Myocardial viability and impact of surgical ventricular reconstruction on outcomes of patients with severe left ventricular dysfunction undergoing coronary artery bypass surgery: results of the Surgical Treatment for Ischemic Heart Failure trial

AATS 2023: Left ventricular restoration with scar exclusion in the surgical treatment for ischemic heart failure

OBJECTIVE

Post-infarction myocardial scar as detected by cardiac magnetic resonance (CMR) is associated with adverse left ventricular (LV) remodeling and negatively affects the prognosis. We sought to analyze the impact of left ventricular restoration (LVR) with asynergic scar exclusion on long-term outcomes for patients with ischemic heart failure (IHF).

METHODS

From January 2005, 134 consecutive patients with IHF underwent scar-exclusive LVR. Among the 131 survivors, 108 patients had paired late gadolinium enhancement (LGE)-CMR preoperatively and one year after, and represent the study population. Patients were divided into two groups according to whether their post-LVR residual percentage of scarred LV perimeter was <35% (%Scar <35; n = 55) or more (%Scar ≥35; n = 53). We compared the two groups, by looking at LGE-CMR outcomes, and at long-term survival and cardiac event (hospitalization for cardiac causes)-free survival.

RESULTS

Postoperative LV end-systolic volume index decreased significantly and ejection fraction increased with significant increase in stroke volume index (P < 0.05 for both). LV diastolic function of the left atrial volume index was significantly improved in patients with residual %Scar <35 than in those with %Scar ≥35 (P interaction = 0.005). Median survival in patients with residual %Scar <35 and ≥ 35 were 8.3 (4.5-12.2) years and 6.8 (1.8-11.8) years respectively (P = 0.106). Median cardiac event-free survival in patients with %Scar <35 and ≥ 35 were 8.0 (3.9-12.1) years and 4.8 (0.8-8.8) years respectively (P < 0.001).

CONCLUSIONS

Scar-exclusive LVR yielded sustainable improvement in LV function and favorable long-term survival regardless of the extent of residual scar. The LVR should be performed to attain scar exclusion in the surgical treatment for IHF, which in turn might protectively affect LV diastolic function and cardiac event-free survival.

Outcomes of Coronary Artery Bypass Grafting in Patients With Poor Myocardial Viability: A Systematic Review and Meta-Analysis of the Last Decade

OBJECTIVES

Our objective is to assess whether the presence of myocardial viability is a predictor of mortality among patients undergoing coronary artery bypasss grafting (CABG) through a systematic review meta-analysis.

METHODS

Comprehensive review of EMBASE and PubMed in accordance with PRISMA guidelines, including studies of patients undergoing CABG with assessment of myocardial viability and recorded long-term mortality, age and sex. Studies were restricted to the last decade, and data were stratified by imaging modality (magnetic resonance imaging [MRI] or nuclear medicine). Random-effects model for assessing pooled effect, heterogeneity assessment using Chi-square and I² statistics, publication bias assessed by funnel plots and Egger's test.

RESULTS

Meta-analysis of contemporary data (January 2010 to October 2020) yielded 3,621 manuscripts of which 92 were relevant, and 6 appropriate for inclusion with 993 patients. Pooled analysis showed that patients with non-viable myocardium undergoing CABG are at 1.34 times the risk of mortality compared to those with viable myocardium (95% CI 1.01-1.79, p=0.05). Subgroup analysis of the MRI or nuclear medicine modalities was not statistically significant and there was no confounding by age or sex in meta-regression. There was significant heterogeneity in imaging modality and diagnostic criteria, but heterogeneity between study findings was low with an I² statistic of 29%. The risk of publication bias was moderate on the Newcastle-Ottawa Scale), but not statistically significant (Egger's Test coefficient=1.3, 95%CI -0.35-2.61, p=0.10).

CONCLUSIONS

There is a multitude of methods for assessing cardiac viability for coronary revascularisation surgery, making meta-analyses fraught with limitations. Our meta-analysis demonstrates that the finding of non-viable myocardium can not be used draw conclusions for risk assessment in coronary surgery.

Left ventricular function and survival in ischemic cardiomyopathy: Implications for surgical ventricular restoration

Objectives

This pilot study evaluates the association of relative wall thickness (RWT) on survival in patients with ischemic cardiomyopathy (ICM). We hypothesized that patients with preserved RWT may be better candidates for surgical ventricular restoration than those with thinner RWT.

Methods

Echocardiography was performed in 165 consecutive patients (aged 58.2 ± 14.7 years) divided into 2 groups based on RWT values. Group 1 had patients with preserved RWT and group 2 had patients with reduced RWT.

