Interaction between two predictors of functional outcome after revascularization in ischemic cardiomyopathy: Left ventricular volume and amount of viable myocardium

Cardiac magnetic resonance imaging for myocardial viability assessment: Optimizing surgical revascularization in ischemic heart disease

BACKGROUND

Patients with poor ejection fraction undergoing coronary artery bypass grafting carry higher operative risk and have poor long-term survival. Cardiac magnetic resonance is a useful modality to assess viability which can identify patients likely to benefit most from revascularization. In this study, we aimed to assess the outcome in patients selected for surgical revascularization by cardiac magnetic resonance imaging and identify predictors associated with poor outcomes.

METHODS

The study included patients with severely impaired left ventricular function but with at least six viable segments. Patients requiring emergency surgery, undergoing combined procedures, or where cardiopulmonary bypass was required were excluded. Cardiac magnetic resonance was carried out both preoperatively and at six months postoperatively by the same radiologist in all cases. Late gadolinium enhancement was used for the evaluation of myocardial viability.

RESULTS

Amongst a total of 493 segments studied, there were 89 (18.1%) non-viable, 117 (23.7%) hibernating and 287 (58.2%) viable segments. At six months, the number of non-viable segments changed from 89 (18.1%) to 97 (19.7%), with an increase in viable segments from 287 (58.2%) to 374 (75.8%) and a corresponding reduction of hibernating segments from 117 (23.7%) to 22 (4.5%). There was improvement in ejection fraction from 28 ± 5.54 to 37 ± 5.86 (p < 0.0001) in the entire cohort at six months. Overall mortality was 1 (3.2%). Preoperative left ventricular end-systolic volume had the strongest negative correlation with post-operative ejection fraction.

CONCLUSION

Cardiac magnetic resonance aided revascularization is associated with low mortality. Preoperative left ventricular end-systolic volume is an important determinant of postoperative ejection fraction.

Notch Signaling-Modified Mesenchymal Stem Cell Patch Improves Left Ventricular Function via Arteriogenesis Induction in a Rat Myocardial Infarction Model

For ischemic cardiomyopathy (ICM) with limited therapeutic options, the induction of arteriogenesis has the potential to improve cardiac function through major restoration of blood flow. We hypothesized that transplantation of a Notch signaling-modified mesenchymal stem cell (SB623 cell) patch would induce angiogenesis and arteriogenesis in ischemic lesions, leading to improvement of left ventricular (LV) function in a rat ICM model. Two weeks after the induction of ischemia, SB623 cell patch transplantation into ICM rats (SB group, n = 10) or a sham operation (no-treatment group, n = 10) was performed. The LV ejection fraction was significantly improved at 6 weeks after SB623 cell patch transplantation (P < 0.001). Histological findings revealed that the number of von Willebrand factor (vWF)-positive capillary vessels (P < 0.01) and alpha smooth muscle actin (αSMA)- and vWF-positive arterioles with a diameter greater than 20 µm (P = 0.002) was significantly increased in the SB group, suggesting the induction of angiogenesis and arteriogenesis. Moreover, rat cardiomyocytes treated with SB623 cell patch transplantation showed upregulation of ephrin-B2 (P = 0.03) and EphB4 (P = 0.01) gene expression, indicating arteriogenesis induction. In conclusion, SB623 cell patch transplantation improved LV function by inducing angiogenesis and arteriogenesis in a rat ICM model.

Ejection Fraction Recovery after Coronary Artery Bypass Grafting for Ischemic Cardiomyopathy

BACKGROUND

 Controversy exists about left ventricular systolic function recovery after coronary artery bypass grafting in patients with ischemic cardiomyopathy. The aim of this study is to evaluate the temporal evolvement of left ventricular systolic function after coronary artery bypass surgery in patients with ischemic cardiomyopathy.

PATIENTS AND METHODS

 A total of 50 patients with coronary artery disease and left ventricular ejection fraction (LVEF) ≤35% underwent isolated coronary artery bypass grafting in a single center in the period 2017 to 2019. We performed a retrospective analysis of the echocardiographic and clinical follow-up data at 3 months and 1 year postoperatively.

RESULTS

 Median LVEF preoperatively was 25% (20-33%), mean patient age was 66 ± 8.2 years, 33 (66%) patients were operated off-pump, and 22 (44%) procedures were non-elective. There was no in-hospital myocardial infarction, stroke, and repeat revascularization. Three (6%) patients underwent re-exploration for bleeding or tamponade. In-hospital mortality was 8% and 1-year mortality was 12%. At 1 year postoperatively, there was no repeat revascularization, no myocardial infarction, 1 (2.6%) patient had a transient ischemic attack, and 10 (20%) patients required an implantable defibrillator. There was a statistically significant median ejection fraction increase at 3 months (15% [5-22%], p < 0.0001) and 1 year (23% [13-25%], p < 0.0001) postoperatively, with an absolute increase ≥10% in 32 (74.4%) and 30 (78.9%) patients at 3 months and 1 year, respectively.

