Layer-specific analysis of myocardial function for accurate prediction of reversible ischaemic dysfunction in intermediate viability defined by contrast-enhanced MRI

Incremental value of myocardial global longitudinal strain in predicting major adverse cardiac events among patients with hypertrophic cardiomyopathy

OBJECTIVES

Endocardial global longitudinal strain (endo-GLS) measured with echocardiography (echo) has been demonstrated to be associated with myocardial fibrosis (MF) and is a prognostic predictor in patients with hypertrophic cardiomyopathy (HCM). Late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) imaging showed that MF is primarily located in the myocardial layer of the extremely hypertrophic septal or ventricular wall. We hypothesized that GLS of the myocardial layer (myo-GLS) is more strongly correlated with the extent of LGE (%LGE) and is a more powerful prognostic factor than endo-GLS.

METHODS

A total of 177 inpatients (54.0 [IQR: 43.0, 64.0] years, female 37.3%) with HCM were retrospectively included from May 2019 to April 2021. Among them, 162 patients underwent echocardiographic examination and contrast-enhanced CMR within 7 days. Myo-GLS and %LGE were blindly assessed in a core laboratory. All the patients were followed after they were discharged.

RESULTS

During a mean follow-up of 33.77 [IQR 30.05, 35.40] months, 14 participants (7.91%) experienced major adverse cardiac events (MACE). The MACE (+) group showed lower absolute endo-GLS and myo-GLS than the MACE (-) group. Myo-GLS was more associated with %LGE (r = -.68, P < .001) than endo-GLS (r = -.64, P < .001). Cox multivariable analysis indicated that absolute myo-GLS was independently associated with MACE (adjusted hazard ratio = .75, P < .05). Myo-GLS was better than endo-GLS at detecting MACE (+) patients (-8.64%, AUC .939 vs. - 16.375%, AUC .898, P < .05).

CONCLUSIONS

Myo-GLS is a stronger predictor of MACE than endo-GLS in patients with HCM and is highly correlated with %LGE.

Usefulness of layer-specific strain for evaluating and predicting recovery of left ventricular myocardial function in patients undergoing hybrid coronary revascularization

PURPOSE

This study aimed to determine if layer-specific strain (LSS) can be used to evaluate and predict left ventricular (LV) recovery in patients with multi-vessel coronary artery disease (CAD) undergoing hybrid coronary revascularization (HCR) using speckle tracking echocardiography (STE).

METHODS

A total of 187 consecutive CAD patients who received HCR in our hospital were prospectively enrolled. 30 healthy individuals with matched age and gender were enrolled as a control group. Echocardiography was performed for CAD patients before and 1, 2, and 6 months after HCR. Comprehensive conventional and LSS echocardiography parameters were collected. LV recovery was defined as improvement in LV ejection fraction (LVEF) > 5% at 6-months follow-up compared with baseline. Logistic regression analysis was used to test the correlates of LV recovery. Receiver operating characteristic curve analysis was used to determine the optimal cutoff value of correlates for predicting LV recovery.

RESULTS

LVEF and LV strain in CAD patients were significantly decreased compared with control subjects. Endocardial global longitudinal strain (Endo-GLS) improved significantly at 1-month follow-up (14.2 ± 1.6% vs. 13.8 ± 1.5%, P < 0.05), and LVGLS and global circumferential strain (GCS) improved significantly at 2-months follow-up. Multivariate regression revealed that Endo-GLS, GLS, and SYNTAX score before HCR were independently correlated to LV recovery. Endo-GLS had an optimal cutoff value of 13.2% for predicting LV recovery with sensitivity of 91% and specificity of 78%.

CONCLUSION

LV myocardial systolic function in CAD patients was impaired before HCR and significantly improved after HCR. Endo-GLS was independently correlated to and has optimal predictive value for LV recovery.

