Global and regional myocardial deformation mechanics of microvascular obstruction in acute myocardial infarction: a three dimensional speckle-tracking imaging study

Clinical, electrocardiographic, echocardiographic, and angiographic predictors for the final infarct size assessed by cardiac magnetic resonance in acute STEMI patients after primary percutaneous coronary intervention

BACKGROUND

Final infarct size (IS) after ST segment elevation myocardial infarction (STEMI) is a major predictor of mortality. Seeking early predictors for final IS can guide individualized therapeutic strategies for those recognized to be at higher risk.

RESULTS

Eighty STEMI patients successfully treated with primary percutaneous coronary intervention (pPCI) underwent baseline (within 48 h) 2D, 3D echocardiography with speckle tracking and then underwent cardiac magnetic resonance (CMR) at 3 months to assess the final IS. After recruitment, 4 patients were excluded for uncontainable claustrophobia while 76 patients completed the final analysis. The mean ± standard deviation age was 54.1 ± 10.9 years, 84% were males, 25% had diabetes, 26% were hypertensives, 71% were current smokers, 82% had dyslipidemia, and 18% had a family history of premature coronary artery disease. By 3 months, CMR was performed to accurately evaluate the final IS. In univariate regression analysis, the admission heart rate, baseline and post-pPCI ST elevation, STEMI location (anterior vs. inferior), highest peri-procedural troponin, large thrombus burden, baseline thrombolysis in myocardial infarction flow grade, the final myocardial blush grade, the 2D and 3D left ventricular ejection fraction (LVEF), and the 2D and 3D global longitudinal strain (GLS) parameters were significant predictors for the final IS. In the multivariate regression analysis, four models were constructed and recognized the residual post-PCI ST segment elevation, the highest peri-procedural troponin, the 2D-LVEF, 3D-LVEF, and 2D-GLS as significant independent predictors for final IS.

CONCLUSIONS

In STEMI patients who underwent successful pPCI, early predictors for the final IS are vital to guide therapeutic decisions. The residual post-pPCI ST elevation, the highest peri-procedural troponin, and the baseline 2D-LVEF, 3D-LVEF, and 2D-GLS can be excellent and timely tools to predict the final IS.

The evaluation of coronary microvascular obstruction in patients with STEMI by cardiac magnetic resonance T2-STIR image and layer-specific analysis of 2-dimensional speckle tracking echocardiography combined with low-dose dobutamine stress echocardiography

This study was designed to assess coronary microvascular obstruction (MVO) in patients with acute ST-segment elevation myocardial infarction (STEMI) by cardiac magnetic resonance T2-weighted short tau inversion recovery (T2-STIR) image and layer-specific analysis of 2-dimensional speckle tracking echocardiography combined with low-dose dobutamine stress echocardiography (LDDSE-LS2D-STE). 32 patients were enrolled to perform cardiac magnetic resonance and echocardiography 5-7 days after primary percutaneous coronary intervention. Infarcted myocardium was categorized into MVO⁺ group and MVO^- group by late gadolinium enhancement as gold standard. At T2-weighted image, the area of hyper-intense region and hypo-intense core inside were marked as A1, A2 and A2/A1 > 0 represented MVO. Strain parameters were composed of longitudinal strain (LS), circumferential strain and radial strain at rest and dobutamine stress. There were 94 MVO⁺ segments, 136 MVO^- segments according to gold standard. 96 segments had hypo-intense core at T2-STIR image. The sensitivity and specificity of T2-STIR in detecting MVO were 91.49 and 92.65%. Endocardial LS was superior to other parameters, and stress endocardial LS was higher than that of resting endocardial LS (sensitivity: 77.11% vs 72.29%, specificity: 93.28% vs 83.19%, AUC: 0.87 vs 0.82, P < 0.05). The combination of T2-STIR and stress endocardial LS in parallel test could improve sensitivity significantly (98.05% vs 91.49%). T2-STIR has higher diagnostic value in detecting MVO with some limitations. However, LDDSE-LS2D-STE with cost-effective and handling may be a good alternative to T2-STIR. It provides additional and reliable diagnostic tools to identify MVO in STEMI patients after reperfusion.

