Altered autonomic neural control of the cardiovascular system in patients with polycystic ovary syndrome.

PURPOSE: Polycystic ovary syndrome (PCOS) is frequently accompanied by the presence of cardiovascular risk factors. It has also been recognized that there is a significant relationship between the autonomic nervous system and adverse cardiac events. Heart rate recovery (HRR) after exercise is a marker of parasympathetic activity and attenuation of this parameter has been shown to be associated with increased cardiac mortality. A delayed recovery of systolic blood pressure (SBP) after peak exercise has been found to have diagnostic value and might reflect sympathetic hyperactivity. The analysis of variations in heart rate has also been used to determine the balance between sympathetic and vagal nerve activities in the heart. Our objective was to determine HRR, the SBP response to exercise and heart rate variability (HRV) in patients with PCOS.

METHODS: The study population consisted of 26 untreated patients with PCOS and 24 healthy controls who were matched with respect to age, body mass index and physical activity. All subjects underwent symptom-limited exercise tolerance test according to a modified Bruce protocol. Following peak exercise, subjects walked a 2-min cool-down period. Heart rate recovery was calculated as the difference between heart rate at peak exercise and heart rate at the relevant minute of recovery. Blood pressure recovery indexes were determined by dividing the systolic blood pressure at 1, 2 and 3 min in recovery to the systolic blood pressure at peak exercise.

RESULTS: HRR at 1 min (HRR1) of the patients with PCOS were significantly lower than that of controls (20+/-4 vs 28+/-8 bpm, p<0.0001). Although, resting SBP of the two groups were similar (117+/-7 vs 117+/-10 mmHg, p=0.663), the SBP of the patients with PCOS at peak exercise were significantly higher when compared to controls (172+/-12 vs 156+/-14 mmHg, p<0.0001). In addition, the SBP of the patients with PCOS remained significantly elevated when compared to controls at the first, second and third minute of recovery (168+/-13 vs 148+/-15 mmHg, 162+/-13 vs 136+/-16 mmHg, 152+/-17 vs 127+/-15 mmHg, respectively, p<0.0001 for all three). The SBP recovery index at 2 and 3 min of the patients with PCOS were significantly higher than that of controls (0.93+/-0.04 vs 0.87+/-0.07, p<0.0001 and 0.87+/-0.07 vs 0.82+/-0.09, p=0.017, respectively). Both time domain and frequency domain parameters of patients with PCOS were significantly lower than that of controls.

CONCLUSION: This study shows that the patients with PCOS have attenuated HRR1, exaggerated SBP response to exercise which is delayed to recover and a depressed HRV. These findings might also suggest alterations in autonomic neurol control of the cardiovascular system in this disorder.