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Graphical representation of electro-mechanical parameters statistical comparisons. (A) Rotational angle. (B) Local activation time. (C) LEMD. (D) TEMD. (E) Unipolar voltage. (F) Bipolar voltage. LEMD, Local electromechanical delay. TEMD total electromechanical delay. *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001.
Source publication
Left ventricle, LV wringing wall motion relies on physiological muscle fiber orientation, fibrotic status, and electromechanics (EM). The loss of proper EM activation can lead to rigid-body-type (RBT) LV rotation, which is associated with advanced heart failure (HF) and challenges in resynchronization. To describe the EM coupling and scar tissue bu...
Citations
... In a previous study, Maffessanti et al. 16 showed that presence of scar impairs EM coupling, even when scar is remote from late activated segments. Furthermore, Jadczyk et al. 17 presented data confirming influence of EM coupling on kinetics and rotational pattern in patients with HF and LBBB. The poor performance of the TD-TPS relation in predicting CRT response may be explained by the limitations of TPS as mechanical marker, because in particular in the septum its measurement is complicated by multiple peaks. ...
Aims
Electromechanical coupling in patients receiving cardiac resynchronization therapy (CRT) is not fully understood. Our aim was to determine the best combination of electrical and mechanical substrates associated with effective CRT.
Methods and results
Sixty-two patients were prospectively enrolled from two centres. Patients underwent 12-lead electrocardiogram (ECG), cardiovascular magnetic resonance (CMR), echocardiography, and anatomo-electromechanical mapping (AEMM). Remodelling was measured as the end-systolic volume (ΔESV) decrease at 6 months. CRT was defined effective with ΔESV ≤ −15%. QRS duration (QRSd) was measured from ECG. Area strain was obtained from AEMM and used to derive systolic stretch index (SSI) and total left-ventricular mechanical time. Total left-ventricular activation time (TLVAT) and transeptal time (TST) were derived from AEMM and ECG. Scar was measured from CMR. Significant correlations were observed between ΔESV and TST [rho = 0.42; responder: 50 (20–58) vs. non-responder: 33 (8–44) ms], TLVAT [−0.68; 81 (73–97) vs. 112 (96–127) ms], scar [−0.27; 0.0 (0.0–1.2) vs. 8.7 (0.0–19.1)%], and SSI [0.41; 10.7 (7.1–16.8) vs. 4.2 (2.9–5.5)], but not QRSd [−0.13; 155 (140–176) vs. 167 (155–177) ms]. TLVAT and SSI were highly accurate in identifying CRT response [area under the curve (AUC) > 0.80], followed by scar (AUC > 0.70). Total left-ventricular activation time (odds ratio = 0.91), scar (0.94), and SSI (1.29) were independent factors associated with effective CRT. Subjects with SSI >7.9% and TLVAT <91 ms all responded to CRT with a median ΔESV ≈ −50%, while low SSI and prolonged TLVAT were more common in non-responders (ΔESV ≈ −5%).
Conclusion
Electromechanical measurements are better associated with CRT response than conventional ECG variables. The absence of scar combined with high SSI and low TLVAT ensures effectiveness of CRT.
... Therefore, it is important to optimize CRT parameters for each patient and LV rotation has become increasingly important for this purpose (Rüssel et al., 2009b). Jadczyk et al. (2021) investigated electromechanical coupling and scar tissue burden with respect to rotational patterns observed in patients showing heart failure with reduced ejection fraction (HFrEF) and LBBB. In their cohort of 30 patients, they found six cases showing normal wringing rotation and 24 cases showing RBT rotation. ...
... In contrast, following a physiological propagation of electrical and mechanical activation, an intact electromechanical coupling (with constant electromechanical delay) will result in a wringing motion. However, due to the small number of study participants the results by Jadczyk et al. (2021) should be considered with caution. To elucidate the role of the different contributing mechanisms suggested by Jadczyk et al. (2021), we performed an in silico study under controlled conditions informed by their in vivo electromechanical mapping data. ...
... However, due to the small number of study participants the results by Jadczyk et al. (2021) should be considered with caution. To elucidate the role of the different contributing mechanisms suggested by Jadczyk et al. (2021), we performed an in silico study under controlled conditions informed by their in vivo electromechanical mapping data. Specifically, we hypothesized that the altered electrical activation pattern is sufficient to change wringing rotation to RBT. ...