Comparison of Diagnostic Value Between STE+LDDSE and CMR-FT for Evaluating Coronary Microvascular Obstruction in Post-PCI Patients for STEMI

Background

Coronary microvascular obstruction (CMVO) is closely associated with poor prognosis of ST-segment elevation myocardial infarction (STEMI) patients. However, data showing the comparison between cardiac magnetic resonance feature tracking (CMR-FT) and speckle tracking echocardiography (STE) combined with low-dose dobutamine stress echocardiography (LDDSE) in evaluating CMVO was scarcely available. We aimed to explore and compare the predictive value between CMR-FT and STE+LDDSE in detecting CMVO.

Methods

Sixty-one STEMI patients were executed cardiac magnetic resonance and echocardiography within the first 5–7 days after primary percutaneous coronary intervention (PCI). The myocardial strain analysis was performed in STE, STE+LDDSE, and CMR-FT, and strain parameters included radial strain (RS), circumferential strain (CS), and longitudinal strain (LS). ROC curves were performed to predict infarcted myocardium segments with CMVO.

Results

Finally, 324 infarcted myocardium segments were analyzed, including 100 infarcted segments with CMVO and 224 segments without CMVO by the gold standard assessment of late gadolinium-enhancement cardiac magnetic resonance imaging (LGE-CMR). The results showed that CS was generally superior to RS and LS in identifying CMVO. CS in CMR-FT facilitated the detection of CMVO, with a sensitivity, specificity, and accuracy of 78.00%, 81.25%, and 80.25%, respectively. The sensitivity, specificity, and accuracy of CS in STE combined with LDDSE were better than STE alone (76.00% vs 60.00%, 79.91% vs 64.29%, and 78.70% vs 62.96%, P < 0.05). In addition, CMR-FT is not superior to STE+LDDSE for detection of CMVO (P > 0.05).

Conclusion

Low-dose dobutamine can improve the clinical value of STE for evaluating CMVO in STEMI patients. Compared with CMR-FT, STE+LDDSE might be a better choice for STEMI patients because of its safety, convenience, and low-cost.

Comprehensive Assessment of the Left Ventricular Systolic Function in the Elderly with Acute Myocardial Infarction Using Echocardiography

Aim

To evaluate the left ventricular (LV) systolic function in elderly with non-ST elevation myocardial infarction (NSTEMI) and ST elevation myocardial infarction (STEMI) using real-time three-dimensional echocardiography (RT-3DE) and two-dimensional speckle tracking imaging (STI).

Methods

Forty NSTEMI and forty STEMI patients after undergoing percutaneous coronary artery intervention (PCI) were enrolled. The myocardial segments were supplied by the infarct-related artery (Myo-_IRA) which were indicated by the selective coronary arteriography (SCA). The LV end-diastolic volume (LVEDV), end-systolic volume (LVESV), stroke volume (LVSV) and ejection fraction (LVEF) were acquired by 4D LV Volume Tom Tec. LV longitudinal peak systolic strain (LPSS), radial peak systolic strain (RPSS), circumferential peak systolic strain (CPSS) of Myo-_IRA segments, LV rotational peak degree in the base (rot-_base) and in the apex (rot-_apex), and twist were acquired by strain analysis software. Forty older healthy individuals were included as normal controls.

Results

The LVEF of the NSTEMI and STEMI patients at 1 week after PCI were significantly lower (P<0.05), then, this parameter was improved in both groups after 3 months, but was still significantly lower than that of the controls (P<0.05). The LPSS, RPSS, CPSS of the Myo_−IRA segments, rot_−Base, rot_−Apex and twist in both groups were significantly lower than those in the controls. The LPSS and CPSS of the Myo-IRA segments, rot_−Base, rot_−Apex and twist in NSTEMI patients were obviously higher than those in STEMI patients in 1 week and 3 months after PCI (P<0.05). After 3 months, the RPSS of NSTEMI patients was improved notably and was obviously higher than that of STEMI patients (P<0.05). All these values in STEMI and NSTEMI patients were improved after 3 months, apart from LPSS in STEMI patients (P>0.05), but were still significantly lower than those in the controls (P<0.05).

