Myocardial viability testing: all STICHed up, or about to be REVIVED?

Patients with ischaemic left ventricular dysfunction frequently undergo myocardial viability testing. The historical model presumes that those who have extensive areas of dysfunctional-yet-viable myocardium derive particular benefit from revascularization, whilst those without extensive viability do not. These suppositions rely on the theory of hibernation and are based on data of low quality: taking a dogmatic approach may therefore lead to patients being refused appropriate, prognostically important treatment. Recent data from a sub-study of the randomized STICH trial challenges these historical concepts, as the volume of viable myocardium failed to predict the effectiveness of coronary artery bypass grafting. Should the Heart Team now abandon viability testing, or are new paradigms needed in the way we interpret viability? This state-of-the-art review critically examines the evidence base for viability testing, focusing in particular on the presumed interactions between viability, functional recovery, revascularization and prognosis which underly the traditional model. We consider whether viability should relate solely to dysfunctional myocardium or be considered more broadly and explore wider uses of viability testingoutside of revascularization decision-making. Finally, we look forward to ongoing and future randomized trials, which will shape evidence-based clinical practice in the future.

Evolution of Diastolic Dysfunction in Patients with Coronary Slow Flow Phenomenon and Acute Non-ST Segment Elevation Myocardial Infarction

BACKGROUND

Diastolic function has been reported to be impaired in many patients with coronary slow flow phenomenon (CSFP). CSFP has broad spectrum of clinical presentations, including non-ST elevation myocardial infarction (NSTEMI). We sought to study the short-term evolution of diastolic function in CSFP patients presenting with NSTEMI.

METHODS

This study included 92 patients with CSFP and acute NSTEMI. Conventional echocardiography Doppler imaging and tissue Doppler echocardiography imaging were used to evaluate diastolic function during index NSTEMI and after 3 months.

RESULTS

Mean age of study patients was 45.7 ± 6.8 years. The prevalence of diastolic dysfunction (DD) at baseline was 69 patients (75%) and 28 patients (30.4%) at 3 months, p < 0.001. Various diastolic function indices showed significant improvement from baseline to 3 months follow-up. E/Em was 17.32 ± 3.41 at baseline compared to 12.41 ± 5.58 at 3 months, p = 0.039. Septal e' velocity was 5.67 ± 4.56 cm/s at baseline compared to 7.78 ± 3.22 cm/s at 3 months, p = 0.023. Medications used were not significantly different between those with improved versus unimproved DD.

CONCLUSIONS

Diastolic function seems to improve over short-term follow-up in patients with CSFP presenting with NSTEMI. This could reflect a transient worsening during acute NSTEMI.

Effect of Percutaneous Coronary Intervention on Diastolic Function in Coronary Artery Disease

Background:

Left ventricle (LV) diastolic dysfunction is often present in patients with significant coronary artery disease (CAD), even in the absence of regional or global LV systolic dysfunction. It has been suggested that abnormalities in LV diastolic function may actually precede LV systolic dysfunction, and therefore, serve as an early and sensitive marker of ischemia. This study aims to find improvement of diastolic function after percutaneous coronary intervention (PCI) in patients with stable or unstable angina.

Methods:

In this single-center hospital-based study, we enrolled 309 patients with either stable or unstable CAD and with normal systolic function who underwent successful PCI. Two-dimensional transthoracic echocardiography was performed at baseline (before PCI) and repeated 48 h after PCI. LV diastolic parameters were compared before and after PCI using paired samples t-test results.

Results:

Mean age of study population was 56.65 ± 9.65 years. Majority of patients were male (63%). There was significant increase in mitral E-wave velocity (68.39 ± 17.52 cm/s vs. 71.64 ± 18.23 cm/s), E/A ratio (0.85 ± 0.29 vs. 0.89 ± 0.32), and early diastolic mitral annular motion (e') (7.02 ± 0.89 cm/s vs. 8.45 ± 0.86 cm/s) following PCI (P < 0.0001). Left atrial volume index (22.53 ± 4.43 vs. 20.81 ± 4.14), tricuspid jet velocity (0.91 ± 0.57 m/s vs. 0.76 ± 0.67 m/s), and E/e' ratio (10.03 ± 3.5 vs. 8.62 ± 2.61) decreased significantly following PCI (P < 0.001).

