The effect of hypertension on heart rate variability

Introduction and Aim: Cardiovascular diseases continue to be one of the most important causes of death in developed and developing countries. Although there are many risk factors in cardiovascular diseases, new risk factors are needed because cardiovascular diseases are observed in patients without risk factors. Many studies have shown that heart rate variability (HRV) is associated with mortality and morbidity in patients with cardiovascular disease. The aim of our study is to investigate the effect of newly diagnosed hypertension (HT) on HRV. Materials and Methods: A total of 90 people, including 50 newly diagnosed hypertension patients and 40 control group, who applied to the cardiology outpatient clinic of Zonguldak Bülent Ecevit University, Health Practice and Research Hospital were included in the study. HRV parameters were examined with 10-minute electrocardiographic recording. HRV was compared by forming groups according to HT stages and the presence of left ventricular hypertrophy (LVH). Results: Systolic blood pressure (SBP) (158. 3±11. 3 vs. 117. 3±11. 2, p<0. 001) and diastolic blood pressure (DBP) (92. 9±8. 1 vs. 66. 7±7. 8, p<0. 001) were significantly higher in HT patients. When HT and control groups were compared in terms of HRV parameters, SDNN value (49. 2±25. 3 vs. 62. 2±34. 4, p=0. 042), LF/HF value (1. 23±1. 40 vs. 2. 05±1. 71, p=0. 015) and pNN50 value ( 2. 64± 5. 61 vs. 6. 38±8. 17, p=0. 012) was higher in the control group. LVH was detected in 38 of 50 HT patients, while 12 did not have LVH. SDNN value was statistically significantly lower in patients with LVH (45. 3±24. 4 vs. 61. 3±25. 3, p=0. 049). When analyzed according to HT stages, 30 patients had stage 1 HT, while 20 patients had stage 2 HT. The LF/HF ratio was found to be lower in those with stage 2 HT compared to those with stage 1 (1. 93±1. 86 vs. 1. 12±0. 77, p=0. 041). SBP (143. 0±23. 5 mmHg vs. 135. 4±20. 4 mmHg) and DBP (85. 0. ±15. 0 mmHg vs. 77. 4±14. 9 mmHg) were higher in the low LF/HF group. While this difference was not statistically significant for SBP, it reached a significant level for DBP (p=0. 106, p=0. 019, respectively) Conclusion: HRV parameters (SDNN, LF/HF and pNN50) were lower in HT patients compared to the control group. The decrease in HRV values was more pronounced in patients with LVH and Stage 2 HT. HRV decreases in newly diagnosed HT patients, especially in those with advanced stage and organ damage.