Atrioventricular Interval Modulation (AVIM) therapy for ambulatory systolic blood pressure (aSBP) reduction with a dual chamber pacemaker: comparison of conduction system vs. right ventricular pacing

Abstract

Abstract Background AVIM is a pacing algorithm incorporated into dual-chamber pacemakers to treat hypertension. AVIM delivers repeating sequences of short and longer atrioventricular delays leading to reduced preload and afterload. The therapy lowers blood pressure while simultaneously modulating the autonomic nervous system. The marked blood pressure reducing capability of AVIM has been already confirmed by a previous randomized clinical trial using conventional right ventricular (RV) pacing. Nevertheless, whether a similar blood pressure reduction could be also achieved by AVIM when conduction system pacing (CSP) is applied instead of RV pacing has not been investigated yet. Considering the facts that CSP using Left Bundle Branch Area Pacing (LBBAP) has been found to elicit more synchronous ventricular contraction and improved hemodynamics compared to RV pacing and AVIM is associated with a signficant burden of ventricular pacing, it is tempting to hypothesize that AVIM with CSP could be particularly beneficial. Purpose To compare the effects of AVIM therapy when delivered via an LBBAP location with the effects when delivered using a traditional RV lead location. Methods This single-center study evaluated subjects indicated for a dual chamber pacemaker who also had uncontrolled hypertension despite a stable dose of ³ 1 antihypertensive drug. Leads were placed in the RV or the LBBAP position. Subjects entered a run-in period of 4 weeks in which baseline office (oSBP)and 24-hour aSBP were measured. Subjects with baseline aSBP >130 mmHg and oSBP>140 mmHg at week 4 were included in the study. AVIM therapy was activated and a 24-hour aSBP was performed immediately after activation. Results Using a dedicated CSP pacemaker lab setup, CSP was performed in 5 patients with the Select Secure electrode (model 3830-69 cm) delivered via a fixed curve sheath (C315HIS). During the run in phase, in 3 out of the 5 CSP-AVIM patients, high blood pressure did not reach the level of inclusion and therefore these patients were not used for further analysis. In the remaining two patients, AVIM was activated. These two patients had a V6 stimulus-peak time of 69 ms and 61 ms, while V1 stimulus peak time was: 121ms and 109ms respectively. The effect of AVIM on 24-hour aSBP in the activated CSP-AVIM patients was compared to the average effect seen in patients from the same center enrolled in the prior randomized study with leads in the RV. Table 1 shows individual aSBP values for the two patient groups. Results suggest that delivery of AVIM therapy through leads in either position generates a significant reduction in blood pressure: -24.1 mmHg vs. -15.4 mmHg when the lead is placed in LBBAP or RV positions respectively. Conclusion These results demonstrate a significant reduction in aSBP in both lead locations. Additional studies evaluating larger sample sizes are required to assess if specific lead positions are preferable.Table 1