Results

There were 120 (72.7%) patients with hypertension and 112 (67.8%) patients had diabetes mellitus. The patients with preserved RWT (group 1) had significantly more hypertension and diabetes. The patients with decreased RWT (group 2) were in a higher New York Heart Association functional class and had significantly greater incidence of anterior wall myocardial infarction. The entire cohort was followed over 24 months (group 1: n = 117 and group 2: n = 48). The overall all-cause mortality in group 1 (preserved RWT) was 7 (5.9%) and in group 2 (reduced RWT) was 35 (72.9%) (P < .0001). When readmission for congestive heart failure was analyzed, group 2 patients with lower RWT (P < .0001) had an increased rate of readmissions for heart failure.

Conclusions

In patients with ischemic cardiomyopathy, a lower RWT indicative of dilated LV remodeling was associated with increased mortality and readmission for heart failure. The RWT may be a simple benchmark of viable or contractile myocardium in ICM. It can be hypothesized that patients with preserved RWT may benefit from surgical ventricular restoration.

Glycemic control and risk factors for in-hospital mortality and vascular complications after coronary artery bypass grafting in patients with and without preexisting diabetes

BACKGROUND

The purpose of this study was to investigate risk factors of in-hospital mortality and vascular complications after coronary artery bypass grafting (CABG), particularly the effect of different glycemic control levels on outcomes in patients with and without previous evidence of diabetes.

METHODS

A total of 8682 patients with and without previous diabetes undergoing CABG were categorized into strict, moderate, and liberal glucose control groups according to their mean blood glucose control level <7.8 mmol/L, 7.8 to 10.0 mmol/L, and ≥10.0 mmoL/L after in-hospital CABG.

RESULTS

The patients with previous diabetes had higher rates of in-hospital mortality (1.3% vs 0.4%, P < .001) and major complications (7.0% vs 4.8%, P < .001) than those without diabetes. Current diabetes was significantly associated with a higher risk of in-hospital mortality (odds ratio [OR] = 3.14, 95% confidence interval [CI] 1.87-5.27) and major complications (OR = 1.49, 95% CI 1.24-1.80), and smoking and higher low-density lipoprotein cholesterol (LDL-C) levels showed similar results. Among patients with previous diabetes, strict glucose control was significantly associated with an increased risk of in-hospital mortality (OR = 8.32, 95% CI 3.95-17.51) compared with moderate glucose control. Nevertheless, among non-previous diabetic patients with stress hyperglycemia, strict glucose control led to a lower risk of major complications (OR = 0.71, 95% CI 0.52-0.98).

CONCLUSIONS

Diabetes status, smoking, and LDL-C levels were modifiable risk factors of both in-hospital mortality and major complications after CABG. Strict glucose control was associated with an increased risk of in-hospital mortality among patients with diabetes, whereas it reduced the risk of major complications among non-previous diabetic patients.

Phase analysis of gated myocardial perfusion single-photon emission computed tomography after coronary artery bypass graft surgery: reflection of late reverse remodeling in patients with patent grafts after coronary artery bypass graft surgery

OBJECTIVE

Phase analysis using gated myocardial perfusion single-photon emission computed tomography (GMPS) is a tool used to assess left ventricular (LV) dyssynchrony. We attempted to investigate the role of LV dyssynchrony assessed by GMPS using phase analysis for the late LV function after coronary artery bypass graft surgery (CABG) in patients with patent grafts.

METHODS

A total of 45 patients who received off-pump CABG with patent graft 1 year after CABG and preserved perfusion reserve were enrolled retrospectively. All patients underwent GMPS before and 3 months and 1 year after CABG. Using the Emory Cardiac Toolbox, both phase histogram bandwidth (PBW) and phase SD derived by phase analysis were used for the analysis, in addition to the conventional perfusion parameters. For the evaluation of LV function, transthoracic echocardiography was also performed.

RESULTS

All of the patients showed perfusion improvement (paired t-test, P<0.05) after CABG. Nonetheless, 30 of 45 patients showed LV dyssynchrony 3 months after CABG. One year after CABG, however, 25 out of 45 patients showed reverse remodeling. Among those patients with reverse remodeling, 19 patients had shown LV 3 months after CABG. Using stepwise logistic regression with forward selection, PBW 3 months after CABG could predict reverse remodeling 1 year after CABG (odds ratio 1.03, P<0.05). Using receiver operating characteristic analysis, PBW 3 months after CABG had the largest area under the curve to detect reverse remodeling 1 year after CABG with a cut-off value of 82 (sensitivity 0.95, specificity 0.56, P<0.001).

CONCLUSION

Postoperative LV dyssynchrony assessed by GMPS using phase analysis may reflect late reverse remodeling and potential of further functional improvement in patients with patent grafts and preserved perfusion reserve after CABG.