Conclusion

RT-3DE and STI can sensitively assess LV systolic function with different extents of transmural damage.

Tissue Mitral Annular Displacement in Patients With Myocardial Infarction - Comparison With Global Longitudinal Strain

Background: Global longitudinal strain (GLS) can predict prognosis after myocardial infarction (MI). Tissue mitral annular displacement (TMAD) is another index of longitudinal left ventricular deformity, and is less dependent on image quality than GLS. We investigated the relationship between TMAD and GLS, and their ability to predict outcomes after MI. Methods and Results: GLS and TMAD were measured on echocardiograms 2 weeks after MI in 246 consecutive patients (median age 62 years, 85.7% male). TMAD was measured from apical 4- and 2-chamber views (TMAD4ch and TMAD2ch, respectively), and a mean value (TMADav) was calculated. TMAD4ch, TMAD2ch, and GLS were successfully measured in 240 (97.5%), 210 (85.3%) and 214 patients (87.0%), respectively. All TMAD parameters were significantly correlated with GLS (R=0.71-0.75) and left ventricular ejection fraction (LVEF; R=0.48-0.53). TMAD parameters were weakly correlated with peak creatine kinase (CK; R=0.20) and CK-MB (R=0.21-0.25). GLS and TMADav were significantly associated with LVEF after 6 months (R=0.48-0.53) and all-cause mortality during the follow-up period (median 1,242 days). TMADav discriminated patients with higher all-cause mortality when patients were divided into 3 groups, namely upper 25%, middle range, and lower 25% of TMADav (P=0.041, log-rank test). GLS detected high-risk patients using 15.0% as a cut-off value. Conclusions: TMAD could be a simple and reliable alternative to GLS for predicting outcomes in patients with MI.

Impact of Three-Dimensional Strain on Major Adverse Cardiovascular Events after Acute Myocardial Infarction Managed by Primary Percutaneous Coronary Intervention-A Pilot Study

BACKGROUND

Three-dimensional speckle-tracking echocardiography (3D-STE) allows simultaneous assessment of multidirectional components of strain. However, there are few data on its usefulness to predict prognosis in patients with acute myocardial infarction (AMI). The objective of our pilot study was to evaluate the prognostic value of four different 3D-STE parameters (global longitudinal strain (GLS-3D), global circumferential strain (GCS-3D), global radial strain (GRS-3D), and global area strain (GAS)) in AMI, after successful revascularization by primary PCI.

METHODS

We enrolled 94 AMI patients (66 ± 13 years, 56% men) who underwent coronary angiography. All patients had been 3D-STE assessed and followed-up for 1 year for the occurrence of MACE.

RESULTS

A total of 25 MACE were recorded over follow-up. Cut-off values of -17% for GAS (HR = 3.1, 95% CI: 1.39-6.92, p = 0.005), -12% for GCS-3D (HR = 3.06, 95% CI: 1.36-6.8, p = 0.006), -10% for GLS-3D (HR = 3.04, 95% CI: 1.36-6.78, p = 0.006), and 25% for GRS-3D (HR = 2.89, 95% CI: 1.29-6.46, p = 0.009) showed moderate accuracy in MACE prediction. Multivariate regression showed that GAS (HR = 1.1, 95% CI: 1.03-1.16), GLS-3D (HR = 1.13, 95% CI: 1.03-1.26), and GCS-3D (HR = 1.13, 95% CI: 1.03-1.23) remained independent predictors of MACE (HR = 1.07, 95% CI: 1.01-1.14 for GAS, and HR = 1.1, 95% CI: 1.01-1.2 for GCS-3D). However, post hoc power analysis indicated adequate sample size (power of 80%) only for GAS and GCS-3D for the ROC curve analysis and for GAS, GCS-3D, and GRS-3D for the log-rank test.

