Long Term Stability of the Immediate Effect of Cardiac Neuromodulation Therapy for Hypertension.

Background: We have previously shown chronic effects of Cardiac Neuromodulation Therapy (CNT) in patients with elevated systolic blood pressure (SBP) despite multi-drug antihypertensive regimens. The results are believed to reflect long term benefits of the immediate autonomic nervous system modulation by CNT, which can be tuned to prevent sympathetic activation.

Purpose: Demonstrate the ability to optimize CNT effect on SBP.

Methods: CNT was optimized in 36 subjects prior to activation. Dual SBP measurements were used to evaluate changes in SBP. The first and last 30 sec of 1 min activations with 60ms AV delay (AV60) were compared to initial and late SBP measurements on 10min activations with CNT. SBP changes were further compared with SBP values after a year of therapy.

Results: Initial SBP reductions with AV60 and CNT were equivalent (-14+9 and -15+8mmHg respectively). However, as expected with AV60 activations, baroreceptor responses resulted in significant immediate increases in SBP of 6.2+5mmHg after 60sec (p<0.001). On the other hand, SBP remained significantly lower even after 10 minutes of CNT, with a minimal non-significant increase of 0.8+9mmHg (p=0.5). Chronic SBP reductions correlated with the acute CNT effect, demonstrating a chronic change of -15.6+14mmHg.

Conclusions: CNT therapy modulates the baroreceptor mediated sympathetic responses to reduced SBP resulting in an enduring improvement. CNT effects on SBP are immediate and remain clinically significant in the long term. The therapy can be tuned using a relatively simple optimization procedure when needed.