased post-CPB but this was not accompanied by significant hemodynamic changes.

Paradoxical Septal Motion after Uncomplicated Cardiac Surgery: A Consequence of Altered Regional Right Ventricular Contractile Patterns

Paroxysmal interventricular septal motion (PSM) is the movement of the septum toward the right ventricle (RV) during cardiac systole. It occurs frequently after uncomplicated cardiac surgery (CS), including coronary bypass (on-pump and off-pump), valve repair or replacement, and with all types of incisions (sternotomy or mini-thoracotomy). It sometimes resolves quickly but may persist for months or become permanent. Global RV systolic function, stroke volume and ejection fraction remain normal after uncomplicated CS, but regional contractile patterns are altered. There is a decrease in longitudinal shortening but an increase in transverse shortening in the endocardial and epicardial right ventricular muscle fibers, respectively. PSM is a secondary event as there is no loss of septal perfusion or thickening. The increased RV transverse shortening (free wall to septal fibers) may modify septal movement resulting in PSM that compensates for the reduced RV longitudinal shortening, thus preserving normal global right ventricular function.

Representation of Women in Randomized Trials in Cardiac Surgery: A Meta-Analysis

Background

Women have traditionally been underrepresented in randomized clinical trials (RCTs). We performed a systematic evaluation of the inclusion of women in cardiac surgery RCTs published in the past 2 decades.

Methods and Results

MEDLINE, EMBASE, and the Cochrane Library were searched (2000 to July 2020) for RCTs written in English, comparing ≥2 adult cardiac surgical procedures. The percentage of women enrolled and its association with year of publication, sample size, mean age, funding source, geographic location, number of sites involved, and interventions tested were analyzed using a meta‐analytic approach. Fifty‐one trials were included. Of 25 425 total patients, 5029 were women (20.8%; 95% CI, 17.6–24.4; range, 0.5%–57.9%). The proportion of women dropped significantly during the study period (29.6% in 2000 versus 13.1% in 2019, P<0.001). Women were significantly more represented in European trials (26.2%; 95% CI, 21.2–31.9), and less represented in trials of coronary bypass surgery versus other interventions (16.8%; 95% CI, 12.3–22.7 versus 33.6%; 95% CI, 27.4–40.5; P=0.0002) and in trials enrolling younger patients (P=0.009); the percentage of women was higher in industry‐sponsored versus non‐industry sponsored trials (31.7%; 95% CI, 27.2–36.6 versus 15.5%; 95% CI, 10.0–23.2; P=0.0004) and was not associated with trial sample size (P=0.52) or study design (multicenter versus monocenter: P=0.22). After exclusion of trials conducted at Veteran Affairs centers, women representation was 24.4% (95% CI, 21.1–28.0; range, 10.4%–57.9%), with no significant changes during the study period.

Conclusions

The proportion of women in cardiac surgery trials is low and likely inadequate to provide meaningful estimates of the treatment effect.

Preoperative right ventricular dysfunction requires high vasoactive and inotropic support during off-pump coronary artery bypass grafting

Objectives

The association of preoperative RV function with hemodynamics during OPCAB or emergency conversion is not clear. The aim of this study was to investigate the association of vasoactive-inotropic score with tricuspid annular plane systolic excursion and tricuspid regurgitation in off-pump coronary artery bypass grafting, and to calculate the optimal cut-off value of tricuspid annular plane systolic excursion to predict emergency conversion to cardiopulmonary bypass.

Methods

Patients over 20 years of age who had undergone off-pump coronary artery bypass grafting between April 2015 and March 2020 were enrolled in this study. We retrospectively assessed the association of intraoperative maximum “vasoactive-inotropic score”, a weighted sum of various inotropes and vasoconstrictors, with tricuspid annular plane systolic excursion and tricuspid regurgitation. A receiver operating characteristic curve of conversion on tricuspid annular plane systolic excursion was also constructed.

Results

135 patients were included in final analysis. Conversion was performed in 10 cases. Multiple regression analysis showed that tricuspid annular plane systolic excursion, mild or more tricuspid regurgitation and experienced surgeon were significantly related to vasoactive-inotropic score. The receiver operating characteristic curve to predict conversion by tricuspid annular plane systolic excursion showed an optimal cut-off value of 15.0 mm and area under the curve of 0.808.

Conclusions

Tricuspid annular plane systolic excursion and tricuspid regurgitation were associated with vasoactive-inotropic score in off-pump coronary artery bypass grafting. The optimal cut-off value of tricuspid annular plane systolic excursion to predict emergency conversion was 15 mm.

Effect of Age on Clinical Outcomes Following On-/Off-Pump Coronary Artery Bypass: Meta-Analysis and Meta-Regression

Objective

There is currently much debate about which patients would benefit more after on- or off-pump coronary artery bypass grafting (CABG). The aim of this meta-analysis and meta-regression is to investigate the effect of age on short-term clinical outcomes after these approaches.