Speckle-tracking echocardiography for predicting improvement of myocardial contractile function after revascularization: a meta-analysis of prospective trials

Some studies have indicated that the use of 2D-Speckle tracking echocardiography (2DSTE) aids in predicting recovery of myocardial contractile function after revascularization in patients with chronic ischemic left ventricular (LV) dysfunction or acute myocardial infarction (MI). The purpose of this meta-analysis was to evaluate the diagnostic accuracy of 2DSTE strain in the detection of myocardial viability at rest and during low-dose dobutamine (LDD) stress. A systematic review for all prospective trials using 2DSTE to assess myocardial viability until January 2019 was done. Using a standard approach of meta-analysis for diagnostic tests. Overall, nine studies including 525 patients with either chronic ischemic heart disease or acute MI fulfilled the inclusion criteria. Seven studies used longitudinal strain (LS) at rest, nine studies used circumferential strain (CS) at rest, four studies used LS during LDD stress, and four studies used CS during LDD stress. LS and CS during LDD stress showed equally high sensitivity (81.5% and 81.5% respectively) and specificity (81.3% and 81.4% respectively) for detecting reversible dysfunction. At rest, LS and CS showed equally lower sensitivity (67.1%, p < 0.0001 vs. LDD stress and 68.7%, p < 0.0001, vs. LDD stress, respectively) and specificity (64%, p < 0.0001 vs. LDD stress and 65.7%, p = 0.0008 vs. LDD stress, respectively) as compared with LDD stress. LS and CS by 2DSTE during LDD stress accurately identify reversible ischemic myocardial dysfunction in patients with chronic ischemic LV dysfunction or after MI. The use of LDD stress can be recommended over resting strain measures in this setting.

Strain by speckle tracking echocardiography correlates with electroanatomic scar location and burden in ischaemic cardiomyopathy

AIMS

Ventricular tachycardia (VT) in ischaemic cardiomyopathy (ICM) originates from scar, identified as low-voltage areas with invasive high-density electroanatomic mapping (EAM). Abnormal myocardial deformation on speckle tracking strain echocardiography can non-invasively identify scar. We examined if regional and global longitudinal strain (GLS) can localize and quantify low-voltage scar identified with high-density EAM.

METHODS AND RESULTS

We recruited 60 patients, 40 ICM patients undergoing VT ablation and 20 patients undergoing ablation for other arrhythmias as controls. All patients underwent an echocardiogram prior to high-density left ventricular (LV) EAM. Endocardial bipolar and unipolar scar location and percentage were correlated with regional and multilayer GLS. Controls had normal GLS and normal bipolar and unipolar voltages. There was a strong correlation between endocardial and mid-myocardial longitudinal strain and endocardial bipolar scar percentage for all 17 LV segments (r = 0.76-0.87, P < 0.001) in ICM patients. Additionally, indices of myocardial contraction heterogeneity, myocardial dispersion (MD), and delta contraction duration (DCD) correlated with bipolar scar percentage. Endocardial and mid-myocardial GLS correlated with total LV bipolar scar percentage (r = 0.83; 0.82, P < 0.001 respectively), whereas epicardial GLS correlated with epicardial bipolar scar percentage (r = 0.78, P < 0.001). Endocardial GLS -9.3% or worse had 93% sensitivity and 82% specificity for predicting endocardial bipolar scar >46% of LV surface area.

CONCLUSIONS

Multilayer strain analysis demonstrated good linear correlations with low-voltage scar by invasive EAM. Validation studies are needed to establish the utility of strain as a non-invasive tool for quantifying scar location and burden, thereby facilitating mapping and ablation of VT.

Direct comparison of multilayer left ventricular global longitudinal strain using CMR feature tracking and speckle tracking echocardiography

Background

Cardiac magnetic resonance feature tracking (CMR-FT) and speckle tracking echocardiography (STE) are well-established strain imaging modalities. Multilayer strain measurement permits independent assessment of endocardial and epicardial strain. This novel and layer specific approach to evaluating myocardial deformation parameters may provide greater insight into cardiac contractility when compared to whole-layer strain analysis. The aim of this study is to validate CMR-FT as a tool for multilayer strain analysis by providing a direct comparison between multilayer global longitudinal strain (GLS) values between CMR-FT and STE.

Methods

We studied 100 patients who had an acute myocardial infarction (AMI), who underwent CMR imaging and echocardiogram at baseline and follow-up (48 ± 13 days). Dedicated tissue tracking software was used to analyse single- and multi-layer GLS values for CMR-FT and STE.

