LAUSR

Myocardial work, assessed by speckle tracking echocardiography, reflects mechanical efficiency of the left ventricle. In heart failure patients, characterization of acute changes in regional (septal and lateral) left ventricular (LV) myocardial walls after cardiac resynchronization therapy (CRT) may enhance understanding of CRT response. To evaluate the interaction between CRT response and components of myocardial work of the lateral wall and septum in patients with heart failure. Regional LV myocardial work was calculated by integrating non-invasive blood pressure measurements, timing of mitral and aortic valve opening and closure and speckle tracking-derived LV longitudinal strain. From pressure-strain loops, constructive work (CW) and wasted work (WW) were calculated. CRT response was defined as a decrease in LV end-systolic volume ≥15% at 6 months follow-up. Changes in CW and WW of the septal and lateral walls prior to (baseline) and within the first 5 days after CRT implantation were compared between CRT responders and non-responders. At baseline, measurement of regional CW and WW was performed in 168 patients treated with CRT (71% men, 66±10 years). At 6 months, 59% of patients were CRT responders. CRT responders more frequently had non-ischemic heart failure than non-responders (54% vs 36%; p=0.027). At baseline, CRT responders were characterized by a significantly higher septal WW (270.5 [160.0; 451.5] mmHg% vs. 210.5 [106.3; 336.5] mmHg%; p=0.038) and lateral CW (989.5 [574.0; 1439.0] mmHg% vs. 689.0 [463,3; 1140.0] mmHg%; p=0.005). On multivariable analysis, only CW of the lateral wall at baseline was independently associated with CRT response (HR 1.001; 95% CI, 1.000–1.001; p=0.048). Immediately after CRT implantation, measurement of regional CW and WW was feasible in 115 patients. CRT responders showed improvement in CW (433.0 [254.5; 686.5] mmHg% to 664.5 [424.5; 977.8] mmHg%; p<0.001) and WW (305.0 [169.0; 461.3] mmHg% to 145.0 [80.0; 306.3] mmHg%; p=0.005) of the septum whereas the lateral wall demonstrated a significant decrease in CW (1036.5 [561.0; 1402.0] to 818.0 [491.0; 1154.3] mmHg%; p=0.005) and increase in WW (132.5 [80.3; 269.3] to 198.5 [107.5; 331.0] mmHg%; p=0.025). Non-responders showed only a decrease in WW of the septum (202.8 [102.9; 332.5] to 168.5 [67.6; 258.4] mmHg%; p=0.049). CRT responders are characterized by increased WW of the septum and CW of the lateral wall at baseline, which are corrected immediately after CRT implantation. Constructive work of the LV lateral wall at baseline is independently associated with CRT response. Study was supported by ESC Research grant 2018