CONCLUSION

 Patients with ischemic cardiomyopathy undergoing coronary artery bypass surgery show continuous recovery of left ventricular systolic function in the first postoperative year.

Incidence, determinants and clinical impact of left ventricular function recovery after surgical treatments for ischaemic cardiomyopathy

 

OBJECTIVES

This retrospective study aimed to clarify the incidence, determinants and clinical impact of left ventricular (LV) function non-recovery after coronary artery bypass grafting (CABG) in patients with ischaemic cardiomyopathy.

METHODS

A total of 490 patients with ischaemic cardiomyopathy (LV ejection fraction ≤ 40%) undergoing CABG were analysed. Follow-up echocardiography was performed at 1 month, 1 year, and annually thereafter. LV function recovery was defined as ejection fraction (EF) ≥40% at least once during follow-up. LV function non-recovery was defined as EF <40% at any follow-up. The primary and secondary end points were changes in LV function and all-cause mortality, respectively. Clinical follow-up was completed in 461 patients (94.1%; mean follow-up: 64.5 ± 45.5 months).

RESULTS

During follow-up, echocardiographic assessments were performed 1863 times (mean, 3.8 ± 2.4), and 193 patients (39.4%) exhibiting LV function non-recovery were identified. Overall survival was significantly higher in the recovery group (53.9%) than in the non-recovery group (31.4%) at 10 years (P < 0.001). Independent predictors of LV function non-recovery were preoperative LV end-systolic diameter [odds ratio (OR) 1.07, 95% confidence interval (CI) 1.04-1.10; P < 0.001] and bilateral internal thoracic artery grafting (OR 0.61, 95% CI 0.39-0.95; P = 0.028). In a multivariable Cox proportional hazards model, LV function non-recovery was significantly associated with all-cause mortality (hazard ratio 2.14, 95% CI 1.60-2.86; P < 0.001).

CONCLUSIONS

Almost 40% of patients with ischaemic cardiomyopathy undergoing CABG did not achieve LV function recovery and were associated with poor prognosis. To achieve LV function recovery, CABG with bilateral internal thoracic artery may be recommended before excessive LV remodelling occurs.

CLINICAL TRIAL REGISTRATION NUMBER

Institutional review board of Osaka University Hospital, number 16105.

Effects of myocardial viability and left ventricular remodeling on survival of patients with heart failure and reduced ejection fraction after coronary artery bypass grafting

Background

Heart failure with reduced ejection fraction (HFrEF) caused by coronary heart disease (CHD) accounts for the largest proportion of patients with heart failure and is associated with the poorest prognosis. However, date on the perioperative risk and long-term survival of patients with HFrEF are limited. The present study aimed at exploring the effects of the left ventricular end-systolic volume index (LVESVI) and myocardial viability on perioperative risk and long-term survival after coronary artery bypass grafting (CABG) in patients with HFrEF.

Methods

This is a single center, prospective, observational study. CHD patients with symptoms and signs of heart failure and a left ventricular ejection fraction (LVEF) <40% were enrolled consecutively from January 2014 to February 2018. Operative mortality, perioperative complications and long-term survival were compared in the patients with various LVESVIs and myocardial viabilities. The primary outcomes were cardiac death, myocardial infarction, heart failure, stroke and revascularization [percutaneous coronary intervention (PCI) or redo CABG] with a median follow-up of 30±12 months.

Results

Perioperative mortality was 6.8% in the 118 patients in this study. Perioperative mortality was significantly higher in the low myocardial viability (LMV) group than in the high myocardial viability (HMV) group (12.5% vs. 3.8%, P=0.034). The 12-, 24-, 36-month major adverse cardiac event (MACE)-free survival rate of patients with HMV was significantly higher than that of patients with LMV (HMV vs. LMV: 96.9% vs. 88.6%, 93.4% vs. 85.5%, 79.4% vs. 68.2%, P=0.004). There was no difference in MACE-free survival among patients with different degrees of left ventricular remodeling within each group.

Conclusions

Myocardial viability is an important factor that affects the perioperative mortality and long-term survival of patients with ischemic HFrEF after CABG. Left ventricular remodeling increases perioperative mortality but has no effect on long-term survival.