Results

Correlation coefficients for CMR-FT and STE were 0.685, 0.687, and 0.660 for endocardial, epicardial, and whole-layer GLS respectively (all p < 0.001). Bland Altman analysis showed good inter-modality agreement with minimal bias. The absolute limits of agreement in our study were 6.4, 5.9, and 5.5 for endocardial, whole-layer, and epicardial GLS respectively. Absolute biases were 1.79, 0.80, and 0.98 respectively. Intraclass correlation coefficient (ICC) values showed moderate agreement with values of 0.626, 0.632, and 0.671 respectively (all p < 0.001).

Conclusion

There is good inter-modality agreement between CMR-FT and STE for whole-layer, endocardial, and epicardial GLS, and although values should not be used interchangeably our study demonstrates that CMR-FT is a viable imaging modality for multilayer strain

Speckle tracking echocardiography in a patient with viral myocarditis and acute myocardial infarction

The present case of a patient with acute myocarditis with preserved left ventricular (LV) ejection fraction at the acute stage illustrates the obvious impairment of circumferential and rotational deformation, which can be documented by speckle tracking echocardiography. Thus, qualitative patterns of LV twist, radial strain, and circumferential layer strain, might be a new approach to detect acute myocarditis. The early diagnosis of acute myocarditis by echocardiography is important because of the considerable risk of cardiovascular morbidity as documented by the occurrence of an acute myocardial infarction presumably induced by inflammatory process in this case. <Learning objective: The compound of myocardial deformations caused by left ventricular subendomyocardial and subepimyocardial fibers may be a crucial diagnostic target in cardiac diseases. The predominant involvement of viral myocarditis of the outer myocardial layers might induce impairment of circumferential and rotational deformation, which can potentially serve as a new diagnostic key by echocardiography. In contrast, left ventricular ejection fraction and longitudinal deformation are often observed within normal ranges in patients with acute myocarditis. Acute myocardial infarction as a major cardiac event in acute stage of myocarditis causes completely different deformation patterns, mainly by the predominant involvement of the inner myocardial layers inducing severe pathologies of territorial longitudinal deformation. Patients with suspected acute myocarditis and abnormal findings of circumferential and rotational deformation should undergo additional diagnostic procedures as cardiac magnetic resonance and myocardial biopsy to confirm the diagnosis.>.

Intra- and inter-observer reproducibility of multilayer cardiac magnetic resonance feature tracking derived longitudinal and circumferential strain

Background

Multilayer strain measurement with cardiac magnetic resonance feature tracking (CMR-FT) allows independent assessment of endocardial and epicardial strain. This novel method of layer-specific quantification of myocardial deformation parameters provides greater insight into contractility compared to whole-layer strain analysis. The clinical utility of this technique is promising. The aim of this study is to investigate the intra- and inter- observer reproducibility of CMR-FT derived multilayer global longitudinal strain (GLS) and global circumferential strain (GCS) parameters in the setting of normal cardiac function, cardiac pathology, and differing MRI field strengths.

Methods

We studied 4 groups of 20 subjects, comprising of patients with dilated cardiomyopathy, ischemic heart disease, and patients without cardiac pathology at both 1.5 and 3 T. Quantitative measures of whole-layer and multi-layer longitudinal and circumferential strain were calculated using CMR-FT software.

Results

Intraclass correlation coefficients (ICC) for intraobserver reproducibility of endocardial, epicardial, and whole-layer measurements of GLS were 0.979, 0.980, and 0.978 respectively, and those for GCS were 0.986, 0.977, and 0.985. ICCs for inter-observer reproducibility of endocardial, epicardial, and whole-layer measurements of GLS were 0.976, 0.970, and 0.976, and those for GCS were 0.982, 0.969, and 0.981. Bland Altman analysis showed minimal bias and acceptable limits of agreement (LOA) within each patient subgroup and the overall cohort. Circumferential and longitudinal strain parameters were equally reproducible in the overall cohort.

Conclusions

CMR-FT derived multilayer measurements of longitudinal and circumferential strain demonstrate high intra- and inter- observer reproducibility, with suitability for use in clinical practice.

