Evaluation of 24-hour heart rate variability in patients with heart failure with reduced ejection fraction using and not using sodium-glucose co-transporter-2 inhibitor (SGLT-2I)

Evaluation of 24-hour Heart Rate Variability in Patients with Heart Failure with Reduced Ejection Fraction Using and Not Using Sodium-Glucose Co-Transporter-2 Inhibitors (SGLT-2I) Introduction and Objective: Heart failure is a complex condition where the balance between sympathetic and parasympathetic activity is disturbed, leading to decreased blood supply and metabolites to peripheral tissues. Additionally, it is one of the leading causes of morbidity and mortality worldwide. Efforts to reduce hospitalizations in heart failure patients are ongoing to prevent morbidity and mortality, and SGLT-2 inhibitors, which have recently gained a place in current guidelines, stand out due to their cardioprotective and renoprotective effects. Studies have shown that they reduce hospitalization rates and prevent mortality. Additionally, heart rate variability (HRV) continues to be a non-invasive indicator of sympathetic and parasympathetic activity. A reduction in HRV is a predictor of morbidity and mortality. The aim of our study was to evaluate HRV in heart failure patients with reduced ejection fraction (HFrEF) who are followed up at our center, focusing on the effect of SGLT-2 inhibitor use. Materials and Methods: Forty patients with an ejection fraction below 40%, hospitalized for heart failure at the Akdeniz University Faculty of Medicine Cardiology Clinic, were included in the study after stabilization. Patients were divided into two equal groups based on SGLT-2 inhibitor usage. Inclusion criteria included patients over 18 years of age with no additional conditions that could cause decompensation (e.g., anemia, thyroid dysfunction) and who had a rhythm Holter device placed within the same time frame. After data collection, heart rate parameters and HRV parameters were analyzed using the "DMSoftware Cardioscan" rhythm Holter program. Results: A total of 40 patients were included in the study, with an equal number of patients using and not using SGLT-2 inhibitors. Of the patients, 17.5% were female and 82.5% were male, with ages ranging from 40 to 81 years, and the average age was 63.4 years. The average age for the group using SGLT-2 inhibitors was 62.95, and for the group not using them, it was 64. When comparing HRV parameters based on SGLT-2 inhibitor usage, SDNN (p=0.002) and VLF (p=0.012) values were statistically significant. Other parameters such as SDANN, pNN50, TP, rMSSD, and HF did not show statistically significant differences between the groups. Conclusion: In the group of 40 patients included in the study, no statistically significant differences were found in maximum heart rate (p=0.675), minimum heart rate (p=0.255), and average heart rate (p=0.415) between patients using and not using SGLT-2 inhibitors. However, when comparing HRV parameters, SDNN (p=0.002) and VLF (p=0.012) were found to be statistically significant. No significant differences were observed in LF (p=0.344), HF (p=0.607), LF/HF (0.402), SDNN Index (p=0.126), SDANN Index (p=0.05), pNN50 (p=0.817), and rMSSD (p=0.756). Since this study was conducted with a small sample size, further research with larger populations is needed. Keywords: Heart rate variability, sodium-glucose co-transporter 2 inhibitor, heart failure, autonomic nervous system