Managing Heart Failure Patients with Multivessel Disease - Coronary Artery Bypass Graft versus Percutaneous Coronary Intervention

The foundation of treatment for heart failure with reduced ejection fraction is guideline-directed medical treatment. However, surgical revascularisation offers improved survival and quality of life for patients with more extensive coronary disease and the greatest degree of left ventricular systolic dysfunction and remodelling. The most commonly considered surgical interventions for patients with heart failure with reduced ejection fraction are coronary artery bypass surgery, sometimes combined with surgical ventricular reconstruction and surgery for mitral regurgitation. In this review, the author considers the risks and benefits of coronary artery bypass graft versus percutaneous coronary intervention in the management of heart failure patients with multivessel disease.

Predictors of immediate and long-term outcomes of coronary bypass surgery in patients with left ventricular dysfunction

Despite encouraging improvements, outcomes of coronary artery bypass grafting (CABG) in the presence of left ventricular (LV) dysfunction remain poor. In the present study, the authors' experience on this subject was reviewed to establish the predictors of immediate and long-term results of surgery. Out of 4383 consecutive patients with multivessel coronary artery disease who underwent primary isolated CABG at the authors' institution from January 1999 throughout September 2014, 300 patients (mean age 66.1 ± 9.6 years) suffered preoperatively from LV dysfunction (defined as LV ejection fraction ≤35 %). The mean expected operative risk (EuroSCORE II) was 10.3 ± 13 %. Hospital deaths and perioperative complications were analyzed retrospectively. Outcomes were evaluated during a mean follow-up of 6.2 ± 4 years. None, one or both internal thoracic arteries (ITAs) were used in 6.3, 29 and 64.7 % of cases, respectively. There were 16 (5.3 %) hospital deaths. Prolonged invasive ventilation (17.7 %), acute kidney injury (14.7 %) and multiple blood transfusion (21.3 %) were the most frequent major postoperative complications. The 10-year non-parametric estimates of freedom from all-cause death, cardiac death, and major adverse cardiac and cerebrovascular events (MACCEs) were 47.8 [95 % confidence interval (CI) 44.1-51.5], 65.3 (95 % CI 61.4-69.2), and 42.3 % (95 % CI 38.3-46.3), respectively. Shared predictors of decreased late survival and MACCEs were old age (P < 0.04), chronic lung disease (P < 0.01), chronic dialysis (P < 0.0001) and extracardiac arteriopathy (P < 0.045). After adjustment for corresponding risk factors, freedom from cardiac death was higher when both ITAs were used but only for patients with significant increase of LV ejection fraction early after surgery (P = 0.04). In patients with LV dysfunction, CABG may be performed with acceptable hospital mortality and long-term survival. Late outcomes depend mainly on preoperative characteristics of the patients. The use of both ITAs for myocardial revascularization may give long-term survival benefits but only for patients whose LV function improves significantly early after surgery.

Value of Hybrid Imaging with PET/CT to Guide Percutaneous Revascularization of Chronic Total Coronary Occlusion

Chronic total coronary occlusions (CTO) are documented in approximately one fifth of diagnostic invasive coronary angiographies (ICA). Percutaneous coronary interventions (PCI) of CTO are challenging and are accompanied by higher complication and lower success rates in comparison with non-CTO PCI. Scrutinous evaluation of ischemia and viability to justify percutaneous revascularization is therefore of importance to select eligible patients for such a procedure. Furthermore, knowledge of the anatomical features of the occlusion may predict the chances of success of PCI CTO and could even guide the procedural strategy to augment the likelihood of recanalization. Positron emission tomography (PET) is unequivocally accepted as the reference standard for ischemia and viability testing, whereas coronary computed tomography angiography (CCTA) currently allows for non-invasive detailed three-dimensional imaging of the coronary anatomy that adds morphological information over two-dimensional ICA. Hybrid PET/CT could therefore be useful for optimal patient selection as well as procedural planning. This review discusses the potential value of PET/CT to guide PCI in CTOs.

Current and future trends in multimodality imaging of coronary artery disease

Nowadays, there is a wide array of imaging studies available for the evaluation of coronary artery disease, each with its particular indications and strengths. Cardiac single photon emission tomography is mostly used to evaluate myocardial perfusion, having experienced recent marked improvements in image acquisition. Cardiac PET has its main utility in perfusion imaging, atherosclerosis and endothelial function evaluation, and viability assessment. Cardiovascular computed tomography has long been used as a reference test for non-invasive evaluation of coronary lesions and anatomic characterization. Cardiovascular magnetic resonance is currently the reference standard for non-invasive ventricular function evaluation and myocardial scarring delineation. These specific strengths have been enhanced with the advent of hybrid equipment, offering a true integration of different imaging modalities into a single, simultaneous and comprehensive study.