Effects of Pregabalin on Heart Rate Variability in Patients With Painful Diabetic Neuropathy

Many studies have demonstrated that low heart rate variability (HRV) is a risk for high mortality and morbidity in patients with cardiovascular diseases. The primary purpose of the study was to evaluate whether pregabalin improves HRV in patients with diabetes and painful peripheral neuropathy. Resting heart rates were collected by using the LifeShirt System, developed by VivoMetrics (Ventura, Calif), at baseline and at the end of a 4-week intervention of pregabalin or placebo in patients with painful diabetic peripheral neuropathy. Heart rate variability analysis was performed on the collected R-R intervals using the Vivo- VMLA-036-00 3 Logic of the LifeShirt system. Of the 40 patients enrolled in the study, 70% completed the end of 4-week assessments (n = 15 in pregabalin and n = 14 in placebo). Compared with placebo, pregabalin treatment resulted in significant improvement in HRV measured by frequency domain analysis, that is, a reduction in low frequency-high frequency ratio (−1.30 ± 2.89 vs 0.37 ± 0.33, P = 0.03) and power of normalized low frequency (−0.049 ± 0.092 vs 0.0066 ± 0.023, P = 0.02), as well as an increase in power of normalized high frequency (0.039 ± 0.094 vs −0.038 ± 0.066, P = 0.02). Furthermore, pregabalin resulted in greater reduction of pain and symptoms of anxiety and greater improvement of quality of life. The improvement of HRV measures were not correlated with change of those measures. In conclusion, 4-week pregabalin treatment improved HRV in patients with painful diabetic peripheral neuropathy. Trial Registration: NCT00573261 (clinicaltrials.gov) Abbreviations: HRV - heart rate variability, VAS - visual analog scale, BID - twice daily, RSA - respiratory sinus arrhythmia, VLF - very low frequency, LF - low frequency, HF - high frequency, ANN - mean of all R-R intervals, SDNN - standard deviation of R-R intervals, RMSSD - root mean square of successive differences, SDANN - standard deviation of the averages of R-R intervals for all 5-minute segments within the block, PNN50 - number of N-N intervals that differed by more than 50 milliseconds from adjacent intervals divided by the total number of all N-N intervals, NPS - Neuropathic Pain Scale, BPI - Modified Brief Pain Inventory-Short Form, STAI - State-Trait Anxiety Inventory Scale, BDI - Beck Depression Inventory