Left ventricular mechanical dispersion in ischaemic cardiomyopathy: association with myocardial scar burden and prognostic implications

Global longitudinal strain in long-term risk prediction after acute coronary syndrome: an investigation of added prognostic value to ejection fraction

AIMS

This study aimed to investigate the additional value of global longitudinal strain (GLS) on top of left ventricular ejection fraction (LVEF) in long-term risk prediction of combined death and heart failure (HF) re-hospitalization after acute coronary syndrome (ACS).

METHOD AND RESULTS

This retrospective study included patients admitted with ACS between 2008 and 2014 from the three participating university hospitals. LVEF and GLS were assessed at a core lab from images acquired during the index hospital stay. Their prognostic value was studied with the Cox proportional hazards model (median follow-up 6.2 years). A nested model comparison was performed with C-statistics. A total of 941 patients qualified for multivariable analysis after multiple imputation of missing baseline covariables. The combined outcome was reached in 17.7% of the cases. Both GLS and LVEF were independent predictors of the combined outcome, hazard ratio (HR) 1.068 (95% CI 1.017-1.121) and HR 0.980 (95% CI 0.962-0.998), respectively. The C-statistic increased from 0.742 (95% CI 0.702-0.783) to 0.749 (95% CI 0.709-0.789) (P = 0.693) when GLS entered the model with clinical data and LVEF.

CONCLUSION

GLS emerged as an independent long-term risk predictor of all-cause death and HF re-hospitalization. However, there was no significant incremental predictive value of GLS when LVEF was already known.

Left ventricular ejection fraction: clinical, pathophysiological, and technical limitations

Risk stratification of cardiovascular death and treatment strategies in patients with heart failure (HF), the optimal timing for valve replacement, and the selection of patients for implantable cardioverter defibrillators are based on an echocardiographic calculation of left ventricular ejection fraction (LVEF) in most guidelines. As a marker of systolic function, LVEF has important limitations being affected by loading conditions and cavity geometry, as well as image quality, thus impacting inter- and intra-observer measurement variability. LVEF is a product of shortening of the three components of myocardial fibres: longitudinal, circumferential, and oblique. It is therefore a marker of global ejection performance based on cavity volume changes, rather than directly reflecting myocardial contractile function, hence may be normal even when myofibril's systolic function is impaired. Sub-endocardial longitudinal fibers are the most sensitive layers to ischemia, so when dysfunctional, the circumferential fibers may compensate for it and maintain the overall LVEF. Likewise, in patients with HF, LVEF is used to stratify subgroups, an approach that has prognostic implications but without a direct relationship. HF is a dynamic disease that may worsen or improve over time according to the underlying pathology. Such dynamicity impacts LVEF and its use to guide treatment. The same applies to changes in LVEF following interventional procedures. In this review, we analyze the clinical, pathophysiological, and technical limitations of LVEF across a wide range of cardiovascular pathologies.

Clinical study of two-dimensional speckle tracking to evaluate abnormal myocardial motion due to coronary lesions

OBJECTIVE

To investigate the predictive ability of global longitudinal strain (GLS) and mechanical dispersion for coronary stenosis and provide a more reliable noninvasive method for diagnosis of obstructive coronary artery disease(OCAD).

METHODS

Sixty-seven patients diagnosed with suspected CAD were included in the study. Patients with coronary stenosis greater than 50% were assigned as OCAD, while the others were assigned as non obstructive coronary artery disease(NOCAD). General information was collected and patients underwent speckle tracking echocardiogram(STE).

RESULTS

Spearman's correlation analysis showed that GLS and mechanical dispersion were positively correlated with the degree of coronary stenosis (r = 0.383, 0.342, p < 0.05), and there was also a positive correlation between GLS and mechanical dispersion (r = 0.327, p < 0.05). GLS, longitudinal strain (LS) of each chamber, and mechanical dispersion were higher in the OCAD group than in the NOCAD group (p < 0.05). Univariate regression analysis showed that GLS, each lumen LS and mechanical dispersion were statistically significant (p < 0.05). Multifactorial regression analysis showed that elevated GLS (p = 0.007) and elevated mechanical dispersion (p = 0.030) were independent risk factors for OCAD. The ROC curves showed that GLS predicted OCAD (AUC area 0.745, 95% CI 0.624 to 0.865) versus mechanical discrete prediction of OCAD (AUC area 0.702, 95% CI 0.569 to 0.834) were more diagnostic than conventional cardiac ultrasound observations of ventricular wall motion abnormalities (AUC area 0.566, 95% CI 0.463 to 0.669).

