RESUMEN
Therapy adherence significantly determines the success of antihypertensive therapy, especially in patients with resistant hypertension. Our study investigates the impact of drug adherence on the efficacy of Baroreflex-activation-therapy (BAT). In this retrospective analysis, the authors measured blood pressure (BP) and antihypertensive medication adherence (by gas chromatography-mass spectrometry [GC-MS] urine analysis) before and 6 months after BAT initiation. Adherence was defined as detection of ≥80% intake of prescribed medication at the time of follow-up. Response to BAT was defined as BP drop ≥5 mmHg in systolic 24 h-ambulatory BP (ABP) after 6 months. Overall patients (n = 38) median medication adherence was low, but rose from 60% (IQR 25%-100%) to 75% (IQR 38%-100%; p = .0194). After 6 months of BAT, mean systolic and diastolic office BP (-21 ± 25 mmHg and -9 ± 15 mmHg; p < .0001 and .0004) as well as 24 h-ABP dropped significantly (-9 ± 17 mmHg and -5 ± 12 mmHg; p = .0049 and .0280). After 6 months of BAT, 21 patients (60%) could be classified as responders. There was neither significant difference in mean office systolic (-21 ± 23 mmHg vs. -21 ± 28 mmHg; p = .9581) nor in 24 h-systolic ABP decrease (-11 ± 19 mmHg vs. -7 ± 15 mmHg; p = .4450) comparing adherent and non-adherent patients. Whereas Antihypertensive Therapeutic Index (ATI) was unchanged in non-responders, it significantly decreased in responders (from 50 ± 16 to 46 ± 16; p = .0477). These data are the first to show that BAT-initiation leads to a clear BP reduction independently of patients´ medication adherence. Response to BAT is associated with a significant lowering of ATI, which might contribute to an underestimation of BAT efficacy.