CONCLUSION

Patients with AMI might benefit from early risk stratification with the aid of 3D-STE measurements, particularly GAS and GCS-3D, but larger studies are necessary to determine the optimal cut-off values to predict MACE.

Predictors of Microvascular Reperfusion After Myocardial Infarction

Purpose of Review

In acute ST-segment elevation myocardial infarction (STEMI), successful restoration of blood flow in the infarct-related coronary artery may not secure effective myocardial reperfusion. The mortality and morbidity associated with acute MI remain significant. Microvascular obstruction (MVO) represents failed microvascular reperfusion. MVO is under-recognized, independently associated with adverse cardiac prognosis and represents an unmet therapeutic need.

Recent Findings

Multiple factors including clinical presentation, patient characteristics, biochemical markers, and imaging parameters are associated with MVO after MI.

Summary

Impaired microvascular reperfusion is common following percutaneous coronary intervention (PCI). New knowledge about disease mechanisms underpins precision medicine with individualized risk assessment, investigation, and stratified therapy. To date, there are no evidence-based therapies to prevent or treat MVO post-MI. Identifying novel therapy for MVO is the next frontier.

Tagged cine magnetic resonance imaging to quantify regional mechanical changes after acute myocardial infarction

PURPOSE

The conventional volumetric approaches of measuring cardiac function are load-dependent, and are not able to discriminate functional changes in the infarct, transition and remote myocardium. We examined phase-dependent regional mechanical changes in the infarct, transition and remote regions after acute myocardial infarction (MI) in a preclinical mouse model using cardiovascular magnetic resonance imaging (CMR).

METHODS

We induced acute MI in six mice with left anterior descending coronary artery ligation. We then examined cardiac (infarct, transition and remote-zone) morphology and function utilizing 9.4 T high field CMR before and 2 weeks after the induction of acute MI. Myocardial scar tissue was evaluated by using CMR with late gadolinium enhancement (LGE). After determining global function through volumetric analysis, regional wall motion was evaluated by measuring wall thickening and radial velocities. Strain rate imaging was performed to assess circumferential contraction and relaxation at the myocardium, endocardium, and epicardium.

RESULTS

There was abnormal LGE in the anterior walls after acute MI suggesting a successful MI procedure. The transition zone consisted of a mixed signal intensity, while the remote zone contained viable myocardium. As expected, the infarct zone had demonstrated severely decreased myocardial velocities and strain rates, suggesting reduced contraction and relaxation function. Compared to pre-infarct baseline, systolic and diastolic velocities (v_S and v_D) were significantly reduced at the transition zone (v_S: -1.86 ± 0.16 cm/s vs -0.68 ± 0.13 cm/s, P < 0.001; v_D: 1.86 ± 0.17 cm/s vs 0.53 ± 0.06 cm/s, P < 0.001) and remote zone (v_S: -1.86 ± 0.16 cm/s vs -0.65 ± 0.12 cm/s, P < 0.001; v_D: 1.86 ± 0.16 cm/s vs 0.51 ± 0.04 cm/s, P < 0.001). Myocardial peak systolic and diastolic strain rates (SR_S and SR_D) were significantly lower in the transition zone (SR_S: -4.2 ± 0.3 s^-1 vs -1.3 ± 0.2 s^-1, P < 0.001; SR_D: 3.9 ± 0.3 s^-1 vs 1.3 ± 0.2 s^-1, P < 0.001) and remote zone (SR_S: -3.8 ± 0.3 s^-1 vs -1.4 ± 0.3 s^-1, P < 0.001; SR_D: 3.5 ± 0.2 s^-1 vs 1.5 ± 0.4 s^-1, P = 0.006). Endocardial and epicardial SR_S and SR_D were similarly reduced in the transition and remote zones compared to baseline.

