When clinicians hesitate: understanding prescribing thresholds for patients with heart failure and reduced ejection fraction

Guideline-directed medical therapy (GDMT) for heart failure with reduced ejection fraction (HFrEF) improves survival and health-related quality of life, yet prescribing remains suboptimal in both cardiology and primary care. This study aimed to examine clinicians’ perceptions of safety thresholds and the thresholds at which clinicians hesitate to prescribe GDMT. We conducted a concurrent mixed-methods study using a 24-item survey of cardiologists and primary care providers (PCPs) to assess perceived safe cutoffs (knowledge) and hesitancy thresholds (comfort) for prescribing GDMT across four biometric factors: systolic blood pressure, heart rate, estimated glomerular filtration rate (eGFR), and potassium. Open-ended responses were analyzed thematically, and generalized linear models compared responses by specialty. Among 101 respondents (23 cardiologists, 78 PCPs, from 3 unique health systems), clinicians reported more conservative hesitancy thresholds than safety thresholds, with greater differences among PCPs. PCPs consistently reported more conservative safety and hesitancy thresholds across all biometric categories compared to cardiologists, who pushed thresholds further (lower systolic blood pressure, heart rate, and eGFR; higher potassium). These differences were statistically significant except for potassium and eGFR in two GDMT categories. PCPs cited unfamiliarity with certain medications and concerns about adverse effects as drivers of conservative thresholds, whereas cardiologists emphasized strategies to manage adverse effects. When both potassium and eGFR were relevant, potassium more strongly influenced prescribing decisions. Thresholds at which clinicians hesitate to intensify GDMT for HFrEF are more conservative than their perceived safety thresholds, and variability exists in what is considered an evidence-based safe threshold. Cardiologists push safety and hesitancy thresholds further than PCPs and have smaller differences between these thresholds, which may reflect greater familiarity and less concern about adverse effects. Clinicians reported context is an important determinant of threshold. These findings highlight opportunities for targeted interventions to address knowledge gaps and reduce hesitancy, particularly in primary care.