Layer-specific distribution of myocardial deformation from anthracycline-induced cardiotoxicity in patients with breast cancer-From bedside to bench

BACKGROUND

Anthracycline anticancer drugs such as epirubicin and doxorubicin may induce myocardial dysfunction, leading to poor prognosis. Early detection of minor left ventricular (LV) myocardial dysfunction is important for the prevention of anthracylcine-induced cardiotoxicity. Using layer-specific speckle tracking echocardiography (STE), we investigated the progressive distribution of myocardial dysfunction in both breast cancer patients and an animal toxicity model.

METHODS

Patients with preserved LV ejection fraction (LVEF) preparing for epirubicin chemotherapy (N = 125) were prospectively enrolled. Layer-specific STE, including LV longitudinal and circumferential strains on subepicardium and subendocardium, were evaluated at baseline and after the first cycle, third cycle and six months of epirubicin therapy. A decline of LVEF above 10% to <55% at six months was defined as cardiotoxicity. These same strain measures were obtained in doxorubicin-treated rats and the distribution of myocardial fibrosis evaluated.

RESULTS

In patients developing cardiotoxicity, LV longitudinal strain on subendocardium (LVLSendo) was significantly reduced after three cycles of therapy despite no significant changes in conventional LV systolic, diastolic parameters as well as LV circumferential strains at that moment. Compared to conventional echocardiographic parameters, LVLSendo was significantly predictive of cardiotoxicity. Declines in LVLSendo were also observed in doxorubicin-treated rats at an early stage. These reductions also predicted significant fibrosis in the subendocardial layer.

CONCLUSION

LVLSendo is useful for the early detection of minor cardiac dysfunction during chemotherapy, thereby implicating endocardial involvement in the development of cardiotoxicity.

Relationship of Myocardial Strain and Markers of Myocardial Injury to Predict Segmental Recovery After Acute ST-Segment-Elevation Myocardial Infarction

BACKGROUND

Late gadolinium-enhanced cardiovascular magnetic resonance imaging overestimates infarct size and underestimates recovery of dysfunctional segments acutely post ST-segment-elevation myocardial infarction. We assessed whether cardiovascular magnetic resonance imaging-derived segmental myocardial strain and markers of myocardial injury could improve the accuracy of late gadolinium-enhancement in predicting functional recovery after ST-segment-elevation myocardial infarction.

METHODS AND RESULTS

A total of 164 ST-segment-elevation myocardial infarction patients underwent acute (median 3 days) and follow-up (median 9.4 months) cardiovascular magnetic resonance imaging. Wall-motion scoring, feature tracking-derived circumferential strain (Ecc), segmental area of late gadolinium-enhancement (SEE), microvascular obstruction, intramyocardial hemorrhage, and salvage index (MSI) were assessed in 2624 segments. We used logistic regression analysis to identify markers that predict segmental recovery. At acute CMR 32% of segments were dysfunctional, and at follow-up CMR 19% were dysfunctional. Segmental function at acute imaging and odds ratio (OR) for functional recovery decreased with increasing SEE, although 33% of dysfunctional segments with SEE 76% to 100% improved. SEE was a strong predictor of functional improvement and normalization (area under the curve [AUC], 0.840 [95% confidence interval {CI}, 0.814-0.867]; OR, 0.97 [95% CI, 0.97-0.98] per +1% SEE for improvement and AUC, 0.887 [95% CI, 0.865-0.909]; OR, 0.95 [95% CI, 0.94-0.96] per +1% SEE for normalization). Its predictive accuracy for improvement, as assessed by areas under the receiver operator curves, was similar to that of MSI (AUC, 0.840 [95% CI, 0.809-0.872]; OR, 1.03 [95% CI, 1.02-1.03] per +1% MSI for improvement and AUC, 0.862 [0.832-0.891]; OR, 1.04 [95% CI, 1.03-1.04] per +1% SEE for normalization) and Ecc (AUC, 0.834 [95% CI, 0.807-0.862]; OR, 1.05 [95% CI, 1.03-1.07] per +1% MSI for improvement and AUC, 0.844 [95% CI, 0.818-0.871]; OR, 1.07 [95% CI, 1.05-1.10] per +1% SEE for normalization), and for normalization was greater than the other predictors. MSI and Ecc remained as significant after adjustment for SEE but provided no significant increase in predictive accuracy for improvement and normalization compared with SEE alone. MSI had similar predictive accuracy to SEE for functional recovery but was not assessable in 25% of patients. Microvascular obstruction provided no incremental predictive accuracy above SEE.

