ADHERENCE TO GUIDELINE-DIRECTED MEDICAL THERAPY AMONG PATIENTS FOLLOWED AT AN AMBULATORY HEART FUNCTION CLINIC

Foundational quadruple therapy (RAAS inhibition, Beta-blocker, MRA, SGLT2i) for the management of heart failure reduced ejection fraction (HFrEF) confers significant benefit in terms of mortality and heart failure (HF) hospitalization. This approach received a strong recommendation in the CCS/CHFS Heart Failure Guidelines. Recent data indicates that SGLT2i also reduce the risk of HF hospitalization in heart failure preserved ejection fraction (HFpEF). Moghaddam et al. (2021) previously reported gaps in adherence to guideline-directed medical therapy (GDMT) at Canadian hospitals following HF hospitalization. We extended this analysis by evaluating adherence to GDMT among eligible patients followed at an ambulatory Heart Function Clinic.

The study cohort was derived from a single centre Outpatient Heart Function Clinic in Vancouver, BC. Patients aged 18 and older who were referred to the clinic between January 2019 and March 2021 were included. There were no exclusion criteria. From a cohort of 786 patients, 516 had HFrEF (LVEF ≤ 40%), 91 had HFmrEF (LVEF 41-49%), 174 had HFpEF (LVEF ≥ 50%), and 5 had no documented LVEF at the time of referral. Among patients with HFrEF, prescription rates for RAAS inhibition (ACEi, ARB or ARNI), beta-blocker, MRA and SGLT2i were 84.3%, 92.6%, 67.8% and 26.4% respectively. Foundational quadruple therapy was prescribed in 21.1% of HFrEF patients. Among eligible patients with HFmrEF and HFpEF, 12.6% were on SGLT2i. Renal dysfunction in the HFrEF group was associated with lower odds of RAAS inhibitor (OR 0.23, 95% CI 0.13 – 0.40; p < 0.0001) and MRA (OR 0.37, CI 0.25 – 0.55; p < 0.0001) prescription. The odds of initiating an SGLT2i was approximately half in those who experienced recovered LVEF (≥ 50%) between time of initial referral and the most recent follow-up (OR 0.47, CI 0.28 – 0.80; p = 0.0049). In this study population, there was no significant association between prescription of GDMT and hypotension (SBP < 100 mmHg) at the most recent visit (RAAS inhibitor OR 0.96, CI 0.52 – 1.78, p = 0.90; Beta-blocker OR 1.98, 0.68 – 5.75, p = 0.21; MRA OR 1.31, CI 0.80 – 2.16, P = 0.28; SGLT2i OR 1.55, CI 0.96 – 2.50, p = 0.07).

Even with longitudinal multidisciplinary care afforded by an ambulatory clinic, there remain gaps in adherence to GDMT; particularly for MRAs and SGLT2i. A minority of eligible patients receive quadruple therapy. Blood pressure and renal function do not fully explain this disparity.