Background: In many cardiovascular diseases (CVD), white blood cell counts with differentials are used to predict adverse events. Both platelet-to-lymphocyte ratio (PLR) and neutrophil-to-lymphocyte ratio (NLR) are studied in various CVDs.

Aim: The role of inflammatory condition assessed using routine laboratory tests in cardiac resynchronisation therapy (CRT) response has not been investigated thoroughly. Therefore, we aimed to assess the association of NLR, PLR, and relative lym­phocyte count (L%) with response to CRT.

Methods: A total of 157 patients (76.4% male; mean age 58.7 ± 11.8 years) who underwent CRT implantation at our tertiary referral hospital were retrospectively analysed.

Results: Among included patients, a total of 50 (31.8%) patients were defined as “non-responders”. Median NLR and PLR were significantly higher in the non-responder group (p < 0.001), and median L% was significantly lower in the non-responder group (p < 0.001). Also, median NLR was significantly higher in patients with New York heart Association (NYHA) class II–III when compared to patients with NYHA class I after six months of CRT implantation (p < 0.001, p = 0.004, respectively). Correlation analysis demonstrated a positive correlation between paced QRS duration and NLR (p = 0.031) and a negative correlation between paced QRS duration and L% (p = 0.002). In addition, both NLR and L% showed significant correlations with post-procedural NYHA functional classes (p < 0.001; p = 0.008, respectively). Patients with PLR > 173.09 had a 2.9‑fold and NLR > 3.45 had a 12.2-fold increased risk of CRT nonresponse, respectively.

Conclusions: In the current study non-responders to CRT had higher NLR and PLR and lower L%, which may support the deleterious effects of baseline inflammatory condition in advanced heart failure.