Burden of Ventricular Arrhythmias in Cardiac Resynchronization Therapy Defibrillation and Implantable Cardioverter-Defibrillator Recipients with Recovered Left Ventricular Ejection Fraction: The Additive Role of Speckle-Tracking Echocardiography

Magnetic resonance imaging quantification of left ventricular mechanical dispersion and scar heterogeneity optimize risk stratification after myocardial infarction

BACKGROUND

Left ventricular (LV) myocardial contraction patterns can be assessed using LV mechanical dispersion (LVMD), a parameter closely associated with electrical activation patterns. Despite its potential clinical significance, limited research has been conducted on LVMD following myocardial infarction (MI). This study aims to evaluate the predictive value of cardiac magnetic resonance (CMR)-derived LVMD for adverse clinical outcomes and to explore its correlation with myocardial scar heterogeneity.

METHODS

We enrolled 181 post-MI patients (median age: 55.7 years; 76.8% male) who underwent CMR examinations. LVMD was calculated using the CMR-feature tracking (CMR-FT) technique, defined as the standard deviation (SD) of the time from the R-wave peak to the negative strain peak across 16 myocardial segments. Entropy was quantified using an algorithm implemented with a generic Python package. The primary composite endpoints included sudden cardiac death (SCD), sustained ventricular arrhythmias (VA), and new-onset heart failure (HF).

RESULTS

Over a median follow-up of 31 months, LVMD and border zone (BZ) entropy demonstrated relatively high accuracy for predicting the primary composite endpoints, with area under the curve (AUC) values of 0.825 and 0.771, respectively. Patients with LVMD above the cut-off value (86.955 ms) were significantly more likely to experience the primary composite endpoints compared to those with lower LVMD values (p < 0.001). Multivariable analysis identified LVMD as an independent predictor of the primary composite endpoints after adjusting for entropy parameters, strain, and left ventricular ejection fraction (LVEF) (hazard ratio [HR]: 1.014; 95% confidence interval [CI]: 1.003-1.024; p = 0.010). A combined prediction model incorporating LVMD, BZ entropy, and LVEF achieved the highest predictive accuracy, with an AUC of 0.871 for the primary composite endpoints. Spearman rank correlation analysis revealed significant linear correlations between LVMD and entropy parameters (p < 0.001 for all).

CONCLUSIONS

Myocardial heterogeneity, as assessed by LVMD and BZ entropy, represents reliable and reproducible parameters reflecting cardiac remodeling following MI. LVMD has independent prognostic value, and the combination of LVMD and BZ entropy with the guideline-recommended LVEF as a unified model enhances the accuracy of forecasting the risk of primary combined endpoints in patients after MI.

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.

Heart failure with improved ejection fraction: Beyond diagnosis to trajectory analysis

Left ventricular (LV) systolic dysfunction represents a highly treatable cause of heart failure (HF). A substantial proportion of patients with HF with reduced ejection fraction (EF;HFrEF) demonstrate improvement in LV systolic function (termed HF with improved EF [HFimpEF]), either spontaneously or when treated with guideline-directed medical therapy (GDMT). Although it is a relatively new HF classification, HFimpEF has emerged in recent years as an important and distinct clinical entity. Improvement in LVEF leads to decreased rates of mortality and adverse HF-related outcomes compared to patients with sustained LV systolic dysfunction (HFrEF). While numerous clinical and imaging factors have been associated with HFimpEF, identification of which patients do and do not improve requires further investigation. In addition, patients improve at different rates, and what determines the trajectory of HFimpEF patients after improvement is incompletely characterized. A proportion of patients maintain improvement in LV systolic function, while others experience a recrudescence of systolic dysfunction, especially with GDMT discontinuation. In this review we discuss the contemporary guideline-recommended classification definition of HFimpEF, the epidemiology of improvement in LV systolic function, and the clinical course of this unique patient population. We also offer evidence-based recommendations for the clinical management of HFimpEF and provide a roadmap for future directions in understanding and improving outcomes in the care of patients with HFimpEF.

