Abstract 9609: Impact of Mesenchymal Stem Cell Left Ventricular Implantation on Heart Rate Variability: Results From the POSEIDON Trial

Abstract

Introduction: Patients (pts) with ischemic cardiomyopathy (ICM) may have impaired heart rate variability (HRV) which is associated with worse prognosis. We tested the hypothesis that cardiac mesenchymal stem cell (MSC) implantation is associated with improvement in HRV in patients with severe LV dysfunction and abnormal HRV at baseline Methods: The POSEIDON Trial evaluated transendocardial MSC implantation in pts with ICM. We examined 24-48 hour ambulatory monitoring data from 25 pts at baseline, immediately post MSC implant, and intermittently up to 13 months following implantation. HRV was assessed using 3 parameters: (1) standard deviation of NN intervals (SDNN), (2) the square root of the mean squared differences of successive NN intervals (RMSSD), and (3) standard deviation of the average normal NN intervals (SDANN). HRV indices were correlated to changes in ejection fraction (EF), end systolic volumes (ESV), end diastolic volumes (EDV), and sphericity index (SI) using t-test. Results: The cohort had a mean age of 62 ± 10 years, EF 26.5 ± 9.4%, ESV 204.2 ± 80.6 ml and EDV 271.5 ± 85.4 ml. Compared with pre-implantation values, RMSSD trended to improve in the cohort (30.2 ± 15 to 51.9 ± 39.3 msec, p=0.08), significantly improved in the group with EF improvement (24.6 ± 10 to 57.3 ± 43.5, p= 0.04) and tended to improve in the group with improved EDV, ESV, SI (Table). SDNN and SDANN also tended to improve in the cohort, but showed significant improvement in the group with less structural improvement noted by EDV or ESV decrease by <5% (Table). Conclusions: There was a trend towards improvement in HRV after MSC implant. RMSSD, a variable more closely related with vagal tone, correlated better with greater improvements in EF, EDV, ESV and SI and may be a better marker of anatomical improvement. In contrast, SDNN and SDANN, which track not only vagal tone but diurnal variation, tended to improve in the overall cohort but showed improvement in the group with less structural improvement.