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Failing Hearts are Preconditioned against Myocardial Infarction and Exhausted their Ischemic Preconditioning Reserve
Author(s) -
AbdEfattah Anwar Saad,
Guo JainHua,
Gao ShinPing
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.1033.23
Subject(s) - cardiology , medicine , myocardial infarction
Background Ischemic preconditioning (IPC) is well documented in naïve animals' hearts; however its clinical efficacy remains questionable. To test whether IPC is clinically applicable, we determined IPC reserve in normal and failing canine hearts. Methods Heart failure was created by chronic rapid pacing (250 bpm for 6 weeks). LV remodeling was confirmed by echocardiography (EF=10–20%, LV dilation). Anesthetized control (n=18) and failing heart (n=27) animals were subjected to 45, 60 or 90 min index ischemia (LAD coronary artery occlusion) and 4 hrs reperfusion. Collateral blood was measured colored microspheres. ATP pool and HSP70 were determined in tissue biopsies. Monastral blue and TTC were used to delineate risk area and infarct size. Results The risk areas were comparable between groups. The infarct sizes (INF) were lower (1.95±1.50*, 8.50±1.38* and 19.70±0.72 *) in the failing hearts than control groups (p<0.05) following 45, 60 and 90 min of ischemia, respectively. After 90 min ischemia, INF size of the naïve hearts were significantly greater (INF%=32.10±2.90) than failing hearts (INF%= 19.70±0.72). IPC limited INF size of the naïve hearts but did not affect the small INF size in failing hearts. Conclusion Failing hearts are chronically preconditioned against an acute MI and exhausted their IPC reserve. Drugs that abolish this tolerance would jeopardize patients' safety.