Re-classification of response to cardiac resynchronization therapy: the long-term effect of echocardiographic non-progression

Introduction Approximately one-third of patients undergoing cardiac resynchronization therapy (CRT) implantation fail to show echocardiographic improvement and are categorized as non-responders, despite of probable beneficial clinical response. Purpose We aimed to evaluate the long-term outcome of CRT patients by their echocardiographic response outsorting those with unchanged parameters. Methods Altogether 1019 patients undergoing CRT implantation between 2000-2020 in our center were analyzed retrospectively. Patients were grouped by their echocardiographic response defined as LVEF change upto12 months: super-responders ≥20% (n=113), responders 6-19% (n=448), non-progressors 0-5% (n=244), and progressors <0% (n=214). The primary endpoint was the composite of all-cause mortality, heart transplantation, or left ventricular assist device implantation. Results During the median follow-up time of 4.7 years 547 (54%) patients died, 35 (31%) super-responders, 223 (50%) responders, 133 (55%) non-progressors, and 156 (73%) progressors. The mean change in LVEF occurred as follows: super-responders 24.5% ± 4.1%, responders 11.5% ± 3.8%, non-progressors 2.8% ± 1.8%, and progressors -6.6% ± 4.5% (p<0.001). Univariate Cox regression analysis revealed that non-progressors had a similar outcome to responders (HR 1.17; 95%CI 0.94-1.45; p=0.15) and a superior outcome to progressors (HR 0.60; 95%CI 0.48-0.76; p<0.001), which was also confirmed by multivariate analysis: non-progressors vs. responders (HR 1.25; 95%CI 0.98-1.58; p=0.07) and non-progressors vs. progressors (HR 0.62; 95%CI 0.47-0.80; p<0.001). Conclusion In our current analysis, non-progressors had a superior outcome to progressors suggesting that CRT moderates the remodeling process. These findings indicate their selection and the re-classification of CRT response by echocardiographic changes.Survival by responseMean change in LVEF by response