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

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.