Afterload dependence of right ventricular pacing-induced left ventricular dysfunction in patients with aortic stenosis undergoing transcatheter aortic valve implantation

Abstract

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): TKP2021-EGA-23 János Bolyai Research Scholarship of the Hungarian Academy of Sciences. Introduction Recent experimental data indicates that patients with left bundle branch block are particularly sensitive to increased arterial afterload. Nevertheless, whether the detrimental hemodynamic consequence of right ventricular pacing (RVP) is also associated with afterload dependency has not been investigated yet. Purpose Hence, the present preliminary study aimed to examine the acute effect of RVP on left ventricular (LV) function in patients with aortic stenosis before (with elevated arterial afterload) and after (without elevated arterial afterload) transcatheter aortic valve implantation (TAVI). Methods Patients with a previously implanted permanent pacemaker (PM) and significant aortic stenosis referred for TAVI at the Heart and Vascular Center of our university were screened for this observational study. Only those patients who had an intrinsic, regular, narrow QRS rhythm (including junctional escape rhythm) were included. Four patients with a DDD PM (with sick sinus syndrome and maintained AV conduction) and two patients with a VVI PM (with atrial fibrillation and AV block) were enrolled. Echocardiography was performed immediately before TAVI and on the second postoperative day. The ultrasound measurements were carried out during intrinsic, narrow QRS rhythm (80/min AAI pacing in patients with DDD PM and 30/min backup VVI pacing to allow the narrow QRS escape rhythm in patients with VVI PM) and during frequency-matched RVP with wide QRS (>150ms) (DDD pacing with a short AV interval ensuring ventricular capture or VVI pacing, respectively). From the sonographic recordings, speckle-tracking echocardiography-derived global myocardial work index (GMWI) was calculated by commercially available software to assess LV function. Results TAVI resulted in decreased mean aortic gradient (35.4±3.6 mmHg vs. 5.3±1.4 mmHg before vs. after TAVI, P<0.001) indicating successful alleviation of the increased arterial afterload. Compared to the intrinsic, narrow QRS rhythm, RVP reduced GMWI before and after TAVI as well. Nevertheless, a significant reduction was only noted when the increased afterload was present (pre-TAVI GMWI: 1710±169 vs. 1170±199mmHg%, P=0.008), while following pressure unloading only a strong tendency could be observed (post-TAVI GMWI: 1127±76 vs. 865±83mmHg%, P=0.065). Conclusion Our preliminary results indicate that RVP-induced LV dysfunction might be afterload dependent. Hence, in patients with aortic stenosis and a high percentage of ventricular pacing, afterload reduction could entail a great clinical benefit.