Doppler-derived cardiac performance and evaluation of alternative measures of AV conduction to predict unvfavuorable haemodynamics in patients with long PR (DEEPER PR Study)
Authors: Auge R E , Dittrich K , Muehlisch A K , Wuttke U , Beierle A S , Knebel F , Kutyifa V , Stockburger M 
Published: May 2023

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background
Prolonged atrio-ventricular (AV) conduction has been shown to compromise cardiac performance. Long PR relates to unfavorable clinical outcome and even increased mortality. The PR interval is traditionally used to describe AV conduction, but this parameter comprises inter-atrial and AV conduction delays and may therefore not optimally reflect hemodynamic consequences of prolonged AV conduction. Ventricular conduction delay also impacts ventricular filling and cardiac performance, while delayed inter-atrial activation may alleviate LV hemodynamic compromise. It is unknown, which parameter of AV conduction relates closest to cardiac performance. The objective of this study is to characterize segments of the PR interval in patients with long PR vs. matched controls with normal PR and to investigate the association of various measures of AV conduction to Doppler-derived cardiac performance.

Methods
52 hospitalized pts with AVB I° (group A), and 52 controls (matched according to age, gender, LVEF, group B) were studied in detail by digitalized 12 lead ECG and 2-D, Doppler, and tissue Doppler echocardiography. Segments of PR were compared between matched groups. Seven measures of AV conduction were correlated to LV and RV filling fraction, total isovolumic times, and Tei indices and ranked by logistic regression and ROC-AUC in the combined patient cohort.

Results
PR was 227.5 (212;251)ms (A) vs. 182 (164;190)ms (B); p&lt;0.001). P wave duration was 127(114;136)ms (A) vs. 113(102.5;126.8)ms (B); p&lt;0.001 with longer RA and LA activation in group A. Reduced LV filling fraction (PQ Δ0.045, PePV6 Δ0.050, AUC 0.681 vs. 0.719), prolonged combined LV isovolumic times (PR: Δ19ms, 15.8%, PePV6: Δ31ms, 26.9%, AUC 0.619 vs 0.698), and higher LV Tei indices (PR: Δ0.045, 10.3%, PePV6: Δ0.083, 19.8%, AUC 0.566 vs 0.626) were best predicted by the variable PePV6 (interval between the end of P in V1 and Rpeak in V6) according to bivariate correlations, logistic regression analyses, and ROC-AUC. Applying PePV6 instead of PR re-categorized 20% of pts as having prolonged vs normal AV conduction. Prolonged PePV6 was also best suited to predict worse RV hemodynamics. Although significant linear correlations were demonstrated, a non-linear component of the association between AV timing and LV filling appeard to be present with pronounced impairment of cardiac performance beyond the 3rd quartile of PePV6 (148ms), respectively.

Conclusion
Prolonged PR comprises prolonged atrial activation (30%) and delayed AV conduction (70%). In this study, PePV6, a novel parameter eliminating P wave duration and accounting for initial LV activation, was best suited to identify compromise of Doppler-derived LV and RV hemodynamics by delayed AV conduction. PePV6 prolongation beyond the 3rd quartile may particularly affect cardiac performance. These findings inform future clinical studies and should give rise to investigation of PePV6 in larger patient populations.