Septal contraction predicts acute haemodynamic improvement and paced QRS width reduction in cardiac resynchronization therapy

Aims: Three distinct septal contraction patterns typical for left bundle branch block may be assessed using echocardiography in heart failure patients scheduled for cardiac resynchronization therapy (CRT). The aim of this study was to explore the association between these septal contraction patterns and the acute haemodynamic and electrical response to biventricular pacing (BIVP) in patients undergoing CRT implantation.

Methods and results: Thirty-eight CRT candidates underwent speckle tracking echocardiography prior to device implantation. The patients were divided into two groups based on whether their septal contraction pattern was indicative of dyssynchrony (premature septal contraction followed by various amount of stretch) or not (normally timed septal contraction with minimal stretch). CRT implantation was performed under invasive left ventricular (LV) pressure monitoring and we defined acute CRT response as ≥10% increase in LV dP/dtmax. End-diastolic pressure (EDP) and QRS width served as a diastolic and electrical parameter, respectively. LV dP/dtmax improved under BIVP (737 ± 177 mmHg/s vs. 838 ± 199 mmHg/s, P < 0.001) and 26 patients (68%) were defined as acute CRT responders. Patients with premature septal contraction (n = 27) experienced acute improvement in systolic (ΔdP/dtmax: 18.3 ± 8.9%, P < 0.001), diastolic (ΔEDP: -30.6 ± 29.9%, P < 0.001) and electrical (ΔQRS width: -23.3 ± 13.2%, P < 0.001) parameters. No improvement under BIVP was observed in patients (n = 11) with normally timed septal contraction (ΔdP/dtmax: 4.0 ± 7.8%, P = 0.12; ΔEDP: -8.8 ± 38.4%, P = 0.47 and ΔQRS width: -0.9 ± 11.4%, P = 0.79).

Conclusion: Septal contraction patterns are an excellent predictor of acute CRT response. Only patients with premature septal contraction experienced acute systolic, diastolic, and electrical improvement under BIVP.