Ramadan fasting is one of the five fundamental rituals of Islam. Heart rate variability (HRV) is an independent predictor of increased mortality of patients with myocardial infarction and congestive heart failure. The effects of fasting on the HRV are not known.

Aim: To study the effects of Ramadan fasting on HRV in hypertensive patients.

Our study is a prospective study that includes a total of 20 hypertensive patients, with sinus rhythm and without coronary artery disease, between July and October 2014. HRV was determined twice by ambulatory 24-hour Holter recordings at fasting in the middle of Ramadan and two months after Ramadan. Informed consent was obtained from each study subject prior to participation in study. Mean values of continuous variables were compared by using the Student t-test.

The mean age of patients was 55,2±4,4 years with 8 women and 12 men. The mean BMI was 27,9±4,4.

When two groups compared, statistically significant differences were found in terms of heart rate (during Ramadan 70,5±9,4, post-Ramadan 76,3±9,7, p=0.001), SDNN (during Ramadan 51,6±13,7, post-Ramadan 52,2±16,4, p=0.000), SDNNI (during Ramadan 105,5±44,4, post-Ramadan 131,7±48,7, p=0.001) RMSSD (during Ramadan 38,1±14,4, post-Ramadan 39,9±18,5, p=0.02), T power (during Ramadan 2327,5±1151, post-Ramadan 2597,5±1678,3, p=0.001), LF (during Ramadan 539,9±301, post-Ramadan 591,2±476,3, p=0.001), HF (during Ramadan 276±173,2, post-Ramadan 304±325,3, p=0.015) and LF/HF (during Ramadan 2,9±2,3, post-Ramadan 3,6±3,5, p=0.000) values.

In our study, HRV parameters were found to be decreased in Ramadan month compared to after Ramadan in hypertensive patients. So we think that Ramadan fasting enhances the activity of the sympathetic system in hypertensive patients.