Optimized Local Infarct Restraint Improves Left Ventricular Function and Limits Remodeling

Background. Preventing expansion and dyskinetic movement of a myocardial infarction (MI) can limit left ventricular (LV) remodeling. Using a device designed to produce variable alteration of infarct stiffness and geometry, we sought to understand how these parameters affect LV function and remodeling early after MI. Methods. Ten pigs had posterolateral infarctions. An unexpanded device was placed in 5 animals at the time of infarction and 5 animals served as untreated controls. One week after MI animals underwent magnetic resonance imaging to assess LV size and regional function. In the treatment group, after initial imaging, the device was expanded with 2, 4, 6, 8, and 10 mL of saline. The optimal degree of inflation was defined as that which maximized stroke volume (SV). The device was left optimally inflated in the treatment animals for 3 additional weeks. Results. One week after MI, device inflation to 6 mL or greater significantly (p < 0.05) decreased end-systolic volume (0 mL, 59.9 mL +/- 3.8; 6 mL, 54.0 mL +/- 3.1; 8 mL, 50.5 mL +/- 4.8; and 10 mL, 46.1 mL +/- 2.2) and increased ejection fraction (EF) (0 mL, 0.346 +/- 0.016; 6 mL, 0.0397 +/- 0.009; 8 mL, 0.431 +/- 0.027; and 10 mL, 0.441 +/- 0.009). Systolic volume significantly (p < 0.05) improved for the 6 mL and 8 mL volumes (0 mL, 31.2 mL +/- 2.6; 6 mL, 35.7 mL +/- 2.0; and 8 mL, 37.5 mL +/- 1.9) but trended downward for 10 mL (36.6 mL +/- 2.8). At 4 weeks after MI, end-diastolic volume and end-systolic volume were unchanged from 1-week values in the treatment group while the control group continued to dilate. Systolic volume (38.2 +/- 4.4 mL vs 34.0.1 +/- 4.8 mL, p = 0.08) and EF (0.360 +/- 0.026 vs 0.276 +/- 0.014, p = 0.04) were also better in the treatment animals. Conclusions. Optimized isolated infarct restraint can limit adverse LV remodeling after MI. The tested device affords the potential for a patient-specific therapy to preserve cardiac function after MI. (Ann Thorac Surg 2013;95:155-62) (C) 2013 by The Society of Thoracic Surgeons