Secondary erythrocytosis / polycythemia due to sodium glucose co-transporter 2 inhibitors: a real world heart failure cohort

Abstract Background Sodium glucose co-transporter 2 inhibitors (SGLT2-i) are one of the four pillars of guideline-directed medical therapy in heart failure with reduced ejection fraction and preserved ejection fraction according to the current ESC and AHA/ACC heart failure guidelines 1,2. As a result, there has been a significant increase in their use worldwide. Although SGLT2 inhibitors are known to increase hemoglobin and hematocrit levels, there is a lack of data on the burden of erythrocytosis or polycythemia in pivotal trials 3,4. Purpose In this retrospective cohort study, we investigated the prevalence and clinical outcomes of SGLT2-i related erythrocytosis in a tertiary heart failure outpatient clinic. Methods We reviewed clinical data from heart failure patients treated with an SGLT2 inhibitor at our tertiary centre between September 2019 and October 2023. Patients were included if they were taking SGLT2-i continuously for more than one month. Data were collected on Hb/Hct levels at baseline before initiation of SGLT2-i, at peak levels during therapy and at the last follow-up. Erythrocytosis was defined according to the 2017 WHO classification as Hb> 10.3 mmol/L and/or Hct> 49% in men and Hb> 10.0 mmol/L and/or Hct> 48% in females. Results A total of 173 patients with heart failure were included (median age 58 [49-66] years, 65% male). One hundred and fifty-six patients (90%) were using dapagliflozin, while 16 patients (9%) were using empagliflozin. The overall prevalence of SGLT2i related erythrocytosis was 39/173 (22.5%; median age 60 and 82% males). Eleven (6.3%) patients had pre-existing erythrocytosis at baseline. During a mean follow-up of 14±10 months, 28/173 (16.2%) patients developed new onset erythrocytosis. The median time to the peak of the Hb/Hct level was 6.5 months. Although the group with erythrocytosis had significantly higher Hb and Hct at baseline compared to the group without erythrocytosis (Hb 9.7 mmol/L ± 1.0 vs. 8.5 mmol/L ± 1.0; p<0.001 in men and 9.1 mmol/L ± 0.8 mmol/L vs. 8.1 ± 0.8; p=0.006 in females), they also experienced a significantly greater median increase in Hb from baseline to peak (1.05 mmol/L vs. 0.60mmol/L; p=0.01) (see Figure 1) There were significantly more males (82% vs 60%; p=0.01) in the erythrocytosis group compared to the non-erythrocytosis group. In addition, the prevalence of OSAS was significantly higher in the group with erythrocytosis compared to the group without erythrocytosis (31% vs. 8%; p<0.001). Conclusion Secondary erythrocytosis or polycythemia is common in patients with chronic heart failure. It is particularly common in men and in patients with obstructive sleep apnoea syndrome (OSAS). There were no excess thrombotic or thromboembolic events, probably because of the routine use of anticoagulants/antiplatelets and limited follow-up. To avoid unnecessary haematological referrals and potential clinical adverse events, increased awareness among clinicians is needed.Table 1.Baseline and clinical outcomesFig1.Hemoglobin levels over time