Conclusion:

This study suggests that LV diastolic filling pattern is modified significantly as early as 48 h after successful PCI. Improvement in impaired relaxation appears to be most likely explanation for these changes. PCI may be potential therapeutic target to improve diastolic function in patients with CAD.

Prognostic Implications of Diastolic Dysfunction Change in Patients With Coronary Artery Disease Undergoing Percutaneous Coronary Intervention

BACKGROUND

The association between a change in diastolic function (DF) and long-term clinical outcomes in patients undergoing percutaneous coronary intervention (PCI) is unknown. The aim of this study was to investigate the prognostic effect of changes in diastolic dysfunction in patients undergoing PCI.Methods and Results:Consecutive patients who underwent PCI and echocardiography before and after revascularization were prospectively included. Major adverse cardiac event (MACE) was defined as a composite of cardiac death, myocardial infarction, and repeat revascularization. A total of 1,235 patients were identified. Baseline diastolic dysfunction was present in 1,033 patients (83.6%). At follow-up echocardiography, DF had worsened in 219 (17.8%) patients and was unchanged in 623 patients (50.4%). The risk of MACE was significantly higher in the worsened DF group compared with the unchanged DF group (adjusted hazard ratio [aHR]: 2.15; 95% confidence interval [CI]: 1.59 to 2.90; P<0.001) and the improved or normal DF group (aHR: 2.20; 95% CI, 1.49 to 3.27; P<0.001). Patients with worsened DF consistently had a higher risk of MACE in various subgroups, especially irrespective of left ventricular systolic function.

CONCLUSIONS

Aggravation of DF was independently associated with an increased risk of MACE in patients undergoing PCI. Evaluating changes in DF after PCI is a simple but useful method for predicting long-term clinical outcomes.

Abnormal diastolic function underlies the different beneficial effects of cardiac resynchronization therapy on ischemic and non-ischemic cardiomyopathy

OBJECTIVES:

To investigate the association between diastolic function and the different beneficial effects of cardiac resynchronization therapy in patients with heart failure due to different causes.

METHODS:

The 104 enrolled patients were divided into an ischemic cardiomyopathy group (n=27) and a non-ischemic cardiomyopathy group (n=77) according to the cause of heart failure. Before implantation, left ventricular diastolic function was evaluated in all patients using echocardiography. After six months of follow-up, the beneficial effects of cardiac resynchronization therapy were evaluated using a combination of clinical symptoms and echocardiography parameters.

RESULTS:

The ischemic cardiomyopathy group included significantly more patients with restrictive filling than the non-ischemic cardiomyopathy group. The response rate after the implantation procedure was significantly higher in the non-ischemic cardiomyopathy group than in the ischemic cardiomyopathy group. Degrees of improvement in echocardiography parameters were significantly greater in the non-ischemic cardiomyopathy group than in the ischemic cardiomyopathy group. Multivariate regression analysis showed that a restrictive filling pattern was an independent factor that influenced responses to cardiac resynchronization therapy.

CONCLUSIONS:

This study again confirmed that the etiology of heart failure affects the beneficial effects of cardiac resynchronization therapy and a lower degree of improvement in ventricular systolic function and remodelling was observed in ischemic cardiomyopathy patients than in non-ischemic cardiomyopathy patients. In addition, systolic heart failure patients with severe diastolic dysfunction had poor responses to cardiac resynchronization therapy. Ischemic cardiomyopathy patients exhibited more severe diastolic dysfunction than non-ischemic cardiomyopathy patients, which may be a reason for the reduced beneficial effect of cardiac resynchronization therapy.