CONCLUSIONS

Combining GLS with mechanical dispersion can rapidly assess OCAD in a very short period, which has strong promotion value and in-depth research value.

Prognostic implications of left ventricular inward displacement assessed by cardiac magnetic resonance imaging in patients with myocardial infarction

Risk stratification of patients with ischemic heart disease (IHD) still depends mainly on the left ventricular ejection fraction (LVEF). LV inward displacement (InD) is a novel parameter of LV systolic function, derived from feature tracking cardiac magnetic resonance (CMR) imaging. We aimed to investigate the prognostic impact of InD in patients with IHD and prior myocardial infarction. A total of 111 patients (mean age 57 ± 10, 86% male) with a history of myocardial infarction who underwent CMR were included. LV InD was quantified by measuring the displacement of endocardially tracked points towards the centreline of the LV during systole with feature tracking CMR. The endpoint was a composite of all-cause mortality, heart failure hospitalization and arrhythmic events. During a median follow-up of 142 (IQR 107-159) months, 31 (27.9%) combined events occurred. Kaplan-Meier analysis demonstrated that patients with LV InD below the study population median value (23.0%) had a significantly lower event-free survival (P < 0.001). LV InD remained independently associated with outcomes (HR 0.90, 95% CI 0.84-0.98, P = 0.010) on multivariate Cox regression analysis. InD also provided incremental prognostic value to LVEF, LV global radial strain and CMR scar burden. LV InD, measured with feature tracking CMR, was independently associated with outcomes in patients with IHD and prior myocardial infarction. LV InD also provided incremental prognostic value, in addition to LVEF and LV global radial strain. LV InD holds promise as a pragmatic imaging biomarker for post-infarct risk stratification.

Associations between cardiovascular risk factors, biomarkers, and left ventricular mechanical dispersion: insights from the ACE 1950 Study

Aims

Mechanical dispersion measures left ventricular contraction heterogeneity and is associated with the risk of sudden cardiac death. However, the associations between mechanical dispersion and cardiovascular risk factors in early mid-life, and established biomarkers of sub-clinical myocardial injury and dysfunction are not known. We aimed to examine this in the general population.

Methods and results

During 2012–15, we included 2527 Norwegian individuals from the general population born in 1950, with measurements of mechanical dispersion by 2D speckle tracking echocardiography and concentrations of high-sensitivity cardiac troponin T (hs-cTnT) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) available. Mechanical dispersion was calculated as the standard deviation of the contraction duration of 17 strain segments. We assessed the associations between mechanical dispersion, concentrations of hs-cTnT and NT-proBNP, and cardiovascular risk factors collected at a national health screening survey two decades earlier. At echocardiography baseline, median age was 64 (interquartile range 63.5–64.5) years, 49.8% were women, 59.1% had hypertension, and 5.9% reported established coronary artery disease. Median mechanical dispersion was 38.0 (29.5–47.0) ms, median hs-cTnT concentration 6 (4–8) ng/L, and the median NT-proBNP concentration 54 (34–93) ng/L. Mechanical dispersion was associated with both hs-cTnT and NT-proBNP concentrations in multivariable models adjusted for clinical and echocardiographic variables. High body mass index, serum triglyceride concentrations, and low resting heart rate at Age 40 were independently associated with increased mechanical dispersion two decades later.

Conclusion

Established risk factors at Age 40 are associated with mechanical dispersion two decades later, and mechanical dispersion is cross-sectionally associated with biomarkers of subclinical myocardial injury and dysfunction.

Impact of inter-vendor variability on evaluation of left ventricular mechanical dispersion

PURPOSE

Left ventricular mechanical dispersion (LVMD) is a novel speckle tracking parameter for prognostic assessment of arrhythmic risk prediction. There is growing evidence to support its use in a variety of cardiomyopathic processes. There is paucity of data addressing any presence of inter-vendor discrepancies for LVMD. The aim of this study was to assess inter-vendor variability of LVMD in vendor specific software (VSS) and vendor independent software (VIS) in subjects with preserved and reduced left ventricular function.

METHODS

Fifty-nine subjects (14 normal subjects and 45 subjects with cardiac disease) were recruited and 2D speckle tracking echocardiographic images were acquired on two different ultrasound machines (GE and Philips). LVMD was measured by two different VSS (EchoPac GE and QLAB Philips) and one VIS (TomTec Arena).