Methods

To identify potential studies, systematic searches were carried out in the Excerpta Medica dataBASE (EMBASE), PubMed, Web of Science, and the Cochrane Central Register of Controlled Trials (CENTRAL). The search strategy included the key concepts of “cardiopulmonary bypass” AND “coronary artery bypass grafting” AND “off pump” OR “on pump”. This was followed by a meta-analysis and meta-regression investigating the effect of age on the incidences of stroke, myocardial infarction (MI), and mortality.

Results

Thirty-seven studies including 15,324 participants were analysed. Overall, there was a significant odds reduction for patients receiving off-pump CABG suffering a stroke (odds ratio [OR] 0.770, 95% confidence intervals [CI] 0.594, 0.998, P=0.048); however, when patients were subdivided according to different age bands, this difference disappeared. There were also no significant differences in the odds of mortality (OR 0.876, 95% CI 0.703, 1.093, P=0.241) or MI (OR 0.937, 95% CI 0.795, 1.105, P=0.439). Meta-regression analysis revealed no significant relationship between age and stroke (P=0.652), age and mortality (P=548), and age and MI (P=0.464).

Conclusion

Patients undergoing CABG are becoming older and may suffer from multiple comorbidities increasing their risk profile. However, with respect to short-term clinical outcomes, the patient’s age does not help in determining whether off- or on-pump is superior.

Changes in Right Ventricular Function After Off-Pump Coronary Artery Bypass Grafting

OBJECTIVE

Right ventricular (RV) dysfunction is associated with poor outcomes after cardiac surgery. The aim of this study was to assess RV systolic and diastolic function in the perioperative period after off-pump coronary artery bypass grafting (OPCAB).

DESIGN

Prospective observational study.

SETTINGS

Tertiary care hospital.

PARTICIPANTS

Thirty adult patients undergoing OPCAB.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Transthoracic echocardiography was performed twice: first preoperatively and second postoperatively, when patients were moved to wards. The following five parameters of RV systolic function were used: tricuspid annular plane systolic excursion (TAPSE), systolic tissue Doppler imaging of lateral tricuspid annulus (S'), fractional area change (FAC), RV myocardial performance index (RIMP), and isovolumic acceleration (IVA). Grading of RV diastolic function (RVDD) was done as per guidelines. Paired t test was used for comparing means and χ² test was used for categorical and ordinal data. The parameters of RV longitudinal function (TAPSE and S') reduced significantly (preoperative 21.93 ± 2.80 mm and 13.24 ± 2.24 cm/s to postoperative 11.67 ± 1.91 mm and 10.31 ± 1.56 cm/s, respectively, p < 0.001), whereas parameters of RV global function (FAC, RIMP, and IVA) remained preserved (preoperative 46.75 ± 6.80%, 0.34 ± 0.06, and 4.66 ± 0.87 m/s² to postoperative 46.21 ± 6.44%, 0.36 ± 0.06, and 4.37 ± 0.83 m/s²; p values of 0.76, 0.13, and 0.11, respectively). The median grade of RVDD worsened from normal in the preoperative period to pseudo-normal in the postoperative period (p < 0.001). The changes in both RV systolic and diastolic function were similar in patients with normal and reduced left ventricular systolic function.

CONCLUSIONS

RV function can be assessed in perioperative settings with two-dimensional and tissue Doppler imaging. For systolic function assessment, exclusive measurement of longitudinal parameters might be inadequate; use of complementary global parameters like FAC, RIMP, and IVA is essential to complete the RV assessment after OPCAB. RVDD worsened significantly after OPCABG.

Off- Versus On-Pump Coronary Surgery and the Effect of Follow-Up Length and Surgeons' Experience: A Meta-Analysis

Background The debate on the relative benefits of off-pump and on-pump coronary artery bypass surgery ( OPCABG and ONCABG ) is still open. We aimed to provide an updated and complete summary of the evidence on the differences between OPCABG and ONCABG and to explore whether the length of the follow-up and the surgeons' experience in OPCABG modify the comparative results. Methods and Results All randomized clinical trials comparing OPCABG and ONCABG were included. Primary outcome was follow-up mortality. Secondary outcomes were operative mortality, perioperative stroke, perioperative myocardial infarction, and late repeated revascularization. Subgroup analyses were performed based on the length of the follow-up and the percentage of crossover from the OPCABG group (used as a surrogate of surgeon experience with OPCABG ). One hundred four trials were included (20 627 patients, OPCABG : 10 288; ONCABG : 10 339). Weighted mean follow-up time was 3.7 years (range 1-7.5 years). OPCABG was associated with a higher risk of follow-up mortality (incidence rate ratio 1.11, 95% confidence interval 1.00-1.23, P=0.05). The difference was significant only for trials with mean follow-up of ≥3 years and for studies with a crossover rate of ≥10%. There was a trend toward lower risk of perioperative stroke and higher need for late repeated revascularization in the OPCABG arm. Conclusions OPCABG is associated with a higher incidence of incomplete revascularization, an increased need for repeated revascularization, and decreased midterm survival compared with ONCABG . Surgeon inexperience in OPCABG is associated with late mortality.

