Low prevalence of CRT upgrade in patients with significant RV pacing: 10-year real-world data in a UK DGH

In heart failure patients with reduced ejection fraction (HFrEF) requiring a pacemaker, biventricular cardiac resynchronisation therapy (CRT) is preferred to right ventricular (RV) pacing. Moreover, HFrEF patients who already have a conventional pacemaker in situ should be considered for CRT 'upgrade' in the presence of worsening symptoms and a significant proportion of RV pacing. While international guidelines are clearly defined, the 'real-world' prevalence of upgrading to CRT in patients with a significant proportion of RV pacing remains unclear. We aim to report the prevalence and characteristics of CRT upgrades in a UK district general hospital over a 10-year period. We performed a retrospective univariate analysis of consecutive adult patients who underwent pacemaker implantation for Mobitz type 2 and complete atrioventricular (AV) block from January 2009 to December 2018. Over the study period, 34 patients were upgraded to CRT (prevalence 4.6%). Male patients were more likely to receive CRT upgrade (p=0.027). There was no statistically significant difference in RV-pacing burden or RV-paced QRS duration between CRT upgrade and non-upgrade groups. Patients who received CRT had lower baseline left ventricular (LV) ejection fraction than the non-upgrade group (50% vs. 60%, p=0.049). In conclusion, this real-world study supports the notion that patients with impaired LV function and likely high requirements for RV pacing should be informed of the possible future need for device CRT upgrade. CRT should be considered upfront in selected patients with lower baseline LV systolic function.