CONCLUSIONS

This multicenter study confirms that SEE is a strong predictor of functional improvement post ST-segment-elevation myocardial infarction, but recovery occurs in a substantial proportion of dysfunctional segments with SEE >75%. Feature tracking-derived Ecc and MSI provide minimal incremental benefit to SEE in predicting segmental recovery.

CLINICAL TRIAL REGISTRATION

URL: http://www.isrctn.com. Unique identifier: ISRCTN70913605.

Intra-procedural determination of viability by myocardial deformation imaging: a randomized prospective study in the cardiac catheter laboratory

BACKGROUND

The benefit of revascularization for functional recovery depends on the presence of viable myocardial tissue.

OBJECTIVE

Myocardial deformation imaging allows determination of myocardial viability.

METHODS

In a first approach, we assessed the optimal cutoff value to determine preserved viability by layer-specific echocardiographic myocardial deformation imaging at rest and low-dose dobutamine (DSE) echocardiography: regional endocardial circumferential strain (eCS) <-19% at rest was as accurate as eCS at DSE. In a main study, 123 patients (66% men, age 59 ± 6 years) with relevant coronary stenoses and corresponding severe regional myocardial dysfunction were included and randomized in 2 groups after coronary angiography: group A: intra-procedural myocardial deformation imaging in the cardiac catheter laboratory (CLab), determination of myocardial viability by regional eCS <-19%, in case of positive viability immediate coronary intervention in the same session. Group B: two-step determination of myocardial viability by cardiovascular magnetic resonance (CMR), in case of positive viability coronary intervention. After 18 months follow-up an analysis of the endpoints regarding cardiovascular events, left ventricular (LV) function, and comparison of cost was performed.

RESULTS

Group A (N = 61) and group B (N = 62) showed no differences concerning localization of the coronary stenosis, comorbidities, or medical therapy. Cardiovascular events at 18-month follow-up were as follows: group A 13% (N = 10) vs. group B 14% (N = 9, p = 0.288); improvement of LV function: group A: +7 ± 2% vs. group B: +7 ± 3%, p = 0.963; costs: group A: 3096 Dollar vs. group B: 6043 Dollar, p < 0.001.

CONCLUSION

Intra-procedural determination of myocardial viability by myocardial deformation imaging in the CLab is feasible, safe, and cost effective and may become an emerging alternative to the current practice of two-stage viability diagnostics.

Optimization-Based Speckle Tracking Algorithm for Left Ventricle Strain Estimation: A Feasibility Study

Speckle tracking echocardiography (STE) is a widespread method for calculating myocardial strains and estimating left ventricle function. Since echocardiographic clips are corrupted by speckle decorrelation noise, resulting in irregular, nonphysiological tissue displacement fields, smoothing is performed on the displacement data, affecting the strain results. Thus, strain results may depend on the specific implementations of 2-D STE, as well as other systems' characteristics of the various vendors. A novel algorithm (called K-SAD) is introduced, which integrates the physiological constraint of smoothness of the displacement field into an optimization process. Simulated B-mode clips, modeling healthy and abnormal cases, were processed by K-SAD. Peak global and subendocardial longitudinal strains, as well as regional strains, were calculated. In addition, 410 healthy subjects were also processed. The results of K-SAD are compared with those of one of the leading commercial product. K-SAD provides global mid-wall strain values, as well as subendocardial and regional strain values, all in good agreement with the ground-truth-simulated phantom data. K-SAD peak global longitudinal systolic strain values for 410 healthy subjects are quite similar for the different regions: - 17.02 ± 4.02%, - 19.00 ± 3.45%, and - 19.72 ± 5.06% at the basal, mid, and apical regions, respectively. Improved performance under noisy conditions was demonstrated by comparing a subgroup of 40 subjects with the best image quality with the remaining 370 cohort: K-SAD provides statistically similar global and regional results for the two cohorts. Our study indicates that the sensitivity of strain values to speckle noise, caused by the post block-matching weighted smoothing, can be significantly reduced and accuracy enhanced by employing an integrated one-stage, physiologically constrained optimization process.