CONCLUSIONS

This study, for the first time, utilized state-of-the art high-field CMR algorithms in a preclinical mouse model for a comprehensive and controlled evaluation of the regional mechanical changes in the transition and remote zones, after acute MI. Our data demonstrate that CMR can quantitatively monitor dynamic post-MI remodeling in the transition and remote zones, thereby serving as a gold standard tool for therapeutic surveillance.

Sex-specific echocardiographic reference values: the women's point of view

: Clinical presentation, diagnosis and outcomes of cardiac diseases are influenced by the activity of sex steroid hormones. These hormonal differences explain the later development of heart diseases in women in comparison with men and the different clinical picture, management and prognosis. Echocardiography is a noninvasive and easily available technique for the analysis of cardiac structure and function. The aim of the present review is to underline the most important echocardiographic differences between sexes. Several echocardiographic studies have found differences in healthy populations between women and men. Sex-specific difference of some of these parameters, such as left ventricular (LV) linear dimensions and left atrial volume, can be explained on the grounds of smaller body size of women, but other parameters (LV volumes, stroke volume and ejection fraction, right ventricular size and systolic function) are specifically lower in women, even after adjusting for body size and age. Sex-specific differences of standard Doppler and Tissue Doppler diastolic indices remain controversial, but it is likely for aging to affect LV diastolic function more in women than in men. Global longitudinal strain appears to be higher in women during the childbearing age - a finding that also highlights a possible hormonal influence in women. All these findings have practical implications, and sex-specific reference values are necessary for the majority of echocardiographic parameters in order to distinguish normalcy from disease. Careful attention on specific cut-off points in women could avoid misinterpretation, inappropriate management and delayed treatment of cardiac diseases such as valvular disease and heart failure.

Prediction for Improvement and Remodeling in First-Onset Myocardial Infarction by Speckle Tracking Echocardiography: Is Global or Regional Selection Better?

Cardiac function improvement and chamber remodeling after the onset of acute myocardial infarction (AMI) is crucial as it is closely related to the outcomes of patients. We sought to investigate the predictive value of left ventricular (LV) global and region of interest (ROI) assessment for prognosis of AMI patients by speckle tracking echocardiography (STE). We prospectively enrolled 81 first-onset AMI patients for baseline and 6-mo follow-up analysis. The echocardiography-derived parameters were compared in receiver operator characteristics (ROC) analysis for prediction of LV remodeling (LVR) (a minimum 20% increase of LV end-diastolic volume) and cardiac function improvement (a minimum 5% increase of LV ejection fraction). The ROI strain was selected by wall motion score index (WMSI) scores ≥2. The time of whole analysis process was recorded. Cut-off values of -9.92% for global circumferential strain (CS) and -5.53% for ROI CS predicted LVR. Cut-off values of -10.40% for global longitudinal strain (LS) and -5.33% for ROI LS predicted cardiac function improvement. Areas under curves of global and ROI parameters were comparable in ROC analysis (p > 0.05, all). The time of global analysis was less than the time of ROI analysis (p < 0.05) and the reproducibility of global analysis was slightly better than the ROI analysis. Our results demonstrated that STE was valuable for the prediction of LVR and cardiac function improvement after AMI. Compared with ROI parameters, global parameters were more integral and efficient as predictive factors with high predictive power, less analysis time and better reproducibility.

Cardiac remodeling following reperfused acute myocardial infarction is linked to the concomitant evolution of vascular function as assessed by cardiovascular magnetic resonance

BACKGROUND

Left ventricular (LV) remodeling following acute myocardial infarction (MI) is difficult to predict at an individual level although a possible interfering role of vascular function has yet to be considered to date. This study aimed to determine the extent to which this LV remodeling is influenced by the concomitant evolution of vascular function and LV loading conditions, as assessed by phase-contrast Cardiovascular Magnetic Resonance (CMR) of the ascending aorta.

