Objective: To determine the levels of circulating cell-free DNA (cfDNA), a marker of endothelial damage, in patients with sleep apnea-hypopnea syndrome (AHS) with or without hypertension, and the influence of continuous positive airway pressure (CPAP) therapy on its levels.
Design and method: We included 30 consecutive patients recently diagnosed of AHS (apnea-hypopnea index (AHI) higher than 15) with no previous treatment with CPAP. We evaluated these patients before and after 3 months of treatment with CPAP. Ambulatory blood pressure monitoring was performed in each patient. There were no changes on drug treatment during the study. The levels of circulating cfDNA were quantified by real time PCR.
Results: Mean age was 51.7 +/- 11.5 years, and mean AHI: 56.3 +/- 25.5. Hypertension was present in 56.7% of patients. Mean 24-hour systolic blood pressure (BP) was 25.3 +/- 12.3 and diastolic 76.0 +/- 10.5 mmHg diastolic; no dipper pattern 79.3%; the mean heart rate during day was 79.5 +/- 10.5 bpm and during the night 70.1 +/- 9.9 bpm. After CPAP: systolic BP 121.2 +/- 12.6 and diastolic BP72.6 +/- 10.9 mmHg, p < 0.01; no dipper pattern 44.8%, p = 0.02; heart rate day 76.8 +/- 10.7 (p = 0.04) and night 65.1 +/- 9,52 bpm (p < 0.01). Mean circulating cfDNA was 187,93 +/- 115,81ng/mL and after 3 months with CPAP therapy it decreased to 121,28 +/- 78,98 ng/mL, p < 0.01, but this improvement was due to hypertensive patients, with no changes in normotensives.
Conclusions: The circulating cfDNA is considered as a biomarker of cell damage. We have observed that hypertensive patients with AHS under treatment with CPAP have significant lower levels of circulating cfDNA, suggesting that this disorder seems to improve with CPAP in hypertensive patients.
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