Effect of L-Carnitine Supplementation on Reverse Remodeling in Patients with Ischemic Heart Disease Undergoing Coronary Artery Bypass Grafting: A Randomized, Placebo-Controlled Trial

During cardiac failure, cardiomyocytes have difficulty in using the substrates to produce energy. L-carnitine is a necessary nutrient for the transport of fatty acids that are required for generating energy. Coronary artery graft surgery reduces the plasma levels of L-carnitine and increases the oxidative stress. This study demonstrates the effect of L-carnitine supplementation on the reverse remodeling of patients undergoing coronary artery bypass graft. Patients with ischemic heart failure who underwent coronary graft surgery were randomized to group A - supplemented with L-carnitine or group B controls. Left ventricular ejection fraction, left ventricular systolic and diastolic diameters were assessed preoperatively, 60 and 180 days after surgery. Our study included 28 patients (26 [93.0%] males) with a mean age ± SD of 58.1 ± 10.5 years. The parameters for the evaluation of reverse remodeling did not improve after 60 and 180 days of coronary artery bypass grafting in comparison between groups (p > 0.05). Evaluation within the L-carnitine group showed a 37.1% increase in left ventricle ejection fraction (p = 0.002) and 14.3% (p = 0.006) and 3.3% (p > 0.05) reduction in systolic and diastolic diameters, respectively. L-carnitine supplementation at a dose of 50 mg/kg combined with artery bypass surgery did not demonstrate any additional benefit in reverse remodeling. However, evaluation within the L-carnitine group may indicate a clinical benefit of L-carnitine supplementation.

Diastolic Dysfunction and Hypertension

Left ventricular (LV) diastolic dysfunction (LVDD) is characterized by alterations in LV diastolic filling, and is a strong predictor of cardiovascular events and heart failure. Hypertension is the most important risk factor for LVDD in the community and promotes LVDD through several mechanisms, including hemodynamic overload and myocardial ischemia. Associated factors such as age, ethnicity, dietary sodium, obesity, diabetes mellitus, and chronic kidney disease also contribute to LVDD in hypertensive individuals. Blood pressure lowering using antihypertensive medications can improve LVDD; however, it remains unclear whether this improvement in LV diastolic function can improve cardiovascular outcomes.

Dynamic changes in left ventricular function after a percutaneous coronary intervention: prevalence, predictors, and prognosis

OBJECTIVES

To estimate the prevalence, identify predictors, and assess the prognostic implications of left ventricular ejection fraction (LVEF) changes after an elective percutaneous coronary intervention (PCI).

METHODS

We included all consecutive patients who underwent elective PCI in our institution and were evaluated with echocardiography before and within 1 year of the procedure. Patients were grouped in terms of baseline LVEF. Hazard ratios (HRs) for all-cause mortality and acute myocardial infarction were calculated for baseline LVEF groups and in terms of LVEF normalization or decline.

RESULTS

A total of 974 patients were included. Patients with moderately impaired (HR 1.41, P=0.01) and poor LVEF (HR 2.44, P<0.001) had significantly worse survival in comparison with patients with good LVEF. Decline from preserved to impaired LVEF following PCI was associated with an increased 1-year risk (HR 3.48, P<0.001) and 5-year risk (HR 2.79, P<0.001) for the composite outcome of all-cause mortality and acute myocardial infarction. LVEF recovery from impaired to preserved was associated with a decreased 5-year risk for the composite outcome (HR 0.5, P<0.001).

CONCLUSION

Changes in LVEF after elective PCI occur often. Both higher baseline LVEF and post-PCI LVEF normalization are associated with improved outcomes.

Late percutaneous coronary intervention prevents left ventricular remodeling and improves clinical outcomes in patients with ST-elevation myocardial infarction

BACKGROUND

The optimal strategy for treating late presenters of ST-elevation myocardial infarction (STEMI) remains uncertain.

HYPOTHESIS

percutaneous coronary intervention (PCI) has a favorable effect on left ventricular (LV) remodeling and clinical outcomes in late presenters of STEMI.

METHODS

Patients with STEMI who were hospitalized between 2009 and 2011 at 7 PCI-capable hospitals in China were selected. Cardiac characteristics were reassessed by echocardiography between August 2013 and January 2014. The clinical endpoints were evaluated during a median follow-up period of 36 months.

