September 17, 2025

Noninvasive cardiovascular MRI pressure-volume loops reveal impact of left bundle branch block beyond impaired ejection fraction

Key Points

LBBB patients show 22% lower contractility versus controls, indicating significant hemodynamic effects.
Despite matching for ejection fraction, LBBB reveals unique cardiac performance metrics through PV loop analysis.
This study uses noninvasive PV loops, enhancing our understanding of LBBB's impact beyond traditional measurements.
The findings suggest PV loop-derived metrics can better assess LBBB, supporting treatment optimization through cardiac resynchronization.

Abstract

Motivation: Left bundle branch block (LBBB) exacerbates heart failure through left ventricular (LV) dyssynchrony. Hemodynamic understanding of LBBB could potentially be improved using Pressure-Volume (PV) loop analysis. Goal(s): We aimed to compare LBBB patients to controls matched for age-, sex-, and ejection fraction using a method to calculate PV loops noninvasively using cardiovascular magnetic resonance short-axis cine images and brachial blood pressure. Approach: We compared noninvasive PV loops in LBBB patients (n=40) and matched controls (n=40). Results: Noninvasive PV loops revealed 22 % lower contractility in LBBB patients compared with controls (p=0.002) despite matching for LV ejection fraction. Impact: Cardiovascular magnetic resonance-derived noninvasive PV loops reveal lower contractility in LBBB, independently of the conventional measure of left ventricular ejection fraction. Therefore, PV loop derived contractility could potentially help assess and optimize treatment of LBBB using cardiac resynchronization therapy.

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