METHODS

CMR was performed in 121 patients, 2-4 days after reperfusion of a first ST-segment elevation myocardial infarction and 6 months thereafter. LV remodeling was: (i) assessed by the 6-month increase in end-diastolic volume (EDV) and/or ejection fraction (EF) and (ii) correlated with the indexed aortic stroke volume (mL.m-2), determined by a CMR phase-contrast sequence, along with derived functional vascular parameters (total peripheral vascular resistance (TPVR), total arterial compliance index, effective arterial elastance).

RESULTS

At 6 months, most patients were under angiotensin enzyme converting inhibitors (86%) and beta-blockers (84%) and, on average, all functional vascular parameters were improved whereas blood pressure levels were not. An increase in EDV only (EDV+/EF-) was documented in 17% of patients at 6 months, in EF only (EDV-/EF+) in 31%, in both EDV and EF (EDV+/EF+) in 12% and neither EDV nor EF (EDV-/EF-) in 40%. The increase in EF was mainly and independently linked to a concomitant decline in TPVR (6-month change in mmHg.min.m2.L-1, EDV-/EF-: +1 ± 8, EDV+/EF-: +3 ± 9, EDV-/EF+: -7 ± 6, EDV+/EF+: -15 ± 20, p < 0.001) while the absence of any EF improvement was associated with high persisting rates of abnormally high TPVR at 6 months (EDV-/EF-: 31%, EDV+/EF-: 38%, EDV-/EF+: 5%, EDV+/EF+: 13%, p = 0.007). By contrast, the 6-month increase in EDV was mainly dependent on cardiac as opposed to vascular parameters and particularly on the presence of microvascular obstruction at baseline (EDV-/EF-: 37%, EDV+/EF-: 76%, EDV-/EF+: 38%, EDV+/EF+: 73%, p = 0.003).

CONCLUSION

LV remodeling following reperfused MI is strongly influenced by the variable decrease in systemic vascular resistance under standard care vasodilating medication. The CMR monitoring of vascular resistance may help to tailor these medications for improving vascular resistance and consequently, LV ejection fraction.

TRIAL REGISTRATION

NCT01109225 on ClinicalTrials.gov site (April, 2010).

Regional Longitudinal Myocardial Deformation Provides Incremental Prognostic Information in Patients with ST-Segment Elevation Myocardial Infarction

Background

Global longitudinal systolic strain (GLS) has recently been demonstrated to be a superior prognosticator to conventional echocardiographic measures in patients after myocardial infarction (MI). The aim of this study was to evaluate the prognostic value of regional longitudinal myocardial deformation in comparison to GLS, conventional echocardiography and clinical information.

Method

In total 391 patients were admitted with ST-Segment elevation myocardial infarction (STEMI), treated with primary percutaneous coronary intervention and subsequently examined by echocardiography. All patients were examined by tissue Doppler imaging (TDI) and two-dimensional strain echocardiography (2DSE).

Results

During a median-follow-up of 5.3 (IQR 2.5–6.1) years the primary endpoint (death, heart failure or a new MI) was reached by 145 (38.9%) patients. After adjustment for significant confounders (including conventional echocardiographic parameters) and culprit lesion, reduced longitudinal performance in the anterior septal and inferior myocardial regions (but not GLS) remained independent predictors of the combined outcome. Furthermore, inferior myocardial longitudinal deformation provided incremental prognostic information to clinical and conventional echocardiographic information (Harrell's c-statistics: 0.63 vs. 0.67, p = 0.032). In addition, impaired longitudinal deformation outside the culprit lesion perfusion region was significantly associated with an adverse outcome (p<0.05 for all deformation parameters).

Conclusion

Regional longitudinal myocardial deformation measures, regardless if determined by TDI or 2DSE, are superior prognosticators to GLS. In addition, impaired longitudinal deformation in the inferior myocardial segment provides prognostic information over and above clinical and conventional echocardiographic risk factors. Furthermore, impaired longitudinal deformation outside the culprit lesion perfusion region seems to be a paramount marker of adverse outcome.