Cardiac resynchronization therapy is a valuable tool to restore left ventricular function in patients experiencing dyssynchronous ventricular activation. However, the non-responder rate is still as high as 40%. Recent studies suggest that left ventricular torsion or specifically the lack thereof might be a good predictor for the response of cardiac resynchronization therapy. Since left ventricular torsion is governed by the muscle fiber orientation and the heterogeneous electromechanical activation of the myocardium, understanding the relation between these components and the ability to measure them is vital. To analyze if locally altered electromechanical activation in heart failure patients affects left ventricular torsion, we conducted a simulation study on 27 personalized left ventricular models. Electroanatomical maps and late gadolinium enhanced magnetic resonance imaging data informed our in-silico model cohort. The angle of rotation was evaluated in every material point of the model and averaged values were used to classify the rotation as clockwise or counterclockwise in each segment and sector of the left ventricle. 88% of the patient models ( n = 24) were classified as a wringing rotation and 12% ( n = 3) as a rigid-body-type rotation. Comparison to classification based on in vivo rotational NOGA XP maps showed no correlation. Thus, isolated changes of the electromechanical activation sequence in the left ventricle are not sufficient to reproduce the rotation pattern changes observed in vivo and suggest that further patho-mechanisms are involved.
... Current literature supports the feasibility of this approach as Yadczyk et al used similar methodology to evaluate the rotational mechanics of the left ventricle in heart failure patient population with concomitant left bundle branch block. In addition to unipolar and bipolar voltage, the authors also evaluated the LAT, local electromechanical delay (LEMD), and total electromechanical delay (TEMD) 21 . They were able to establish an association between the LAT, LEMD, and TEMD and the electromechanical coupling properties and scar tissue burden of the failing myocardium 21 . ...
... In addition to unipolar and bipolar voltage, the authors also evaluated the LAT, local electromechanical delay (LEMD), and total electromechanical delay (TEMD) 21 . They were able to establish an association between the LAT, LEMD, and TEMD and the electromechanical coupling properties and scar tissue burden of the failing myocardium 21 . Furthermore, Maffesanti et al used electroanatomical parameters to define areas of latest electrical and mechanical activation of the left ventricle in heart failure patients, eligible for either cardiac resynchronization therapy (CRT) device therapy or intramyocardial biological therapy 22 . ...
We investigated the effects of cell therapy on local mechanical dyssynchrony (LMD) in patients with nonischemic dilated cardiomyopathy (NICM). We analyzed electromechanical data of 30 NICM patients undergoing CD34 ⁺ cell transplantation. All patients underwent bone marrow stimulation; CD34 ⁺ cells were collected by apheresis and injected transendocardially. At baseline and at 6 months after therapy, we performed electromechanical mapping and measured unipolar voltage (UV) and LMD at cell injection sites. LMD was defined as a temporal difference between global and segmental peak systolic displacement normalized to the average duration of the RR interval. Favorable clinical response was defined as increase in the left ventricular ejection fraction (LVEF) ≥5% between baseline and 6 months. Using paired electromechanical point-by-point analysis, we were able to identify 233 sites of CD34 ⁺ cell injections in 30 patients. We found no overall differences in local UV between baseline and 6 months (10.7 ± 4.1 mV vs 10.0 ± 3.6 mV, P = 0.42). In contrast, LMD decreased significantly (17 ± 17% at baseline vs 13 ± 12% at 6 months, P = 0.00007). Favorable clinical response at 6 months was found in 19 (63%) patients (group A), and 11 (37%) patients did not respond to cell therapy (group B). At baseline, the two groups did not differ in age, gender, LVEF, or N terminal-pro brain natriuretic peptide (NT-proBNP) levels. Similarly, we found no differences in baseline UV (9.5 ± 2.9 mV in group A vs 8.6 ± 2.4 mV in group B, P = 0.41) or LMD at cell injection sites (17 ± 19% vs 16 ± 14%, P = 0.64). In contrast, at 6 months, we found higher UV in group A (10.0 ± 3.1 mV vs 7.4 ± 1.9 mV in group B, P = 0.04). Furthermore, when compared with group B, patients in group A displayed a significantly lower LMD (11 ± 12% vs 16 ± 10%, P = 0.002). Thus, it appears that favorable clinical effects of cell therapy in NICM patients may be associated with a decrease of LMD at cell injection sites.
