A larger reduction of spatial mean QRS-T angle during cardiac resynchronisation therapy is associated with a lower risk of mortality and heart failure hospitalisation

Abstract Background Predicting clinical outcome in heart failure patients undergoing cardiac resynchronization therapy (CRT) remains challenging, necessitating improved risk stratification for CRT recipients. Previous studies have shown an association between large spatial peak and mean QRS-T angles and cardiovascular disease. Little is known, however, about their relation to clinical outcome following CRT. Purpose To investigate the association between spatial peak and mean QRS-T angles and long-term clinical outcome following CRT initiation. Methods All patients with native LBBB receiving CRT at a large-volume tertiary care center between 2015 and 2020 were retrospectively evaluated. Spatial peak and mean QRS-T angles were derived from digital pre- and post-CRT 12-lead ECGs that were processed using Glasgow algorithm and Kors’ regression transformation. The QRS-T angles and their change after CRT were analyzed in relation to the primary composite endpoint of heart failure hospitalisation or all-cause mortality using Cox regression analysis adjusted for clinical covariates (age, gender, CRT-P or CRT-D, secondary ICD indication, ischemic etiology, NYHA class, LVEF, diabetes, atrial fibrillation, baseline QRS duration, NT-proBNP, and eGFR). Results The study group comprised 250 patients (a median age [Q1–Q3] of 72.2 years [64.5–76.3]; 22% female; 58% New York Heart Association (NYHA) class III-IV; LVEF 27% [22–30]) who were followed over a median follow-up time of 4.5 years [3.2–5.8] after CRT implantation. The median post-CRT spatial peak and mean QRS-angles were 142° [116–160] and 152° [127–166], and the median angle was decreased by 16° [-0.6–41] and 14° [-0.4–38], respectively. Both a larger post-CRT mean QRS-T angle (HR 1.20, 95%CI 1.08-1.33, p=<.001) and peak QRS-T angle (HR 1.08, 95%CI 1.01-1.17, p=0.046) were associated with the primary endpoint. A larger reduction of mean QRS-T angle, but not peak QRS-T angle, was associated with a risk reduction (HR 0.87, 95%CI 0.79-0.95, p<0.003). In Kaplan-Meier analysis, patients with a post-CRT mean QRS-T angle above median had a higher risk of reaching the endpoint (log-rank p=0.002, Figure 1). Conclusion Our results show that a larger magnitude of the post-CRT spatial peak and mean QRS-T angles, and a larger reduction of the latter, are associated with long-term heart failure hospitalisation and death. These findings suggest that spatial QRS-T angle may have a potential role in refined risk stratification of CRT patients.Figure 1.K-M curve spatial mean QRS-T