Atrioventricular dromotropathy: evidence for a distinctive entity in heart failure with prolonged PR interval?

Abstract

Heart failure (HF) is often accompanied by atrioventricular (AV) conduction disturbance, represented by prolongation of the PR interval on the electrocardiogram. Studies suggest that PR prolongation exists in at least 10% of HF patients, and it seems more prevalent in the presence of prolonged QRS duration. A prolonged PR interval may result in elevated left ventricular (LV) end-diastolic pressure, diastolic mitral regurgitation, and reduced LV pump function. This seems especially the case in patients with heart disease, in whom it is associated with an increased risk for atrial fibrillation, advanced AV heart block, HF, and death. These findings point towards the importance of proper AV coupling in HF patients. A few studies, strongly differing in design, suggest that restoration of AV coupling in patients with PR prolongation by pacing improves cardiac function and clinical outcomes. These observations argue for AV-dromotropathy as a potential target for pacing therapy, but other studies show inconsistent results. Given its potential clinical implications, restoration of AV coupling by pacing warrants further investigation. Additional possible future research goals include assessing different techniques to measure compromised AV coupling, determine the best site(s) of ventricular pacing, and assess a potential influence of diastolic mitral regurgitation in the efficacy of such therapy.

Electrical Reverse Remodeling of the Native Cardiac Conduction System after Cardiac Resynchronization Therapy

“…Although no causal relationship between abnormal PRi and worse clinical outcomes has been fully elucidated, PRi can significantly affect hemodynamics. A short PRi causes truncation of mitral A-waves [ 7 , 8 ]. In contrast, prolonged PRi leads to the fusion of mitral E- and A-waves and diastolic mitral regurgitation [ 7 , 8 ].…”

“…A short PRi causes truncation of mitral A-waves [ 7 , 8 ]. In contrast, prolonged PRi leads to the fusion of mitral E- and A-waves and diastolic mitral regurgitation [ 7 , 8 ]. Both short and prolonged PRi decrease LV diastolic filling, and eventually result in low cardiac output.…”

PR Prolongation predicts inadequate resynchronization with biventricular pacing in left bundle branch block

“…Prolongation of the electrocardiogram (ECG) PR interval >200 ms is associated with increased adjusted risks of atrial fibrillation and all‐cause mortality . Prior studies on the association between baseline PR interval and outcomes after cardiac resynchronization therapy (CRT) are conflicting, patients with left bundle branch block (LBBB) and prolonged baseline PR interval have increased likelihood of heart failure‐related hospitalization or death after CRT compared to patients with LBBB normal baseline PR interval while patients with non‐LBBB conduction abnormalities and PR prolongation may have lower likelihood of adverse events after CRT compared to patients with non‐LBBB conduction abnormalities and normal PR interval . Whether the poorer outcomes after CRT among patients with LBBB and PR prolongation are related to a higher burden of medical comorbidity or if different implantation, programming, or follow‐up techniques may be needed to optimize outcomes remains unclear.…”

“…[1][2][3][4] Prior studies on the association between baseline PR interval and outcomes after cardiac resynchronization therapy (CRT) are conflicting, patients with left bundle branch block (LBBB) and prolonged baseline PR interval have increased likelihood of heart failure-related hospitalization or death after CRT compared to patients with LBBB normal baseline PR interval while patients with non-LBBB conduction abnormalities and PR prolongation may have lower likelihood of adverse events after CRT compared to patients with non-LBBB conduction abnormalities and normal PR interval. [5][6][7] Whether the poorer outcomes after CRT among patients with LBBB and PR prolongation are related to a higher burden of medical comorbidity or if different implantation, programming, or follow-up techniques may be needed to optimize outcomes remains unclear. Little information is available comparing the ECG and echocardiographic response to CRT among patients with normal and prolonged baseline PR interval and LBBB and prior studies are limited by lack of data regarding device programming and biventricular pacing percentage.…”

Rationale and design of the randomized multicentre His Optimized Pacing Evaluated for Heart Failure (HOPE‐HF) trial

“…In patients with heart failure and a reduced ejection fraction, a prolonged atrioventricular (AV) delay is associated with increased mortality. [1][2][3] Pacing is able to reduce a prolonged AV delay; however, in patients with a narrow QRS, both right ventricular and biventricular pacing can induce additional ventricular dyssynchrony. 4 His-bundle pacing however avoids this as it activates the ventricles using the intrinsic conduction system.…”