RESULTS

1090 patients who either underwent late PCI (n = 786) or received standard medical therapy alone (n = 304) was analyzed. Left ventricular remodeling was more pronounced in the conservative-treatment group. Logistic regression revealed that late PCI was independently and negatively correlated with LV remodeling (odds ratio: 0.356, 95% confidence interval [CI]: 0.251-0.505, P < 0.001). Kaplan-Meier analysis showed the lower risks of major adverse cardiovascular events (MACE), all-cause death, and rehospitalization for heart failure in the late-PCI group. Multivariate Cox regression revealed that late PCI was significantly associated with lower risks for MACE, all-cause death, and rehospitalization for heart failure both in all patients (hazard ratio [HR]: 0.507, 95% CI: 0.412-0.625, P < 0.001; HR: 0.419, 95% CI: 0.314-0.559, P < 0.001; and HR: 0.583, 95% CI: 0.379-0.896, P = 0.014, respectively) and in the matched patients (HR: 0.466, 95% CI: 0.358-0.607, P < 0.001; HR: 0.398, 95% CI: 0.277-0.571, P < 0.001; and HR: 0.498, 95% CI: 0.283-0.878, P = 0.016, respectively) by propensity-score analysis.

CONCLUSIONS

Late-PCI strategy prevents LV remodeling and improves clinical outcomes in STEMI patients compared with conservative strategies.

[Analysis of the diastolic function by myocardial perfusion gated SPECT after coronary revascularization in acute myocardial infarction]

OBJECTIVE

To evaluate the evolutive changes in diastolic function after percutaneous coronary revascularization (PCR) in acute myocardial infarction (AMI), using myocardial perfusion gated SPECT.

METHODS

Thirty-two patients (mean 61.9±9.7 years, 7 women) were studied by two at rest gated SPECT: the first gated-SPECT-1 was performed with an injection of a dose of (99m)Tc-tetrofosmin prior to PCR and the second gated-SPECT-2 between the fourth and fifth weeks after AMI. Changes of peak filling rate (PFR) and the time to peak filling rate (TTPF) were assessed between both studies, and were related to the extent of salvaged myocardium (SM), end-diastolic (EDV) and end-systolic (ESV) volumes, and left ventricular ejection fraction (LVEF) changes.

RESULTS

An improvement was observed in diastolic function parameters Gated-SPECT-2: PFR increased significantly (P=0.011) while the TTPF decreased without reaching statistical significance (P=0.288). In multivariate analysis, adjusted by clinical and coronary variables, improvement of PFR was significantly associated with percentage of SM (P=0.030), increase in LVEF (P=0.004) and with ESV volume reduction (P=0.005). Improvement of TTPF was only related significantly to the percentage of SM (P=0.046). PFR increased 0.01 EDV/sec. and TTPF decreased 1.14ms for each cm(2) increase of the area of SM.

CONCLUSIONS

After PCR in AMI, the myocardial perfusion gated SPECT makes it possible to assess the significant improvement in diastolic function mainly related to the amount of MS.

Plasma metalloproteinase-9 and restrictive filling pattern as major predictors of outcome in patients with ischemic cardiomyopathy

OBJECTIVE

Assessment of plasma matrix metalloproteinase-9 (MMP-9) and Doppler markers of increased left ventricular (LV) filling pressure may be added to risk stratify patients with ischemic cardiomyopathy (IC). Therefore, we aimed at investigating the value of plasma MMP-9 and restrictive filling pattern (RFP) in IC patients.

METHODS

Eighty-eight consecutive patients hospitalized for heart failure (LV ejection fraction ≤ 40%) due to IC were enrolled. A complete M-mode and two-dimensional echo-Doppler examination were performed. Patients were defined as having RFP if they had a mitral E wave deceleration time<150 ms. Plasma MMP-9 and N-terminal protype-B natriuretic peptide levels were assessed at the time of the index echocardiogram. The end point was all-cause mortality or hospitalization for worsening HF. Follow-up period was 25 ± 17 months.

