Cardiac remodelling and functional status after cardiac resynchronization therapy: comparison between de-novo...

Patients with heart failure induced by chronic right ventricular (RV) pacing commonly undergo upgrade to cardiac resynchronization therapy (CRT). We aimed to compare the effect size of improvement in cardiac function and functional capacity between patients with RV pacing and intrinsic conduction at baseline.

We included patients from the ImagingCRT, ElectroCRT and DANISH-CRT trials aged ≥40 years with left ventricular ejection fraction (LVEF) ≤35% and prolonged QRS. The primary endpoint was change in left ventricular end-systolic volume (LVESV) from baseline to 6-month follow-up. Secondary endpoints included change in QRS duration, echocardiographic measures (LVEF, left ventricular end-diastolic volume, left ventricular mass index, and left atrial volume index), N-terminal prohormone of brain natriuretic peptide, six-minute walk test, quality of life, New York Heart Association functional class and loop diuretic use.

We included 592 patients [mean age 70.7 ± 9 years; 24.8% women; mean LVEF 27 ± 6%; 97 (16.4%) with RV pacing and 495 (83.6%) with intrinsic conduction at baseline]. We found significant relative reduction in LVESV in patients with RV pacing (-34 ± 25%) and intrinsic conduction (-32 ± 26%) with no difference between the groups [mean difference -2%, 95% CI (-8; 4), P = .469]. Absolute LVEF improvement was 14 ± 9% and 13 ± 10%, respectively. Reduction in QRS duration was larger with RV pacing compared with intrinsic conduction (-38 ± 26 vs -26 ± 24 ms). We found significant improvements in the remaining secondary endpoints, with no difference between the groups.

Patients with RV paced QRS morphology who are upgraded to CRT derive substantial improvement in cardiac function and functional capacity, comparable to patients with intrinsic conduction undergoing CRT.