Inpatient Cardiac Resynchronization Therapy During Heart Failure Hospitalization: A Distinct High-Risk Phenotype

The role of cardiac resynchronization therapy (CRT) during hospitalization for heart failure (HFH) is uncertain, because hospitalized patients were routinely excluded from landmark CRT trials. Despite this, CRT implantation during HFH is common. This study aimed to compare the clinical profiles and post-implantation outcomes of patients undergoing inpatient CRT during HFH with those receiving deferred outpatient CRT after HFH.

Institutional CRT data were linked with the National Heart Failure Audit from January 2014 to December 2024. Patients were stratified by inpatient or outpatient CRT implantation setting. Baseline characteristics, HFH within one year of CRT and long-term survival were compared. Multivariable Cox proportional hazards modelling assessed the association between implantation setting and mortality.

130 patients underwent inpatient CRT during HFH and 90 received deferred outpatient CRT. Inpatients had lower estimated glomerular filtration rates (46.26±19.0 vs. 55.19±18.4 mL/min/1.73m², p = 0.01), more ischemic cardiomyopathy (40.8% vs. 18.9%, p = 0.01), less left bundle branch block (36.9% vs. 51.1%, p = 0.04), and more HF hospitalizations in the year before CRT (1.12±0.87 vs. 0.84±0.86, p = 0.01). The risk of ≥1 HF re-hospitalization within one year of CRT was higher (23.1% vs. 7.8%; p = 0.004) in the inpatient group. Median survival after CRT was 2.9 years shorter for the inpatient group (1192 vs. 2262 days, p = 0.003). After adjustment, deferred outpatient CRT remained associated with lower all-cause mortality (HR 0.56, 95% CI 0.35-0.88, p = 0.01).

Patients selected for inpatient CRT during HFH represent a clinically distinct, higher-risk subgroup with worse post-implant outcomes. Prospective studies are needed to optimize patient selection for inpatient CRT.