Magdalena Potapowicz-Krysztofiak

Cardiac resynchronization therapy (CRT) is an effective treatment for selected patients with heart failure with reduced ejection fraction, but 30–40% of recipients do not respond. This narrative review summarizes predictors of a favourable response to CRT. Typical left bundle branch block (LBBB) and a QRS duration ≥ 150 ms remain the best-established baseline predictors. Sex, etiology, age and comorbidities affect how much benefit is gained rather than acting as yes/no predictors (the benefit is greater in women, partly because of their smaller heart size) and should not by themselves exclude an otherwise eligible patient. QRS duration indexed to left ventricular size, advanced electrocardiographic markers (QRS notching, intrinsicoid deflection, QRmax, QRS area) and echocardiographic markers of mechanical dyssynchrony (apical rocking, septal flash, the classical LBBB strain pattern, systolic stretch index, mechanical dispersion and myocardial work) have been linked to response in observational studies and may add prognostic information. Combining mechanical dyssynchrony with septal viability on cardiac magnetic resonance appears to improve selection further. Procedure-related factors, including left ventricular lead position and a high percentage of biventricular pacing, are critical for success. A multimodal approach that combines clinical, electrocardiographic, echocardiographic and imaging data, supported in the future by machine learning, appears most promising.

Background: Mechanical dispersion of left ventricular contraction reflects electromechanical heterogeneity and may contribute to arrhythmogenesis. We evaluated whether myocardial work dispersion is associated with ventricular arrhythmia (VA) risk in patients with heart failure with reduced ejection fraction (HFrEF). Methods: Eighty-five patients with HFrEF and no history of atrial fibrillation of any type and with complete arrhythmia follow-up (mean age 65 ± 12 years, 83.5% male, mean LVEF 30.5 ± 6.6%) underwent echocardiography one day before elective implantable cardioverter-defibrillator (ICD) or cardiac resynchronisation therapy (CRT) implantation and were followed for one year. Results: VAs—sustained or non-sustained ventricular tachycardia, or ventricular fibrillation—occurred in 32.9% of patients. Myocardial work index (MWI) dispersion, expressed as standard deviation (SD) or Range, showed the highest single-parameter discrimination (AUC 0.848 and 0.859). Models combining MWI dispersion with right atrial (RA) area performed best (AUC 0.912 and 0.911). In multivariable logistic regression, both MWI dispersion and RA area were independently associated with VAs; odds ratios per 10-unit increase were 1.116 for MWI dispersion (SD), 1.030 for MWI dispersion (Range) and 1.276 per 1 cm² of RA area. Conclusions: In this cohort, MWI dispersion showed the highest single-parameter discrimination for VAs among the echocardiographic variables tested, and its combination with RA area gave the best model. The two variables were independently associated with VAs in the same model. These exploratory findings are hypothesis-generating and require external validation before clinical application.

Background: Heart failure with reduced ejection fraction (HFrEF) may be caused by various factors. The etiology of HFrEF may influence prognosis and further management. Objectives: In this study we aimed to assess differences between ischemic and non-ischemic etiology in the context of clinical features, hemodynamic evaluation, and left ventricular (LV) and left atrial (LA) remodeling in a selected cohort of patients referred for device implantation. Methods: This prospective single-center study included 86 patients with HFrEF in sinus rhythm, without a history of atrial fibrillation, referred for ICD or CRT implantation. All patients underwent comprehensive echocardiography, electrocardiography, impedance cardiography and laboratory testing. This was a cross-sectional analysis without clinical follow-up. The pre-specified question was whether the two etiological groups differed in LV remodeling and LA function. All regression analyses were exploratory. Guideline-directed medical therapy was recorded in all patients. Results: Among 86 patients, 58 had ischemic and 28 had non-ischemic HFrEF. Patients with ischemic etiology were older, had worse renal function, and had higher N-terminal pro–B-type natriuretic peptide levels. They also exhibited lower left ventricular mass index (LVMI), left atrial reservoir strain (LASr), left atrial emptying fraction (LAEF), and higher left atrial stiffness index (LASI). Among myocardial work parameters, only global wasted work (GWW) differed significantly, with higher values in the non-ischemic group. Patients with ischemic HFrEF also had a higher Heather index (HI) in impedance cardiography. The two groups did not differ in guideline-directed medical therapy. In univariable logistic regression, older age, lower LVMI, reduced LASr and LAEF, higher LASI, higher HI, and lower eGFR were associated with ischemic HFrEF etiology. In the multivariable model, older age, lower LVMI, and reduced LASr remained independently associated with ischemic HFrEF (area under the ROC curve 0.82). Conclusions: Patients with ischemic and non-ischemic HFrEF referred for device implantation differ in LV remodeling and LA function. The between-group differences were small in absolute terms, with widely overlapping distributions, and the study was not designed to test whether echocardiography can replace established methods of establishing HFrEF etiology. These exploratory findings are hypothesis-generating and require confirmation in larger, independent cohorts.

Background: Left bundle branch block (LBBB) and QRS prolongation are markers of electrical dyssynchrony in heart failure, but they do not fully reflect its mechanical consequences. Myocardial work (MW)-derived indices may provide a more comprehensive assessment of left ventricular (LV) mechanical dyssynchrony. We evaluated associations between LV MW parameters, QRS duration, and LBBB in patients with heart failure with reduced ejection fraction (HFrEF) referred for ICD/CRT implantation. Methods: In this single-centre observational cross-sectional study, 96 consecutive patients referred for ICD or CRT implantation were screened. All patients underwent standardized baseline comprehensive echocardiography followed by advanced MW analysis. Myocardial work index (MWI) dispersion was assessed using two complementary methods. MWI dispersion (SD) was calculated as the standard deviation of segmental MWI values across all LV segments, and MWI dispersion (IQR) was defined as the interquartile range (IQR) of segmental MWI values. We evaluated the associations between QRS duration and MW-derived dyssynchrony parameters (individual and composite), as well as their discriminative performance for LBBB. Seven patients were excluded from further analysis due to inadequate echocardiography image quality. Results: The final study group comprised 89 patients with HFrEF (median age 65.5 years), of whom 67.4% were assigned to CRT. LBBB was present in 41.6%, and the median QRS duration was 142 ms (112–162). All analyzed LV MW indices were significantly associated with QRS duration (all q < 0.01). The strongest correlations were observed for MWI dispersion (IQR) (r = 0.58), peak strain dispersion (PSD) (r = 0.54), lateral–septal work asymmetry (r = 0.53), and MWI dispersion (SD) (r = 0.52) (all q < 0.0001). All MW indices differed significantly between patients with and without LBBB (all q ≤ 0.0001). MWI dispersion (IQR) showed the best single-marker discrimination of LBBB (AUC = 0.852). Composite indices achieved AUC = 0.84 but did not significantly improve discrimination versus MWI dispersion (IQR) alone. Conclusions: Myocardial work-derived indices of left ventricular dyssynchrony are strongly associated with QRS duration and the presence of LBBB in patients with HFrEF. Among them, MWI dispersion (IQR) was shown to be the best-performing MW marker for identifying LBBB. These findings suggest that MW dispersion may serve as a robust echocardiographic marker of mechanical dyssynchrony and warrants further investigation as a potential tool for predicting CRT response.