Short-term ventricular restraint attenuates post-infarction remodeling in rats☆

Abstract Background/objectives Left ventricular restraint attenuates post-infarction remodeling, but may be associated with unfavorable long-term histological response. We hypothesized that beneficial effects can be obtained with short-term restraint during the early post-infarction period; for this purpose, we evaluated a biodegradable scaffold in the in vivo rat model and compared it with epicardial hydrogel application. Methods A total of 230 Wistar rats (358±7g) were studied. Implantation was performed with and without prior myocardial infarction, induced by permanent coronary artery ligation. Diastolic filling was evaluated by left ventricular pressure recordings after scaffold implantation. Degradation rates and inflammatory/foreign body response were studied at 3, 7 and 15days post-ligation. Remodeling indices were evaluated by echocardiography 15days post-ligation. Results No differences were found in diastolic pressure. Biodegradability was ~50% by 7days and 100% by 15days for both materials. Likewise, inflammatory/foreign body response peaked at 3days post-implant, with subsequent remission, but fibroblastic reaction was more pronounced after scaffold than after hydrogel implantation. Post-ligation, ejection fraction was higher in the scaffold (40.0±1.5%) or hydrogel groups (37.0±1.3%), compared to controls (30.6±1.9%). Wall tension index was lower with either biomaterial, but left ventricular end-diastolic diameter was shorter (p=0.044) and sphericity was attenuated (p=0.029) after scaffold, compared to hydrogel implantation. Conclusions Both biomaterials showed a favorable histological response and attenuated remodeling, but epicardial restraint produced better results compared to hydrogel alone. The latter approach merits further investigation due to the ease of implantation.