The influence of pectus excavatum on cardiac kinetics and function in otherwise healthy individuals: A systematic review

BACKGROUND

A number of anterior chest wall deformities, most notably pectus excavatum (PE), may have a detrimental effect on cardiac motion and function. Interpretation of transthoracic echocardiography (TTE) and speckle-tracking echocardiography (STE) results may be hampered by the possible influence of PE on cardiac kinetics.

METHODS

A comprehensive search of all articles assessing cardiac function in PE individuals was carried out. Inclusion criteria were: 1) individuals aged >10 years; 2) studies providing objective assessment of chest deformity (Haller index). Studies that measured myocardial strain parameters in PE patients were also included.

RESULTS

The search (EMBASE and Medline) yielded a total of 392 studies, 36 (9.2%) of which removed as duplicates; a further 339 did not meet inclusion criteria. The full-texts of 17 studies were then analyzed. All studies concordantly reported impaired right ventricular volumes and function. With respect to left ventricle (LV), TTE studies uniformly demonstrated a significant impairment in conventional echoDoppler indices in PE individuals, whereas STE studies provided conflicting results. Importantly, LV functional alterations promptly reverted upon surgical correction of chest defect. In subjects with PE of mild-to-moderate severity, we observed that degree of anterior chest wall deformity, as noninvasively assessed by modified Haller index (MHI), was strongly associated with myocardial strain magnitude, in heterogenous cohorts of otherwise healthy PE individuals.

CONCLUSIONS

Clinicians should be aware that in PE individuals, TTE and STE results may not always be indicative of intrinsic myocardial dysfunction, but may be, at least in part, influenced by artifactual and/or external chest shape determinants.

Trajectory of left ventricular ejection fraction in response to therapies in patients with muscular dystrophy

BACKGROUND

Patients with muscular dystrophy (MD) are at elevated risk of serious cardiac complications and clinical assessment is limited due to inherent physical limitations. We assessed the utility of left ventricular ejection fraction (LVEF) derived from transthoracic echocardiogram (TTE) as a prognostic marker for major adverse cardiac events (MACE) in a mixed adult MD cohort.

METHODS

One hundred and sixty-five MD patients (median age: 36 (interquartile range [IQR]: 23.0-49.0) years; 65 [39.4%] females) were enrolled in our prospective cohort study. Diagnoses included dystrophinopathies (n = 42), limb-girdle MD (n = 31), type 1 myotonic dystrophy (n = 71), and facioscapulohumeral MD (n = 21). Left ventricular ejection fraction, ventricular dimensions at end-diastole and end-systole, and serial measures (n = 124; follow-up period: 2.19 [IQR: 1.05-3.32] years) stratified patients for MACE risk.

RESULTS

Cardiomyopathy was diagnosed in 60 (36.4%) patients of the broader cohort (median LVEF: 45.0 [IQR: 35.0-50.0] %). Ninety-eight MACE occurred over the 7-year study period. At baseline, patients with a LVEF < 55.0% had a high risk of MACE (adjusted odds ratio: 8.30; 95% confidence interval [CI]: 3.18-21.7), concordant with the analysis of LV dimensions. Forty-one percent of these patients showed an improvement in LVEF with the optimization of medical and device therapies. Relative to patients with preserved LVEF, patients with reduced LVEF were at an elevated risk of MACE (adjusted hazard ratio [aHR]: 7.21; 95% CI: 1.99-26.1), and improved LVEF resulted in comparable outcomes (aHR: 1.84; 95% CI: .49-6.91) associated with optimization of medical and device therapies. Reduction in QRS duration by CRT therapy was associated with an improvement in LVEF (average improvement: 12.8 [± 2.30] %; p = .04).

CONCLUSIONS

Reduction in LVEF indicates an increased risk of cardiovascular events in patients with MD. Baseline and serial LVEF obtained by TTE can prognosticate patients for MACE and guide clinical management.