FAILURE OF ANTIHYPERTENSIVE TREATMENT TO RESTORE NORMAL SYMPATHETIC ACTIVITY

Background: Sympathetic deactivation represents a major goal of the antihypertensive drug treatment (T). However, whether T normalizes the hypertension-related sympathetic cardiovascular overdrive remains uncertain. Methods: In 219 middle-age essential hypertensives we measured, along with office systolic (S), diastolic (D) blood pressure (BP) and heart rate (HR), muscle sympathetic nerve traffic (MSNA, microneurography) before and after 3 months T, either as monotherapy or as combination drug. Controls were represented by 100 age-matched normotensives. Results: T caused along with a small HR decrease a clear BP reduction (from 160.5/95.5 to 142.3/85.0 mmHg, P<0.01) and a significant MSNA inhibition (from 70.7±11.5 to 65.0±10.2 bursts/100 heartbeats, means±SD, P<0.01). A similar pattern was detected in patients under monotherapy (n=81) or combination T (n=138). MSNA was significantly related to SBP before and during T, but unrelated to HR. In treated patients achieving the lower BP (135.1/84.5 mmHg, n=90), the MSNA reduction was greater than that detected in patients with the higher on-T BP (146.7/87.4 mmHg, n=129). However, even in patients achieving a BP target <140/90 mmHg, MSNA remained markedly higher (on average +66.4%) compared to controls. This was the case even when treated BP was <130/80 mmHg. Data were similar for different antihypertensive drug classes. Conclusions: Thus T, even when effective in achieving a BP control, fails to restore the level of normotension-related MSNA, with a persistence of the pattern of heightened sympathetic influences typical of untreated hypertensive patients. Failure of normalization may participate at the development of the residual cardiovascular risk reported in treated hypertensives.