RESULTS

There was significant bias and wide limits of agreement (LOA) in the overall cohort observed between two different VSS (17.6 ms; LOA: -29.6 to 64.8; r: .47). There was acceptable bias and narrower LOA with good agreement for LVMD between images obtained on different vendors when performed on VIS (-3.1 ms; LOA: -27.6 to 21.4; r: .75). QLAB LVMD was consistently higher than GE LVMD and TomTec LVMD in both preserved and reduced left ventricular function. LVMD measurements have high intra-vendor reproducibility with excellent inter and intra-observer agreement.

CONCLUSIONS

There was acceptable bias and narrower LOA for LVMD assessment on a VIS. Inter-vendor variability exists for LVMD assessment between VSS. Serial measurements of LVMD should be performed using a single vendor for consistent and reliable results.

The year 2020 in the European Heart Journal-Cardiovascular Imaging: part II

The European Heart Journal-Cardiovascular Imaging was launched in 2012 and has during these years become one of the leading multimodality cardiovascular imaging journal. The journal is now established as one of the top cardiovascular journals and is the most important cardiovascular imaging journal in Europe. The most important studies published in our Journal from 2020 will be highlighted in two reports. Part II will focus on valvular heart disease, heart failure, cardiomyopathies, and congenital heart disease. While Part I of the review has focused on studies about myocardial function and risk prediction, myocardial ischaemia, and emerging techniques in cardiovascular imaging.

Impact of myocardial scars on left ventricular deformation in type 2 diabetes mellitus after myocardial infarction by contrast-enhanced cardiac magnetic resonance

Background

Type 2 diabetes mellitus (T2DM) is a major risk factor for coronary artery disease and myocardial infarction (MI). The interaction of diabetic cardiomyopathy and MI scars on myocardial deformation in T2DM patients is unclear. Therefore, we aimed to evaluate myocardial deformation using cardiac magnetic resonance (CMR) in T2DM patients with previous MI and investigated the influence of myocardial scar on left ventricular (LV) deformation.

Methods

Overall, 202 T2DM patients, including 46 with MI (T2DM(MI+)) and 156 without MI (T2DM(MI−)), and 59 normal controls who underwent CMR scans were included. Myocardial scars were assessed by late gadolinium enhancement. LV function and deformation, including LV global function index, LV global peak strain (PS), peak systolic strain rate (PSSR), and peak diastolic strain rate (PDSR), were compared among these groups. Correlation and multivariate linear regression analyses were used to investigate the relationship between myocardial scars and LV deformation.

Results

Decreases were observed in LV function and LV global PS, PSSR, and PDSR in the T2DM(MI+) group compared with those of the other groups. Reduced LV deformation (p < 0.017) was observed in the T2DM(MI+) group with anterior wall infarction. The increased total LV infarct extent and infarct mass of LV were related to decreased LV global PS (radial, circumferential, and longitudinal directions; p < 0.01) and LV global PSSR (radial and circumferential directions, p < 0.02). Multivariate analysis demonstrated that NYHA functional class and total LV infarct extent were independently associated with LV global radial PS (β =  − 0.400 and β =  − 0.446, respectively, all p < 0.01; model R² = 0.37) and circumferential PS (β = 0.339 and β = 0.530, respectively, all p < 0.01; model R² = 0.41), LV anterior wall infarction was independently associated with LV global longitudinal PS (β = 0.398, p = 0.006).

Conclusions

The myocardial scarring size in T2DM patients after MI is negatively correlated with LV global PS and PSSR, particularly in the circumferential direction. Additionally, different MI regions have different effects on the reduction of LV deformation, and relevant clinical evaluations should be strengthened.

The year 2020 in the European Heart Journal - Cardiovascular Imaging: part I

The European Heart Journal - Cardiovascular Imaging was launched in 2012 and has during these 9 years become one of the leading multimodality cardiovascular imaging journals. The journal is currently ranked as number 20 among all cardiovascular journals. Our journal is well established as one of the top cardiovascular journals and is the most important cardiovascular imaging journal in Europe. The most important studies published in our Journal in 2020 will be highlighted in two reports. Part I of the review will focus on studies about myocardial function and risk prediction, myocardial ischaemia, and emerging techniques in cardiovascular imaging, while Part II will focus on valvular heart disease, heart failure, cardiomyopathies, and congenital heart disease.

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.