RESULTS

Median value of MMP-9 was 714 ng/ml. On univariate analysis, a number of measurements predicted the composite end point: NYHA class>2, RFP, MMP-9>60.5 ng/ml, LV ejection fraction<27%, anemia, pulmonary pressure ≥ 35 mm Hg, N-terminal protype-B natriuretic peptide>1742 pg/ml, and glomerular filtration rate<60 ml/min/1.73 m(2). Independent variables of outcome were anemia (HR=1.9, p=0.031), and the combination of plasma MMP-9 and RFP (HR=3.2, p=0.004). On Kaplan-Meier survival curves, patients with elevated MMP-9 levels and RFP had the lowest event-free survival rate (log-rank: 29.0, p<0.0001). The net reclassification improvement showed a significant increase in the prediction model when elevated MMP-9 and RFP were added to the base model that included clinical, biochemical and echocardiographic parameters (p<0.0001).

CONCLUSION

MMP-9 levels and RFP have an incremental predictive value to risk classify IC patients.

Prognostic value of left ventricular diastolic dysfunction in patients undergoing cardiac catheterization for coronary artery disease

We hypothesized that left ventricular (LV) diastolic dysfunction assessed by cardiac catheterization may be associated with increased risk for cardiovascular events. To test the hypothesis, we assessed diastolic function by cardiac catheterization (relaxation time constant (Tau) and end-diastolic pressure (EDP)) as well as Doppler echocardiography (early diastolic mitral annular velocity (e') and a ratio of early diastolic mitral inflow to annular velocities (E/e')) in 222 consecutive patients undergoing cardiac catheterization for coronary artery disease (CAD). During a followup of 1364 ± 628 days, 5 cardiac deaths and 20 unscheduled cardiovascular hospitalizations were observed. Among LV diastolic function indices, Tau > 48 ms and e' < 5.8 cm/s were each significantly associated with lower rate of survival free of cardiovascular hospitalization. Even after adjustment for potential confounders (traditional cardiovascular risk factors, the severity of CAD, and cardiovascular medications), the predictive value of Tau > 48 ms and e' < 5.8 cm/s remained significant. No predictive value was observed in EDP, E/e', or LV ejection fraction. In conclusion, LV diastolic dysfunction, particularly impaired LV relaxation assessed by both cardiac catheterization and Doppler echocardiography, is independently associated with increased risk for cardiac death or cardiovascular hospitalization in patients with known or suspected CAD.

The role of cardiac magnetic resonance imaging following acute myocardial infarction

BACKGROUND

Advances in the management of myocardial infarction have resulted in substantial reductions in morbidity and mortality.

METHODS

However, after acute treatment a number of diagnostic and prognostic questions often remain to be answered, whereby cardiac imaging plays an essential role.

RESULTS

For example, some patients will sustain early mechanical complications after infarction, while others may develop significant ventricular dysfunction. Furthermore, many individuals harbour a significant burden of residual coronary disease for which clarification of functional ischaemic status and/or viability of the suspected myocardial territory is required.

CONCLUSION

Cardiac magnetic resonance (CMR) imaging is well positioned to fulfil these requirements given its unparalleled capability in evaluating cardiac function, stress ischaemia testing and myocardial tissue characterisation. This review will focus on the utility of CMR in resolving diagnostic uncertainty, evaluating early complications following myocardial infarction, assessing inducible ischaemia, myocardial viability, ventricular remodelling and the emerging role of CMR-derived measures as endpoints in clinical trials.

KEY POINTS

Cardiac magnetic resonance (CMR) imaging identifies early complications after myocardial infarction. • Adenosine stress CMR can reliably assess co-existing disease in non-culprit arteries. • Assessment of infarct size and microvascular obstruction a robust prognostic indicator. • Assessment of myocardial viability is important to guide revascularisation decision-making.

Improvement of myocardial performance (Tei) index closely reflects intrinsic improvement of cardiac function: assessment in revascularized hibernating myocardium

BACKGROUND

Myocardial performance index (MPI), or Tei index, is an indicator of systolic and diastolic myocardial function. MPI increases in case of cardiac dysfunction; however, whether reversal of left ventricular dysfunction is also reflected by concomitant improvement (i.e., decrease) of MPI is unknown.

