Abstract 3378: Response to Biventricular Pacing is Associated With Improvement in Endothelial Function
Background: Endothelial dysfunction is a hallmark of heart failure and is associated with increased mortality. Endothelial function may improve with resolution of heart failure, however it is unclear whether this is due to a direct effect of medications (e.g. ACE-I) on the endothelium or to a primary improvement in hemodynamics. We hypothesized that biventricular (BiV) pacing independently improves endothelial function in heart failure patients.
Methods: Assessment of brachial artery flow-mediated dilatation (FMD) was performed pre-implantation (FMD0) and 14 days post-implant (FMD14) in patients (n=14, 10 males, age 65.6±15.0 yrs) undergoing BiV ICD placement (LVEF 21.4±6.6%, QRS duration 158±27 ms). All patients were NYHC III [ischemic cardiomyopathy 9/14 (64%)] and were on a stable medical regimen with no change during the study period. Pre- and post-implant FMD as well as the extent of FMD change (ΔFMD0–14) were compared between responders and non-responders (assessed clinically by symptoms and NYHC).
Results: For the entire cohort, mean FMD0 at baseline was 6.67±6.2% and mean FMD14 at follow-up was 11.46±9.1%. FMD change (ΔFMD0–14) for all patients was 4.79% (95% CI: -0.71% - 10.3%, p=0.082). When the cohort was divided by clinical response to BiV pacing, there were 7/14 patients (50%) who were determined to be responders (7/14 non-responders). Mean ΔFMD0–14 was +9.70% for responders vs. -0.84% for non-responders (absolute difference 10.54%, 95% CI: 1.08%–19.99%, p=0.032). Subgroup analysis showed no difference in QRS duration between responders (169±30 ms) and non-responders (148±20 ms, p=0.15). Pts with ischemic and non-ischemic cardiomyopathy had similar FMD0 (6.29±6.2% vs 7.34±6.9% respectively, p=0.76) and similar ΔFMD0–14 (4.15±6.3% vs 6.3±15.1% respectively, p=0.71).
Conclusions: BiV pacing alone, independent of pharmacological intervention, improves endothelial function. This effect is likely due to direct hemodynamic improvement and is not related to the etiology of heart failure (ischemic vs non-ischemic). Patients who respond to BiV pacing exhibit marked improvement in FMD compared to non-responders, implying that endothelial dysfunction may play an important role in clinical response.