Injectable human recombinant collagen matrices limit adverse remodeling and improve cardiac function after myocardial infarction

Despite the success of current therapies for acute myocardial infarction (MI), many patients still develop adverse cardiac remodeling and heart failure. With the growing prevalence of heart failure, a new therapy is needed that can prevent remodeling and support tissue repair. Herein, we report on injectable recombinant human collagen type I (rHCI) and type III (rHCIII) matrices for treating MI. Injecting rHCI or rHCIII matrices in mice during the late proliferative phase post-MI restores the myocardium's mechanical properties and reduces scar size, but only the rHCI matrix maintains remote wall thickness and prevents heart enlargement. rHCI treatment increases cardiomyocyte and capillary numbers in the border zone and the presence of pro-wound healing macrophages in the ischemic area, while reducing the overall recruitment of bone marrow monocytes. Our findings show functional recovery post-MI using rHCI by promoting a healing environment, cardiomyocyte survival, and less pathological remodeling of the myocardium.

Contrasting Effects of Pharmacological, Procedural, and Surgical Interventions on Proportionate and Disproportionate Functional Mitral Regurgitation in Chronic Heart Failure

Two distinct pathways can lead to functional mitral regurgitation (MR) in patients with chronic heart failure and a reduced ejection fraction. When remodeling and enlargement of the left ventricle (LV) cause annular dilatation and tethering of the mitral valve leaflets, there is a linear relationship between LV end-diastolic volume and the effective regurgitant orifice area of the mitral valve. These patients, designated as having proportionate MR, respond favorably to treatments that lead to reversal of LV remodeling and a decrease in LV volumes (eg, neurohormonal antagonists and LV assist devices), but they may not benefit from interventions that are directed only at the mitral valve leaflets (eg, transcatheter mitral valve repair). In contrast, when ventricular dyssynchrony causes functional MR attributable to unequal contraction of the papillary muscles, the magnitude of regurgitation is greater than that predicted by LV volumes. These patients, designated as having severe but disproportionate MR, respond favorably to treatments that are directed to the mitral valve leaflets or their supporting structures (eg, cardiac resynchronization or transcatheter mitral valve repair), but they may derive little benefit from interventions that act only to reduce LV cavity size (eg, pharmacological treatments). This novel conceptual framework reflects the important interplay between LV geometry and mitral valve function in determining the clinical presentation of patients, and it allows characterization of the determinants of functional MR to guide the most appropriate therapy in the clinical setting.

Severity of Remodeling, Myocardial Viability, and Survival in Ischemic LV Dysfunction After Surgical Revascularization

OBJECTIVES

This study sought to test the hypothesis that end-systolic volume (ESV), as a marker of severity of left ventricular (LV) remodeling, influences the relationship between myocardial viability and survival in patients with coronary artery disease and LV systolic dysfunction.

BACKGROUND

Retrospective studies of ischemic LV dysfunction suggest that the severity of LV remodeling determines whether myocardial viability predicts improved survival with surgical compared with medical therapy, with coronary artery bypass grafting (CABG) only benefitting patients with viable myocardium who have smaller ESV. However, this has not been tested prospectively.

METHODS

Interactions of end-systolic volume index (ESVI), myocardial viability, and treatment with respect to survival were assessed in patients in the prospective randomized STICH (Comparison of Surgical and Medical Treatment for Congestive Heart Failure and Coronary Artery Disease) trial of CABG versus medical therapy who underwent viability assessment (n = 601; age 61 ± 9 years; ejection fraction ≤35%), with a median follow-up of 5.1 years. Median ESVI was 84 ml/m(2). Viability was assessed by single-photon emission computed tomography or dobutamine echocardiography using pre-specified criteria.

RESULTS

Mortality was highest among patients with larger ESVI and nonviability (p < 0.001), but no interaction was observed between ESVI, viability status, and treatment assignment (p = 0.491). Specifically, the effect of CABG versus medical therapy in patients with viable myocardium and ESVI ≤84 ml/m(2) (hazard ratio [HR]: 0.85; 95% confidence interval [CI]: 0.56 to 1.29) was no different than in patients with viability and ESVI >84 ml/m(2) (HR: 0.87; 95% CI: 0.57 to 1.31). Other ESVI thresholds yielded similar results, including ESVI ≤60 ml/m(2) (HR: 0.87; 95% CI: 0.44 to 1.74). ESVI and viability assessed as continuous rather than dichotomous variables yielded similar results (p = 0.562).

CONCLUSIONS

Among patients with ischemic cardiomyopathy, those with greater LV ESVI and no substantial viability had worse prognosis. However, the effect of CABG relative to medical therapy was not differentially influenced by the combination of these 2 factors. Lower ESVI did not identify patients in whom myocardial viability predicted better outcome with CABG relative to medical therapy. (Comparison of Surgical and Medical Treatment for Congestive Heart Failure and Coronary Artery Disease [STICH]; NCT00023595).

