Heart rate variability and cardiac function in heart failure rats treated with allogeneic mesenchymal stem cells (547.21)

The effect of Mesenchymal Stem Cells (MSC) on cardiac function and non‐linear dynamics of heart rate variability was evaluated after myocardial infarction (MI) in rats. MSC (N=7) or saline (N=11) were given iv to male Wistar rats 1 week after sham (N=9) or left coronary artery ligation. Infarct size, assessed by SPECT, was found similar among rats (51±1%). Cardiac function was assessed by isotopic ventriculography before and 4 weeks after MSC therapy. 5 weeks after MI the rats underwent ECG and arterial pressure recording. The infarct size was reduced by MSC (36±2% vs 48±2% saline). Left ventricular ejection fraction (LVEF) was normal in sham but lower after MI (54±3 vs 20±2%). No effect of MSC was seen in LVEF (20±4%). Interstitial collagen was increased in rats with MI (15±2% vs 10±1%), but not in MSC treated ones (11±1%). Arterial pressure and heart rate were similar among groups in conscious rats. Baroreflex sensitivity was reduced after MI (1.80±2 vs 1.10±0.1 bmp/mmHg), while MSC prevented this outcome (1.74±0.2 bpm/mmHg). QT and QTc intervals were lengthened by MI and MSC did not affect this parameter. A reduction in sample entropy (SampEn) and increase in detrended fluctuation analysis (DFA) of RR interval were observed after MI. MSC therapy did not affect SampEn but protected the DFA. In conclusion, MSC reduced MI and interstitial fibrosis in left ventricle, combined with improvement of baroreflex sensitivity and DFA. Grant Funding Source : Financial support: FAPESP, CAPES, CNPq, NIC‐USP