Improvement of Cardiac Stem Cell Sheet Therapy for Chronic Ischemic Injury by Adding Endothelial Progenitor Cell Transplantation: Analysis of Layer-Specific Regional Cardiac Function

The transplantation of cardiac stem cell sheets (CSC sheets) is a promising therapeutic strategy for ischemic cardiomyopathy, although potential ischemia in the transplanted area remains a problem. Injected endothelial progenitor cells (EPCs) can reportedly induce angiogenesis in the injected area. We hypothesized that concomitant CSC sheet transplantation and EPC injection might show better therapeutic effects for chronic ischemic injury model than the transplantation of CSC sheets alone. Scaffold-free CSC sheets were generated from human c-kit-positive heart-derived cells. A porcine chronic ischemic injury model was generated by placing an ameroid constrictor around the left coronary artery for 4 weeks. The animals then underwent a sham operation, epicardial transplantation of CSC sheet over the ischemic area, intramyocardial injection of EPCs into the ischemic and peri-ischemic area, or CSC sheet transplantation plus EPC injection. The efficacy of each treatment was then assessed for 2 months. Speckle-tracking echocardiography was used to dissect the layer-specific regional systolic function by measuring the radial strain (RS). The epicardial RS in the ischemic area was similarly greater after treatment with the CSC-derived cell sheets alone (19 ± 5%) or in combination with EPC injection (20 ± 5%) compared with the EPC only (9 ± 4%) or sham (7 ± 1%) treatment. The endocardial RS in the ischemic area was greatest after the combined treatment (14 ± 1%), followed by EPC only (12 ± 1%), compared to the CSC only (11 ± 1%) and sham (9 ± 1%) treatments. Consistently, either epicardial CSC sheet implantation or intramyocardial EPC injection yielded increased capillary number and reduced cardiac fibrosis in the ischemic epicardium or endocardium, respectively. Concomitant EPC injection induced the migration of transplanted CSCs into the host myocardium, leading to further neovascularization and reduced fibrosis in the ischemic endocardium, compared to the CSC sole therapy. Transplantation of CSC sheets induced significant functional recovery of the ischemic epicardium, and concomitant EPC transplantation elicited transmural improvement in chronic ischemic injury.

Magnetic resonance-derived circumferential strain provides a superior and incremental assessment of improvement in contractile function in patients early after ST-segment elevation myocardial infarction

BACKGROUND

We evaluate whether circumferential strain derived from grid-tagged CMR is a better method for assessing improvement in segmental contractile function after STEMI compared to late gadolinium enhancement (LGE).

METHODS

STEMI patients post primary PCI underwent baseline CMR (day 3) and follow-up (day 90). Cine, grid-tagged and LGE images were acquired. Baseline LGE infarct hyperenhancement was categorised as ≤25 %, 26-50 %, 51-75 % and >75 % hyperenhancement. The segmental baseline circumferential strain (CS) and circumferential strain rate (CSR) were calculated from grid-tagged images. Segments demonstrating an improvement in wall motion of ≥1 grade compared to baseline were regarded as having improved segmental contractile-function.

RESULTS

Forty-five patients (aged 58 ± 12 years) and 179 infarct segments were analysed. A baseline CS cutoff of -5 % had sensitivity of 89 % and specificity of 70 % for detection of improvement in segmental-contractile-function. On receiver-operating characteristic analysis for predicting improvement in contractile function, AUC for baseline CS (0.82) compared favourably to LGE hyperenhancement (0.68), MVO (0.67) and baseline-CSR (0.74). On comparison of AUCs, baseline CS was superior to LGE hyperenhancement and MVO in predicting improvement in contractile function (P < 0.001). On multivariate-analysis, baseline CS was the independent predictor of improvement in segmental contractile function (P < 0.001).

CONCLUSION

Grid-tagged CMR-derived baseline CS is a superior predictor of improvement in segmental contractile function, providing incremental value when added to LGE hyperenhancement and MVO following STEMI.