Impact of left ventricular remodelling on outcomes after left ventriculoplasty for ischaemic cardiomyopathy: Japanese surgical ventricular reconstruction group experience

OBJECTIVES

Surgical ventricular reconstruction (SVR) for patients with severe left ventricular (LV) remodelling due to ischaemic cardiomyopathy is still controversial, because the Surgical Treatment for Ischaemic Heart Failure (STICH) trial demonstrated that SVR not only has no beneficial effect on survival compared with coronary artery bypass grafting (CABG) alone, but also is worse for those with a larger LV. Therefore, we assessed the impact of LV remodelling on the outcomes after SVR for ischaemic cardiomyopathy in Japan, using Di Donato's LV shape classification.

METHODS

From 2000 to 2010, 627 patients underwent SVR for ischaemic heart failure in 11 Japanese hospitals. To assess the patients with an LV ejection fraction (LVEF) of ≤ 35% like the STICH trial, considering the severity of LV remodelling, the patients with a preoperative LVEF of >35%, no preoperative LV volume assessment and no preoperative LV shape classification were excluded. Finally, 323 patients were selected as the study subjects. The LV shape was divided into three types according to Di Donato's classification. Types 1 and 3 indicate the aneurysmal and globally akinetic LV, respectively. Type 2 is the intermediate shape.

RESULTS

Type 1, 2 and 3 LV shapes were observed in 85 (26%), 104 (32%) and 134 (42%) of the patients, respectively. The preoperative LV volume and diameter increased if the LV became more akinetic (Type 3 > 2 > 1, P < 0.001). LVEF was lower in those with more akinetic LV (P = 0.002). The preoperative LV end-diastolic volume index and LVEF in Type 3 patients were 133 ± 47 ml/m(2) and 22 ± 7%, respectively. Mitral valve repair was more frequently performed for patients with the Type 3 LV shape (65%) than for the others (P < 0.001). The hospital mortality rates were 2.4, 2.9 and 7.4% for Type 1, 2 and 3 patients, respectively (P = 0.16). Kaplan-Meier analysis demonstrated no significant difference in mortality among the three groups (log-rank P = 0.37). The 5-year survival rates were 81, 70 and 73% for Type 1, 2 and 3 patients, respectively.

CONCLUSIONS

The severity of LV remodelling did not affect survival after SVR plus CABG. The results of SVR were acceptable even for those with globally akinetic LV due to ischaemic cardiomyopathy.

Anterior wall viability and low ejection fraction predict functional improvement after CABG

BACKGROUND

Absence of myocardial hyperenhancement on cardiac magnetic resonance imaging (CMR) predicts functional improvement after coronary artery bypass graft surgery (CABG). However, not all patients with absence of hyperenhancement improve their left ventricular ejection fraction (LVEF) after CABG. We sought to identify other characteristics associated with improvement in LVEF after CABG.

METHODS

Preoperative CMR was obtained in 95 patients who underwent CABG from 2003 to 2007 at The Ohio State University Medical Center. Follow-up LVEF was assessed by echocardiogram between 3 wk and 2 y postoperatively (mean: 7±0.5 mo). Improvement in LVEF was defined as a postoperative increase in LVEF≥10%. CMR and clinical factors were analyzed for predictors of functional improvement.

RESULTS

Mean age was 61±1 y with 79 males. LVEF improved from 28%±2% preoperatively, to 38%±2% postoperatively (P<0.0001). Forty-three patients improved their LVEF. Patients who improved their LVEF had a lower preoperative LVEF (P=0.0001) and higher anterior wall viability (P=0.03). Preoperative LVEF (odds ratio 0.89, 95% CI 0.83-0.95, P=0.001) and left ventricular end systolic volume index (odds ratio 0.97, 95% CI 0.95-0.99, P=0.015) were predictors of improvement in LVEF by multivariable logistic regression analysis.

CONCLUSIONS

Recruitment of viable non functioning myocardium of the anterior wall is responsible for the improvement in ejection fraction. Low LVEF, non-remodeled left ventricle, and anterior wall viability predict improvement in ejection fraction after CABG. These criteria may help clinicians select patients who would benefit from surgical revascularization.

Ischemic cardiomyopathy: a clinical nuclear cardiology perspective

Ischemic cardiomyopathy results from severe extensive coronary artery disease, which is associated with left ventricular dysfunction and also, in many cases, with significant left ventricular dilatation. Mortality is high, especially in patients who satisfy myocardial viability criteria but who have not undergone revascularization. Although age, exercise capacity and comorbidity influence survival, the most important prognostic factors are the extent of the ischemia, myocardial viability and left ventricular remodeling, all of which can be successfully evaluated by gated myocardial perfusion single-photon emission computed tomography (SPECT).