METHODS

Fifty-two patients with chronic ischemic cardiomyopathy and viable myocardium by dobutamine stress echocardiography were studied by echocardiography before and more than 4 months after cardiac revascularization. Patients were in optimal medical therapy, which remained unchanged following revascularization.

RESULTS

At baseline, ejection fraction (EF: 32 ± 6%) and wall motion score index (WMSI: 2.37 ± 0.32) were impaired, and MPI averaged 0.71 ± 0.19. Revascularization markedly improved EF (44 ± 10%, P < 0.0001) and WMSI (1.77 ± 0.44, P < 0.0001). MPI also improved (0.59 ± 0.26, P < 0.0001), and its decrease was significantly correlated with the improvement in EF (r =-0.68, P < 0.0001) and to the extent of viable myocardium (r =-0.45, P = 0.0007). Responders to revascularization (≥5% increase in EF at follow-up, n = 40% and 77%) achieved a significant improvement in MPI at follow-up in contrast with nonresponders (-23 ± 25% vs. 0.02 ± 0.18%, P = 0.001). Improvement in MPI was largely driven by a significant reduction in isovolumic contraction time (P < 0.001) with consequent prolongation of the ejection phase.

CONCLUSION

In patients with chronic ischemic cardiomyopathy, MPI improves along with recovery of function, reflecting the intrinsic improvement of viable segments induced by revascularization.

Imaging: guiding the clinical translation of cardiac stem cell therapy

Stem cells have been touted as the holy grail of medical therapy, with promises to regenerate cardiac tissue, but it appears the jury is still out on this novel therapy. Using advanced imaging technology, scientists have discovered that these cells do not survive nor engraft long-term. In addition, only marginal benefit has been observed in large-animal studies and human trials. However, all is not lost. Further application of advanced imaging technology will help scientists unravel the mysteries of stem cell therapy and address the clinical hurdles facing its routine implementation. In this review, we will discuss how advanced imaging technology will help investigators better define the optimal delivery method, improve survival and engraftment, and evaluate efficacy and safety. Insights gained from this review may direct the development of future preclinical investigations and clinical trials.

Intramyocardial bone marrow-derived mononuclear cell injection for chronic myocardial ischemia: the effect on diastolic function

BACKGROUND

The present substudy of a recently published randomized trial aimed to investigate the effect of intramyocardial bone marrow cell injection on diastolic function in patients with chronic myocardial ischemia.

METHODS AND RESULTS

In a total of 50 patients, diastolic function was evaluated before and 3 months after bone marrow cell injection using standard echocardiography and strain analysis. In addition, MRI-derived transmitral flow measurements were obtained in a subset of 36 patients. Left ventricular ejection fraction increased from 50±5% to 54±7% in the bone marrow cell group, which was a significant improvement as compared with the placebo group (52±5% versus 51±7%, P=0.001). Filling pressure estimate E/E' ratio improved from 14±5 at baseline to 12±4 at 3 months in the bone marrow cell group, whereas no improvement was observed in the placebo group (13±4 versus 13±5). The improvement in E/E' ratio was significantly larger in the bone marrow cell group (P=0.008). Furthermore, the E/A peak flow ratio as assessed by MRI showed a significant increase in the bone marrow cell group as compared with the placebo group (+0.16±0.25 versus -0.04±0.21, P=0.01), which was mainly related to an increase in the early (E) peak flow rate in the bone marrow cell group (from 407±96 mL/s to 468±110 mL/s, P=0.009 as compared with the placebo group).

CONCLUSIONS

The current study demonstrates that intramyocardial bone marrow cell injection is associated with a beneficial effect on myocardial relaxation and filling pressures in patients with chronic myocardial ischemia.

Cardiac imaging after myocardial infarction

After myocardial infarction, optimal clinical management depends critically on cardiac imaging. Remodelling and heart failure, presence of inducible ischaemia, presence of dysfunctional viable myocardium, future risk of adverse events including risk of ventricular arrhythmias, need for anticoagulation, and other questions should be addressed by cardiac imaging. Strengths and weaknesses, recent developments, choice, and timing of the different non-invasive techniques are reviewed for this frequent clinical scenario.