ORIGINAL ARTICLES  CARDIAC SECTION 

The Journal of Cardiovascular Surgery 2006 December;47(6):719-25

Copyright © 2006 EDIZIONI MINERVA MEDICA

lingua: Inglese

Comparison of a b-blocker and an If current inhibitor in rabbits with myocardial infarction

Langenbach M. R. ¹, Schmitz-Spanke S. ², Brockert M. ², Schepan M. ², Pomblum V. J. ², Gams E. ³, Zirngibl H. ¹, Schipke J. D. ²

¹ Department of Surgery, Helios Klinikum Wuppertal, University Witten/Herdecke 2 Research Group Experimental Surgery, University Hospital Duesseldorf, Duesseldorf, Germany 3 Department of Thoracic and Cardiovascular Surgery, University Hospital Duesseldorf, Duesseldorf, Germany

Aim. We compared protective effects of a ß-adrenoceptor blocker (metoprolol; Met) and a If current (Ivabradine; Iva) in a rabbit model of myocardial infarction.
Methods. Experiments were performed on 44 adult New-Zealand-White (NZW) rabbits. The effects of either metoprolol or ivabradine were assessed 15 min after experimental occlusion of a coronary artery (CAO), 28 days after CAO (drug gavage), and in vitro hearts (Langendorff apparatus). The results were compared with sham and placebo hearts.
Results. Metoprolol (0.25 mg/kg) slightly reduced heart rate and left ventricular systolic function. Ivabradine (0.25 mg/kg) reduced heart rate significantly (P<0.05) (18% vs control). Both drugs provided advantages over placebo: mortality was significantly (P<0.01)smaller (6/13 Pla animals died, 2/10 Met animals, and 3/11 Iva animals), left ventricular function was better preserved after 28 days (external power; Pla; Met; Iva=56%; 76%; 74%), and dilatation (BNP) was reduced (P<0.05). In the Pla group, the ST segment was significantly (P<0.05) elevated by 0.35 mV after CAO and exhibited in 50% of the animals Q waves after 28 days, while after ivabradine or metoprolol, ST displacement and Q waves had disappeared. The uneconomic myosin isoenzyme V3 predominated in Met hearts and Iva hearts (V3/V1: 63/37% and 62/38%), while it was further increased in Pla hearts (78/21%). External efficiency was lowest in Pla hearts (1.00±0.50 a.u.; P<0.05) and was significantly higher both in Met hearts (4.0±1.8 a.u.) and in Iva hearts (3.3±1.6 a.u.).
Conclusions. Met and Iva seem suited for the treatment of chronic myocardial infarction.