Efficacy and effectiveness of on- versus off-pump coronary artery bypass grafting: A meta-analysis of mortality and survival

BACKGROUND

Despite many studies comparing on- versus off-pump coronary artery bypass graft (CABG), there is no consensus as to whether one of these techniques offers patients better outcomes.

METHODS

We searched PubMed from inception to June 30, 2015, and identified additional studies from bibliographies of meta-analyses and reviews. We identified 42 randomized controlled trials (RCTs) and 31 rigorously adjusted observational studies (controlling for the Society of Thoracic Surgeons-recognized risk factors for mortality) reporting mortality for off-pump versus on-pump CABG at specified time points. Trial data were extracted independently by 2 researchers using a standardized form. Differences in probability of mortality (DPM) were estimated for the RCTs and observational studies separately and combined, for time points ranging from 30 days to 10 years.

RESULTS

RCT-only data showed no significant differences at any time point, whereas observational-only data and the combined analysis showed short-term mortality favored off-pump CABG (n = 1.2 million patients; 36 RCTs, 26 observational studies; DPM [95% confidence interval (CI)], -44.8% [-45.4%, -43.8%]) but that at 5 years it was associated with significantly greater mortality (n = 60,405 patients; 3 RCTs, 5 observational studies; DPM [95% CI], 10.0% [5.0%, 15.0%]). At 10 years, only observational data were available, and off-pump CABG showed significantly greater mortality (DPM [95% CI], 14.0% [11.0%, 17.0%]).

CONCLUSIONS

Evidence from RCTs showed no differences between the techniques, whereas rigorously adjusted observational studies (with >1.1 million patients) and the combined analysis indicated that off-pump CABG offers lower short-term mortality but poorer long-term survival. These results suggest that, in real-world settings, greater operative safety with off-pump CABG comes at the expense of lasting survival gains.

Postoperative Right Ventricular Failure in Cardiac Surgery

Two cases of patients that developed right ventricular failure (RVF) after cardiac valve surgery are presented with a narrative revision of the literature. RVF involves a great challenge due to the severity of this condition; it has a low incidence among non-congenital cardiac surgery patients, is more likely associated with cardiovascular and pulmonary complications related to cardiopulmonary bypass (CPB), and is a cause of acute graft failure and of a higher early mortality in cardiac transplant. The morphologic and hemodynamic characteristics of the right ventricle and some specific factors that breed pulmonary hypertension after cardiac surgery are in favor of the onset of RVF. Due to the possibility of complications after cardiac valve repair or replacement, measures as appropriate hemodynamic monitoring, to manage oxygenation, ventilation, sedation, acid base equilibrium and perfusion goals are a requirement, as well as a normal circulating volume, and the prevention of a disproportionate rise in the afterload, to preserve the free wall of the right ventricle (RV) and the septum's contribution to the right ventricular global function and geometry. If there is no response to these basic measures, the use of advanced therapy with inotropics, intravenous or inhaled pulmonary vasodilation agents is recommended; the use of mechanical ventricular assistance stands as a last resource.

Off-pump coronary artery bypass grafting improves short-term outcomes in high-risk patients compared with on-pump coronary artery bypass grafting: Meta-analysis

OBJECTIVES

To assess the benefits and risks of off-pump coronary artery bypass (OPCAB) versus coronary artery bypass grafting (CABG) through a meta-analysis of randomized controlled trials (RCTs), and to investigate the relationship between outcomes and patient risk profile.

METHODS

PubMed, Embase, the Cumulative Index of Nursing and Allied Health Literature, Scopus, Web of Science, Cochrane Library, and major conference proceedings databases were searched for RCTs comparing OPCAB and CABG and reporting short-term (≤ 30 days) outcomes. Endpoints assessed were all-cause mortality, myocardial infarction (MI), and cerebral stroke.

RESULTS

The meta-analysis included 100 studies, with a total of 19,192 subjects. There was no difference between the 2 techniques with respect to all-cause mortality and MI (odds ratio [OR], 0.88; 95% confidence interval [CI], 0.71-1.09; P = .25; I(2) = 0% and OR, 0.90; 95% CI, 0.77-1.05; P = .19; I(2) = 0%, respectively). OPCAB was associated with a significant 28% reduction in the odds of cerebral stroke (OR, 0.72; 95% CI, 0.56-0.92; P = .009; I(2) = 0%). A significant relationship between patient risk profile and benefits from OPCAB was found in terms of all-cause mortality (P < .01), MI (P < .01), and cerebral stroke (P < .01).

CONCLUSIONS

OPCAB is associated with a significant reduction in the odds of cerebral stroke compared with conventional CABG. In addition, benefits of OPCAB in terms of death, MI, and cerebral stroke are significantly related to patient risk profile, suggesting that OPCAB should be strongly considered in high-risk patients.