Myocardial work in electrical dyssynchrony due to left bundle branch block

Aim. To evaluate myocardial function in different groups of patients with left bundle branch block (LBBB) and the LBBB "model" — right ventricular pacing (RVP).

Material and methods. Global longitudinal strain (GLS) and myocardial function parameters, such as global constructive work (GCW), global wasted work (GWW), global work index (GWI), and global work efficiency (GWE), were measured in 25 patients with dilated cardiomyopathy (DCM) and LBBB (DCM-LBBB group), 20 patients with DCM and a narrow QRS complex (DCM-nonLBBB group), 15 patients with LBBB developed after transcatheter aortic valve implantation (TAVI LBBB group), 12 patients with idiopathic LBBB (I-LBBB group), 27 patients with permanent RVP, and 10 healthy volunteers (HVs). The segments with maximum and minimum GWI were determined in all patients.

Results. The GLS, GWI and GCW values were comparable in the I-LBBB and RVP groups, and were significantly lower in the TAVI-LBBB and both DCM groups than in HVs (p=0,049, 0,006, 0,025; p<0,001, respectively). Patients in the I-LBBB, TAVI-LBBB, RVP and DCM-LBBB groups were characterized by an increased GWW value (261 [203,5; 291,5], 273 [184,8; 385,3] and 237 [149,5; 445,3] versus 108 [74,3; 137,3] mm Hg%, p=0,033, 0,006, <0,001, <0,001, respectively), while the GWW value in the DCM-LBBB group was the highest (346,5 [255,5; 437,8] mm Hg%). The GWW value was associated with the QRS width (r=0,456, p<0,001). The GWE value was reduced in the I-LBBB, TAVI-LBBB, RVP and DCM-LBBB groups compared to HVs (p=0,033, 0,007, 0,023, <0,001, respectively). The area of maximum GWI was located in the posterolateral wall, and the minimum GWI in the interventricular septum in most patients with LBBB, while in the RVP group it was very diverse.

Conclusion. Despite the fact that all patients with an electrical activation pattern corresponding to LBBB are characterized by significant wasted work, its contribution to the global myocardial work is significant only in patients with DCM. Lost work does not lead to a decrease in constructive work in patients with I-LBBB and RVP and normal left ventricular systolic function.

1. Rimskaya EM, Mironova NA, Sokolov SF, Golitsyn SP. Left bundle branch block — dilated cardiomyopathy — heart failure: common links in the closed pathogenetic chain. Kardiologiia. 2023;63(2):68-76. (In Russ.) doi:10.18087/cardio.2023.2.n1773.

2. Sanna GD, Merlo M, Moccia E, et al. Left bundle branch block-induced cardiomyopathy: a diagnostic proposal for a poorly explored pathological entity. Int J Cardiol. 2020;299:199-205. doi:10.1016/j.ijcard.2019.06.008.

3. Strauss DG, Selvester RH, Wagner GS. Defining Left Bundle Branch Block in the Era of Cardiac Resynchronization Therapy. The American Journal of Cardiology. 2011; 107(6):927-34. doi:10.1016/j.amjcard.2010.11.010.

4. Varma N. Left ventricular electrical activation during right ventricular pacing in heart failure patients with LBBB: visualization by electrocardiographic imaging and implications for cardiac resynchronization therapy. J Electrocardiol. 2015;48(1):53-61. doi:10.1016/j.jelectrocard.2014.09.002.

5. Kashtanova SY, Mironova NA, Shitov VN, et al. Role of electrocardiographic and echocardiographic types of left bundle branch block in prediction of response to cardiac resynchronization therapy. Terapevticheskii arkhiv. 2018;90(12):76-83. (In Russ.) doi:10.26442/00403660.2018.12.000012.

6. Aalen J, Remme EW, Larsen CK, et al. Mechanism of Abnormal Septal Motion in Left Bundle Branch Block.JACC: Cardiovascular Imaging. 2019;12(12):2402-13. doi:10.1016/j.jcmg.2018.11.030.

7. Russell K, Eriksen M, Aaberge L, et al. Assessment of wasted myocardial work: a novel method to quantify energy loss due to uncoordinated left ventricular contractions. Am J Physiol Heart Circ Physiol. 2013;305(7):H996-1003. doi:10.1152/ajpheart.00191.2013.

8. Lang RM, Badano LP, Mor-Avi V, et al. Recommendations for cardiac chamber quantification by echocardiography in adults: An update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging. Eur. Hear J. Cardiovasc. Imaging. 2015;16:233-71. doi:10.1093/ehjci/jev014.

9. Manganaro R, Marchetta S, Dulgheru R, et al. Echocardiographic reference ranges for normal non-invasive myocardial work indices: results from the EACVI NORRE study. Eur Heart J Cardiovasc Imaging. 2019;20(5):582-90. doi:10.1093/ehjci/jey188.

10. Morbach C, Sahiti F, Tiffe T, et al.; STAAB consortium. Myocardial work — correlation patterns and reference values from the population-based STAAB cohort study. PLoS One. 2020;15(10):e0239684. doi:10.1371/journal.pone.0239684.

11. Rimskaya EM, Kashtanova SYu, Salami HF, et al. Diagnostic criteria for proximal left bundle branch block and their significance in predicting the success of cardiac resynchronization therapy. Russian Journal of Cardiology. 2023;28(8):5403. (In Russ.) doi:10.15829/1560-4071-2023-5403.

12. Gao Y, Zhang Y, Tang Y, et al. Myocardial work and energy loss of left ventricle obtained by pressure-strain loop and vector flow mapping: a new perspective on idiopathic left bundle branch block. Quant Imaging Med Surg. 2023;13(1):210-23. doi:10.21037/qims-22-284.

13. Aalen J, Storsten P, Remme EW, et al. Afterload Hypersensitivity in Patients With Left Bundle Branch Block. JACC: Cardiovascular Imaging. 2019;12(6):967-77. doi:10.1016/j.jcmg.2017.11.025.

14. Malagù M, Vitali F, Massafra RF, et al. Three-Dimensional Electro-Anatomical Mapping and Myocardial Work Performance during Spontaneous Rhythm, His Bundle Pacing and Right Ventricular Pacing: The EMPATHY Study. J Cardiovasc Dev Dis. 2022;9(11):377. doi:0.3390/jcdd9110377.