Background: This study investigates the prognostic impact of thiazide and loop diuretics in heart failure with mildly reduced ejection fraction (HFmrEF). While diuretics are widely used to manage fluid retention in HF, data on their prognostic impact in HFmrEF remain limited.
Methods: Consecutive HFmrEF patients hospitalized at the University Medical Centre Mannheim between 2016 and 2022 were retrospectively included and stratified by diuretic therapy at discharge: none (N), thiazide-only (T), loop diuretic-only (L), or combined diuretic therapy (T+L). The primary endpoint was all-cause mortality at 30 months (median follow-up), secondary endpoint was HF-related rehospitalization.
Results: Among 2,109 HFmrEF patients discharged alive, 43% had no diuretics, 9% were on thiazides only, 40% on loop diuretics only, and 9% had combined diuretic therapy. Thiazide-only patients had the lowest risk of long-term all-cause mortality (11%) compared to no diuretics (20%), while patients on loop diuretics (39%), and combined diuretic therapy (48%) experienced significantly higher long-term mortality (log rank p=0.001) and HF-rehospitalization rates (N: 5% and T: 6% vs. L: 20% and L+T: 30%, log rank p=0.001). After multivariable adjustment, thiazide-only therapy was still associated with lower mortality risk (HR=0.523, p=0.010), while loop and combined diuretic therapy remained associated with increased mortality (L: HR=1.342, p=0.015; T+L: HR=1.774, p=0.001) and HF-rehospitalization (L: HR=1.965, p=0.001; T+L: HR=2.553, p=0.001).
Conclusion: In HFmrEF, patients receiving thiazides only experienced the lowest mortality while those requiring loop diuretics or combined diuretic therapy had increased mortality and HF-rehospitalization rates. Further studies investigating optimal diuretic regimes in HFmrEF patients are needed.
