Sympathetic nervous system seems to play an important role in resistant hypertension (RH) as both renal denervation and baroreflex stimulation reduce BP in such patients. Heart rate (HR) is an indirect, but probably the only clinical marker of sympathetic activity which can be measured in every hypertensive. We aimed to evaluate differences in clinical and ambulatory HR, as well as in HR variability between RH and those controlled on therapy. Moreover, we examined differences among RH patients, depending on ABPM normalcy.
We included 14627 RH (uncontrolled with 3 drugs or treated with ≥
4 drugs) versus 11951 controlled patients (on ≤ 3 drugs). Moreover, among 13555 patients uncontrolled with ≥ 3 drugs, we compared those with elevated 24h BP (≥ 130 and/or 80 mmHg; 8730 true-RH) versus those with normal 24-h BP (<130/80 mmHg; 4825 white-coat RH). Variables analyzed were office, 24-h, daytime and nighttime HR, and HR variability (nocturnal HR dip, SD and coefficient of variation of HR).
After adjusting for age, gender and the use of beta blockers, HR values and variability were slightly, but significantly elevated in RH vs controlled patients and in true vs false RH (Table shows adjusted means±sem). In logistic regression models a blunted HR dip and elevated HR-SD increased the risk of having RH, whereas elevated nocturnal HR, HR-SD and a blunted HR dip were associated with true RH. In conclusion, RH present increased HR variability, whereas night HR and increased variability are both associated with true RH. The increase in HR and HR variability may suggest the involvement of the sympathetic nervous system in the development of resistance to antihypertensive treatment.