Effect of expanding evidence and evolving clinical guidelines on the prevalence of indication for cardiac resynchronization therapy in patients with heart failure.

Aims: To assess the prevalence of indication for cardiac resynchronization therapy (CRT) in patients with heart failure (HF) and reduced ejection fraction (EF) when recommendations from evolving European Society of Cardiology (ESC) guidelines are considered.

Methods And Results: Unique patients (n=17 193) with EF ≤39% and key data available for evaluation of CRT indication from the Swedish HF Registry were included. Indication for CRT was defined as either CRT implanted or CRT device absent but fulfilling criteria for class I-IIa recommendations in ESC guidelines published between 2005/2007 and 2016. Prevalence was calculated as the ratio of patients with CRT indication to the study population. The prevalence of CRT indication increased from 24.5% when the 2005/2007 ESC guidelines were considered to a peak of 30.0% when the 2013 ESC guidelines were considered (P<0.001, 22.4% relative increase). Compared to the 2013 ESC guidelines, the prevalence declined significantly when the 2016 ESC guidelines were used as determinant for CRT indication (26.8%, 10.7% relative reduction, P<0.001). Actual CRT utilization was 6.8%.

Conclusion: Among patients with HF and reduced EF, the prevalence of CRT indication increased significantly comparing recommendations from ESC guidelines published between 2005/2007 and 2013, but then declined when the 2016 ESC guidelines were considered. The 2005-2013 increase may reflect the expansion of documented CRT efficacy to New York Heart Association class II, whereas the subsequent drop likely results from the more stringent criteria for QRS duration in the 2016 ESC guidelines. Actual CRT utilization is lower than indicated, regardless of which guidelines are considered.