KEY POINTS

Baseline CS predicts contractile function recovery better than LGE and MVO following STEMI. Baseline CS predicts contractile function recovery better than baseline CSR following STEMI. Baseline CS provides incremental value to LGE and MVO following STEMI.

Salvage assessment with cardiac MRI following acute myocardial infarction underestimates potential for recovery of systolic strain

OBJECTIVES

Our aim was to evaluate the relationship between the degree of salvage following acute ST elevation myocardial infarction (STEMI) and subsequent reversible contractile dysfunction using cardiac magnetic resonance (CMR) imaging.

METHODS

Thirty-four patients underwent CMR examination 1-7 days after primary percutaneous coronary intervention (PPCI) for acute STEMI with follow-up at 1 year. The ischaemic area-at-risk (AAR) was assessed with T2-weighted imaging and myocardial necrosis with late gadolinium enhancement. Myocardial strain was quantified with complementary spatial modulation of magnetisation (CSPAMM) tagging.

RESULTS

Ischaemic segments with poor (<25 %) or intermediate (26-50 %) salvage index were associated with worse Eulerian circumferential (Ecc) strain immediately post-PPCI (-9.1 % ± 0.6, P = 0.033 and -11.8 % ± 1.3, P = 0.003, respectively) than those with a high (51-100 %) salvage index (-14.4 % ± 1.3). Mean strain in ischaemic myocardium improved between baseline and follow-up (-10.1 % ± 0.5 vs. -16.2 % ± 0.5 %, P < 0.0001). Segments with poor salvage also showed an improvement in strain by 1 year (-9.1 % ± 0.6 vs. -15.3 % ± 0.6, P = 0.033) although they remained the most functionally impaired.

CONCLUSIONS

Partial recovery of peak systolic strain following PPCI is observed even when apparent salvage is less than 25 %. Late gadolinium enhancement (LGE) may not equate to irreversibly injured myocardium and salvage assessment performed within the first week of revascularisation may underestimate the potential for functional recovery.

KEY POINTS

• MRI can measure how much myocardium is damaged after a heart attack. • Heart muscle that appears initially non-viable may sometimes partially recover. • Enhancement around the edges of infarcts may resolve over time. • Evaluating new cardio-protective treatments with MRI requires appreciation of its limitations.

Layer-specific analysis of myocardial deformation for assessment of infarct transmurality: comparison of strain-encoded cardiovascular magnetic resonance with 2D speckle tracking echocardiography

AIMS

Separate analysis of endocardial and epicardial myocardial layer deformation has become possible using strain-encoded cardiovascular magnetic resonance (SENC) and 2D-dimensional speckle tracking echocardiography (Echo). This study evaluated and compared both modalities for the assessment of infarct transmurality as defined by late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR).

METHODS AND RESULTS

In 29 patients (age 62.4 ± 11.7 years, 23 male) with ischaemic cardiomyopathy, SENC using 1.5 T CMR and Echo were performed. Peak circumferential systolic strain of the endocardial and the epicardial layer of 304 myocardial segments was assessed by SENC and by Echo. The segmental transmurality of myocardial infarction was determined as relative amount of LGE (0%: no infarction; 1-50%: non-transmural infarction; 51-100%: transmural infarction). Endocardial and epicardial strain defined by SENC and by Echo differed significantly between segments of different infarct transmurality determined by CMR. Endocardial layer circumferential strain analysis by Echo and by SENC allowed distinction of segments with non-transmural infarction from non-infarcted segments with similar accuracy [area under the curve (AUC) 0.699 vs. 0.649, respectively, P = 0.239]. Epicardial layer circumferential strain analysis by Echo and by SENC allowed distinction of transmural from non-transmural myocardial infarction defined by LGE CMR with similar accuracy (AUC 0.721 vs. 0.664, respectively, P = 0.401). Endocardial strain by SENC correlated moderately with endocardial strain by Echo (r = 0.50; standard error of estimate = 5.2%).

CONCLUSION

Layer-specific analysis of myocardial deformation by Echo and by SENC allows discrimination between different transmurality categories of myocardial infarction with similar accuracy. However, accuracy of both methods is non-optimal, indicating that further tools for improvement should be evaluated in the future.