Initial Dip in Estimated Glomerular Filtration Rate After Dapagliflozin Affects Renal Function in Chronic Phase in Chronic Heart Failure

<b>Background</b>: Dapagliflozin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor, has been shown to improve prognosis in patients with chronic heart failure (CHF), in whom a transient decline in the estimated glomerular filtration rate (eGFR), known as the "initial dip," is often observed within the first 1-2 weeks of SGLT2 inhibitor therapy. This study aimed to investigate the factors associated with this initial dip and its impact on long-term renal function in patients with CHF initiating dapagliflozin. <b>Methods and Results</b>: This retrospective study included 123 consecutive CHF patients who were started on dapagliflozin at our institution. The presence of an initial dip was defined as a decrease in the eGFR of ≥5 mL/min/1.73 m² within two weeks of initiating therapy. Baseline clinical characteristics and renal function data were analyzed. Older age, hypertension, diabetes mellitus, and a higher baseline eGFR were identified as significant risk factors for the initial dip. Furthermore, both age and the presence of an initial dip were significantly associated with changes in the eGFR at 6 months and 1 year. In patients who experienced an initial dip, the eGFR showed a persistent downward trajectory from the baseline over time. <b>Conclusions</b>: An initial dip is more likely to occur in older patients and those with hypertension and/or diabetes mellitus. The presence of an initial dip may also influence long-term renal outcomes and could serve as an indicator of long-term renoprotective efficacy.