Abstract Background Approximately 50% of patients with chronic heart failure (HF), either with preserved or reduced left ventricular ejection fraction (LVEF), have secondary pulmonary hypertension, which results in poorer prognosis. In previous studies, sodium-glucose cotransporter 2 inhibitors (SGLT2i) have shown a reduction in cardiovascular death, HF hospitalization and pulmonary artery pressure (PAP) in patients with HF, regardless of LVEF, but exact mechanisms remain unclear. Purpose The main objective of this study is to analyse effects of SGLT2i on PAP in patients with chronic HF followed by a PAP sensor (CardioMEMS HF system). The secondary objective is to analyse effects in subgroups of LVEF. Methods We included chronic HF patients (regardless of LVEF) with previously implanted a PAP sensor, from July 2019 to February 2023. SGLT2i had been added in fourth position in patients with reduced LVEF, since they were previously on optimal HF treatment as chronic patients. Changes in PAP, renal function and N-terminal pro B-type natriuretic peptide (NTproBNP) were compared between two periods of time: "30 days before" and "30 days after" SGLT2i initiation. Patients were then classified in two groups: group 1 (LVEF ≤40%) and group 2 (LVEF >40%) and repeated same analyses. Results Overall, 61 patients were screened, and 17 finally were included, mean age 71.7 ± 9.6 years, 64.7% were men, mean LVEF was 49.4 ± 17.5%, 23.5% had ischaemic aetiology and 64.7% were in NYHA class III (Table 1). There were more men in group 1 than in group 2 (p=0.043), without other differences in basal characteristics between groups (Table 1). Dapagliflozin (10mg daily) was initiated in 14 patients (82.4%), 5 from group 1 and 9 from group 2 (p=1.000), and empagliflozin (10mg daily) in 3 patients (17.6%), 1 from group 1 and 2 from group 2 (p=1.000). Before SGLT2i, mean diastolic PAP (dPAP) was 17.3 ± 5.6 mmHg and median NTproBNP was 2841.5 (289-10515) pg/mL. SGLT2i significantly reduced dPAP; average dPAP ("30 days after" period) was 1.5 mmHg lower (95% CI, 0.26-2.74; p=0.021) compared to "30 days before" period (Figure 1). SGLT2i also reduced systolic PAP (-2.2 mmHg), mean PAP (-1.7 mmHg), NTproBNP (-183 pg/mL) and creatinine (-0.2 mg/dL), but not statistically significant. SGLT2i reduced PAP, NTproBNP and creatinine too in group 1 (6 patients), but did not achieve statistical significance. Reductions were as well observed in group 2 (11 patients), and SGLT2i significantly reduced dPAP (-2.04 mmHg) (95% CI, 0.31-3.77; p=0.025). Conclusions In patients with chronic HF and a PAP sensor, SGLT2i, added to previous HF treatment, significantly reduced dPAP. PAP reductions were observed regardless LVEF, but results were more robust in patients with LVEF >40%.Figure 1