gms | German Medical Science

Background: Clinical/functional parameters currently identify patients who benefit from the cardiac resynchronization therapy (CRT). Electrical and mechanical alterations in both ventricles have not been well evaluated yet.

Objective: To establish ventricular electrical activation criteria that can distinguish patients whose clinical-functional parameters improved after CRT, using a non-invasive method, the body surface potential mapping (BSPM).

Methods: Twenty-two patients with heart failure and left bundle-branch block (LBBB) undergoing CRT, mean age 64+/-10 years, left ventricle ejection fraction (LVEF) 30%+/-8%, QRS 169+/-19 ms, NYHA class III – 86%, IV – 14%, underwent 87-lead BSPM assessment (58 leads on the anterior chest and 29 on the back), before and after CRT. BSPM isochronal maps were used to analyze the ventricular activation time (VAT) in the right (RV) and left ventricles (LV) in three situations, (1) native LBBB, (2) single-site RV pacing, and (3) biventricular pacing. CRT clinical/functional improvement was measured by LVEF on echocardiography, and by NYHA functional class. VAT’s were compared using the Mann-Whitney’s non-parametric method. The groups with and without clinical/functional improvement who showed RV/LV difference of VAT less than or equal to 20ms, and >20ms were compared by the Fisher’s test. Significance level was P<0.05.

Results: Although only a trend towards a shorter VAT RV/LV difference during biventricular pacing was found among patients who improved (12.9+/-10.9ms vs 23.1+/-12.9ms, respectively; P=0.08), the majority of the patients with clinical/functional improvement had a VAT RV/LV difference shorter than or equal to 20 ms during biventricular pacing, P=0.026 (79% vs 25%, RR 2.5, CI=95% 0.09–6.58). Baseline characteristics were not significant. Conclusion: BSPM could distinguish patients who improved clinically-functionally after CRT when VAT difference between the ventricles was shorter than 20 ms.